TIME-COURSE OF HEMODYNAMIC-CHANGES AND IMPROVEMENT OF EXERCISE TOLERANCE AFTER CARDIOVERSION OF CHRONIC ATRIAL-FIBRILLATION UNASSOCIATED WITH CARDIAC-VALVE DISEASE

This study prospectively assessed the time course, magnitude and mecha nism of the hemodynamic changes after restoration of sinus rhythm in p atients with chronic atrial fibrillation (AF) unassociated with valvul ar disease. Severe cardiac dysfunction may occur after chronic suprave ntricular tachycardia in patients with and without underlying cardiac disease. Improvement may follow abolishment of the arrhythmia or adequ ate slowing of the ventricular rate. Eight patients were studied with a mean previous duration of AF of 10 +/- 9 months. Ejection fraction, exercise capacity and the atrial contribution to the left ventricular filling (only during sinus rhythm) were studied before cardioversion, after cardioversion and 1 week, 1 month and 6 months thereafter. A sig nificant improvement in ejection fraction from 36 +/- 13 to 53 +/- 8% (p < 0.05) occurred at 1 month after cardioversion. concomitantly, pea k oxygen consumption had increased at 1 month, from 20.1 +/- 7 to 25.2 +/- 6 ml/min/kg (p < 0.05). Thereafter, no further improvement in hem odynamic parameters occurred. The atrial systole improved already at 1 week (from 3 +/- 5 to 16 +/- 11%, p < 0.05) and remained unchanged th ereafter. Thus, restoration of sinus rhythm was associated with a dela yed improvement in ejection fraction and maximal exercise capacity, pr eceded by an early restoration of atrial contractility and an acute sl owing of the heart rate. The discrepancy in time course of restoration of atrial and ventricular function parameters suggests that an intrin sic left ventricular cardiomyopathy is present in patients with AF.