Ambulatory sudden cardiac death: mechanisms of production of fatal arrhythmia on the basis of data from 157 cases.

The study of the tapes of ambulatory patients who died while wearing Holter devices allows us to know the terminal electrical events of death in these cases and which are the electrical triggering mechanisms leading to the terminal event. From the evaluation of seven published series with 10 or more cases, we can see that the most frequent causes of sudden death are ventricular tachyarrhythmias (84% of cases) and bradyarrhythmias (16%). VF was the most frequent ventricular tachyarrhythmia, usually secondary to VT. The rest were due to torsades de pointes in patients often without heart disease but who were taking antiarrhythmic drugs. The VT leading to VF was often preceded by sinus tachycardia or new atrial tachyarrhythmia. Only a small percentage of patients presented ischemic ST changes. In patients who died due to bradyarrhythmias, this was more often due to sinus depression than to atrioventricular block.