Complex valve disease: pre-surgical functional capacity evaluation using peak oxygen consumption.

BACKGROUND AND AIM OF THE STUDY

Complex heart valve disease constitutes both mixed and multiple valve pathologies that coexist in a single heart. The chronicity of complex valve disease results in a slow decline in functional capacity. Currently, very few data exist relating to chronic complex valve disease. The clinical assessment of exertional dyspnea (NYHA class) is central to the decision to operate and predict a prognosis. Dyspnea causes significant functional limitations. Peak oxygen consumption (peak VO2) is the 'gold standard' of objectively measuring functional aerobic capacity, and is an important predictor of prognosis. The onset of dyspnea is the most common indication for valve surgery. The study aim, in patients with complex valve disease, was to: (i) objectively assess functional aerobic capacity using peak VO2; and (ii) compare the differences between NYHA classes I and II in relation to body composition, echocardiographic severity, and functional capacity

METHODS

A total of 45 patients with complex valve disease, who had been referred for the timing of surgery, was evaluated. The control group comprised 15 healthy subjects. All patients underwent a clinical assessment (to determine NYHA class), echocardiography and cardiopulmonary testing (peak VO2).

RESULTS

Patients with complex valve disease achieved significantly lower peak VO2 values than controls (16 +/- 5.9 versus 31.4 +/- 5.9 ml/kg/min; p = 0.0001). The peak VO2 (percentage predicted) was significantly different between asymptomatic (NYHA class I) patients (70.9 +/- 20%) and symptomatic (NYHA class II) patients (55.1 +/- 21%; p = 0.003), with an overlap between classes. There was no significant difference in the echocardiographic severity of the valve lesions between NYHA classes. In a multivariable regression analysis, the peak VO2 and VEN/VCO2 slope were powerful predictors of poor outcome (Hazards ratio 2.15, 5.62; p <0.05).

CONCLUSION

Patients with complex valve disease show significant functional capacity impairment, which may be difficult to detect from their clinical presentation. Consequently, peak VO2 measurements are required for the objective evaluation of functional capacity. The detection of a decline in peak VO2 will improve the timing of valve replacement and repair, and avoid adverse outcomes.