Refractory exercise-induced severe mitral regurgitation in a patient with hypertrophic cardiomyopathy

Excerpt

A-58-year-old man was hospitalized for recurrent pulmonary edema and cardiogenic shock. Cardiac magnetic resonance imaging revealed basal interventricular septal thickening with late gadolinium enhancement. Exercise stress echocardiography revealed left ventricular outflow tract obstruction (LVOTO) secondary to systolic anterior movement of the anterior mitral leaflet and severe mitral regurgitation (MR) (Fig. 1A, B), and therefore, he was initially diagnosed as having hypertrophic cardiomyopathy with exercise-induced LVOTO. Exercise test was terminated at 50 W, because his blood pressure dropped from 120/90 to 90/40 mmHg and heart rate increased from 60/min to 125/min with cold sweat. During the stress echocardiography, pressure gradient at LVOT was increased from 10 to 60 mmHg. As medical treatment was ineffective, he underwent percutaneous transluminal septal myocardial ablation (PTSMA) (Fig. 1C). However, repeated excise echocardiography after complete hemodynamic recovery showed exercise-induced severe functional MR despite the elimination of LVOTO. Detailed echocardiographic examination revealed that the mitral annular diameter had increased from 28 × 26 mm to 33 × 30 mm during exercise (Fig. 1D, E), whereas the coaptation depth of the mitral leaflet, tenting height and area had changed only mildly (from 7 to 5 mm, from 8 to 7 mm, and from 1.4 to 1.6 cm², respectively). Therefore, the patient was clinically diagnosed as having isolated exercise-induced severe MR, and mitral valve surgery was planned. Surgical mitral annuloplasty was ultimately performed, because there was no obvious abnormality in the valvular tissue except for mitral annular dilatation. This resulted in dramatic improvement of the excise-induced MR (Fig. 1F). The patient complained no symptom except leg fatigue during exercise echocardiography, and his blood pressure did not drop. The exercise-induced LVOTO made it challenging to detect the precise cause of excise-induced MR in the present case.

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