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document
Exercise capacity in atrial fibrillation : a substudy of the Sotalol-Amiodarone Atrial Fibrillation Efficacy Trial ( SAFE-T ) . BACKGROUND Therapy for chronic atrial fibrillation ( AF ) focuses on rate versus rhythm control , but little is known about the effects of common therapeutic interventions on exercise tolerance in AF . METHODS Six hundred fifty-five patients with chronic AF underwent maximal exercise testing at baseline and 8 weeks , 6 months , and 1 year after randomization to sotalol , amiodarone , or placebo therapy and attempted direct current cardioversion . Analyses of baseline determinants of exercise capacity , predictors of change in exercise capacity at 6 months and 1 year , and the short- and long-term effects of cardioversion on exercise capacity were made . RESULTS Age , obesity , and presence of symptoms accompanying AF were inversely associated with baseline exercise capacity , but these factors accounted for only 10 % of the variance in exercise capacity . Patients most likely to benefit from cardioversion were those most limited initially , younger , not obese or hypertensive , and with an uncontrolled ventricular rate at baseline . Conversion to sinus rhythm ( SR ) resulted in significant reductions in resting ( approximately 25 beat/min ) and peak exercise ( approximately 40 beat/min ) heart rates at 6 months and 1 year ( P < .001 ) . Successful cardioversion improved exercise capacity by 15 % at 8 weeks , and these improvements were maintained throughout the year . This improvement was observed both among those who maintained SR and those with intermittent AF . CONCLUSION Cardioversion resulted in a sustained improvement in exercise capacity over the course of 1 year , and this improvement was similar between those in SR and those with SR and recurrent AF . Patients most likely to improve with treatment tended to be younger and nonobese and have the greatest limitations initially .
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Intervention_Physical
maximal exercise testing
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Intervention_Pharmacological
sotalol
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Intervention_Pharmacological
amiodarone
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Intervention_Pharmacological
placebo
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Intervention_Physical
attempted direct current cardioversion
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Intervention_Physical
cardioversion
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Intervention_Physical
Cardioversion
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Outcome_Physical
Exercise capacity
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Outcome_Physical
resting
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Outcome_Physical
peak exercise
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Outcome_Physical
heart rates
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Outcome_Physical
exercise capacity