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News

CARDIOLOGY – A Prohealthservicezone Special Report

American College Of Cardiology : 03 April, 2008  (Special Report)
The past week has seen a number of cardiology research studies report on their recent work. This Special Report highlights some of the research activities and technology developments that are advancing cardiology.
Many of the studies featured in this Special Report were presented at the SCAI Annual Scientific Sessions in Partnership with ACC i2 Summit (SCAI-ACCi2) in Chicago, USA.

SCAI-ACCi2 is a scientific meeting for practicing cardiovascular interventionalists sponsored by the Society for Cardiovascular Angiography and Interventions (SCAI) in partnership with the American College of Cardiology (ACC).


WAKE FOREST UNIVERSITY HEALTH SCIENCES, WINSTON-SALEM, USA

Percutaneous coronary intervention (PCI) can be performed safely and successfully in medical centres without on-site cardiac surgical back-up, provided programmes are well-organized, highly skilled and committed to quality.

These are the findings of the largest clinical study ever to compare PCI programmes that have on-site cardiac surgery to PCI programmes that transfer patients to a surgical hospital in case of emergency.

The study's findings, though reassuring, should not be interpreted as an endorsement of ‘boutique’ angioplasty, said lead investigator Michael A Kutcher, MD, director of interventional cardiology at Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA.

'These medical centres are very accomplished and represent the premier programmes offering PCI with off-site cardiac surgical back-up,' Dr Kutcher said. 'And they are doing angioplasty for the right reasons: to improve outcomes for heart attack patients and to better serve patients in remote geographic areas.'

Performing PCI at medical centres with off-site cardiac surgical back-up is controversial. Clinical guidelines accept this practice for patients who are experiencing a heart attack - so-called primary PCI - but advise against it in elective PCI, when the procedure is less urgent. However, medical centres that offer primary PCI argue they need to include elective PCI in the mix in order to survive economically and to keep staff skill levels high.

Further complicating the issue: Emergency bypass surgery is rare – it is needed in about 0.3 percent of PCI patients - but the mortality rate is high, about 13 percent.

For the new study, Dr Kutcher and co-investigators analysed data from the NCDR CathPCI Registry (an ACC initiative conducted in partnership with SCAI) on 9,029 patients treated at 61 medical centres with off-site cardiac surgical back-up and 299,132 patients treated at 404 medical centres with on-site cardiac surgery programmes.

Programmes with off-site surgical back-up tended to be smaller - more than half of the medical centres had fewer than 200 beds - and to perform fewer PCIs.

Only 30 percent of off-site programmes performed more than 200 PCI procedures annually, and only 43 percent performed more than 36 primary PCIs annually, as compared with 94 percent and 80 percent of on-site centres, respectively (p less than 0.0001).

In addition, off-site hospitals treated higher-risk patients: Some 41 percent of patients treated at off-site centres were experiencing a heart attack at the time of PCI, as compared with 29 percent of patients treated at on-site centres (p less than 0.0001).

Still, the two types of hospitals had similar rates of procedural success (94 percent for off-site centres vs 93 percent for on-site centres), overall complications (6.4 percent vs 6.3 percent, respectively), emergency surgery (0.31 percent vs 0.37 percent), and mortality with emergency surgery (13.64 percent vs 12.59 percent).

In a risk-adjusted analysis, hospitals with on-site cardiac surgery were more likely to perform emergency bypass surgery, but overall in-hospital mortality was no different in the two groups (odds ratio, 1.08 for on-site vs off-site centres, p equals 0.507).

That the hospitals in this study voluntarily chose to submit data to the NCDR is one sign of their commitment to quality, Dr Kutcher said. Two additional statistics are telling: 92 percent of PCI centres with off-site surgery were prepared to do PCI 24 hours a days, seven days a week, and when treating patients with heart attack, the time from patient arrival at the hospital until blood flow was restored in the coronary artery was a median of 1.4 hours at hospitals with off-site surgical back-up, as compared with 1.5 hours for PCI centres with on-site surgery.

'The NCDR database provided an excellent opportunity to look at contemporary angioplasty practice patterns in the USA. The safety and effectiveness of PCI programmes with off-site cardiac surgery is a very important question, and we need ongoing information to reach evidence-based answers,' said Dr Kutcher. 'However, the results of this study should not be used to encourage the wild expansion of more off-site PCI programmes; rather they should be used to confirm the appropriateness of this strategy for programmes that have made a strong commitment to excellent organization and data submission for quality assurance.'


AUCKLAND CITY HOSPITAL, AUCKLAND, NEW ZEALAND

A device that catches bits of plaque and blood clot that break loose during percutaneous coronary intervention (PCI) has failed to show that it can reduce rates of major cardiovascular complications in patients with acute coronary syndromes, a condition that encompasses unstable angina and a type of heart attack known as non-ST-elevation myocardial infarction (NSTEMI).

Although the EZ FilterWire captured debris in the bloodstream in nearly half of patients, it did not reduce damage to the heart muscle.

Investigators for the Angioplasty Balloon-Associated Coronary Debris and the EZ FilterWire (A-F) study had expected the results to be more encouraging. First, the study focused on patients with arterial blockages that appeared particularly likely to be a source of downstream debris during PCI. In addition, myonecrosis, or debris-caused damage to the heart muscle resulting from blockage of tiny blood vessels, is fairly common.

