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

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).

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.

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.