Background: The incidence, determinants, and outcome of postoperative atrial fibrillation (AF) after surgery for mitral regurgitation (MR) are poorly defined but may have important implications for timing of mitral valve surgery.
Methods and Results: In 762 patients in sinus rhythm with no AF history undergoing MR surgical correction, we examined the rates and prognostic implications of postoperative AF for early AF (within 2 weeks postoperatively) and late AF (>2 weeks after surgery). During postoperative follow-up, 180 patients (24%) experienced new AF (early AF in 136 and late AF in 111). Isolated early AF without recurrence was observed in 69 patients characterized by high angina class and lower left ventricular ejection fraction but no significant left atrial (LA) enlargement. However, overall early AF predicted late AF: 62±5% of patients with early AF had late AF at 10 years compared with 9±1% of patients without early AF (P<0.0001). Large LA size strongly and independently predicted early AF (P=0.01) and late AF (P=0.003). For late AF, the predictive value of an enlarged LA was cumulative to that of early AF. Postoperative AF was associated with an increased subsequently higher risk of stroke or congestive heart failure (adjusted risk ratio=1.46 [1.04 to 2.05], P=0.03).
Conclusions: Postoperative AF is common after surgical correction of MR in patients with no prior history of AF and is associated with increased subsequent morbidity. LA enlargement is independently predictive of postoperative AF and as such, should be integrated into the clinical decision-making process in patients with MR.