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We report the case of a man in his 60s who had dilated cardiomyopathy with severe functional mitral regurgitation. Four years after a cardiac resynchronization therapy (CRT) device with an implantable cardioverter defibrillator was implanted, this device was replaced with an adaptive CRT device because of battery consumption. Seven months after replacement of this device, the left ventricular pacing to right ventricular activation and the atrioventricular delay from automatic adjustments contributed to less functional mitral regurgitation. The findings from our case suggest that optimal CRT, by measuring intracardiac conduction parameters, is effective for functional mitral regurgitation.

Introduction: The Rho/Rho-kinase pathway has been related to various physiological responses of the cardiovascular system. Previous reports have suggested a significant effect of Rho signals on the electrophysiological characteristics of the heart. We hypothesized that the Rho/Rho-kinase system would contribute to the rapid pacing-related change of atrial effective refractory period (AERP). Methods and Results: In 17 dogs, AERP was measured at the right atrial appendage (RAA) and posterior left atrium (LA) before, during, and after 6-hours rapid atrial pacing at 500 bpm. Saline control (n = 5), verapamil (n = 5), or fasudil (n = 7) were infused throughout the protocol. The shortening of AERP after rapid pacing was abrogated by the administration of verapamil, as reported in previous studies. Furthermore, fasudil (Rho/Rho-kinase inhibitor) influenced the change of AERP in a manner similar to the infusion of verapamil throughout the experiments. Conclusions: Since the AERP was attenuated by fasudil, rapid pacing-related atrial electrophysiological changes might involve the Rho/Rho-kinase pathway.