Relationship between left atrial volume and atrial fibrillation following coronary artery bypass grafting

Atrial fibrillation (AF) is a common complication of coronary artery bypass grafting (CABG). However, limited information is available about the role of preoperative echocardiographic left atrial evaluation to predict AF occurrence after CABG. Thus, we prospectively compared the ability of echocardiographic measurements of left atrial volume to predict AF in this setting.

From January to December 2009, 220 patients (75% males, 66.8 ± 10.0 years) met the inclusion criteria of our study (isolated and elective CABG, no valve surgery, no permanent AF, or other chronic atrial arrhythmias). The day before CABG a complete echocardiographic evaluation was performed with left atrial volume measurements. The primary endpoint of the study was postoperative AF (POAF) lasting >30 seconds.

POAF was observed in 61 patients (27.7%). POAF patients showed increased left atrial M-mode anteroposterior dimension (41.2 ± 6.4 mm vs. 43.6 ± 7.3 mm; p = 0.020) and increased left atrial volume (59.0 ± 18.3 mL vs. 70.6 ± 28.1 mL; p = 0.0004). Left atrial volume was an independent risk factor for POAF (OR 10.03; 95% CI 10.01 to 10.05; p = 0.01), along with postoperative bleeding with hemoglobin levels below 8 g/dL (OR 20.84; 95% CI 10.12 to 70.19; p = 0.03) and preoperative left ventricular ejection fraction below 40% (OR 10.08; 95% CI 10.01 to 10.15; p = 0.02). Conversely, preoperative statin therapy exerted a protective role (OR 0.30; 95% CI 0.12 to 0.74; p = 0.009).

Preoperative echocardiographic evaluation of patients with isolated CABG demonstrated that left atrium volume measurements were independently correlated to the occurrence of POAF. Further investigations should focus on the opportunity to target prophylactic antiarrhythmic treatments to patients with large left atrial volumes.