Abstract
BACKGROUND: Cardiac resynchronization therapy (CRT) is an effective treatment for patients with advanced heart failure (HF). Nearly 30% of candidates are inadequate responders. The benefit of patients with right sided heart failure from CRT is still a matter of debate. We examined the effect of CRT on right ventricular (RV) dimensions and overall systolic function and whether RV function prior to CRT could have an impact on CRT response. METHODS: 94 patients with a mean age of 53.7±14.6 years including 19 (20%) females, with advanced HF (EF<35%, LBBB>120ms, or non-LBBB>150ms, with NYHA -III or ambulatory class IV) were enrolled and underwent CRT implantation. Standard two dimensional (2D) echocardiography, tissue Doppler imaging, for assessment of Left ventricular (LV) end-diastolic (LVEDV), and end-systolic volumes (LVESV), ejection fraction, RV maximum basal (RVD basal), maximum mid (RVD mid) transverse, maximum longitudinal (RVD long) diameters, TAPSE, fractional area change (FAC), and tricuspid lateral annular systolic velocity (S'), in addition to RV global longitudinal strain (RVGLS) measured by speckle tracking echocardiography, were done before CRT implantation and at the end of the follow up period (5.9±1.2 months). Patients presenting with reductions of LVESV of >15% were termed volumetric responders for further statistical analysis. RESULTS: 63 (67%) cases were volumetric responders. Both groups were matched regarding demographic, clinical, ECG, and echocardiographic criteria apart from the RV significantly smaller transverse diameters and significantly better systolic function parameters in the responders group prior to CRT compared to non-responders (NR) group. At the end of the follow up, only the responders group had further significant reduction in RV basal, mid and longitudinal diameters (33.6±7.1 vs 40.7±8.6, 21.4±4.9 vs 27±6.1, 68.3±10.8 vs 81.2±15, respectively), p<0.01, together with significant improvement in RV systolic performance: FAC (47.7±7.3 vs 40.9±6.4), TAPSE (25.2±4.6 vs 22.1±4.9), S' (15.3±2.3 vs 12.8±2.3), and GLS (26.1±2.1 vs 18.5±1.6), P<0.01, compared to baseline readings. S' and GLS were the only independent predictors of CRT response by multivariate analysis. S'>9cm/s, and GLS >12.45% had 100% sensitivity and 70%, 99.7% specificity, respectively for prediction of response to CRT. CONCLUSIONS: CRT induces RV reverse remodeling and improves RV systolic function particularly in cardiac volumetric responders. RV systolic dysfunction before CRT implantation could identify patients that might not benefit from CRT thus helping proper patient selection and optimizing CRT response.