'PCI is associated with myonecrosis in about 25 percent of patients with non-STEMI acute coronary syndromes,' said Mark W I Webster, MD, director of the cardiac catheterization laboratory at Auckland City Hospital, Auckland, New Zealand. 'Although there are other mechanisms, distal embolism of atherosclerotic plaque and/or thrombus is recognised to be a frequent cause.'

The EZ FilterWire is a coronary guidewire with a plastic sack shaped like a windsock attached. The windsock has multiple small holes to allow blood to flow through, but it catches larger debris. During PCI, the FilterWire is positioned in the coronary artery downstream of the lesion; both the device and any debris are removed after the procedure.

The A-F trial is the first randomized controlled trial to evaluate a vascular protection device in patients with NSTEMI acute coronary syndromes. For the study, Dr Webster and his colleagues recruited 151 patients treated at 14 medical centres in New Zealand, Australia and Canada, randomly assigning them to protection with the FilterWire or to conventional PCI without vascular protection.

The researchers found that the rates of major cardiovascular complications during hospitalization - consisting of death, heart attack, emergency bypass surgery, or repeat procedure in the treated artery - were no different in the two groups (12 percent in the FilterWire group vs 10 percent in the control group). There were also no significant differences between the groups in the post-procedure release of enzymes that signal damage to the heart muscle.

'The device does not appear warranted for routine use in these patients,' Dr Webster said. 'However, there are some patients who have major complications from distal embolism. We need better ways of identifying high-risk patients and lesions.'


SOUTHLAKE REGIONAL HEALTH CENTRE, NEWMARKET, ONTARIO, CANADA

Percutaneous coronary intervention (PCI) - which uses a combination of catheter-mounted balloons and stents to open a completely blocked coronary artery and restore blood flow to the heart - is the best treatment for heart attack when performed rapidly.

However, few hospitals can meet the 90-minute treatment goal unless they have a cardiac catheterization laboratory on site.

A new study is expected to shed light on whether patients who are first treated with clot-busting drugs should be routinely transferred to a medical centre with a cardiac catheterization laboratory for follow-up PCI, or be observed for an hour or more and sent for PCI only if clot-busting drugs fail, the standard approach today.

The study - the Trial of Routine Angioplasty and Stenting After Fibrinolysis to Enhance Reperfusion in Acute Myocardial Infarction (TRANSFER-AMI).

Early studies in the 1980s showed that performing PCI after treating patients with clot-busting drugs - also known as thrombolytic or fibrinolytic agents - offered no benefit and might even be harmful. Since then, however, thrombolytic medications have changed, stents are routinely used, and interventional cardiologists have refined protocols for delivering newer anti-clotting medications.

'There's good reason to believe that performing PCI after thrombolytic therapy is safer and more effective now than in previous studies,' said Warren J Cantor, MD, medical director of the interventional and invasive programme at Southlake Regional Health Centre, Newmarket, Ontario, Canada. 'It is an important question, because more than 75 percent of hospitals in North America don't have PCI facilities.'

TRANSFER-AMI is the largest-ever randomized trial to investigate this question. For the study, Dr Cantor and his colleagues enrolled 1,060 high-risk patients with either a large or complicated heart attack, also known as ST-segment-elevation myocardial infarction (STEMI). All patients initially sought treatment at a hospital without PCI capability and were treated with tenecteplase, a clot-busting drug.

Patients were then randomly assigned to urgent transfer for PCI within six hours, or to standard therapy, consisting of observation for 60 to 90 minutes, with transfer for PCI only in the case of continuing chest pain or other evidence of treatment failure.

The study will evaluate 30-day combined rates of death, repeat heart attack, recurring ischemia, heart failure and shock in the two groups of patients.
'Many hospitals have difficulty getting patients to the cath lab within the recommended 90 minutes, but six hours is a much more realistic goal,' Dr Cantor said. 'If routine PCI is clearly superior to standard therapy in the TRANSFER-AMI trial, then all institutions that use thrombolysis for treating STEMI will need to develop strategies to get those patients to a cardiac catheterization laboratory within six hours.'


UNIVERSITY MEDICAL CENTRE GRONINGEN, THE NETHERLANDS

Use of a special Catheter that sucks out, or aspirates, bits of plaque and blood clot that break loose during percutaneous coronary intervention (PCI) significantly enhances blood flow deep in the heart muscle in patients who are experiencing a heart attack, according to a recently published study.

Now, a new analysis of the Thrombus Aspiration during Percutaneous Coronary Intervention in Acute Myocardial Infarction (TAPAS) study has shown that the link between deep myocardial perfusion and better clinical outcomes that was apparent at 30 days is still strong after one year.

The one-year results of the TAPAS study, which focused on patients suffering from a type of heart attack known as ST-elevation acute myocardial infarction (STEMI).
PCI is considered the best treatment for STEMI when it is delivered in a timely fashion by experienced clinicians, because it can rapidly and reliably open an artery on the surface of the heart that has been blocked by a blood clot.

However, bits of atherosclerotic plaque and blood clot can break loose during angioplasty and stenting, traveling downstream to occlude the tiny vessels, or microcirculation, that supply blood deep into the heart muscle. When this happens - even if the surface artery has been successfully opened during PCI - the amount of tissue damaged by the heart attack tends to be greater, recovery of heart function reduced, and the risk of death higher.

