Implantable Loop Recorder in Survivors of Acute Myocardial Infarction

Prevention of sudden death after myocardial infarction (MI) is a challenge on which governmental agencies and industry have spent millions of dollars over the past 3 decades. Although survival of patients after MI has improved over this time period, the major cause of this improvement derives from reduction of infarct size as a result of aggressive reperfusion with thrombolytic agents and percutaneous coronary intervention, as well as evolution of pharmacological management after the acute phase of MI, including β-adrenergic blocking agents, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists. In spite of these advances, we have seen little or no reduction in the relative contribution of sudden death to overall cardiac mortality after MI: Thirty years ago, sudden death accounted for approximately 50% of cardiac deaths in patients with left ventricular ejection fraction (EF) ≤0.40 after MI.1,2 Observations since the institution of reperfusion therapy for acute MI suggest the relative proportion of sudden deaths has declined to approximately 30% of cardiac deaths in some studies3,4; however, other analyses find that sudden death remains the cause of one-half of all cardiac mortality after MI.5 In this issue of Circulation , we see that sudden death accounted for 50% of cardiac mortality in patients with recent MI and EF ≤0.40.6Article see p 1258These findings document that in spite of recent impressive declines in mortality due to coronary disease, sudden death remains a significant challenge. This challenge persists for multiple reasons. First, sudden death in patients with coronary disease and MI is not a single entity; its mechanisms are heterogeneous and change over time after MI. The heterogeneity of mechanisms means one test will not suffice to identify all patients at risk, and one treatment modality will not be optimal for …