Cardiopulmonary exercise testing in transthyretin amyloid cardiomyopathy patients: a long-term follow-up study.

Abstract

Patients with transthyretin amyloid cardiomyopathy (ATTR-CM) experience reduced functional capacity. We evaluated changes in functional capacity over extensive follow-up using cardiopulmonary exercise testing (CPX). ATTR-CM patients underwent CPX and blood testing at baseline, first [V1, 8 (6-10) months] and second follow-up (V2) at 35 (26-41) months after start of disease-specific therapy. We included 34 ATTR-CM patients, aged 77 (±6) years (88.2% men). CPX showed two patterns with functional capacity improvement at V1 and deterioration at V2. Peak work capacity (P = 0.005) and peak oxygen consumption (VO2, P = 0.012) increased at V1 compared with baseline and decreased at V2. The ventilation to carbon dioxide relationship slope (VE/VCO2) increased at V2 compared with baseline and V1 (P = 0.044). A cut-off for peak VO2 at 14 ml/kg·min showed more events (composite of death and heart failure hospitalization): less than 14 vs. greater than 14 ml/kg·min (P = 0.013). Cut-offs for VE/VCO2 slope at 40 showed more events greater than 40 vs. less than 40 (P = 0.009). ATTR-CM patients showed an improvement and deterioration in the short-term and long-term follow-up, respectively, with a better prognosis for those with peak VO2 above 14 ml/kg·min and for a VE/VCO2 slope below 40.