[Disorders of cardiac rhythm and conduction during attacks of stenocardia].

Heart rhythm and conductivity disorders, developing during anginal attacks, and their relation to the pattern of myocardial ischemia have been studied, using 24-hour ECG monitoring, in 60 patients with stable angina, and in 67 patients with unstable angina. Heart rhythm and conductivity disorders at the ventricular level were much more common in Prinzmetal's angina (73%), as compared to the attacks involving ST depression (10%). Their incidence depended both on the direction and magnitude of ST displacement. The probability of supraventricular arrhythmias was unrelated to the magnitude and direction of ST displacement. They tended to develop during the attacks, accompanied by slanting ST depressions (43%) rather than flat ones (8%). Arrhythmias were considerably more common as a complication of the attacks of unstable angina (42%) rather that stable angina (15%) owing to more severe myocardial ischemia.