Restoring Sinus Rhythm Improves Excessive Heart Rate Response to Exercise in Patients With Atrial Fibrillation.

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Abstract
The aim of this study was to investigate improvement in the cardiovascular response to isometric and isotonic exercises after reverting rhythm to sinus in patients with atrial fibrillation. Twenty seven cases with nonvalvular paroxysmal atrial fibrillation were included in the study. Sinus rhythm could not be restored in two cases so they were excluded. The remaining cases were divided into two groups according to the existence of cardiac diseasc. Group 1 (n:14, mean age. 60.8 +/- 14.9 years) included cases with cardiac diseases (8 of the patients had hypertension in addition to the cardiac disease) and group 2 (n:11, mean age. 64.8 +/- 13.9 years) included those without cardiac disease (patients with hypertension and diabetes mellitus). Isometric and isotonic exercise tests were performed in all of the patients before and 48 hours after the rhythm was reverted to sinus and the values in atrial fibrillation were compared with those in sinus rhythm (following cardioversion). The isotonic exercise period increased significantly in only group 1 patients following cardioversion (P = (0.0061). In both groups, the increase in heart rate during atrial fibrillation was significantly higher compared to those after being reverted to sinus, at all stages of the isotonic exercise (in groups 1 and 2, heart rate in patients with atrial fibrillation increased from 96.5 +/- 19.3 to 173.3 +/- 19.3 beats/min and 96.1 +/- 12.6 to 185.0 +/- 12.1 beats/ min, respectively; and in sinus rhythm, it ranged from 85.1 +/- 11.4 to 164.6 +/- 9.1 beats/min and 81.3 +/- 11.4 to 157.6 +/- 15.1 beats/min, respectively). Systolic arterial pressure increased significantly during atrial fibrillation in group 1, at the 2nd stage of the isotonic exercise test (P = 0.0070). In group 2, systolic arterial pressure increased significantly at the 3rd stage in sinus rhythm and at the 4th stage when in rhythm in atrial fibrillation. Also, diastolic arterial pressure increased significantly during atrial fibrillation only at the 3rd stage of the exercise. As a result, restoring sinus rhythm by cardioversion improves excessive heart rate responses to exercise significantly in patients with atrial fibrillation during both isometric and isotonic exercises. Also, we have revealed that the exercise time increased significantly by restoring sinus rhythm in patients with heart disease.