Holter ECG study of the electrocardiographic phenomena in Prinzmetal angina attacks with emphasis on the study of ventricular arrhythmias.

The ECG phenomena in 20 outpatients (121 episodes) suffering from variant angina with transient ST segment elevation greater than 1.5 mm. (Prinzmetal angina) were studied by Holter monitoring. The most important changes in the ECG morphology were: a) increased height of the R wave in all cases, b) the S wave decreased or disappeared, c) the ST segment elevation varied from 1.5 to 38 mm, d) the TQ interval was ascending in 78 episodes, e) there was a double alternance of ST-TQ in 20 episodes and f) the first modification of the ECG was an increase of the T wave height. Arrhythmias were seen in 19 patients (44 episodes). The most frequent were premature ventricular contractions. The prevalence and importance of the ventricular arrhythmias were statistically related to the duration of the episodes (p less than 0.005), the degree of the ST segment elevation (p less than 0.005), the presence of ST-TQ alternance (p less than 0.005) and the presence of increased R wave greater than 25% (p less than 0.025).