FUNCTIONAL-CAPACITY BEFORE AND AFTER CARDIOVERSION OF ATRIAL-FIBRILLATION - A CONTROLLED-STUDY

Objective-To evaluate the effect of cardioversion on peak oxygen consu mption (peak Vo(2)) in patients with long-standing atrial fibrillation , to assess the importance of underlying heart disease with respect to the response to exercise, and to relate functional capacity to long-t erm arrhythmia outcome. Design-Prospective controlled clinical trial. Setting-Tertiary referral centre. Patients-63 consecutive patients wit h chronic atrial fibrillation accepted for treatment with electrical c ardioversion. Before cardioversion all patients were treated with digo xin, verapamil, or combination of both to attain a resting heart rate less than or equal to 100 beats per minute. Interventions-Electrical c ardioversion. Main outcome measures-Peak Vo(2) measured before and 1 m onth after electrical cardioversion to compare patients who were in si nus rhythm and those in atrial fibrillation at these times. Maintenanc e of sinus rhythm for a mean follow up of 19 (7) months. Results-Mean (1SD) peak Vo(2) in patients in sinus rhythm after 1 month (n = 37) in creased from 21.4 (5.8) to 23.7 (6.4) ml/min/kg (+11%, P < 0.05), wher eas in patients with a recurrence of atrial fibrillation 1 month after cardioversion (n = 26) peak Vo(2) was unchanged. In patients who were in sinus rhythm both those with and without underlying heart disease improved, and improvement was not related to funct ional capacity or l eft ventricular function before cardioversion. Baseline peak Vo(2) was not a predictive factor for longterm arrhythmia outcome. Conclusion-R estoration of sinus rhythm improved peak Vo, in patients with atrial f ibrillation, irrespective of the presence of underlying heart disease. Peak Vo(2) was not a predictive factor for long-term arrhythmia outco me after cardioversion of atrial fibrillation. These findings suggest that cardioversion is the best method of improving functional capacity in patients with atrial fibrillation, whether or not they have underl ying heart disease and whatever their functional state.