We assessed whether the presence of latent myocardial dysfunction, evaluated by echocardiographic derived force-frequency relationship (FFR) during exercise, predicts the appearance of stress-induced pulmonary hypertension in minimally symptomatic patients with severe mitral regurgitation (MR). Two groups of patients were identified: group I with normal (</=40 mm Hg) and group II with abnormal (>40 mm Hg) peak stress systemic pulmonary artery pressure. Group I had normal and upsloping FFR and group II had abnormal flat or biphasic FFR. Therefore, in patients with severe MR and apparently normal left ventricular function, the stress-induced pulmonary hypertension seems to be related to the presence of latent left ventricular dysfunction.