Ventricular arrhythmias after coronary artery bypass graft surgery: incidence, risk factors and long-term prognosis.

The incidence, risk factors and long-term prognosis of complex ventricular arrhythmias after coronary artery bypass graft surgery are not known. Complex ventricular arrhythmias are defined as Lown grades 4a (couplets), 4b (ventricular tachycardia) and 5 (R on T phenomenon). Ninety-two patients with normal left ventricular function who underwent elective coronary artery bypass graft surgery were prospectively evaluated. Ventricular arrhythmias were documented by predischarge 24 hour ambulatory electrocardiographic monitoring; 43% of patients had no or simple ventricular arrhythmias (Lown grades 1 to 3) and 57% had complex ventricular arrhythmias. Risk factors analyzed included age, sex, diabetes, hypertension, smoking, preoperative digoxin or propranolol therapy, cardiopulmonary bypass time, aortic cross-clamp time, number of vessels bypassed, peak creatine kinase (CK) elevation and pericarditis. No risk factor identified patients at higher risk for complex ventricular arrhythmias. Patients were followed up for 6 to 24 months (mean 16). Patients with complex ventricular arrhythmias did not have a higher incidence of sudden death, cardiac death, syncope, angina, myocardial infarction or cerebrovascular accident. It was concluded that: Complex ventricular arrhythmias are common after coronary artery bypass graft surgery. None of the risk factors considered identify high risk patients. Complex ventricular arrhythmias after coronary artery bypass graft surgery do not indicate a poor prognosis in patients with normal left ventricular function.