Survey to evaluate arrhythmia rate in so-called high-risk MI patients

Sep 2 2007

Sudden cardiac death is the leading cause of mortality in European and North-American countries. Studies have been attempting to identify the right population of patients at high risk of Sudden Cardiac Death ever since the introduction of the Implantable Cardioverter Defibrillators (ICD).

The results of the North American MADIT-II randomized clinical trial revealed, in March 2002, that post-myocardial infarction (post-MI) patients enrolled on the basis of reduced left ventricular ejection fraction, without prior ventricular tachyarrhythmia, exhibited a decreased mortality in the implanted defibrillator arm.

This led the cardiology societies of America and Europe (ACC/AHA/ESC) to amend guidelines on the clinical management of patients at risk for Sudden Cardiac Death and to recommend ICD implants for prophylactic indications. Yet, many important clinical questions do not lend themselves to clinical trials, and recent guidelines state that such data could be obtained from "additional studies with broad objectives … and additional registry data". In particular, data is needed to increase the knowledge about the treatment effect and efficacy of ICD therapies in different population strata (such as gender, age, history of diabetes, severity of heart failure)

Immediately after the publication of the MADIT-II study results, a debate thus emerged on the possibility to translate the benefits observed in strictly controlled trial-selected patients to “real world” practice. SEARCH-MI was thus created in 2002 to prospectively evaluate the arrhythmic rate, ICD interventions and adherence to trial-based recommendations on post-MI patients in regular clinical practice. The study was carried out in 69 centers across Italy, Germany, Austria, Israel and Saudi-Arabia. 788 patients were admitted for ICD indication as primary prevention after myocardial infarction, enrolled and followed for an average of 2 years. SEARCH-MI thus represents the current clinical management of post-MI patients with left ventricular dysfunction with a primary indication for defibrillator implant. These implantations have also been influenced by other heart failure landmark trials and guidelines which appeared in the last 5 years.

All episodes collected in the SEARCH-MI registry were reviewed independently. The final results, with a mean follow-up close to 2 years, demonstrate that one patient in five (1/5) will benefit from successfully treated ventricular arrhythmic events by their implanted ICD. This event rate is similar to that reported for the ICD arm of the MADIT-II trial. A relevant proportion of patients (1/4) enrolled in the SEARCH-MI registry received a device for cardiac resynchronization therapy, also illustrating the evolving trends towards device-based therapy in heart-failure patients.

This registry, designed to enroll MADIT-II like patients, results in outcomes for appropriate ventricular therapy that are comparable to strictly controlled randomized clinical trial conditions. The SEARCH-MI registry supports the benefits of ICD therapy in primary prevention patients in reducing all cause mortality and confirms the extended role of these devices for heart failure patients in routine clinical practice.

Notes:
This study was presented at the ESC Congress 2007 in Vienna.

The European Society of Cardiology (ESC):

The ESC represents nearly 53,000 cardiology professionals across Europe and the Mediterranean. Its mission is to reduce the burden of cardiovascular disease in Europe.

The ESC achieves this through a variety of scientific and educational activities including the coordination of: clinical practice guidelines, education courses and initiatives, pan-European surveys on specific disease areas and the ESC Annual Congress, the largest medical meeting in Europe. The ESC also works closely with the European Commission and WHO to improve health policy in the EU.