Cardiopulmonary exercise testing in patients with 21mm St. Jude Medical aortic prosthesis

Background and aim of the study: Small-sized prostheses may be associated w ith high transprosthetic gradients, particularly in patients with a body su rface area (BSA) >1.70m(2), affecting left ventricular mass regression, sym ptom improvement and long-term survival. However, the influence of such gra dients on exercise tolerance has not been clearly defined. The study aim wa s to verify the utility of cardiopulmonary exercise testing (CPX) in detect ing patient-prosthesis mismatch, and to identify the clinical and echocardi ographic data that predict exercise tolerance at CPX in patients with a 21m m St. Jude Medical (SJM) aortic prosthesis. Methods: Twenty patients (one male, 19 females; mean age 66 +/- 9 years) wi th a 21 mm SJM prosthesis were evaluated by means of 2D echocardiography an d CPX at 36 +/- 10 months after operation. Patients were divided into group s on the basis of a BSA of <1.70 m(2) (group 1, n = 12) or 21.70 m(2) (grou p 2, n = 8). Results: At echocardiography, left ventricular mass reduction was 16 +/- 10 % versus 9 +/- 6% in groups 1 and 2, respectively, mean gradient (MG) was 1 5 +/- 6 versus 17 +/- 4 mmHg (p = NS), effective orifice area index (EOAi) 0.86 +/- 0.10 versus 0.79 +/- 0.09 cm(2)/m(2) (p = 0.05). At CPX, group 2 p atients showed a significantly lower exercise duration (p = 0.02), maximum workload (p = 0.02), peak O-2 uptake (p = 0.01), anaerobic threshold (AT) ( p = 0.03), ventilatory equivalent for CO2 at AT (p = 0.007), and O-2 cost o f work (p = 0.03). Group 1 patients showed a ventilatory origin for their e ffort dyspnea, while group 2 patients showed a significant circulatory comp onent. At multivariate analysis, BSA, age, EOAi and MG were independent pre dictors of CPX results. Conclusions: In patients with a 21 mm aortic SJM prosthesis and a BSA great er than or equal to 1.70m(2), CPX allows detection of patient-prosthesis mi smatch, in terms of impaired exercise tolerance due to circulatory causes. CPX results can be anticipated on the basis of the patient's BSA, age, EOAi and MG. In these patients, technical solutions allowing implantation of a larger prosthesis should be considered whenever an active lifestyle is anti cipated after aortic valve replacement.