Sudden death in hospitalized patients: cardiac rhythm disturbances detected by ambulatory electrocardiographic monitoring.

To determine the cardiac rhythm disturbances underlying sudden death, 15 patients (14 inpatients and 1 outpatient) who had cardiac arrest unexpectedly while undergoing ambulatory electrocardiographic monitoring were identified. Heart disease was present in 11 patients and 7 patients were admitted to the hospital with chest pain before sudden cardiac death occurred. The terminal event at the time of cardiac arrest in 3 (20%) of the 15 patients was a bradyarrhythmia expressed as complete heart block; none survived. A ventricular tachyarrhythmia was the precursor of sudden cardiac death in the remaining 12 patients (80%). Two of these 12 had slow ventricular tachycardia and both died. Five had polymorphous ventricular tachycardia associated with prolonged QT interval (torsade de pointes) and three were receiving a class I antiarrhythmic agent. This rhythm degenerated into ventricular fibrillation in one patient; four of the five patients survived after electrical cardioversion. One patient had ventricular tachycardia followed by asystole. Four patients had ventricular flutter (rate greater than 250/min) that degenerated into ventricular fibrillation in each case; only one of these four patients survived after cardioversion. Frequent (greater than 30/h) premature ventricular complexes were present in 9 of 10 patients with ventricular tachycardia or flutter and R on T phenomenon was seen in only 1 patient. In conclusion, a ventricular tachyarrhythmia is usually found on Holter monitoring during sudden cardiac death in hospitalized patients; torsade de pointes (polymorphous ventricular tachycardia) is a frequent cause of sudden death in these patients. Ventricular fibrillation is always preceded by ventricular tachycardia or ventricular flutter.