Incidence and clinical consequences of atrial fibrillation within 1 year of first-time isolated coronary bypass surgery

Background-Atrial fibrillation (AF) is the commonest complication during cardiac surgery, however, the long-term prevalence of AF following surgery and its clinical consequences remain unclear. Patients and Methods-To investigate this, 877 consecutive patients undergoing first time CABG were followed for 1 year. Rhythm disturbances were diagnosed from serial ECGs and documented notes. The arrhythmia was treated medically and/or by cardioversion. Results-Out of 877, 17 patients (1.9%) died in the hospital and out of the remaining 860 patients 844 (98.1%) had a complete 1-year follow-up. Patients were divided according to their age: Group I (50 to 59 years), Group II (60 to 69 years) and Group III (70 to 79 years). The prevalence of AF in the general population was taken from the Framingham Heart Study. Patients in groups I and II had a higher incidence of AF before the operation than the general population (1.5% versus 0.4% and 3.1% versus 1.6%, respectively, P<0.05) and also higher incidence of AF at the 1-year follow-up (2% versus 0.4% and 4.6% versus 1.6% respectively, P<0.05). The incidence of AF in group III did not differ from the general population before operation, at the 6-week and 1-year follow-ups. As expected most of the patients with preoperative AF remained in AF after 1-year of CABG surgery. Importantly, the incidence of newly developed AF was higher in patients that developed infection and renal dysfunction in the postoperative period. AF did not predict embolic events at any stage of the study. Conclusion-In conclusion, the incidence of AF for the first year following CABG is higher in patients <70 years but not in those >70 years when compared with the general population. AF was also associated to the occurrence of postoperative infection and renal dysfunction. Patients in this study were closely monitored and received timely appropriate treatment, and this may account for the absence of a relationship between AF and embolic events.