INTRODUCTION
Atrial fibrillation (AF) is the most common cardiac arrhythmia. Despite advancements in screening, diagnosis and management, the presence of AF is still associated with an increased risk of stroke, heart failure and death. New-onset AF is frequent after any cardiac surgery, but evidence suggests it has no significant impact on survival if sinus rhythm (SR) is effectively restored early after the onset of the arrhythmia. In contrast, several studies have suggested that preoperative AF is associated with increased morbidity and mortality in patients undergoing cardiac surgery. Management of preoperative AF is often overlooked during or after cardiac surgery despite several proposed protocols. Concomitant surgical AF ablation is recommended to improve left ventricular ejection fraction, exercise tolerance, and long-term survival, and to reduce the risk of stroke and thromboembolic events. However, the presumed additional risk of atriotomy and subsequent surgical ablation still precludes its routine use in a large subset of patients.
AF is common in patients with aortic valve disease, especially aortic stenosis. This is, at least in part, because the incidence of both conditions increases with age. Furthermore, chronically elevated left ventricular afterload secondary to aortic stenosis precipitates impaired diastolic relaxation with resultant upstream transfer of pressure to the left atrium, which provokes left atrial dilatation, fibrosis and arrhythmogenesis . A recent metanalysis suggested an association between preoperative AF and adverse outcomes after surgical aortic valve replacement (AVR). Of note, patients with AF are usually older with multiple comorbidities. They also often require concomitant cardiac surgeries such as coronary artery bypass graft and other valve surgeries. Thus, there is still some debate whether AF is an independent predictor of adverse prognosis after surgical AVR or whether the worse prognosis among AF patients rather reflects increased age and associated comorbidities and/or concomitant surgeries. The AF-TRACER study sought to evaluate the sole impact of preoperative AF on mortality in a large cohort of patients undergoing isolated surgical AVR.