[Duration of electric systole in the acute phase of myocardial infarct. Methodology, natural history, semiological value, therapeutic consequences].

Extension of the duration of electric systol in the acute phase of coronary thrombosis can be analysed in satisfying conditions whatever the physiological frequencies by the measurement (formula; see text) represents the average QT measurement of three non-consecutive complexes in five derivations (DI, DIII, aVF, VI and V6). This extension is of prognostic value when the QTc is greater than 44 c/s. Out of 1 255 acute phase thrombosis patients, 18 Out of 20 cases of ventricular fibrillation revealed a QTc greater than 44 c/s in the 24 hours preceding sudden death. Therapeutic intervention with anti-andrenergic drugs such as bretylium tosylate or beta-blocking agents appears to reduce the QTc of these patients and thus prevent sudden death.