Exercise-induced regurgitation in mitral valve prolapse: is it a new disease?

Since the initial description of mitral valve prolapse as billowing mitral leaflets leading to regurgitation (1-4), physicians have had to contend with the problem of its noninvasive diagnosis (5-9). Lack of specificity of diagnostic criteria led to a "disease by definition" frequently diagnosed in otherwise normal subjects (10-22). Recent efforts have attempted to restore prolapse to the category of a disease more consistent with its surgical and pathologic manifestations (23-25) and to identify those patients at greatest risk for its valve-related complications, namely, the need for mitral valve surgery and the development of endocarditis (26-35). Exercise-induced regurgitation in mitral valve prolapse. The study by Stoddard et al. (36) in the current issue of the Journal begins with the anticipation that exercise-induced mitral regurgitation might be able to predict the development of complications in patients with mitral valve prolapse and no regurgitation at rest. Conceptually, exercise could potentially reveal valves more susceptible to augmented stresses on the prolapsing leaflets and attached papillary muscles (37-39). Nevertheless, although postural and pharmacologic changes in left ventricular volume have been shown to alter the timing of prolapse (40-42), there is virtually no information concerning exercise-induced changes in its associated mitral regurgitation. Bashore et al. (43) found no exercise-induced regurgitation by left/right ventricular stroke-count ratio in 16 patients. The only other studies have used mental stress (44) to increase both click amplitude and the degree of prolapse by two-dimensional echocardiography without evaluating mitral regurgitation (45,46). The concept underlying the current study is therefore highly original. A new disease? The results initially appear to introduce a new condition or variant affecting 32% of patients without mitral regurgitation at rest, affecting relatively young subjects