NONISCHEMIC SUDDEN TACHYARRHYTHMIC DEATH IN ATHEROSCLEROTIC HEART-DISEASE

Atherosclerotic heart disease is the commonest pathologic substrate for tachyarrhythmic sudden cardiac death (SCD). Although acute ischemia contributes to arrhythmogenesis, non-ischemic mechanisms have been given little attention in the literature despite their importance. Sustained monomorphic ventricular tachycardia (SMVT) is a more common manifestation of nonischemic mechanisms than is ventricular fibrillation (VF). Frequent absence of overt or silent ischemia as precursors to spontaneously occurring SMVT or VF, preterminal findings during ECG monitoring, and persistent significant SCD rates in various populations receiving anti-ischemic therapy are some observations supporting the concept of non-ischemic tachyarrhythmic SCD. The importance of scar-related substrate and rationale for distinguishing between - rather than "lumping" - SMVT and VF are discussed. Acute ischemia superimposed on prior infarction is another important arrhythmogenic scenario in tachyarrhythmic SCD. Optimal definition of tachyarrhythmic SCD should include assessment of ischemic burden, arrhythmia substrate, clear definition of arrhythmic mechanisms, hemodynamic parameters and indices of autonomic imbalance.