Association of atrial fibrillation in patients with interatrial block over prospectively followed controls with comparable echocardiographic parameters.

Interatrial block (IAB) (P wave >or=110 ms) is a potential risk of atrial fibrillation (AF). However, few investigations have assessed the relevance of echocardiographic parameters, particularly the contribution of its known correlate, left atrial enlargement in this regard. We identified 32 consecutive patients with comparable echocardiographic parameters, such as left atrial dimension and left ventricular ejection fraction. Patients were evaluated for IAB and followed for 15 months for cardiovascular events (heart failure, transient ischemic attacks, and stroke), atrial tachyarrhythmias (AF/atrial flutter), and death. Preexisting AF and IAB (p = 0.02) were significantly associated with future AF events. However, logistic regression analysis indicated that IAB was not an independent predictor of future AF, only preexisting atrial tachyarrhythmias was (hazard ratio 39.5, 95% confidence interval 2.7 to 576.3, p = 0.007). In conclusion, in patients with comparable echocardiographic parameters, such as left atrial size and left ventricular ejection fraction, IAB remained associated with AF after a 15-month follow-up. Additional investigation is needed to confirm the extent of the association.