Brain natriuretic peptide elevation and the development of atrial fibrillation following coronary artery bypass...

The study was designed to determine whether the development of atrial fibrillation is associated with post-operative left ventricular dysfunction and subsequent left atrial stretch. We recruited 133 patients with well preserved pre-operative left ventricular function undergoing bypass surgery. Brain natriuretic peptide was measured at baseline, 24 and 48 h after the onset of cardiopulmonary bypass, and patients were monitored for 72 h after surgery. Atrial fibrillation occurred in 65 patients. Median 48 h brain natriuretic peptide levels were greater in the atrial fibrillation group (440 pg/ml (AF) and 319 pg/ml (non AF) P=0.001). As atrial fibrillation can cause an elevation in brain natriuretic peptide we divided the subjects into early atrial fibrillation (<48 h) and late (>48 h). In those with early atrial fibrillation there was no difference in the 24 h brain natriuretic peptide levels (381 pg/ml and 365 pg/ml P=0.73). In those with late atrial fibrillation the median 48 h brain natriuretic peptide level was greater than in the control group (405 pg/ml and 319 pg/ml, respectively, P=0.02). Brain natriuretic peptide levels rise significantly following bypass surgery. This increase was more evident in those who develop late atrial fibrillation which may suggest a role for atrial stretch in this arrhythmia.