Prognostic value of cardiopulmonary exercise testing in patients with transthyretin cardiac amyloidosis

The aim of this study is to evaluate the prognostic value of cardiopulmonary testing (CPET) in a cohort of patients with transthyretin cardiac amyloidosis (ATTR-CA). ATTR-CA is associated with a progressive reduction in functional capacity. The prognostic role of CPET parameters and in particular of normalized peak VO2 (%ppVO2) remains to be thoroughly evaluated. In this study, 75 patients with ATTR-CA underwent cardiological evaluation and CPET in a National Referral Center for cardiac amyloidosis (Careggi University Hospital, Florence). Fifty-seven patients (76%) had wild-type ATTR. Median age was 80 (75–83) years, 68 patients (91%) were men. Peak oxygen consumption (14.1 ± 4.1 ml/kg/min) and %ppVO₂ (68.4 ± 18.8%) were blunted. Twenty-seven (36%) patients had an abnormal pressure response to exercise. After a median follow-up of 25 (12–31) months, the composite outcome of death or heart failure hospitalization was registered in 19 (25.3%) patients. At univariate analysis %ppVO₂ was a stronger predictor for the composite outcome than peak VO₂. %ppVO₂ and NT-proBNP remained associated with the composite outcome at multivariate analysis. The optimal predictive threshold for %ppVO₂ was 62% (sensitivity: 71%; specificity: 68%; AUC: 0.77, CI 0.65–0.88). Patients with %ppVO₂ ≤ 62%and NT-proBNP > 3000 pg had a worse prognosis with 1- and 2-year survival of 69 ± 9% and 50 ± 10%, respectively. CPET is a safe and useful prognostic tool in patients with ATTR-CA. CPET may help to identify patients with advanced disease that may benefit from targeted therapy.