Mitral annular calcification is a predictor for incident atrial fibrillation

Background Mitral annular calcification (MAC) has been associated with adverse cardiovascular disease outcomes and stroke in longitudinal and community-based cohorts. Prospective data are limited on its association with atrial fibrillation (AF). Methods: We examined the association between MAC and the long-term risk of AF over 16 years of follow-up in participants in the original cohort of the Framingham Heart Study who attended a routine examination between 1979 and 1981. MAC was assessed by M-mode echocardiography. Cox proportional-hazards models were used to estimate hazard ratios (HR) for incident AF. Results: Of 1126 subjects who had adequate echocardiographic assessment and were AF-free at baseline, 149 (13%) had MAC. There were 217 cases of incident AF (42 in subjects with MAC). The age- and sex-adjusted incidence rate was 362 per 10,000 person-years in subjects with MAC compared with 185 per 10,000 person-years in those without MAC. In multivariable-adjusted analyses, MAC was associated with an increased risk of AF (HR 1.6, 95% Cl 1.1-2.2). This association was attenuated upon further adjustment for left atrial size (HR 1.4, 95% Cl 0.9-2.0). Conclusions: The association between MAC and incident AF may be mediated partially through left atrial enlargement. These data suggest the importance of better understanding the mechanisms involved in cardiac valvular calcification. (C) 2004 Elsevier Ireland Ltd. All rights reserved.