P1495Energy loss by right ventricular pacing: normal left ventricular function vs. hypertrophic cardiomyopathy

Abstract

Abstract Background Right ventricular (RV) pacing causes left ventricular (LV) dysfunction. On the other hand, RV pacing for hypertrophic obstructive cardiomyopathy (HOCM) is an established treatment. LV flow energy loss (EL) is a new hemodynamic index for assessing cardiac function. However, the impact of RV pacing on EL remains unknown. Objective The objective of this study was to investigate the EL by RV pacing on normal LV function and hypertrophic cardiomyopathy (HCM). Methods A total of 28 patients underwent echocardiography for EL assessment under AAI (without RV pacing) and DDD (with all RV pacing) mode. Among them, 16 were sick sinus syndrome (SSS) patients with normal LV function, and 12 were HCM patients. EL was calculated from color Doppler images using a vector flow mapping. Results There were no significant difference in patients' background parameters between the SSS and the HCM groups. In the SSS group, mean systolic EL was significantly increased from AAI to DDD mode (14.9 to 19.2 mW/m, P<0.01, Panel A), whereas diastolic EL was not changed from AAI to DDD mode (22.3 to 18.8 mW/m, P=0.12). In the HCM group, systolic mean EL was significantly decreased from AAI to DDD mode (29.9 to 22.5 mW/m, P<0.01, Panel B) irrespectively of with or without LV outflow obstruction, whereas diastolic mean EL was not changed from AAI to DDD mode (28.6 to 24.3 mW/m, P=0.47). Change of flow energy loss Conclusion RV pacing increased mean systolic EL in normal LV function, but decreased in HCM with or without LV outflow obstruction. In the patients with HCM, the impact of RV pacing on EL is different compared with normal LV function.