Left ventricular remodeling after aortic valve replacement with the Toronto-SPV prosthesis.

The remarkable hemodynamic features of the aortic Toronto SPV prosthesis have been reported. To assess the efficacy of these characteristics to produce a favorable left ventricular remodeling and to test the limits of the dobutamine stress test to check these results, 25 consecutive patients, who had undergone aortic valve replacement with Toronto SPV, were monitored with dobutamine and exercise stress tests for 1 year. Among the prosthetic and left ventricular morphological and functional parameters evaluated, dobutamine infusion produced an overestimation of prosthetic and left ventricular outflow tract gradients, effective orifice area, and prosthetic resistance compared with the more physiological exercise test (P<.01). These misleading results were probably due to the inotropic and unloading effects of dobutamine in still hypertrophied hearts. Indexed myocardial mass and wall thickness decreased significantly during the follow-up period (P<.01), whereas left ventricular diastolic diameter and ejection fraction showed no significant variations. These data show that the positive left ventricular remodeling is due only to the regression of the hypertrophy and not to the reduction of left ventricular diameters. Based on results from this study, the dobutamine stress test should be avoided to evaluate patients with aortic valve prostheses and still present left ventricular hypertrophy. The Toronto SPV produces a favorable left ventricular remodeling during the first year of follow-up, and is likely to improve.