The role of apoptosis in dilated cardiomyopathy

Dilated cardiomyopathy is a cardiac disease of unknown origin which is characterized by the gradual development of cardiac failure. Apoptosis, i. e. suicidal programmed cell death, may play a role in the development of heart failure. Only few studies have been carried out until now that describe the rate of apoptosis in human hearts with dilated cardiomyopathy. The numbers reported vary widely. This is also true for studies in different other cardiac diseases such as myocardial infarction or hibernating myocardium. The methods used to identify apoptosis include electron microscopy, labeling of the DNA fragments (TUNEL), staining with the Hoechst dye, annexin V labeling and documentation of DNA fragmentation using gel electrophoresis (laddering). None of these methods are totally reliable in tissue sections in which apoptosis is not a frequent event when they are not combined with another technique, e. g. TUNEL with electron microscopy or laddering. This has, however, only rarely been done. These technical difficulties may be the reason for the wide variation in the rate of apoptosis reported. From our own data we conclude that apoptosis plays a significant role in acute ischemia and in hibernating myocardium but its significance in the progression to heart failure in dilated cardiomyopathy has still to be established.