In an attempt to improve myocardial perfusion after treatment for heart attack, various catheters have been developed that either aspirate or filter out debris that travels downstream during PCI. The TAPAS study was designed to test the effectiveness of the Export Aspiration Catheter (Medtronic).

Felix Zijlstra, MD, PhD, University Medical Centre Groningen, the Netherlands, was the study's senior investigator. For the study, he and his colleagues recruited 1,071 patients with STEMI, randomly assigning 535 to PCI supported by the Export aspiration Catheter and 536 to PCI using conventional techniques.

To assess the quality of myocardial perfusion, the researchers documented myocardial blush grade. A myocardial blush grade of 0 or 1 indicates that little or no X-ray dye has reached from the surface artery into the heart muscle, a sign that the microcirculation is blocked.

A myocardial blush grade of 3 indicates that X-ray dye has reached deep into the heart muscle, a sign of good blood flow through the microcirculation. A myocardial blush grade of 2 falls in between. Analysis of the elevated ST-segment on the electrocardiogram - specifically, its return to a normal baseline - was also used to gauge the quality of blood flow to the heart muscle.

During angiography, researchers observed a blush grade of 0 or 1 in 17 percent of patients treated with the aid of the aspiration Catheter and in 26 percent of patients treated with conventional PCI (p less than 0.001). At 30 days, clinical outcomes were strongly related to the degree of myocardial reperfusion.

The rate of death in patients with a myocardial blush grade of 0/1, 2 and 3 was 5.2 percent, 2.9 percent and 1.0 percent, respectively (p equals 0.003). The combined rates of repeat heart attack, repeat procedure in the target artery and death in patients with a myocardial blush grade of 0/1, 2 and 3 were 14.1 percent, 8.8 percent and 4.2 percent, respectively (p less than 0.001).

At one-year follow-up, mortality was significantly lower in patients treated with the aspiration Catheter (p equals 0.04), as was a combination of death and heart attack. A similar, highly significant relationship was observed between myocardial blush grade and death, or a combination of death and repeat heart attack (p equals 0.001).

The study team concluded that the degree of blood perfusion into the heart muscle helps to predict the patient's clinical condition, and that aspiration of debris from the treated artery during PCI can reduce the risk of death and repeat heart attack, even one year later.


CARDIOVASCULAR INSTITUTE, AZIENDA OPEDALIERA UNIVERSITARIA DI FERRARA, FERRARA, ITALY

New evidence from a large randomized study is answering questions about the best approach to percutaneous coronary intervention (PCI) in patients with a type of heart attack known as ST-segment-elevation myocardial infarction (STEMI).
In the study, drug-eluting stents outperformed bare-metal stents, and high-dose tirofiban, an anti-clotting medication, proved to be equally effective and have fewer side effects than the Catheter lab standard, abciximab.

'These findings may provide a robust scientific rationale for high-dose tirofiban as an alternative to abciximab in patients with STEMI,' said Marco Valgimigli, MD, PhD, a cardiologist at the Cardiovascular Institute, Azienda Opedaliera Universitaria di Ferrara, Ferrara, Italy. 'In addition, at mid-term follow-up our study did not confirm some of the safety concerns over the use of drug-eluting stents in patients with myocardial infarction. These findings are very reassuring, though we need long-term follow-up to rule out the possibility of late adverse events.'

Drug-eluting stents - which not only prop open the coronary arteries but slowly release medication that prevents re-narrowing of the arteries with scar tissue, or restenosis - are widely used when PCI is performed for stable coronary artery disease. But many cardiologists use bare-metal stents when treating patients with heart attack because studies have reported conflicting results on the benefits of drug-eluting stents in this group of patients and have raised concerns over the risk of blood clotting inside the stent, or Stent thrombosis.

The new study has certain design advantages over previous studies, specifically its size and an enrollment and follow-up protocol that more closely reflects everyday clinical practice.

As for tirofiban and abciximab, both are in a class of medications known as glycoprotein 2b/3a inhibitors and prevent blood clotting by blocking hyperactivation of platelets. Tirofiban is an attractive alternative for several reasons: It is shorter-acting and is cleared from the body more readily than abciximab, it is less likely to cause a dangerous drop in the number of platelets in the blood, and it is far less expensive.

However, previous studies have been too small or have used too low a dose of tirofiban to reach a definitive conclusion about which medication is better, Dr Valgimigli said.

The new study, which involved 16 medical centres, enrolled 745 patients who were set to undergo PCI for STEMI. Patients were randomly assigned to an infusion of abciximab or high-dose tirofiban (25microgram/kg) and, in a second round of randomization, to treatment with either uncoated or sirolimus-eluting stents.

To judge the effectiveness of tirofiban and abciximab, researchers examined electrocardiograms - 722 of which were interpretable - to determine the proportion of patients with at least a 50 percent return of the elevated 'ST-segment' to its normal baseline.

The results were equivalent in the two groups (83.6 percent in the abciximab group vs 85.3 percent in the tirofiban group). In addition, there was no significant difference in the rate of major adverse cardiac events (MACE) - a combination of death, repeat heart attack, and repeat procedure to open the treated coronary artery - in the two groups: 4.8 percent vs 4.5 percent, respectively, at 30 days and 12.3 percent vs 9.9 percent, respectively, at eight months.

