Ambulatory Sudden Death

pp 551-561

Abstract

The electrical events leading to sudden death can be disclosed in ambulatory patients who die while being monitored with Holter devices. In a retrospective analysis of Holter recording from 1986 to1996 we documented 12 episodes of ambulatory sudden death. Patients with acute myocardial infarction, unstable angina or terminal illness were excluded. In each case the following points were analysed: 1) type of the arrhythmia preceding cardiac arrest, 2) Q-Tc interval before the final event, 3) frequency and complexity of ventricular ectopic activity prior to sudden death, 4) ST and T wave changes, 5) variations in heart rate during the previous hour and the last 20 seconds before the fatal event, 6) hourly distribution of the deaths, and7) patient activity preceding the final episode. Eleven out of the 12 patients were man, mean age 65.75 ±8.39 years (range: 54-78). Seven had coronary artery disease, Chagas' cardiomyopathy in two, hypertensive heart disease in one. One had sinus node dysfunction and one chronic renal insufficiency. The basic rhythm was sinus in 11 cases (91.66%), within termittent atrial fibrillation in one patient and runs of accelerated idioventricular rhythm in the other one. One patient had a permanent pacemaker.Eight patients were receiving betaadrenergic blockers, three of them in combination with diure-tics and of these two were taking a third drug, nifedipine or enalapril. Three patients were treated with amiodarone and two of them in combination with diuretics. One patient was receiving enalapril and diuretics. In ten patients (83.33%) sudden death was preceded by ventricular tachyarrhythmias: eight ventricular tachycardia, monomorphic in four patients and polymorphic in four, two with torsades de pointes which degenerated to ventricular fibrillation and two had primary ventricular fibrillation. Two patients (16.66%) died as a consequence of bradyarrhythmias: a systole in one case and electromechanical dissociation in the other one. The mean Q-Tc interval was 493.33 ± 27.97. Eight patients showed ventricular arrhythmias during the entire recording period which increased in complexity and frequency in the hour before the fatal event. Six patients had runs of monomorphic or polymorphic ventricular tachycardia. All the patients with coronary artery disease (58.33%) showed ST segment depression of 0.2 to 0.6 mV; ST segment elevation of 0.15 to 0.3 mV was recorded in two cases. These changes appeared 10 to 40 minutes prior to sudden death. Seven of the 12 patients died between 11:00PM and 08:00 AM; three between 03:00 PM and 09:00PM and two between 09:00 AM and 12:00 AM. At the time of sudden death, five patients were sleep-ing, two were at rest and in five cases the fatal event occurred during efforts. The group of patients with coronary artery disease had a mean increase in heart rate of 15 beats/minute in the previous hour and a mean decrease of 21 beats/minute during the last20 seconds before death. Conclusions The most frequent causes of ambulatory sudden death in our series were ventricular tachyarrhythmias. Ischemic ST changes were present in all the patients with coronary artery disease. A circadian pattern in the incidence of sudden death could not be found. The observed changes in heart rate suggest that the autonomic nervous system may playa role in the triggering mechanisms leading to sud-den death.