Classification of sudden and arrhythmic death.

Since all death is (eventually) sudden and associated with cardiac arrhythmias, the concept of sudden death is only meaningful if it is unexpected, while arrhythmic death is only meaningful if life could have continued had the arrhythmia been prevented or treated. Current classifications of death as being arrhythmic or sudden are all biased by the difficulty of having to decide on the degree of unexpectedness or the likelihood that life could continue without the arrhythmia. The uncertainties are enlarged by the fact that critical data (such as knowledge of arrhythmias at the time of death or autopsy) are available in only a few percent of cases. A main problem in using classifications is the lack of validation data. This situation has, with the MADIT trial, changed in the case of the Thaler and Hinkle classification of arrhythmic death. The MADIT trial demonstrated that arrhythmic death was nearly abolished by the implantable defibrillator, indicating that arrhythmic death by this classification is meaningful, at least in the population studied. For future investigations, a call is made for committees to present data in a way that allows the reader to examine the quality of the data used for evaluation.