The rates of minor and major bleeding did not differ in the two groups, but a marked drop in the blood platelet count - a complication that could cause uncontrolled bleeding - was more common among patients treated with abciximab (4.0 percent vs 0.8 percent, p equals 0.004).

When comparing the two types of stents, investigators found an equivalent MACE rate at 30 days (3.9 percent vs 5.9 percent, p equals 0.12) with sirolimus-eluting and bare-metal stents. However, at eight months, the MACE rate was significantly lower with drug-eluting stents (7.8 percent vs 14.5 percent, p equals 0.0039). This difference was mainly driven by a 69 percent reduction in the need for a repeat procedure to reopen the treated coronary artery (3.2 percent with sirolimus-eluting stents vs 10.2 percent with bare-metal stents, p equals 0.0004).

The rates of death and repeat heart attack were similar, as was the incidence of Stent thrombosis.

'Our study shows that tirofiban is 'noninferior' in its efficacy to abciximab in this high-risk patient population, and has a better safety profile,' said Dr Valgimigli. 'We have also confirmed that, even in STEMI patients, drug-eluting stents are highly effective in reducing reintervention in the target vessel. More important, this came without an extra price to pay in terms of death, myocardial infarction or Stent thrombosis.'

The study is published online in JAMA: Journal of the American Medical Association.


HOPITAL UNIVERSITAIRE NORD, AND UNIVERSITE DE LA MEDITERRANEE, MARSEILLE, FRANCE

A French multicentre study reported that a simple blood test could be used to individualise the loading dose of a medication that prevents blood clotting significantly reduces the risk of major cardiovascular complications after percutaneous coronary interventions (PCI).

The study showed that in some patients, an initial, or loading, dose several times higher than usual is necessary to ensure the effectiveness of clopidogrel, a medication that prevents platelets from clumping together to form blood clots. The payoff for tailoring the clopidogrel dose: a significant reduction one month after PCI in the combined rates of heart attack, death, and need for repeat procedures to open the coronary arteries, with no increased risk of bleeding.

'Tailoring the loading dose of clopidogrel using platelet monitoring seems to be the best way to decrease the rate of major adverse cardiac events, in particular, Stent thrombosis, which is the worst complication after PCI,' said Laurent Bonello, MD, a cardiologist at Hopital Universitaire Nord, and Universite de la Mediterranee, both in Marseille, France.

Giving a large dose of clopidogrel before coronary stenting is standard procedure in cardiac catheterization laboratories. However, there is substantial variability among patients in the response to the anti-clotting drug.

Previous studies have shown that a poor response to clopidogrel is linked to an increased risk of serious complications, including the growth of a blood clot inside the stent, or Stent thrombosis.

To determine whether individualizing the clopidogrel dose could improve outcomes, Dr Bonello and his colleagues enrolled 162 patients who were resistant to clopidogrel and needed stenting for treatment of unstable chest pain or a type of heart attack known as non-ST-elevation acute coronary syndrome.

Clopidogrel resistance was defined as more than 50 percent platelet activity after a standard 600-mg clopidogrel loading dose. Patients were randomly assigned to a control group (84 patients) or to individually tailored therapy (78 patients), which consisted of increasing the clopidogrel dose in 600-mg increments up to a maximum of 2,400 mg until platelet activity dropped to 50 percent or less.

The dose adjustment was effective in 86 percent of patients. On average, patients in the tailored-therapy group received a total of 1,620 mg of clopidogrel before PCI, and experienced a drop in platelet activity from 69.3 after the first loading dose to 37.6 after extra dosing guided by platelet monitoring.

After 30 days of follow-up, no patients in the tailored therapy group had suffered a heart attack, needed repeat PCI or bypass surgery, or died, whereas 10 percent of patients in the standard-dosing group had experienced one or more of these complications (p equals 0.007). The rates of bleeding were the same in both groups (5 percent vs 4 percent).

'This is the first study demonstrating that adjusting the clopidogrel loading dose according to the patient's individual biological response can improve prognosis after percutaneous coronary revascularization,' Dr Bonello said.

The study is published in the Journal of the American College of Cardiology.


IMPERIAL COLLEGE, LONDON, ENGLAND

Lowering the blood pressure of elderly patients could cut their total mortality by a fifth and their rate of cardiovascular events by a third, according to a new study presented by a research team from Imperial College London.

The 3,845 patient Hypertension in the Very Elderly Trial (HYVET), which is co-ordinated by scientists from Imperial College London, is the largest ever clinical trial to look at the effects of lowering blood pressure solely in those aged 80 and over.

Patients were given either a placebo or the diuretic indapamide slow release (SR) 1.5mg, with the addition of the ACE inhibitor perindopril in tablet form once a day.

The over 80s are the fastest growing group in the population worldwide - in the UK currently they account for four percent of the total population and this is expected to rise to over 11 percent by 2050. The risk of stroke increases with age, with some estimates suggesting that the risk doubles every decade after a person reaches 55 years of age. In the UK approximately four percent of the total National Health Service budget is spent on stroke services each year.

The Imperial College research shows that the benefits of treatment include a 21 percent (p equals 0.02) reduction in total mortality rate, a 39 percent (p equals 0.05) reduction in stroke mortality rate, a 64 percent (p less than 0.001) reduction in fatal and non-fatal heart failures and a 34 percent (p<0.001) reduction in cardiovascular events. The benefits were apparent within the first year of follow-up.

