Abstract 13332: Change in Right Ventricular Free Wall Strain is Significantly Associated with Hemodynamic Response to Imatinib in Advanced Pulmonary Arterial Hypertension

Abstract

Background: Right ventricular (RV) free wall longitudinal strain (FWLS) is a novel measure of RV function in pulmonary arterial hypertension (PAH), however little data exists regarding its responsiveness to therapy known to improve hemodynamics and functional capacity in this condition.

Methods: RV FWLS was measured at randomization, 12 weeks and 24 weeks in 60 patients with advanced PAH, decreased exercise capacity, and PVR>800 dynes·sec/cm-5 despite 2 PAH-specific therapies who were randomized to Imatinib or placebo in the Imatinib in PAH, double-blind, placebo-controlled, Randomized Efficacy Study (IMPRES). The treatment associated difference in change in FWLS from baseline to 24 weeks was compared using ANCOVA with the last observation carried forward. Change in FWLS from baseline to 24 weeks was correlated with changes in invasive hemodynamics over the same time period.

Results: FWLS was measureable at baseline and follow-up in 24 Imatinib and 29 placebo treated patients. Mean age was 50.4± 13.3 years and 87% were women. Imatinib was associated with improvement in PVR (-365 ± 330 vs 87 ± 660 dynes·sec/cm-5, p=0.005), MPAP (-6.6 ± 9.3 vs -0.4 ± 11.2 mmHg, p=0.008), and SVI (9.2 ± 9.6 vs 1.9 ± 9.2 ml, p=0.02). Imatinib therapy was also associated with improvement in FWLS compared to placebo (+0.2±4.5% versus -3.8 ± 7.8%, p = 0.009). Improvement in FWLS correlated with reduction in PVR (Spearman coefficient: 0.39, p=0.02) and MPAP (Spearman coefficient: 0.33, p=0.04). Change in tricuspid annular systolic velocity correlated better with changes in invasive hemodynamics than other echo measures of RV function analyzed (Table).

Conclusion: Imatinib, as add-on therapy in advanced PAH, is associated with improvement in RV FWLS compared to placebo. Further, improvement in FWLS correlated with reduction in PVR and MPAP. RV LS may represent a novel sensitive noninvasive measure of RV function in PAH.