Dual-chamber pacemaker in obstructive hypertrophic cardiomyopathy: Gradient variation with stress echocardiography

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 mu g/kg/min infusion, with increases of 10 mu g 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.