The reduction in overall mortality was a novel and unexpected result. Earlier trials had demonstrated that reducing blood pressure in the under-80s reduces stroke and cardiovascular events. However, previous smaller and inconclusive studies also suggested that whilst lowering blood pressure in those aged 80 or over reduced the number of strokes, it did not reduce, and even possibly increased, total mortality.

In July 2007 the trial was stopped early on the recommendation of an independent data monitoring committee after they observed significant reductions in overall mortality and stroke in those receiving treatment. The final results of the trial showed a significant reduction in stroke mortality rate, but the reduction in all strokes of 30 percent did not quite reach statistical significance (p equals 0.06). In those aged 80 and over, up to half of strokes are fatal and the reduction in fatal strokes is an important finding.

Emeritus professor Christopher Bulpitt, the lead investigator on the study from the Care of the Elderly Group at Imperial College London, said: 'Before our study, doctors were unsure about whether very elderly people with high blood pressure could see the same benefits from treatment to lower their blood pressure as those we see in younger people. Our results clearly show that many patients aged 80 and over could benefit greatly from treatment. Populations are living longer and we have growing numbers of people living well into their 80s and beyond, so this is good news. We are very pleased that cardiovascular events were reduced safely with a reduction in total mortality.'

The researchers hope that their findings will clear up uncertainty amongst clinicians about the benefits of treating those aged 80 and over for high blood pressure.

Dr Nigel Beckett, the trial co-ordinator from the Care of the Elderly Group at Imperial College London, added: 'Many very elderly people with high blood pressure are not being treated for it at the moment, because doctors are unsure about whether or not treatment will help them. We hope that following our study, doctors will be encouraged to treat such patients in accordance with our protocol.'

As the trial was stopped early, an extension involving patients receiving active-treatment is now underway to assess the longer term benefits of treatment.
Patients with high blood pressure (defined here as a systolic blood pressure between 160 to 199mmHg), from thirteen countries across the world, were randomised for the double-blind, placebo-controlled trial, which began in 2001.

The mean age of participants was 83 years and 7 months.

Patients were given either placebo or indapamide slow release (SR) with the addition of perindopril, in tablet form once a day as required, to achieve a target blood pressure of 150/80mmHg.

The average follow-up of patients was just over two years by which time 20 percent of the placebo subjects and 48 percent of those taking medication had achieved the target blood pressure of 150/80mmHg. In those patients who were followed up for longer, a larger number of patients receiving active treatment achieved the target blood pressure.

HYVET was co-ordinated by scientists from Imperial College London, working with colleagues around the world. The main trial was funded by both the British Heart Foundation and by Servier.

The Imperial College study is published in the New England Journal of Medicine.


ST ANTONIUS HOSPITAL, NIEUWEGEIN, THE NETHERLANDS

When a clot develops inside a coronary stent, it can block blood flow to the heart, potentially causing a heart attack or even death.

A single incident of Stent thrombosis is bad enough, but the new Dutch Stent Thrombosis Study led by Jochem Wouter van Werkum, MD, a cardiologist at St Antonius Hospital, Nieuwegein, the Netherlands, suggests that one in six patients can expect to experience at least one repeat episode.

According to the study, among the strongest predictors of recurrent Stent thrombosis is implantation of an additional Stent during emergency treatment of the first episode.

Wouter van Werkum and his colleagues enrolled a total of 437 consecutive patients who had Stent thrombosis confirmed by angiography between January 2004 and February 2007.

The researchers collected data on clinical characteristics (for example, diabetes, age and duration of antiplatelet therapy), angiographic characteristics (for example, undersizing of the stent, dissection and whether the lesion was located at an arterial branchpoint), and procedural characteristics (for example, whether a drug-eluting or bare-metal Stent was used and the length and diameter of the stent).

The researchers found that 74 of the 437 patients (16.9 percent) experienced multiple episodes of Stent thrombosis. Of these, 61 patients had two episodes of Stent thrombosis, 12 patients had three episodes and one patient had four episodes.

Further analysis revealed three independent predictors of repeat Stent thrombosis. Patients who had an additional Stent implanted during emergency treatment for the first episode of Stent thrombosis were 4.2 times as likely as other patients to experience a repeat episode of Stent thrombosis (p less than 0.0001).

Patients with a previous heart attack faced 2.6 times the usual risk of repeat Stent thrombosis (p less than 0.001), and patients who developed thrombosis long after Stent implantation (late Stent thrombosis) faced 2.1 times the usual risk of a repeat episode (p equals 0.0127).

Dr van Werkum and his colleagues concluded that additional Stent placement at the time of emergency treatment for the first Stent thrombosis should be avoided.


BRIGHAM AND WOMEN'S HOSPITAL, BOSTON, USA

Prasugrel has been shown to block platelet activity in patients with acute coronary syndromes (ACS) more effectively than clopidogrel, and to cut by more than half the risk of thrombosis, or blood clotting, inside the coronary stent.

Now a new analysis of data from the Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition with Prasugrel (TRITON-TIMI 38) reveals that the investigational drug maintains its edge over clopidogrel regardless of the type of stent, the amount of time since the stenting procedure, or the way Stent thrombosis is defined.

