[Dual-chamber pacemakers in obstructive hypertrophic cardiomyopathy: gradient variation with stress echocardiography]. / Marcapasos bicameral en la miocardiopatía hipertrófica obstructiva: variación del gradiente con ecocardiografía de estrés.

INTRODUCTION: Permanent cardiac pacing with a dual chamber pacemaker has become a valid alternative in treatment of patients with obstructive hypertrophic cardiomyopathy and refractory symptoms to pharmacological treatment, with a significant decrease of left ventricular outflow tract gradient. AIM: To assess any modification of the gradient with dobutamine stress echocardiography. PATIENTS AND METHODS: We study 10 patients with obstructive hypertrophic cardiomyopathy and angina and/or dyspnea refractory to customary pharmacological treatment. A dual chamber pacemaker had been implanted 3-6 months previously. A dobutamine stress echocardiography was performed, beginning with a 10 microgram/kg/min infusion, with increases of 10 micrograms each 3 minutes until a maximum of 40. Modification of subaortic gradient, severity of systolic anterior motion of mitral valve (SAM, degree 0-3/3) and severity of mitral regurgitation (degree 0-4/4) were assessed. RESULTS: Subaortic gradient decreased in all patients after pacemaker implantation (90 +/- 15 vs 20 +/- 10 mmHg; p < 0.001). With stress echocardiography the gradient increased in all patients (20 +/- 10 to 101 +/- 13 mmHg; p < 0.001). After implant there were only two patients with a +1 SAM, while during stress echocardiography SAM developed in all patients in +2 or +3 degree. Three patients had +1 mitral regurgitation after pacemaker implantation but during stress echocardiography 2-4/4 mitral regurgitation developed in all patients. CONCLUSIONS: Permanent dual chamber pacing decreased left ventricular outflow tract gradient in patients with obstructive hypertrophic cardiomyopathy, but during dobutamine stress echocardiography obstruction echocardiographic signs appeared.