The clinical use of beta-blockers in the prevention of sudden death.

Numerous studies now suggest that better prevention of arrhythmic sudden death (SD) is provided by beta-blockers than by type I antiarrhythmic drugs. Analysis of 69 cases of SD recorded at ambulatory ECG showed two important facts: (1) in about 20% of the cases, type I antiarrhythmic drugs were responsible for SD, so that the statistical lack of prevention probably reflects a mixed picture of beneficial and deleterious effects; (2) the apparent ineffectiveness of beta-blockers in daily observed arrhythmias does not imply that they cannot protect the patients against the exceptional circumstances which lead to lethal arrhythmias. Arguments suggesting that sympathetic drive should be tempered for a better protection against SD come from various observations: transient ischaemia preceding the terminal event, increasing heart rate preceding lethal or life-threatening arrhythmias, persistent arrhythmias inducibility with isoprenaline or exercise when they had apparently been controlled, the positive correlation between the number of premature beats and the sinus rate at Holter monitoring and the consistent sinus acceleration before a variety of arrhythmias at Holter monitoring. Electrophysiologic phenomena and the autonomic nervous system are often combined to generate arrhythmias. Drugs may apparently be effective though not specific for the causal mechanism, or may be apparently ineffective though providing real protection against potential arrhythmias. Modes of evaluation of the different situations should be more comprehensive to ensure better adapted treatments.