For the main TRITON-TIMI 38 study, researchers recruited 13,608 patients with ACS who needed stenting from 707 medical centres in 30 countries. Patients were randomly assigned to anti-platelet therapy consisting of either a 300-mg loading dose of clopidogrel before the procedure, followed by a maintenance dose of 75mg daily for one year, or to a loading dose of 60mg of prasugrel, followed by 10mg daily for one year.

Both medications prevent unwanted blood clotting by inhibiting the ability of platelets to clump together.

Stephen D Wiviott, MD, Brigham and Women's Hospital, Boston, led the new Stent analysis.

Of the 12,844 patients who ultimately were treated with at least one coronary stent, 6,461 patients received only bare-metal stents (BMS), and 5,743 patients received only drug-eluting stents (DES).

Overall, prasugrel reduced both early Stent thrombosis - within 30 days of stenting - when compared with clopidogrel (0.64 percent vs 1.56 percent, hazard ratio 0.41, p less than 0.001) - and late Stent thrombosis - more than 30 days after stenting (0.49 percent vs 0.82 percent, hazard ratio 0.60, p equals 0.035).

For bare-metal stents, the respective rates of Stent thrombosis with prasugrel and clopidogrel were 1.3 percent vs 2.4 percent, hazard ratio 0.52, p equals 0.009, and for drug-eluting stents, 0.8 percent vs 2.3 percent, hazard ratio 0.36, p less than 0.001.

Prasugrel's advantage remained highly statistically significant across a broad array of patient and procedural characteristics.

The study is published online in The Lancet.


HARVARD MEDICAL SCHOOL, BOSTON, USA

The investigational antiplatelet drug prasugrel plus aspirin produced a marked and highly statistically significant reduction in the risk of coronary Stent thrombosis (ST) - a major concern for physicians and patients with potentially fatal consequences - in patients who received a Stent as compared to standard therapy with clopidogrel (Plavix) plus aspirin (1.13 percent vs 2.35 percent, p less than 0.0001), according to a Stent analysis from the head-to-head TRITON-TIMI 38 trial.

The findings were presented today by Dr Stephen Wiviott, an assistant professor of medicine at Harvard Medical School and investigator with the Thrombolysis in Myocardial Infarction (TIMI) Study Group.

In the TRITON-TIMI 38 trial, whose overall results were previously published, 12,844 of the 13,608 enrolled patients received at least one intracoronary stent. Of those patients, 6,461 received a bare metal Stent (BMS), 5,743 patients received a drug-eluting Stent (DES), and 640 patients received both BMS and DES at the time of enrollment. Stent thrombosis was a pre-defined secondary endpoint in the trial.

Prasugrel reduced the relative risk of coronary Stent thrombosis (a new clot at the implanted Stent site) over clopidogrel by 52 percent (1.13 percent vs 2.35 percent, p less than 0.0001). In patients who received drug-eluting stents (DES), treatment with prasugrel reduced relative risk by 64 percent over clopidogrel (0.84 percent vs 2.31 percent, p less than 0.0001), and by 48 percent in patients who received bare metal stents (BMS) (1.27 percent vs 2.41 percent, p equals 0.0009).

In the analysis, prasugrel was consistent in reducing Stent thrombosis, compared to clopidogrel, whether assessment occurred early or late ( less than 30 days and greater than or equal to 30 days, out to 450 days, the median duration of therapy), regardless of the type of Stent used (bare metal or drug-eluting), and regardless of which academic research consortium (ARC) definition of Stent thrombosis was used - definite/confirmed Stent thrombosis, definite/confirmed plus probable Stent thrombosis, and definite/confirmed plus probable plus possible Stent thrombosis.

Definite/probable Stent thrombosis was reduced by 59 percent in prasugrel-treated patients within 30 days of Stent placement (0.64 percent vs 1.56 percent, p less than 0.0001), and by 40 percent after 30 days (out to 450 days, 0.49 percent vs 0.82 percent, p equals 0.03).

'Stent thrombosis is very serious, given the high risk of mortality. In TRITON, among 210 patients with definite or probable Stent thrombosis, 186 (89 percent) either died or experienced an MI as a result of the event,' said Francis Plat, MD, vice president, clinical development, Daiichi Sankyo. 'We were excited by the results of this study and the possibility that prasugrel may someday provide an alternative treatment for ACS patients undergoing PCI and receiving coronary stents.'

A 19 percent reduction in risk was observed with prasugrel compared with clopidogrel among all patients receiving a Stent (9.7 percent vs 11.9 percent, p equals 0.0001) in TRITON's primary endpoint of cardiovascular death, non- fatal heart attack, or non-fatal stroke.

A 20 percent relative reduction favoring prasugrel was observed in the primary endpoint in patients who received only a bare metal Stent (10.0 percent vs 12.2 percent, p equals 0.003), and in patients who received only a drug-eluting stent, results showed an 18 percent relative reduction in the primary endpoint favoring prasugrel (9.0 percent vs 11.1 percent, p equals 0.019).

Fatal Stent thrombosis occurred in 18 (0.28 percent) patients treated with prasugrel and 29 (0.46 percent) patients treated with clopidogrel (p equals 0.10).

Of note, of the 210 patients with Stent thrombosis, 89 percent either died or had a myocardial infarction associated with the event.

