The role of cardiopulmonary exercise test in mitral and aortic regurgitation: it can predict post-operative results.

Background: We evaluated the efficacy of the cardiopulmonary exercise test as an objective indicator of functional status and as a pre-operative prognostic indicator in patients with mitral regurgitation (MR) and aortic regurgitation (AR).
Methods: Cardiopulmonary exercise tests and echocardiography were performed in 47 patients (MR: 30, AR: 15, MR + AR: 2) before surgery and repeated one year after surgery. We compared the New York Heart Association (NYHA) functional class, peak oxygen consumption rate (VO2peak), exercise duration, left ventricular dimension and ejection fraction, before and after surgery.
Results: Initial VO2peak and exercise duration were significantly different according to NYHA class. A year later, NYHA functional class improved from 2.1 +/- 0.1 to 1.4 +/- 0.1 (p < 0.001). The VO2peak was significantly increased (21.7 +/- 1.0 to 23.7 +/- 1.0 mL/kg per min, p = 0.008) and exercise duration also increased (521.7 +/- 35.9 to 623.3 +/- 35.7 seconds, p < 0.001). When patients were analysed according to their post-operative NYHA functional class, those with class I showed significantly different pre-operative VO2peak (class I: 23.7 +/- 1.1, II: 18.3 +/- 1.5 mL/kg per min, p = 0.005) and exercise durations (class I: 587.5 +/- 43.2, II: 415.6 +/- 55.7 seconds, p = 0.02). Patients with higher pre-operative VO2peak (19.0 mL/kg per min) more frequently became NYHA functional class I than those with a lower pre-operative VO2peak (76.7% vs. 35.3%, p = 0.02). But baseline left ventricular dimension and ejection fraction by echocardiography were not different between post-operative class I and II group.
Conclusion: VO2peak and exercise duration are excellent parameters to evaluate the subjective functional class and to predict the post-operative functional class of patients with MR and/or AR. Patients with a pre-operative VO2peak of 19.0 mL/kg per min or more will have a better functional status one year after surgery.