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St Jude Medical begins ICD therapy for prevention of SCA clinical trial

St Jude Medical : 14 May, 2008  (Company News)
St Jude Medical has begun initial enrollments into a new landmark clinical trial designed to better identify which patients could benefit from implantable cardioverter defibrillator (ICD) therapy for the prevention of sudden cardiac arrest (SCA).
The DETERMINE (Defibrillators To Reduce Risk by Magnetic resonance imaging Evaluation) study, coordinated by researchers at Northwestern University and sponsored by St Jude Medical, is the first study to look at patients who already have had a heart attack (myocardial infarction), but whose hearts are less damaged, to determine if ICD therapy will prolong their lives.

The study is being conducted under a US Food and Drug Administration (FDA) approved Investigational Device Exemption.

About 325,000 Americans die each year - 900 people per day - from sudden cardiac arrest. Most of them would have survived if they had carried an ICD, a readily available, proven therapy that re-starts the heart's normal electrical activity after cardiac arrest. About half of all victims of sudden cardiac arrest have previously suffered a heart attack. The DETERMINE trial will study patients who have had a heart attack but have not yet had a sudden cardiac arrest, in an effort to identify patients at highest risk.

'We have the solution for treating sudden cardiac arrest - the ICD - but we need a better way to identify in advance those patients who will have the problem,' said Eric S Fain, MD, president of the St Jude Medical Cardiac Rhythm Management Division. 'If we could better predict who these 325,000 victims will be, physicians could provide them with the life-saving therapy they need.'

Current guidelines require that physicians use ‘ejection fraction’ - the amount of blood pumped out of the heart's lower left chamber compared to the total amount of blood in the lower chamber during each heartbeat - to determine if patients qualify for an ICD. Patients with a low ejection fraction (less than 35 percent) already qualify for a device. However, most people who suffer cardiac arrest have an ejection fraction greater than 35 percent and therefore are not currently eligible for the devices.

'Currently the criteria for determining whether a patient gets an ICD is the ejection fraction, or how much blood the heart muscle pumps,' said principal investigator Alan Kadish, MD, Chester C and Deborah M Cooley distinguished professor of cardiology at Northwestern University's Feinberg School of Medicine and associate chief of cardiology at Northwestern Memorial Hospital in Chicago. 'The DETERMINE study will evaluate whether the size of a heart attack scar predicts more accurately which patients can benefit from these devices. If the results of this study verify our hypothesis, we could potentially save tens of thousands of lives per year. It could drastically alter the selection criteria for implanting defibrillators.'

There is an increasing pool of evidence that scar tissue in the lower chamber of the heart, developed after a heart attack and measured by cardiac MRI (magnetic resonance imaging), predicts SCA. Two earlier pilot studies at Northwestern University's Feinberg School of Medicine (conducted collaboratively by Kadish and David Bello, MD, now with Mid-Florida Cardiology Specialists) suggested that the size of a post-heart attack scar predicted which patients would develop a life-threatening arrhythmia.

The DETERMINE trial is designed to investigate these issues by looking at patients for whom:

- The amount of damage caused by a heart attack as measured by the percentage of resulting scar tissue (or ‘infarct mass’) is equal to or greater than 10 percent.

- The ejection fraction is greater than 35 percent.

'When we were approached about the DETERMINE study, we were eager to sponsor it,' said Fain of St Jude Medical. 'This trial could help an entirely new population of patients who may be at risk for SCA, while also providing important risk stratification information for patients currently indicated for ICD therapy.'

DETERMINE is a prospective, randomised, multi-centre study. The first 1,550 patients to meet inclusion criteria will be randomly selected to receive ICD therapy in combination with optimal pharmacological (drug) therapy, or randomly selected to receive optimal pharmacological therapy alone. Enrollment is expected to be completed in 36 months, with follow-up to occur for another 24 months.

In addition to the two-arm randomised DETERMINE trial, the study will include a registry of non-randomised patients, which is expected to ultimately produce the largest database ever of clinical diagnostic cardiac MRI evaluations of post-heart attack patients, as well as provide information on how infarct mass compares to ejection fraction in identifying patients at risk of sudden cardiac arrest. All patient MRIs will be evaluated at a Core Laboratory located at the University of California, Los Angeles, USA, led by Paul Finn, MD.

An ICD is a small device implanted in the chest to treat potentially lethal, abnormally fast heart rhythms, which often lead to sudden cardiac death. An ICD delivers potentially life-saving therapy from the device to the patient's heart through an insulated wire or lead.

SCA occurs when the lower chambers of the heart (the ventricles) suddenly stop beating normally and develop ventricular fibrillation (VF), a very fast, chaotic heart rate. When the ventricles fibrillate, they do not contract normally, so they cannot effectively pump blood. In VF, blood no longer reaches the brain, resulting in sudden cardiac arrest. If the arrhythmia is not corrected immediately via a shock from an ICD or an external defibrillator, death will follow within minutes. The ICD stops the chaotic electrical activity and restores normal heart rhythm.

