Myocardial strain parameters in pulmonary hypertension are determined by changes in volumetric function rather than by hemodynamic alterations

PurposeTo investigate associations of cardiac magnetic resonance feature-tracking-derived left (LV) and right ventricular (RV) global myocardial peak strains and strain rates with volumetric function and hemodynamic parameters to identify the major determinants of myocardial strain alterations in pulmonary hypertension (PH).MethodsSixty-seven patients with PH or at risk of developing PH underwent right heart catheterization (RHC) and cine realtime imaging at 3T. RHC parameters included mean pulmonary arterial pressure (mPAP), which was used for the diagnosis of PH. LV and RV volumetric function and feature-tracking-derived global radial, circumferential, and longitudinal (GLS) peak strains, together with their strain rates, were evaluated from cine images using routine software. Furthermore, myocardial strain parameters of 24 healthy subjects were evaluated as controls. Means were compared by t-test; relationships between parameters were investigated by correlation and regression analysis.ResultsCompared to controls, RV-GLS, all RV systolic strain rates and the LV systolic longitudinal strain rate showed lower magnitudes in PH (RV-GLS: -21±4% vs. -16±5%, p<0.0001); the strongest univariate correlate to mPAP was the RV-GLS (r=0.59). All LV and RV strain parameters yielded stronger correlations with their respective ejection fractions. In bi-linear models using mPAP and ejection fraction as predictors, mPAP remained significant only for diastolic LV radial and circumferential strain rates.ConclusionImpairment of myocardial strains is more strongly associated with alterations in LV and RV volumetric function parameters than elevated mPAP, therefore limiting diagnostic information of myocardial strain parameters in PH.