Right Ventricular to Pulmonary Artery Uncoupling Is Associated With Impaired Exercise Capacity in Patients With Transthyretin Cardiac Amyloidosis.

BACKGROUND

Exercise capacity is related to mortality and morbidity in heart failure (HF) patients. Determinants of exercise capacity in transthyretin cardiac amyloidosis (ATTR-CA) have not been established.

METHODS AND RESULTS

This single-center study retrospectively evaluated ATTR-CA patients and patients with non-amyloidosis HF with preserved/mildly reduced ejection fraction (HFpEF/HFmrEF) (n=32 and n=51, respectively). In the ATTR-CA group, the median age was 75.5 years (interquartile range [IQR] 71.3-78.8 years), 90.6% were male, and the median left ventricular (LV) ejection fraction was 53.5% (IQR 41.4-65.6%). Cardiopulmonary exercise tests revealed a median peak oxygen consumption and anaerobic threshold of 15.9 (IQR 11.6-17.4) and 10.6 (IQR 8.5-12.0] mL/min/kg, respectively, and ventilatory efficiency (minute ventilation/carbon dioxide production [V̇/V̇] slope) of 35.5 (IQR 32.0-42.5). Among exercise variables, V̇/V̇slope has the greatest prognostic value. Univariate analysis revealed a significant correlation between V̇/V̇slope and age, LV global longitudinal strain, tricuspid annular plain systolic excursion/pulmonary arterial systolic pressure (TAPSE/PASP) ratio, and mixed venous oxygen saturation. In multivariate analyses, the TAPSE/PASP ratio was an independent predictor of V̇/V̇slope (95% confidence interval -44.5, -10.8; P=0.0067). In non-amyloidosis HFpEF/HFmrEF patients, the TAPSE/PASP ratio was not independently correlated with V̇/V̇slope.

CONCLUSIONS

Right ventricular-pulmonary artery coupling estimated by the TAPSE/PASP ratio determines exercise capacity in ATTR-CA patients. This highlights the importance of early therapeutic intervention against underappreciated right ventricular dysfunction associated with ATTR-CA.