Abstract 3521: Pulmonary Vascular Resistance Predicts Response to Cardiac Resynchronization Therapy
BACKGROUND: Cardiac resynchronization therapy (CRT) improves functional class and cause reverse remodeling in pts with advanced heart failure (HF). Recently it was shown that elevated pulmonary vascular resistance (PVR) in pts who underwent CRT is an independent predictor of all-cause mortality or transplantation and HF admission However the impact of PVR on response to CRT is not well defined.
METHODS: 87pts (68±10yrs) with advanced HF (NYHA Class=3.3±0.5, EF=18±5%) and optimal medical therapy undergoing CRT formed the study cohort. Reverse remodeling was assessed by left ventricular ejection fraction (LVEF) and LV end systolic volume index (LVESVI) using modified Simpson’s biplane method during a follow up of 19±10 months. The pulmonary vascular resistance in Wood Units (WU) was measured by measuring the maximum velocity of tricuspid regurgitant jet (TR max) and VTI of right ventricular outflow tract (RVOT VTI) and using the validated formula of [TR max/RVOT VTI] ×10 +0.16. Responders were defined by decrease in LVESVI by 15% from baseline.
RESULTS: 51 pts (59%) were responders to CRT and demonstrated significantly increased LVEF compared to non responders (19±5 % to 33±2 % vs 17±2% to 16±3 %; p=0.01 for ΔLVEF), and decreased LVESVI (95±20 ml/m2 to 72±26 ml/m2 vs 89±24 ml/m2 to 82±27 ml/m2; p=0.02 for ΔLVESVI). PVR was significantly higher in non responders (2.9±0.3 vs 1.9±0.3; p=0.02) compared to responders. PVR of 2.7 WU gives a specificity of 80% and sensitivity of 56% to predict non responders to CRT (Figure⇓).
CONCLUSION: A simple measurement of PVR using echocardiography provides clinical and mechanistic insight into which patients will respond to CRT.