The effect of cardioversion on maximal exercise capacity in patients with chronic atrial fibrillation.
To evaluate the effect of cardioversion on exercise capacity, 11 male patients (59 +/- 8 years) with chronic atrial fibrillation underwent maximal exercise testing using gas exchange techniques before and after successful cardioversion to normal sinus rhythm. Testing was conducted 1 day prior to and a mean of 39 (range 10 to 95) days following cardioversion. Heart rate, blood pressure, and respiratory gas exchange responses were evaluated at rest, at a standard submaximal workload (3.0 mph/0% grade), at the gas exchange anaerobic threshold, and at maximal exertion. Cardioversion resulted in a mean decrease in resting heart rate of 37 beats/min (113 +/- 16 versus 76 +/- 10 beats/min, p less than 0.001). While mean heart rate was approximately 50 beats/min lower following cardioversion at both submaximal stages of exercise p less than 0.001), oxygen uptake was not different. At maximal exercise, heart rate was markedly reduced (192 +/- 24 to 144 +/- 21 beats/min, p less than 0.001) and maximal oxygen uptake was higher (1.86 +/- 0.5 to 2.06 +/- 0.5 L/min, p less than 0.05) after cardioversion. In addition, an improved efficiency of ventilation was observed at exercise levels exceeding 60% of maximal oxygen uptake.
Atwood
J E
JE
Cardiology Department, Long Beach Veterans Administration Medical Center, CA 90822.
Myers
J
J
Sullivan
M
M
Forbes
S
S
Sandhu
S
S
Callaham
P
P
Froelicher
V
V
D000368:Aged; D015308:Anaerobic Threshold; D001281:Atrial Fibrillation / Q000503:physiopathology*; D002908:Chronic Disease; D004452:Echocardiography; D004554:Electric Countershock; D005080:Exercise Test; D006801:Humans; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance; D011659:Pulmonary Gas Exchange; D012146:Rest