Prognostic Value of Submaximal Cardiopulmonary Exercise Testing in Patients With Cardiac Amyloidosis.

Abstract

Background: This study assessed the prognostic value of submaximal cardiopulmonary exercise testing (CPET) in cardiac amyloidosis and explored CPET as an alternative to the 6-min walk test (6MWT).

Methods and results: In this single-center prospective observational study, 160 patients with cardiac amyloidosis (87% male; mean age 78±7 years) were evaluated. A total of 145 performed maximum symptom limited CPET. The V̇E/V̇CO₂ slope was 39±8, submaximal power output (SPO) was 24.75±11.50 W, and V̇O₂ at anaerobic threshold (AT) was 8.13±2.29 mL/min/kg. During follow up, 34 (21.25%) patients died, and another 34 (21.25%) experienced heart failure (HF)-related hospitalization, with 15 (9.38%) patients experiencing both events. Univariate analysis showed that V̇E/V̇CO₂ slope (hazard ratio [HR] 0.89; 95% confidence interval [CI] 0.86-0.93; P<0.001) and SPO (HR 0.91; 95% CI 0.87-0.96; P<0.001) were predictors of mortality. In multivariate analysis, V̇E/V̇CO₂ slope remained a significant predictor (HR 0.92; 95% CI 0.88-0.97; P<0.001) for both all-cause mortality and HF-related hospitalization independently. A SPO cut-off of <28 W predicted a worse outcome for both measures independently. Moderate correlations for V̇E/V̇CO₂ slope (-0.56 [CI -0.67, -0.42]) and SPO (0.55 [CI 0.42, 0.67]) with 6MWT distance have been found.

Conclusions: These findings highlight CPET parameters, particularly V̇E/V̇CO₂ slope and SPO with a cut-off <28 W, as predictors of survival and HF-related hospitalization in cardiac amyloidosis.