Delayed Improvement in Exercise Capacity With Restoration of Sinoatrial Node Response in Patients After Combined Treatment With Surgical Repair for Organic Heart Disease and the Maze Procedure for Atrial Fibrillation

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Abstract
Background Although the Maze procedure successfully restores sinus rhythm in patients with heart disease and atrial fibrillation, it is still uncertain whether an addition of the Maze procedure in cardiac surgery is beneficial for exercise performance of the patients after surgery. Methods and Results The Maze procedure was performed in 25 patients (age, 37 to 70 years) during valve surgery (18 patients) or closure of atrial septal defect (7 patients). A cardiopulmonary exercise test using ramp incremental protocol (15 W/min) was performed before and 1 month, 6 months, and 1 year after surgery. Sinus conversion was obtained in 23 of 25 patients 1 month after surgery. However, sinoatrial (SA) node response to exercise was attenuated by surgery: Mean heart rate (HR) was 83±13/min at rest, 94±13/min at 60 W, and 107±17/min at peak exercise. Peak oxygen uptake (Pȯ 2 ) was unchanged at this period (before, 17.6±4.5 mL · min −1 · kg −1 ; 1 month after, 17.5±4.2 mL · min −1 · kg −1 ). Thereafter, SA node response was restored 6 months after surgery: Mean HR was 84±13/min at rest, 104±16/min at 60 W, and 130±20/min at peak exercise ( P <.01 versus 1 month). Pȯ 2 was also improved at this period (20.7±4.0 mL · min −1 · kg −1 , P <.01). The increase in Pȯ 2 from 1 month to 6 months after surgery was correlated with the increase in peak HR ( y =0.73 x ±3.6, r =.79). There were no further changes in heart rate response or Pȯ 2 from 6 months to 1 year after surgery. Conclusions Atrial fibrillation was successfully treated by combined treatment with surgical repair for organic heart disease and the Maze procedure. However, SA node response to exercise was attenuated early after surgery. Thus, exercise capacity was improved at the late phase after surgery, which was related to the extent of restoration in SA node response.