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

Abstract

BackgroundTransthyretin 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. MethodsIn 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). ResultsForty-three patients (78%) had wild-type ATTR. Median age was 80 years (interquartile range [IQR] 76-83 years), and 50 of the patients (91%) were men. At baseline, median peak oxygen consumption (pVO2) was 15 mL/kg/min (IQR 12-18 mL/kg/min), percentage of predicted pVO2 (%ppVO2) was 71% (IQR 60%-83%) and VE/VCO2 slope was 31 (IQR 26-34). After a median follow-up of 14 months (IQR 13-16 months), pVO2, %ppVO2 and VE/VCO2 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. ConclusionsCardiorespiratory 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.