DUAL-CHAMBER PACING IN HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY - BENEFICIAL EFFECT OF ATRIOVENTRICULAR JUNCTION ABLATION FOR OPTIMAL LEFT-VENTRICULAR CAPTURE AND FILLING

Clinical improvement with dual chamber pacing has largely been reporte d in patients suffering from hypertrophic obstructive cardiomyopathy a nd mainly attributed to the reduction of the subaortic pressure gradie nt. To be effective, pacing must induce a permanent and complete captu re of the LV In two patients of our collective, symptoms (angina and d yspnea NYHA Class III and/or syncopes) persisted or relapsed despite p acing. This was related to the inability to obtain full LV capture due to a too-short native PR interval. RF ablation of the AV junction was therefore performed in both patients, resulting in permanent AV block in one and prolonged PR interval up to 310 ms in the second. Pacing t vas thereafter associated with an immediate and significant clinical i mprovement related to permanent LV capture, whatever the patient's act ivity. After RF ablation, the A Ir delay was set up to induce the best LV filling as assessed by Doppler analysis of mitral flow. Our observ ations suggest that RF ablation or modification of the AV junction can be a successful procedure in some patients with residual or recurrent symptoms, when the latter result from a loss of capture or from the i nability to program an AV delay that does not compromise the active co mponent to LV filling. Doppler echocardiography is a simple and effect ive mean to assess the hemodynamic effect of AV interval modulation in this setting.