Sudden Death

pp 453-462

Abstract

Background

Death of cardiac origin is the most frequent cause of mortality and coronary risk factors increase its incidence. Most of the cases are due to tachyarrhythmias (ventricular sustained tachycardia which, turns into ventricular fibrillation or primary ventricular fibrillation) and about 20% are due to bradyarrhythmias.

Methods

In patients with heart disease, sudden death is due to the interaction of lack of electric stability, ischemia and left ventricular disfunction. The following are regarded as risk indicators: postinfarction scar, left ventricular hyper-trophy, decrease of the ejection fraction, functional alteration of the autonomous nervous system, lengthen-ing of the QT interval, and number and characteristics of the ventricular arrhythmias shown by Holter. For sudden death to occur, the vulnerable myocardium should necessarily be affected by some other factors such as stress, ionic or metabolic alterations, tachycardia, or potentially arrhythmogenic drugs. In the case of other heart diseases, such as hypertrophic cardiomyopathies, sudden death occurs also when other factors affect the vulnerable myocardium (stress, arrhythmias). Those patients who have already presented sustained ventricular tachycardia or out-patient infarction are regarded as high risk cases. Sick sinus syndrome and A-V block also increase the risk of sudden death and, in general, patients present an advanced heart disease and bradyarrhythmia is frequently irreversible.

Conclusions

Preventing sudden death implies preventing the appearance of associated conditions, specially ischemic cardiopathies, and identifying, studying and treating those subjects with malignant ventricular arrhythmias or those who have a previous episode of sudden death.