The rate of major bleeding was higher in all patients receiving a Stent treated with prasugrel vs clopidogrel (2.4 percent vs 1.9 percent, p equals 0.06). Major bleeding in both DES and BMS prasugrel-treated groups when compared to clopidogrel-treated patients was 3 percent vs 2 percent (p equals 0.34 DES) and 2 percent vs 2 percent (p equals 0.09 BMS).

In addition to a reduction in the primary endpoint (CV death, non-fatal heart attack, or non-fatal stroke), a significantly lower rate of the composite endpoint of cardiovascular death, heart attack or urgent target vessel revascularization (UTVR) was observed with prasugrel vs clopidogrel for both bare metal stents (10 percent vs 12 percent, p equals 0.009) and for drug- eluting stents (9 percent vs 11 percent, p equals 0.004).

A significant reduction was also seen in heart attack alone (8 percent vs 10 percent, p equals 0.003, BMS and 7 percent vs 9 percent, p equals .006, DES). In DES-implanted patients, regardless of those receiving only sirolimus-eluting or paclitaxel-eluting stents, there was a similar magnitude of event reduction with prasugrel compared to clopidogrel.

For the entire cohort, sub-acute Stent thrombosis (24 hours to 30 days) was 0.36 percent in prasugrel-treated patients vs 1.19 percent in clopidogrel-treated patients (p less than 0.0001). DES-implanted patients had lower rates of Stent thrombosis compared to BMS-implanted patients, and prasugrel was shown to significantly reduce Stent thrombosis in DES-implanted patients within the first three days compared to clopidogrel (0.14 percent vs 0.63 percent, p equals 0.003) as well as for thromboses that occurred more than 30 days following the DES implantation (0.42 percent vs 0.91 percent, p equals 0.04).

The manuscript is published online in The Lancet.


HERZZENTRUM, TECHNICAL UNIVERSITY, MUNICH, GERMANY

Over the years, interventional cardiologists have made many improvements in percutaneous coronary intervention (PCI) for patients with heart attack, among the most important, refinements in the selection and administration of drugs that prevent unwanted blood clotting.

Now a new study has found that high loading doses of clopidogrel, an oral medication that inhibits blood clots by preventing platelets from clumping together, can eliminate the need for intravenous abciximab, a standard cath-lab drug that also interferes with platelets, but through a different pathway.

The BRAVE-3 study is the first to test the influence of high-dose clopidogrel on the value of abciximab exclusively in patients with ST-elevation myocardial infarction (STEMI), a serious form of heart attack.

'Acute myocardial infarction is a major medical problem, and the present study will help to define the optimal treatment strategy,' said Julinda Mehilli, MD, an associate professor and staff cardiologist at Deutsches Herzzentrum, Technical University, Munich, Germany. 'Therapy without abciximab would certainly be more cost-effective and reduce the risk of bleeding complications.'

For the study Dr Mehilli and colleagues recruited 800 patients with STEMI who were undergoing PCI. All patients were pretreated with 600 mg of clopidogrel and then randomly assigned to receive intravenous abciximab or a placebo during the procedure.

The study was designed primarily to compare how the two treatment strategies affected the final amount of heart attack damage, as gauged by blood flow in the heart muscle on a nuclear scan five to 10 days later. The researchers found no difference between the two groups: The damage involved 10 percent of the left ventricle, on average, in the abciximab group and 9 percent of the left ventricle in the placebo group. In addition, the 30-day combined rates of death, heart attack, stroke and urgent repeat coronary procedures were similar in the two groups (5 percent and 3.8 percent, respectively).

'For patients with acute ST-elevation myocardial infarction undergoing primary coronary intervention after pre-treatment with a 600-mg loading dose of clopidogrel, the additional use of abciximab is not associated with any measurable benefit after 30 days,' Dr Mehilli said.


FEIRING KLINIKKEN, FEIRING, NORWAY

When stenting is performed for an arterial narrowing at the branchpoint of two coronary arteries - or a bifurcation lesion - it can be challenging to achieve full coverage of both vessels without blocking the opening to the side branch. A new study aims to provide interventional cardiologists with new information on which of two techniques produces the best long-term results when used with a drug-eluting stent.

The Nordic Stent Technique Study, led by Paal Gunnes, MD, Feiring Klinikken, Feiring, Norway, is comparing the ‘culotte’ and ‘crush’ techniques. With the culotte technique, two similar stents are threaded into the diseased artery. One is positioned in the main artery and the other in the side branch, so that the two stents overlap in the main artery before the branchpoint. With the crush technique, the side branch Stent is positioned so that a small portion protrudes into the main artery. When the Stent in the main artery is expanded, it completely covers and crushes the protruding segment of the side-branch Stent against the wall of the main artery.

For the study, Dr Gunnes and his colleagues recruited 425 patients with bifurcation lesions, randomly assigning them to treatment with a drug-eluting Stent implanted using either a culotte or crush technique. A total of 345 patients are expected to have had quantitative coronary angiography both at the time of stenting and after eight months of follow-up.

The researchers will report on late-lumen loss (how much shrinkage there is over time in the post-stenting diameter), minimal lumen diameter, percent diameter stenosis and the restenosis rate for the entire bifurcation, the main vessel, and the side branch at eight-month follow-up.


