Abstract 16423: Pulmonary Vascular Resistance is a Better Predictor than Pulmonary Artery Pressure of Non-Response to Cardiac Resynchronization Therapy
Background: Cardiac resynchronization therapy (CRT) is an established therapy modality for advanced heart failure (HF). Despite advances, response rates to CRT remain 50-60%. Pulmonary vascular resistance (PVR) is an independent predictor of HF admission, heart transplantation and all-cause mortality. However, the impact of PVR on response to CRT is not defined.
Methods: 72 pts (68 ± 11 yrs, 43 males, 50% ischemic CMP, EF 18 ± 6 %) with advanced HF (NYHA Class 3.1 ± 0.5) on optimal medical therapy underwent CRT. PVR in Wood Units (WU) was measured using the maximum velocity of tricuspid regurgitant jet (TR max) and VTI of right ventricular outflow tract (RVOT VTI), using the validated formula [TR max/RVOT VTI] x10 +0.16. TR max was used to calculate pulmonary artery pressure (PAP). Left ventricular ejection fraction (LVEF) and LV end systolic volume index (LVESVI) were calculated using modified Simpson’s biplane method during a follow up of 22 ± 12 months. Responders were defined by decrease in LVESVI of 15% from baseline.
Results: 39 pts (54%) were responders and demonstrated significant decrease in LVESVI (85 ± 25 ml/m2 to 61 ± 19 ml/m2; p<0.05) and increase in LVEF (19 ± 6 % to 32 ± 12 %; p<0.001) when compared to non-responders (99 ± 18 ml/m2 to 100 ± 27 ml/m2; p=0.12; LVEF 16 ± 6 to 20 ± 11%; p=0.5). PAP (34 ± 12 vs. 37 ± 16; p=0.45) did not differ between the 2 groups but PVR was significantly higher in non-responders (2.7 ± 0.9 vs. 1.9 ± 0.6; p<0.001) compared to responders. ROC curves of PVR revealed an AUC 0.79 (p<0.05) vs. AUC 0.53 (p=0.6) for PAP. In multivariate model using age, gender, QRS duration, PAP, dyssynchrony and ICR, elevated PVR (HR: 0.2, p<0.001) remained a significant independent predictor for non-response to CRT. Using a PVR cut-off of 2.5 WU gives a specificity of 90 % and sensitivity of 60 % to predict non-responders to CRT (Figure).
Conclusion: Echocardiographic PVR can differentiate between CRT responders and non-responders. PVR is a better predictor of CRT response than PAP.
- © 2012 by American Heart Association, Inc.