Cardiopulmonary Exercise Test to Detect Cardiac Dysfunction from Pulmonary Vascular Disease

Background: Cardiac dysfunction from pulmonary vascular disease causes characteristic findings on cardiopulmonary exercise testing (CPET). We tested the accuracy of CPET for detecting inadequate stroke volume (SV) augmentation during exercise, a pivotal manifestation of cardiac limitation in patients with pulmonary vascular disease.

Methods: We reviewed patients with suspected pulmonary vascular disease in whom CPET and right heart catheterization (RHC) measurements were taken at rest and at anaerobic threshold (AT). We correlated CPET-determined O·pulse/O·pulse with RHC-determined SV/SV. We evaluated the sensitivity and specificity of O·pulse/O·pulse to detect SV/SV below the lower limit of normal (LLN). For comparison, we performed similar analyses comparing echocardiographically-measured peak tricuspid regurgitant velocity (TRV) with SV/SV.

Results: From July 2018 through February 2023, 83 simultaneous RHC and CPET were performed. Thirty-six studies measured O·pulse and SV at rest and at AT. O·pulse/O·pulse correlated highly with SV/SV (r = 0.72, 95% CI 0.52, 0.85; p < 0.0001), whereas TRV did not (r = -0.09, 95% CI -0.47, 0.33; p = 0.69). The AUROC to detect SV/SV below the LLN was significantly higher for O·pulse/O·pulse (0.92, SE 0.04; p = 0.0002) than for TRV (0.69, SE 0.10; p = 0.12). O·pulse/O·pulse of less than 2.6 was 92.6% sensitive (95% CI 76.6%, 98.7%) and 66.7% specific (95% CI 35.2%, 87.9%) for deficient SV/SV.

Conclusions: CPET detected deficient SV augmentation more accurately than echocardiography. CPET-determined O·pulse/O·pulse may have a prominent role for noninvasive screening of patients at risk for pulmonary vascular disease, such as patients with persistent dyspnea after pulmonary embolism.