The effect of coronary artery bypass surgery on ventricular arrhythmias

The effect of coronary artery bypass surgery (CAB) on ventricular arrhythmias (VA) was studied in a prospective investigation involving 32 patients (mean age 54 years) who underwent CAB because of severe stable angina pectoris. Prior to CAB as well as 12 months later each patient was subjected to the following investigational programme: resting ECG, exercise ECG, 24-h ECG, selective coronary arteriography, ventriculography and cardiac catheterization. Exercise ECG showed VA in only three patients. The prevalence of VA during 24-h ECG was 56 and 66% on the two occasions (NS), while complicated VA (multiform, repetitive, R on T) was seen in 18 and 28%, respectively (NS). The persistence (number of 6-h periods showing VA) was 33 and 47% with regard to any VA (P less than 0.05), while complicated VA occurred in 13 and 15% of the 6-h periods (NS). Except for an increase in dp/dtmax/P at the postoperative measurement (P less than 0.05), no significant change in the performance of the left ventricle was seen after CAB though the graft patency was 77%. It is concluded that in patients with 'medically intractable' stable angina pectoris, CAB does not effect the occurrence of VA to any great extent--probably because left ventricular function is unchanged one year after as compared with that prior to CAB.