Atrial fibrillatory rate and risk of left atrial thrombus in atrial fibrillation

Aims In atrial fibrillation (AF), a relation between electrocardiogram (ECG) fibrillatory wave amplitude and thrombus formation has been sought for long with conflicting results. In contrast, the possible relation between atrial fibrillatory rate obtained from the surface ECG and left atrial thrombus for-mation in patients with AF is unknown and was consequently evaluated in this study. Methods and results One-hundred and twenty-five patients (mean age 64+ 12 years, 72 % male) with persistent non-valvular AF (mean duration 28+ 80 days) undergoing transesophageal echocardiography were studied. In all patients, standard 12-lead ECG recordings were acquired before the examination. Atrial fibrillatory rate was determined using spatiotemporal QRST cancellation and time–frequency analysis of lead V1. Atrial fibrillatory rate measured 401+ 63 fibrillations per minute (fpm, range 235–566 fpm) and was related with age (R 20.326, P, 0.001), ventricular rate (R 20.202, P 0.024), gender (407+ 62 in males vs. 387+ 64 fpm in females, P 0.038) but not AF duration (R 0.088, P 0.374), presence of lone AF (408+ 66 vs. 394+ 58 fpm, P 0.228), or beta-blocker or calcium channel blocker treatment (398+ 63 vs. 405+ 62 fpm, P 0.556). Age was the only inde-pendent predictor of fibrillatory rate (B 21.714, P, 0.001). In patients with left atrial thrombus (n 10), spontaneous echo contrast (SEC) was more frequentl