Serial Changes in Cardiopulmonary Exercise Testing Parameters in Untreated Patients With Transthyretin Cardiac Amyloidosis

BACKGROUND: Transthyretin amyloid cardiomyopathy (ATTR-CM) is associated with a progressive reduction of functional capacity. The progression of cardiopulmonary exercise testing (CPET) parameters over time is still unknown. METHODS: In this study, 55 patients with ATTR-CM underwent 2 serial cardiologic evaluations and CPETs in a national referral center for cardiac amyloidosis (Careggi University Hospital, Florence). RESULTS: slope were significantly worsened (-1.29 mL/kg/min 95% confidence interval (CI): -1.85 to -0.74; P < 0.01, -4.5% 95% CI: -6.9 to -2.02; P < 0.01, and 8.6 95% CI 6-11; P < 0.01, respectively). Furthermore, exercise time (-39 s, 95% CI: -59 to -19; P < 0.01), exercise tolerance (-0.47 metabolic equivalents, 95% CI: -0.69 to -0.2; P < 0.01), and peak systolic pressure (-10.8 mm Hg, 95% CI: -16.2 to -5.4; P < 0.01) were significantly reduced. The worsening in CPET variables did not correspond with a significant change in echocardiographic parameters. CONCLUSIONS: Cardiorespiratory response to exercise significantly worsened over a short period of time in patients with ATTR-CM. Serial CPET may be useful to identify early disease progression.