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

Abstract

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: Forty-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.

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.