Low vagal tone and supraventricular ectopic activity predict atrial fibrillation and flutter after coronary artery bypass grafting.

Abstract

To investigate the impact of pre-operative autonomic balance and atrial ectopic activity on the risk of atrial fibrillation or flutter after aorto-coronary artery bypass surgery 24-h Holter monitoring was analysed in 102 patients before coronary artery bypass grafting. Index for vagal tone was calculated as % successive RR interval differences > 6%. Twenty-nine (28%) of the 102 patients developed atrial fibrillation or flutter. Independent predictors (90% confidence interval) of postoperative atrial fibrillation or flutter were identified by logistic regression analysis: the independent predictors were older age, relative risk 1.07.year-1 (1.02-1.12), vagal index < 10%, relative risk 4.50 (1.40-14.5), > or = 10 ectopic supraventricular beats . 24 h-1, relative risk 3.03 (1.05-8.72), and one or more events of non-sustained supraventricular tachycardia, relative risk 3.02 (1.11-8.22). Thus, age of the patient, attenuated pre-operative cardiac vagal modulation, ectopic supraventricular beats, and paroxysmal non-sustained supraventricular tachycardia are independent risk factors for the development of atrial fibrillation or flutter after coronary artery bypass surgery.