[Dyspnea of effort with an unusual cause: diagnostic significance of stress echocardiography]. / Dyspnée d'effort de cause inhabituelle: intérêt diagnostique de l'échographie de stress.

Left intra ventricular obstruction occurring during doubutamine stress echography is not exceptional but its clinical significance is controversial, notably due to the non-reproducibility of such a phenomenon during physical exercise in a certain number of patients. Moreover, in the studies which demonstrate a link between symptoms of effort and left intra ventricular obstruction during dobutamine echography, an echography with effort was not systematically performed in order to confirm this relationship. We describe the case of two patients, aged 50 and 62 years respectively, with no notable cardiovascular past history except hypertension, who had dyspnoea of effort in the absence of underlying cardiopathy in resting conditions. Dobutamine stress echography provoked a systolic anterior movement of the mitral valve (SAM) responsible for mitral insufficiency and significant left intra ventricular obstruction (maximum gradient of 77 mmHg for one, 130 mmHg for the other), with reproduction of spontaneous symptoms, in the absence of myocardial ischaemia. An effort echography performed several weeks later confirmed these data, even though a sublingual trinitrate (0.3 mg) test was without effect. In the absence of underlying hypertrophic cardiomyopathy the SAM (with left intra ventricular obstruction and mitral insufficiency) occurring during dobutamine stress echography could have clinical significance in selected cases, notably in hypertensive patients with effort intolerance who have normal systolic and diastolic function in the resting state, and absence of myocardial ischaemia during stress, as illustrated in our two observations. The therapeutic implications are clear, with patients like this successfully treated with beta-blockers.