Cardiopulmonary exercise test to detect cardiac dysfunction from pulmonary vascular disease

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.

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 O₂·pulse_AT/O₂·pulse_rest with RHC-determined SV_AT/SV_rest. We evaluated the sensitivity and specificity of O₂·pulse_AT/O₂·pulse_rest to detect SV_AT/SV_rest below the lower limit of normal (LLN). For comparison, we performed similar analyses comparing echocardiographically-measured peak tricuspid regurgitant velocity (TRV_peak) with SV_AT/SV_rest.

From July 2018 through February 2023, 83 simultaneous RHC and CPET were performed. Thirty-six studies measured O₂·pulse and SV at rest and at AT. O₂·pulse_AT/O₂·pulse_rest correlated highly with SV_AT/SV_rest (r = 0.72, 95% CI 0.52, 0.85; p < 0.0001), whereas TRV_peak did not (r = -0.09, 95% CI -0.47, 0.33; p = 0.69). The AUROC to detect SV_AT/SV_rest below the LLN was significantly higher for O₂·pulse_AT/O₂·pulse_rest (0.92, SE 0.04; p = 0.0002) than for TRV_peak (0.69, SE 0.10; p = 0.12). O₂·pulse_AT/O₂·pulse_rest 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_AT/SV_rest.

CPET detected deficient SV augmentation more accurately than echocardiography. CPET-determined O₂·pulse_AT/O₂·pulse_rest 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.