Left atrial volume, mitral annulus area, and ventricular cycle length causally affect mitral regurgitant orifice area in atrial fibrillation patients with AFMR.
Left atrial volume, mitral annulus area, and cardiac cycle length have a causal effect on the severity of atrial functional mitral regurgitation in patients with atrial fibrillation.
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Abstract Background There are multiple relationships between the factors known to be associated with the severity of functional mitral regurgitation (FMR – Figure A) which makes separation of a cause - effect relationship in the pathogenesis of FMR more difficult. Purpose Given the dynamic nature of atrial functional mitral regurgitation (AFMR) in atrial fibrillation (AF), we applied beat-to-beat analysis and Granger causality to dissect true cause-effect relationships. This type of statistical analysis tests whether a time-series parameter is the cause of another time-series parameter, by analyzing whether past changes of the first parameter predict future changes of the second parameter (Figure B). Methods We included 23 patients (age 79 ± 10 years) who underwent echocardiographic evaluation for FMR, all with atrial FMR and all in atrial fibrillation (AF). Five to ten successive cardiac cycles with 29 – 63 frames/patient, generating a total 441 time stamps, were analyzed to assess variability in the severity of FMR, assessed by effective regurgitant orifice area (EROA) and its determinant factors. Results Median absolute difference in EROA was 7.1 mm2 (range 2.6 – 14.2 mm2) in AF patients. EROA at baseline correlated significantly with the left atrial (LA) volume and mitral annulus (MA) area and (r=0.63, p0.001; r=0.51, p=0.025). Variability of the mitral regurgitant volume correlated mainly with variations in left atrial volume, MA area, mitral valve tenting height, and heart rate (Figure C). In patients with atrial FMR there was Granger causality for the relationships: LA volume - EROA, LV volume - EROA, MA area - EROA, and ventricular cycle length - EROA, identified in 92%, 78%, 47%, and 79% of the patients respectively (Figure D). In a multivariate vector autoregressive model in pooled data from all patients, LA volume, MA area, and ventricular cycle length independently predicted MV EROA. Conclusions Left atrial volume, mitral annulus area, and cardiac cycle length have a causal effect on the mitral valve effective regurgitant orifice area in patients with atrial functional mitral regurgitation. These findings underscore the importance of managing left atrial remodeling and heart rate in atrial fibrillation to potentially reduce the severity of AFMR.
Avram et al. (Sat,) reported a other. Left atrial volume, mitral annulus area, and ventricular cycle length causally affect mitral regurgitant orifice area in atrial fibrillation patients with AFMR.