Effects of digoxin, propranolol, and verapamil on exercise in patients with chronic isolated atrial fibrillation.
OBJECTIVE
The aim was to evaluate the effects of digoxin, propranolol, and verapamil on exercise in patients with chronic isolated atrial fibrillation.


METHODS
Patients with chronic isolated atrial fibrillation underwent maximal exercise testing before and after the administration of digoxin, propranolol, or verapamil. Heart rate, oxygen uptake and oxygen pulse were observed at rest, at gas exchange anaerobic threshold, and at peak exercise.


METHODS
The subjects were 10 patients (aged 48-78 years, mean age 60, SD 9, years) with chronic isolated atrial fibrillation.


RESULTS
During exercise without medication, the heart rate was 85 (SD 8) beats.min-1 at rest, 127(19) at the level of anaerobic threshold, and 175(17) at peak exercise. With digoxin, heart rate was reduced to 75(9) beats.min-1 at rest (control v digoxin, p less than 0.01). However, reduction of heart rate was not seen at anaerobic threshold or at peak exercise. With propranolol, heart rate was 63(7) beats.min-1 at rest, 99(16) at anaerobic threshold, and 138(28) at peak exercise (control v propranolol, all p less than 0.01). Heart rate with verapamil was 70(13) beats.min-1 at rest, 107(30) at anaerobic threshold, and 138(28) at peak exercise (control v verapamil, p less than 0.05 at rest and at anaerobic threshold, p less than 0.01 at peak exercise. Neither digoxin, nor propranolol, nor verapamil changed the oxygen uptake during exercise. Without medication, oxygen pulse was 6.5(2.0) ml.beat-1 at anaerobic threshold and 7.7(2.1) ml.beat-1 at peak exercise. With digoxin, the change of oxygen pulse, versus without medication, was not significant at rest or at anaerobic threshold but was increased at peak exercise, at 8.3(2.1) v 7.7(2.1) ml.beat-1, p less than 0.05. With propranolol, oxygen pulse was increased to 8.2(1.9) ml.beat-1 at anaerobic threshold and 9.2(2.3) ml.beat-1 at peak exercise (control v propranolol, both p less than 0.01). With verapamil, oxygen pulse was increased to 8.7(1.8) ml.beat-1 at anaerobic threshold and 10.0(2.1) ml.beat-1 at peak exercise (control v verapamil, both p less than 0.01).


CONCLUSIONS
Digoxin was effective in reducing heart rate at rest, but failed to reduce it during exercise. Propranolol and verapamil reduced heart rate at all levels of exercise as well as at rest. Oxygen uptake during exercise (total exercise capacity) was not reduced with propranolol or verapamil; this was thought to have been accomplished by an increased oxygen pulse.
Matsuda
M
M
School of Allied Health Sciences, Yamaguchi University, Japan.
Matsuda
Y
Y
Yamagishi
T
T
Takahashi
T
T
Haraguchi
M
M
Tada
T
T
Kusukawa
R
R
D000368:Aged; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology; D002908:Chronic Disease; D004077:Digoxin / Q000627:therapeutic use*; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000187:drug effects; D011433:Propranolol / Q000627:therapeutic use*; D014700:Verapamil / Q000627:therapeutic use*
D004077:Digoxin; D011433:Propranolol; D014700:Verapamil