Nonischemic sudden tachyarrhythmic death in atherosclerotic heart disease.

Sudden cardiac death victims have a high prev- alence of significant coronary arterial stenoses.12This association has led, in part, to the belief that acute ischemia is frequently responsible for the occurrence of sustained ventricular tach- yarrhythmias that result in sudden cardiac death.Although evidence for acute myocardial infarction as a precursor is present in only approximately one third of cases,1,3the occurrence of antecedent chest pain in as many as 60% of sudden coronary deaths56 further implicates acute ischemia as an important precipitant of fatal ventricular tachyarrhythmias-even when such ischemia is not sufficiently prolonged to result in myocardial necrosis.Nevertheless, ischemia remains far from estab- lished as a universal mechanism for sudden tachyarrhythmic death in patients with atherosclerotic heart disease (ASHD).We critically assess this controver- sial issue in light of recent investigations, and focus on the importance of the nonischemic route to sud- den tachyarrhythmic death in the setting of ASHD. Evidence Against Ischemia as the Requisite Preterminal Cause of Sudden Cardiac Death in ASHDFrom a purely anatomic standpoint, the lack of a preterminal ischemic process in many sudden cardiac death victims with ASHD is suggested by the obser- vations that coronary artery segment cross-sectional area narrowing of at least 50% (at autopsy) is absent in 30% of cases,4 whereas angiographically significant stenoses are absent in as many as 10% of cases.7,8Although Davies et a19 found that "acute" coronary arterial lesions (plaque fissuring, mural thrombi, or occlusive thrombi) were detectable in 95% of sudden coronary deaths (6-hour definition of "sudden"), that study included victims of whom one third had an acute myocardial infarction (M.J. Davies, personal communication).In a more recent and larger study