Prevention of sudden cardiac death in ischaemic cardiomyopathy

Abstract

Sudden cardiac death (SCD) is a major health problem in both the United States and worldwide. There is considerable controversy regarding the optimal time after acute myocardial infarction for risk stratification as well as the ideal time to place an implantable cardioverter defibrillator for primary prevention for SCD. Several parameters have been considered and tested for risk stratification of SCD after acute myocardial infarction. However, the only criterion that is currently being implemented is the left ventricular ejection fraction (LVEF). There are different imaging methods to measure LVEF, including echocardiography, cardiovascular magnetic resonance (CMR) imaging, nuclear scintigraphy, and angiography. When compared, these methods have shown modest correlation among them with up to 10% differences in LVEF and wide standard deviations (average 10%), which raises questions about their reliability to make decisions about primary prevention strategies for these patients. Moreover, LVEF assessment after acute myocardial infarction may be significantly affected by transient myocardial stunning and patients with a LVEF greater than 35% are not exempt from ventricular arrhythmias. Despite previous studies showing a considerably higher reduction in cardiac and total mortality when electrophysiological study is performed, current guidelines for prevention of SCD do not recommend electrophysiological study very strongly. CMR imaging has gained popularity for risk stratification of SCD. Delayed gadolinium enhancement has been proven to be useful in the identification of myocardial scar due to acute or chronic myocardial infarction. In the authors’ opinion, electrophysiological study and CMR imaging and probably strain echocardiography as well as cardiac iodine-123 metaiodobenzylguanidine will eventually play more important roles in risk stratification of patients with ischaemic cardiomyopathy based on the data published to date.