Risk Estimation Following Infarction Noninvasive Evaluation (REFINE)

Background. Sudden cardiac death (SCD) kills >450,000 North Americans each year. Patients with a history of myocardial infarction (MI) are at particular risk. Concurrent alterations in myocardial structure & autonomic tone appear important for the development of the arrhythmias leading to SCD.

Given the grave consequences of SCD, an ideal testing procedure should identify most of those at risk (sensitive) & correctly classify risk (accurate). Since >90% of patients who suffer serious arrhythmias post-MI have at least mild left ventricular (LV) dysfunction (ejection fraction [EF] <0.50) this is an optimal group to study.

While noninvasive tests have been developed to estimate SCD risk, prior approaches have failed to: 1) identify the majority of patients at risk for serious arrhythmias (insensitive), 2) evaluate temporal changes in parameters, 3) identify the optimal timing for risk assessment post-MI, & 4) develop a widely-applicable screening tool. This has resulted in a failure to delivery effective therapies (e.g., defibrillator) in a cost-effective manner.

Hypotheses. Primary: Concurrent evaluation of electrical structure & autonomic tone will accurately identify most post-MI patients at risk of serious arrhythmic events. Secondary: 1) assessment later (16 weeks) provides more prognostic information than assessment early post-MI (4 weeks), 2) a single multi-parameter test procedure can be developed, and 3) individually, repolarization alternans provides the most prognostic information.

Methods. 350 persons with a recent MI (<31 days) & EF <0.50 will undergo testing early (4 weeks), intermediate (8 weeks) & late (16 weeks) post-MI.