Therapeutic Research

Abstract

Background：Right ventricular（RV）apical pacing（RVA）is an important and effective treatment in patients with bradycardia or atrioventricular block. However, it is well‒known that RVA pacing promotes left ventricular（LV） dysfunction due to LV dyssynchrony. Real‒time 3D echocardiography（RT3DE）can evaluate LV mechanical dyssynchrony with regional LV dysfunction. Hence, 123I‒15‒（p‒iodophenyl）‒3‒R, S‒methyl pentadecanoic acid myocardial single photon emission computed tomographic（BMIPP‒SPECT）imaging can detect myocardial metabolic abnormality. Object：We assess global and regional LV function in patients after permanent cardiac pacemaker implantations on RVA, in terms of mechanical dyssynchrony and metabolic abnormality of LV using RT3DE and BMIPP‒SPECT. Method and Results：The subjects were 28 patients after pacemaker implantation （79.3±7.7 year‒old, 11 male, 54.8 month after implantation）without coronary heart disease. On RT3DE analysis, ejection fraction was 72.9±8.8％. Five patients had LV dyssynchrony. On regional analysis, early peak contraction located in apex and mid segments of septal and inferior wall. Delayed peak contraction were found more frequently on the basal of septal and inferior wall. Nineteen of 28 patients were performed BMIPP‒SPECT. Thirteen（69％）were found perfusion abnormality, which were located more frequently on the basal of septal and inferior wall. Delayed peak contraction on RT3DE and perfusion abnormality on BMIPP‒SPECT were good conformity （Cohen κ；0.79）. Conclusion：LV mechanical dyssynchrony and metabolic abnormality has a closely relation in this study. It seems to be necessary to evaluate LV function in various modality for risk stratification, even if LV systolic function are normal in patients after permanent pacemaker implantations.