The effect of coronary artery bypass surgery on ventricular arrhythmias

The effect of coronary artery bypass surgery (CAB) on ventriculararrhythmias (VA) was studied in a prospective investigationinvolving 32 patients (mean age 54 years) who underwent CABbecause of severe stable angina pectoris. Prior to CAB as wellas 12 months later each patient was subjected to the followinginvestigational programme: resting ECG, exercise ECG, 24-h ECG,selective coronary arteriography, ventriculography and cardiaccatheterization. Exercise ECG showed VA in only three patients.The prevalence of VA during 24-h ECG was 56 and 66% on the twooccasions (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 regardto any VA (P<0.05), while complicated VA occurred in 13 and15% of the 6-h periods (NS). Except for an increase in dp/dt_max/Pat the postoperative measurement (P<0.05), no significantchange in the performance of the left ventricle was seen afterCAB though the graft patency was 77%. It is concluded that inpatients with ‘medically intractable’ stable anginapectoris, CAB does not effect the occurrence of VA to any greatextent — probably because left ventricular function isunchanged one year after as compared with that prior to CAB.     

Ventricular arrhythmias in relation to coronary artery stenosis and left ventricular performance

The relationship between ischaemic heart disease and occurrenceof ventricular arrhythmias has been studied in a prospectiveinvestigation of 41 patients with severe stable angina pectoris.The patients had a median age of 54 years (range 38–67).Following the therapeutic evaluation of the patients, they weresubjected to exercise testing, 24 h ambulatory ECG monitoring,selective coronary arteriography, ventriculography and cardiaccatheterization. Nineteen patients had been under treatmentwith a beta blocking agent, 16 with verapamil, three with bothand three had not been receiving any anti-anginal treatment.The treatment was discontinued over a period of three days priorto coronary arteriography and haemodynamic measurements. A comparisonof the patients under treatment with a beta blocking agent andthose receiving verapamil demonstrated no difference in thenon-invasive and invasive variables. Ventricular arrhythmias were found in only one patient duringexercise testing. The occurrence of ST segment deviation duringexercise was not correlated with the number of stenotic coronaryvessels due to low maximum heart rate and treatment. A heartrate during maximum exercise of < 120/min was observed significantlymore frequently in patients with multivessel disease. The data of the 24 h Holter monitoring were analysed in orderto evaluate whether the prevalence (percentage number of patientswith ventricular ectopic beats) or the persistence (number of6 h periods with ventricular ectopic beats) is the better indicatorof myocardial function and coronary artery anatomy. The resultsdemonstrated a significant correlation between a high persistenceand elevated left ventricular enddiastolic presure, high dp/dt/_max/P,reduced ejection fraction as well as the number of stenoticcoronary arteries and hypokinetic segments in the left ventricularwall. The latter correlation especially applies when the hypokinesiais localized to the anterior wall of the left ventricle. It is concluded from this investigation that a high persistenceof ventricular arrhythmias during 24 h of ECG monitoring reflectsmultivessel disease and poor left ventricular function. Thecombination of a high persistence of complicated ventriculararrhythmias and only a slight rise in heart rate during maximumexercise can possibly identify a group with an especially highrisk of sudden cardiac death.