Prediction of atrial fibrillation in patients with severe mitral stenosis—role of atrial contribution to ventricular filling

OBJECTIVE: Atrial contribution to ventricular filling was studied to assess its role in predicting the future development of atrial fibrillation (AF) in patients with severe mitral stenosis (MS) and sinus rhythm. DESIGN: Two hundred and eight patients with severe MS and sinus rhythm were followed up for 1 year. Baseline data were compared between group I (who developed AF at follow-up) and group II (who maintained sinus rhythm). Left atrial size, severity of MS, velocity time integral (VTI) of mitral valve flow and VTI due to atrial systole (A-VTI) were noted. Percentage contribution of A-VTI to the total VTI (A-%) was calculated. Sensitivity and specificity of A-% to predict the onset of AF was obtained. RESULTS: Left atrial size, severity of MS and total VTI were similar in the two groups. Group I patients were older (31.1 +/- 9.1 and 18.4 +/- 6.5 years, respectively, p < 0.03) with smaller A-VTI (5.3 +/- 2.2 and 6.7 +/- 3.4 cm, respectively, p < 0.01) and A-% (8.9 +/- 1.8 and 11.2 +/- 2.7, respectively, p < 0.003). A-% of <9% (mean value of A-VTI in group I) had high sensitivity (84%, positive predictive value 76%) and specificity (80%, negative predictive value 87%) to predict the development of AF. CONCLUSION: Atrial contribution to ventricular filling is reduced in patients prone to develop AF (due to inefficient left atrial contraction, much before its dilatation). It can be used for early identification of patients likely to develop AF with high sensitivity and specificity. It is simple, easily available, cost-effective and will guide earlier intervention and more frequent follow-up. There is a preclinical loss in atrial pump function much before the eventual onset of AF.