Atrial fibrillation complicating the course of degenerative mitral regurgitation: Determinants and long-term outcome

OBJECTIVES: The study was done to define the incidence, determinants and prognostic implications of onset of atrial fibrillation (AF) during follow-up of mitral regurgitation (MR) initially in sinus rhythm. BACKGROUND: The rates and clinical implications of AF in MR are undefined. METHODS: We analyzed the occurrence of AF under conservative management in two populations of patients with degenerative MR in sinus rhythm at diagnosis: 1) 360 patients (65 ± 13 years, 74% men) with MR due to flail leaflets; and 2) 89 residents of Olmsted County, Minnesota (67 ± 17 years, 56% men) with grade 3 or 4 MR due to simple mitral valve prolapse (MVP) diagnosed echocardiographically. RESULTS: In patients with MR due to flail leaflets, AF rates at 5 and 10 years were 18 ± 3% and 48 ± 6%, respectively, and the linearized rate was 5.0 ± 0.7% per year. Development of AF during follow-up was independently associated with high risk of cardiac death or heart failure (adjusted risk ratio 2.23, p = 0.025). The AF rate at 10 years was higher in patients ≥65 years (75 ± 10% vs. 24 ± 6%, p < 0.0001) and in those with baseline left atrial (LA) dimension ≥50 mm (67 ± 8% vs. 37 ± 9%, p < 0.001). In multivariate analysis, independent baseline predictors of AF were age and LA diameter (both p < 0.01). In patients with MR due to MVP, similar rates of AF (41 ± 7% vs. 44 ± 6% at nine years, p > 0.50) and predictors of AF (age and LA dimension, both p < 0.006) were noted. CONCLUSIONS: In patients with degenerative MR in sinus rhythm at diagnosis, the incidence of AF occurring under conservative management is high and similar whether the cause of MR is flail leaflet or simple MVP. After onset of AF, an increased cardiac mortality and morbidity are both observed under conservative management. The risk of AF increases with advancing age and larger LA dimension. These data suggest that the clinical management of MR should take into account the high incidence, excess risk, and predictors of AF.