The diagnosis of fatal arrhythmia in pathology is a diagnosis of exclusion. What this means is that there are no positive autopsy findings that definitively point to arrhythmia, and no way to ever exclude that possibility. If all other, more viable and reasonable causes of death are excluded, one may suggest that the death may have been a “probable” arrhythmia. Arrhythmia as a pathologic diagnosis at autopsy requires the qualifier “probable” or “possible” unless clinical ECG (electrocardiogram) findings ante- or perimortem are diagnostic. In fact, the only way to diagnose an arrhythmia is by clinical ECG studies while the patient is still alive. Because of the inability to ever diagnose or completely exclude the possibility of arrhythmia, it is also a common fallback diagnosis when trying to refute another cause of death in a legal proceeding.
Fatal arrhythmia medical expert witness specialties include forensic pathology and cardiac electrophysiology.