Sites that enrolled the initial patients in the DETERMINE Randomized Trial include: LeBauer Cardiovascular Research Foundation and Moses H Cone Memorial Hospital, Greensboro, North Carolina; AHS Hillcrest Medical Center, LLC and Oklahoma Heart Institute, Tulsa, Oklahoma; and Lutheran Hospital of Indiana and Northern Indiana Research Alliance of the Heart Center Medical Group, Fort Wayne, Indiana.

Sites that enrolled initial patients in the DETERMINE MRI Registry include: Lehigh Valley Hospital and Health Network, Allentown, Pa.; Emory University, Atlanta; Northwestern University, Chicago; North Ohio Research, Elyria, Ohio; Huntington Hospital, Pasadena, California.; Glendale Memorial Hospital and Health Center, Glendale, California; Lutheran Hospital of Indiana and Northern Indiana Research Alliance of the Heart Center Medical Group, Fort Wayne, Indiana; LeBauer Cardiovascular Research Foundation and Moses H Cone Memorial Hospital, Greensboro, North Carolina; Kentucky Heart Institute, Ashland, Kentucky; St. Luke's Episcopal Hospital, Houston; Caritas St. Elizabeth's Medical Center, Boston; University of Nebraska Medical Center, Omaha, Nebraska; Cornell University, Weill Medical College, New York City; West Michigan Heart and Spectrum Health Hospitals, Grand Rapids, Michigan; St. Francis Hospital, Roslyn, New York; and AHS Hillcrest Medical Center, LLC and Oklahoma Heart Institute, Tulsa, Oklahoma.

St Jude Medical is committed to supporting scientific and medical advancements through clinical research, and the number and scope of clinical trials sponsored by St Jude Medical demonstrate the company's dedication to advancing the science behind new therapies. Landmark cardiac rhythm management studies include:

St Jude Medical has sponsored four comprehensive, prospective studies evaluating lead performance in more than 7,000 patients. Data from these studies will be presented at Heart Rhythm Society's 29th Annual Scientific Sessions in San Francisco, USA, on May 15, 2008.

The David Trial compared single-chamber and dual-chamber ICD therapy to assist physicians in refining recommendations regarding the use of these defibrillators and their associated pacing functions. The David Trial demonstrated that for patients with standard indications for ICD therapy, no indication for cardiac pacing, and an LVEF of 40 percent or less, dual-chamber pacing offers no clinical advantage over ventricular backup pacing and may be detrimental by increasing the combined end point of death or hospitalisation for heart failure.

The David II Trial demonstrated that the effect of atrial-based pacing (AAI-70) on event-free survival and quality of life is not substantially worse than, and is likely equivalent to, ventricular backup pacing (VVI-40). Atrial pacing may be considered a ‘safe alternative’, but affords neither clear advantage nor disadvantage over ventricular back-up pacing.

The Optimal Pharmacological Therapy in Implantable Cardioverter Defibrillator Patients Trial (OPTIC) study found that combining antiarrhythmic drug therapy with dual-chamber ICD therapy reduces the number of shocks experienced by patients with ICDs for ventricular tachycardia.

The Post AV Nodal Ablation Evaluation Trial (PAVE) was the first large-scale study to show the benefits of biventricular pacing in patients with atrial fibrillation undergoing AV node ablation. The beneficial effects of biventricular pacing were greater in patients with impaired heart function or symptomatic heart failure.

The Defibrillator IN Acute Myocardial Infarction Trial DINAMIT assessed ICD therapy for prevention of death in high-risk patients who have recently had a myocardial infarction (heart attack). The study demonstrated that ICDs do not reduce overall mortality when implanted early (within 40 days) after a myocardial infarction.

The Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation Trial (DEFINITE) found that patients with non-ischemic heart failure (not due to coronary artery disease) who receive an ICD are at lower risk for sudden cardiac death than patients treated with standard drug therapy.

The Atrial Dynamic Overdrive Pacing Trial-A (ADOPT-A) demonstrated that overdrive pacing with the AF Suppression(TM) algorithm decreases symptomatic AF burden significantly in patients with sick sinus syndrome, paroxysmal AF and standard pacemaker indications.

The Alternans Before Cardioverter Defibrillator Trial (ABCD) found that a non-invasive test called microvolt T-Wave Alternans (which uses computer technology to predict a patient's risk for sudden cardiac death) is comparable to an invasive and more expensive procedure commonly used by cardiac electrophysiologists to determine a patient's eligibility for an implanted defibrillator.

The Resynchronization Therapy In Normal QRS Trial (RethinQ) demonstrated that patients with a narrow QRS complex (the time required for the heart muscle to contract, as measured by electrocardiogram) and certain measures of left ventricular mechanical dyssynchrony (when the heart's main pumping chambers do not contract together efficiently) do not benefit from biventricular pacing (cardiac resynchronization therapy).
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