BRIGHAM AND WOMEN'S HOSPITAL, BOSTON, USA
HARVARD MEDICAL SCHOOL, USA
HARVARD CLINICAL RESEARCH INSTITUTE, USA

Although drug-eluting stents have become widely used for the treatment of stable coronary artery disease, many cardiologists choose bare-metal stents for patients with heart attack, or myocardial infarction (MI), citing conflicting data about the safety and effectiveness of drug-eluting stents in this patient group. Such concerns are being challenged by an analysis of a large Massachusetts database.

The analysis showed a significantly lower risk of arterial renarrowing, or restenosis, among heart attack patients who were treated with drug-eluting stents, with no increase in mortality, when compared to those treated with bare-metal stents.

'This study confirms that the same benefits that drug-eluting stents offer other patients in preventing restenosis of the coronary arteries are still there for patients with MI, and there doesn’t appear to be any trade-off in increased risk of repeat MI or death,' said Laura Mauri, MD, MSC, an interventional cardiologist at Brigham and Women's Hospital, an assistant professor of medicine at Harvard Medical School, and chief scientific officer at the Harvard Clinical Research Institute, all in Boston.

Cardiologists have had to decide which type of Stent to use in heart attack patients based on small randomized trials that didn't include long-term follow-up and reported conflicting results. There have also been concerns that, because heart attack patients are already prone to forming blood clots in the coronary arteries, they might be at high risk for Stent thrombosis, or sudden clotting inside the stent, particularly a drug-eluting stent.

To evaluate the long-term safety and effectiveness of drug-eluting stents, Dr Mauri and her colleagues analyzed data from 7,216 patients who underwent stenting for acute MI in Massachusetts, where hospitals are required to submit data on all coronary interventions to a state database. Of these, 4,016 patients were treated with a drug-eluting Stent and 3,200 were treated with a bare-metal stent. To adjust for differences in baseline risk, patients in the two groups were matched on up to 63 variables.

Researchers found that the two-year, risk-adjusted rate of revascularization - or the need for a repeat procedure to open the coronary arteries as a result of renarrowing, or restenosis - was significantly lower in patients treated with drug-eluting stents when compared with bare-metal stents (15.5 percent vs 20.8 percent; p<0.001). Mortality was 10.4 percent and 13.2 percent, respectively, in the two groups (p equals 0.002), and repeat MI occurred in 9.5 percent and 11.0 percent, respectively (p equals 0.08).

'These findings are reassuring,' Dr Mauri said. 'Although neither bare-metal stents nor drug-eluting stents were originally approved in the setting of acute myocardial infarction, it is probably the most important condition we treat with stents. I would feel comfortable considering drug-eluting stents on the basis of these results - with the caveats that treated patients must be able to take antiplatelet therapy and that we definitely want to see even longer-term follow-up.'
The researchers plan to continue follow-up in Massachusetts and re-examine the findings when more data are available.


DEUTSCHES HERZZENTRUM AND TECHNICAL UNIVERSITY, MUNICH, GERMANY

Dr Kastrati’s study entitled ‘The Intracoronary Stenting and Antithrombotic Regimen: Rapid Early Action for Coronary Treatment 3 (ISAR-REACT 3)’ reported a large randomised trial designed to shed light on the ideal combination of medications for preventing unwanted blood clotting during and shortly after percutaneous coronary intervention (PCI).

Specifically, study investigators expect to determine whether bivalirudin, a direct inhibitor of the clotting protein thrombin, is better than unfractionated heparin, an indirect thrombin inhibitor, in patients who have also been treated with high-dose clopidogrel.

Bivalirudin has outperformed unfractionated heparin in some previous studies of PCI, but it is not clear how the two anti-clotting medications measure up when used in combination with what has become standard protocol in the cardiac catheterization laboratory: preloading with a 600mg dose of clopidogrel, a medication that prevents clotting by inhibiting platelets.

'The distinguishing feature of our study is that a double-blind comparison of the two different anti-thrombotic regimens was performed against a backdrop of optimal oral anti-platelet loading therapy,' said Adnan Kastrati, MD, a professor of cardiology and head of the catheterization laboratory at Deutsches Herzzentrum and Technical University, Munich, Germany. 'We hypothesized that in patients who were optimally pre-treated with clopidogrel, bivalirudin would continue to prove superior to unfractionated heparin, at least in terms of safety - by reducing bleeding side effects.'

Bivalirudin has several potential advantages over unfractionated heparin: It does not rely on antithrombin to achieve its effects, it has a more predictable dose-response pattern (and, therefore, does not require routine blood test monitoring) and it has a short plasma half-life, which is important if a patient develops a bleeding problem.

For the study, Dr Kastrati and his fellow ISAR-REACT 3 investigators recruited 4,570 low-to-intermediate-risk patients who were undergoing PCI for reasons other than heart attack, randomly assigning them to receive either unfractionated heparin or bivalirudin during the procedure. All patients received 600mg of clopidogrel at least two hours before PCI, and all patients continued to take 75mg of clopidogrel for at least one month after balloon angioplasty or implantation of bare-metal stents, and for at least six months after implantation of drug-eluting stents. Patients continued to take aspirin indefinitely.

The study will determine whether use of bivalirudin influences rates of bleeding during the initial hospitalisation or the 30-day combined rates of death, heart attack or urgent procedure to reopen the treated artery.

'This population under study is important, as it reflects the predominant group undergoing PCI, perhaps up to 70 percent,' said Dr Kastrati. 'Our results may clarify the paradigm for peri-procedural adjunctive therapy in this important group.'
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