Objectives. This study investigated the incidence, predisposing factors and significance of the onset of atrial fibrillation (AF) in patients with chronic congestive heart failure (CHF). Background. The association between CHF and AF is well documented, but the factors that predispose to the onset of the arrhythmia and its impact remain controversial. Methods. We prospectively followed up 344 patients with CHF and sinus rhythm (SR). Over a period of 19 ± 12 months (mean ± SD), 28 patients developed atrial fibrillation (AF), which became chronic in 18. Results. At baseline, no differences were found in any clinical and hemodynamic variables between patients who developed chronic AF and those who did not. Reversible AF occurring during follow-up and lower mitral flow velocity at atrial contraction as detected at the last evaluation in SR were independent predictors of the subsequent development of chronic AF. When AF occurred, New York Heart Association functional class worsened (from 2.4 ± 0.5 to 2.9 ± 0.6, p = 0.0001), peak exercise oxygen consumption declined (from 16 ± 5 to 11 ± 5 ml/kg per min, p = 0.002), cardiac index decreased (from 2.2 ± 0.4 to 1.8 ± 0.4, p = 0.0008), and mitral and tricuspid regurgitation increased (from grade 1.8 ± 1.1 to grade 2.4 ± 1.4, p = 0.0001 and from grade 1.0 ± 1.2 to grade 1.8 ± 1.2, p = 0.001, respectively). Systemic thromboembolism occurred in 3 of the 18 patients with AF. Nine of 18 patients died after AF, and the occurrence of AF was a predictor of major cardiac events. Conclusions. In patients with CHF, reversible AF and reduction of left atrial contribution to left ventricular filling predict the subsequent development of chronic AF. The onset of AF is associated with clinical and hemodynamic deterioration and may predispose to systemic thromboembolism and poorer prognosis.
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