Cardiopulmonary Exercise Testing for Characterization of Hypertrophic Cardiomyopathy: A Meta-Analysis.

Background: Hypertrophic cardiomyopathy (HCM) is associated with substantial risk of adverse cardiac events. Consequently, detailed physiologic assessment and accurate risk stratification in HCM are of high clinical importance. This systematic review and meta-analysis synthesizes current evidence on the utility of cardiopulmonary exercise testing (CPET) for characterization and prognostication of HCM.

Methods: PubMed, Embase, Scopus, and Web of Science were systematically searched for eligible studies from database inception to November 2023. The primary outcome of mortality was assessed using meta-analyzed hazard ratios (HRs) and 95% confidence intervals (CIs) from Cox proportional hazard models.

Results: Sixty full-length articles focusing on CPETs performed in patients with HCM were included, comprising 12 914 patients. Despite male predominance (66%) and a mean age of 48 years, peak oxygen uptake (pVO) was only 22.4 mL/kg per min (95% CI, 22.3-22.5), consistent with significant functional limitation. Compared with commonly used metrics such as New York Heart Assocation functional class, CPET markedly enhances sensitivity to detect impaired cardiac performance. This meta-analysis highlights easily derived CPET variables that predict HCM prognosis. For the primary outcome, the hazard ratio per 1-mL/kg per min difference in pVO₂ was 0.86 (95% CI, 0.82-0.90; <0.001), and the HR per 1-unit difference in minute ventilation/carbon dioxide output slope was 1.09 (95% CI, 1.05-1.13; <0.001). Abnormal blood pressure response to exercise, defined as failure to increase systolic blood pressure by ≥20 mm Hg or a drop in systolic blood pressure >20 mm Hg, was associated with an HR of 2.29 (95% CI, 1.13-4.64; =0.02) for mortality.

Conclusions: CPET is a valuable objective method for multidimensional physiologic assessment and prognostication in HCM. With further standardization, CPET is well suited for more widespread clinical utilization in patients with HCM.