Right ventricular adaptation and subclinical damage by echocardiography in heart transplantation recipients: insights from myocardial work index

Abstract

Abstract Aim Right ventricular (RV) dysfunction is an important cause of graft failure after heart transplantation (HTx) and a challenge for echocardiographic evaluation. We sought to evaluate the accuracy of the most novel echocardiographic tools for the assessment of RV remodelling and function in asymptomatic HTx recipients with and without rejection. Methods All patients underwent right heart catheterization with biopsy, cardiac magnetic resonance (CMR) and echocardiography in a row within the same day while fasting, irrespective of symptoms, as part of institutional follow up protocol dedicated to HTx recipients. Invasively measured systolic pulmonary artery pressure was used to calculate RV myocardial work index (MWI) from strain-pressure loops by using the custom software (EchoPAC BT204, Horten, Norway). Event timings were determined from pulmonic and tricuspid valve opening and closures. With the aim to generate full bull's eye map by automated function imaging, we computed RV LS data from the apical 4-chamber view 3 times, from 3 consecutive cycles substituting apical LV views. Other indices of RV function were measured according to the EACVI 2015 recommendations for chamber quantification. RV volumes and ejection fraction (EF) were quantified by CMR. Echocardiographic measurements were compared with CMR derived RV EF and biopsy findings as the reference for microstructural changes. We also evaluated by echocardiography organ donors as healthy controls. Results Sixty-one fully matching studies (echo, CMR, catheter, biopsy) were analyzed. Tricuspid systolic annular velocity (S'), peak systolic excursion (TAPSE) and longitudinal strain (LS) were significantly lower in healthy HTx recipients as compared to controls (p<0.001 for all). Whereas, RV volumes, EF and fractional area change (FAC) were not different between HTx recipients and healthy controls (Figure 1, EDV:end-diastolic volume). In the overall HTx recipients, only FAC (r=0.51, p<0.001) but not S', TAPSE, LS or MWI correlated with CMR derived EF. Biopsy defined subclinical rejections however were nicely mirrored by LS, and MWI (Figure 2), whereas other indices failed to reflect microstructural changes. In addition, MWI had higher accuracy than LS to discriminate biopsy findings. RV volumes, EF, FAC as well as TAPSE, S' were insensitive to subclinical myocardial damage. Conclusion RV adaptation in healthy HTx recipients is characterized by decreased longitudinal function but preserved overall RVFAC, EF, and volumes. MWI seems to be more reliable than other echocardiographic parameters to track subclinical RV myocardial damage due to rejection, while the RV EF remains preserved. Funding Acknowledgement Type of funding sources: None.