977 Quantitative assessment of myocardial contractile reserve during exercise in patients with mitral valve prolapse

Abstract

Background: Although the actual trends is toward early surgery in patients with asymptomatic severe organic mitral regurgitation (MR), some of them might already have latent left ventricular (LV) dysfunction. This study sought to examine whether tissue Doppler imaging measurement of longitudinal function could be used to identify contractile reserve (CR) during exercise in NYHA I-II patients with MR due to mitral valve prolapse. Methods: Forty-seven patients underwent quantitative off-line assessment of longitudinal function by averaging peak mitral annular velocities (PSv) obtained at rest and during semi-supine exercise test. Results: During test, CR defined by 34% improvement in ejection fraction was present in 25 patients. As compared to patients with CR, the degree of MR at rest (effective regurgitant orifice (ERO): 43±18 vs 24±14 mm2, p=0.0048) and at peak exercise (ERO 46±22 vs 23±19 mm2, p=0.0049) was greater in the absence of CR whereas ejection fraction was similar (69±6 vs 66±6%, p=ns). The increase in PSv (11±1.9 vs 8±2.5 cm/s, p=0.00029) and changes in LV end-systolic volume (-14±7 vs 4.4±12 ml p=0.0029) during exercise were higher in the CR group. In multivariate analysis, exercise-induced changes in LV end-systolic volume and in PSv independently predicted the presence of CR. An increase in PSv by 32 cm/s yielded a sensitivity of 88% and a specificity of 82% to identify positive CR. Conclusions: Latent LV dysfunction in patients with mitral valve prolapse could be reliably identified using tissue Doppler imaging.