[Relationship between exercise capacity and brain natriuretic peptide in patients after cardiac surgery].

OBJECTIVES

Physical training in cardiac patients can increase exercise capacity and reduce plasma brain natriuretic peptide(BNP) concentration, but these effects may depend on the etiology of cardiac disease. The change in exercise capacity and BNP during the training period were investigated in patients with different cardiac diseases.

METHODS

Ninety-one patients after coronary artery bypass grafting(CABG) and 78 patients after valve replacement (VR) underwent a symptom-limited incremental cardiopulmonary exercise test before (1 month) and 6 months after physical training. Anaerobic threshold and peak oxygen uptake(peak-Vo2) were measured during the cardiopulmonary exercise test. Before each cardiopulmonary exercise test, a blood sample was obtained in the resting condition for measuring BNP.

RESULTS

Anaerobic threshold and peak-Vo2 were increased significantly from 1 month to 6 months in both groups. BNP in the CABG group indicated a tendency to decrease (194.6 +/- 155.3-->144.2 +/- 232.2 pg/ml, p < 0.1) from 1 month to 6 months. BNP in VR group was significantly decreased (159. 9 +/- 115.5-->112.8 +/- 131.7 pg/ml, p < 0.05) during the training period. The CABG group showed a significant negative correlation between peak-Vo2 and BNP at 1 month(r = -0.28, p < 0.01) and at 6 months(r = -0.39, p = 0.001). The VR group showed a significant negative correlation between peak-Vo2 and BNP at 6 months(r = -0.32, p < 0.01), but not at 1 month.

CONCLUSIONS

Six months of physical training in patients after cardiac surgery may improve exercise capacity and reduce BNP. BNP concentration in the VR group before physical training did not reflect functional capacity.