Indexed left atrial volume is superior to left atrial diameter in predicting nonvalvular atrial fibrillation recurrence after successful cardioversion: a prospective study.
BACKGROUND
Although indexed left atrial volume (iLAV) is the most accurate measure of left atrial size, it has not been evaluated prospectively as predictor of recurrence of atrial fibrillation (AFib) after successful cardioversion (CV).


METHODS
We prospectively selected 76 patients (mean age 66.1 ± 13.6 years, 65.8% men) with AFib who underwent successful CV. Baseline clinical and echocardiographic characteristics were obtained before CV. LAV was measured using Simpson's method and indexed to body surface area. All patients were scheduled for follow-up visit at 1, 6, 12 months, and then annually. A 24-hour Holter ECG was performed within 6 months and each time the patients reported symptoms suggestive of arrhythmia.


RESULTS
The 52 patients (68.4%) with AFib recurrence had larger iLAV (35.5 ± 8.9 mL/m(2) vs 27.0 ± 6.7 mL/m(2) , P < 0.001). Anteroposterior LA diameter was not associated with AFib relapse (OR 1.08, 95% CI: 0.96-1.21, P = 0.09). Each unit increase in iLAV was associated with a 1.15-fold increased risk of recurrence (OR 1.15, 95% CI: 1.06-1.25, P < 0.001). In a multivariable model, iLAV remained the only independent predictor of relapse (adjusted OR 1.14, 95% CI: 1.02-1.28, P = 0.02). The area under ROC curves, generated to compare LA diameter, and iLAV as predictors of AFib recurrence were 0.56 (SE 0.07) versus 0.78 (SE 0.05), respectively (P = 0.003).


CONCLUSION
This is the first prospective study to show that larger iLAV, as a more accurate measure of LA remodeling than anteroposterior diameter, is strongly and independently associated with a higher risk of AFib recurrence after CV.