Atrial fibrillation in congestive cardiomyopathy: Echocardiographic and hemodynamic correlates

Abstract Previous studies have suggested an unexpectedly low incidence of atrial fibrillation in patients with congestive cardiomyopathy. To further investigate the incidence of chronic atrial fibrillation in these patients and its relationship to left atrial dimension and pressure, we retrospectively examined M‐mode echocardiographic and cardiac catheterization data from 54 patients with idiopathic (n = 29) and ischemic (n = 25) congestive cardiomyopathy. The incidence of atrial fibrillation (17%) was surprisingly low given the degree of left atrial enlargement (51 ± 5 mm; mean ± SD) and left atrial hypertension (19 ± 8 mm Hg). In addition, there were no significant differences in left atrial pressure or left atrial dimension between those congestive cardiomyopathy patients in sinus rhythm and those in atrial fibrillation, nor was there a higher incidence of secondary mitral regurgitation in patients in atrial fibrillation. Comparisons were also made between congestive cardiomyopathy patients and 21 patients with primary mitral valve disease and atrial fibrillation. Left atrial pressure was not significantly different between these groups. However, the mean left atrial dimension of the patients with mitral valve disease (56 ± 8 mm) was greater (P < 0.01) than that of patients with idiopathic (51 ± 6 mm) or ischemic (50 ± 4 mm) cardiomyopathy in sinus rhythm and also greater (P = 0.07) than left atrial dimension (51 ± 6 mm) of congestive cardiomyopathy patients in atrial fibrillation. Furthermore, massive enlargement of the left atrium (greater than 60 mm) was a common feature of mitral valve disease (33% incidence) but occurred only rarely in congestive car‐diomyopathy (5% incidence). We conclude that while left atrial volume and pressure loads may be important contributors to the pathogenesis of atrial fibrillation, these factors are not sufficient to produce the arrhythmia in most patients with congestive cardiomyopathy. Other variables such as disease duration or the degree of atrial fibrosis or inflammation may also be important in determining which patients with left atrial enlargement will develop atrial fibrillation. Furthermore, massive left atrial enlargement (left atrial dimension > 60 mm) is rarely associated with ischemic or idiopathic congestive car‐diomyopathy and suggests underlying primary mitral valve disease.