Apoptosis and oncosis in acute coronary syndromes: Assessment and implications

The rational design of therapeutic interventions for protection of ischemic myocardium from ultimate death requires an understanding of the mechanistic basis of cardiomyocyte (CM) cell death, its timing and the tools for its quantification. Until recently, CM cell death following ischemia and/or reperfusion was considered to involve necrosis or `accidental cell death' from very early on. Collective evidence over the past decade indicates that early CM cell death after myocardial ischemia and post-ischemic reperfusion involves apoptosis with cell shrinkage and drop-out, and/or oncosis with cell swelling followed by necrosis. This paradigm shift suggests that different approaches for cardioprotection are required. Oncologists, pathologists, anatomists and basic scientists who have studied apoptosis over the last three decades separated physiological apoptosis from inappropriate apoptosis in pathological states. Until recently, cardiologists resisted the concepts of CM apoptosis and regeneration. Cumulative evidence indicating that apoptosis in the heart may occur in different cell types, spread from one cell type to another, and occur in bursts, may have profound implications for therapies aimed at protection of ischemic myocardium by targeting CM apoptosis in acute coronary syndromes. This review focuses on a critique of the methods used for the assessment of CM apoptosis and the implications of CM apoptosis in acute coronary syndromes.