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 V0₂) 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 usingpeak 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 V0₂). 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 V0₂ (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 V0 ₂ and VE/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 V0₂ measurements are required for the objective evaluation of functional capacity. The detection of a decline in peak V0₂ will improve the timing of valve replacement and repair, and avoid adverse outcomes.