Increased Aortic Stiffness Index is Associated with Reduced Exercise Capacity Following Heart Transplantation

Abstract

Augmentation of the central aortic pressure is associated with increased arterial stiffness, which is known to be a predictor for cardiovascular events. We investigated the association between aortic stiffness index and exercise capacity after heart transplantation. We retrospectively analyzed the patients who underwent cardiopulmonary exercise test (CPET) and examined central hemodynamics using applanation tonometry (SphygmoCor, AtCor Medical) after 1 year from heart transplantation, from Jan 2011 to June 2019. Total 143 patients received HTx in this period. A total of 54 patients (49 years, 72% male) were analysed with available data, CPET and central hemodynamics measurements. Study subjects were divided into 2 groups according to peak exercise oxygen uptake (peak VO2; median cutoff 21.1 ml/kg/min). There was no significant difference between the 2 groups. Recipients with high peak VO2 (≥median) were likely to have increased hemoglobin (13 ± 1 vs. 12 ± 2 g/dL, p=0.032), lower aortic augmentation pressure (2.4 ± 17.5 vs. 12.6 ± 12.1%, p=0.018) and lower augmentation index at heart rate 75 beats per minute (Aix@75, 9.4 ± 15.9 vs 19.3 ± 11.9%, p=0.013). Aix@75 was correlated with peak VO2 (R=-0.53, p<0.001). In multivariate linear regression analysis, Aix@75 (ß=-0.15, p=0.010) were significantly associated with peak VO2 after HTx. In the present study, increased aortic stiffness is associated with reduced exercise capacity after HTx. Further study to determine whether lowering arterial stiffness may improve exercise tolerance in HTx recipients can warrant these findings.