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-2<middle dot>pulse(AT)/O-2<middle dot>pulse(rest) with RHC-determined SVAT/SVrest. We evaluated the sensitivity and specificity of O-2<middle dot>pulse(AT)/O-2<middle dot>pulse(rest) to detect SVAT/SVrest below the lower limit of normal (LLN). For comparison, we performed similar analyses comparing echocardiographically-measured peak tricuspid regurgitant velocity (TRVpeak) with SVAT/SVrest. Results From July 2018 through February 2023, 83 simultaneous RHC and CPET were performed. Thirty-six studies measured O-2<middle dot>pulse and SV at rest and at AT. O-2<middle dot>pulse(AT)/O-2<middle dot>pulse(rest) correlated highly with SVAT/SVrest (r = 0.72, 95% CI 0.52, 0.85; p < 0.0001), whereas TRVpeak did not (r = -0.09, 95% CI -0.47, 0.33; p = 0.69). The AUROC to detect SVAT/SVrest below the LLN was significantly higher for O-2<middle dot>pulse(AT)/O-2<middle dot>pulse(rest) (0.92, SE 0.04; p = 0.0002) than for TRVpeak (0.69, SE 0.10; p = 0.12). O-2<middle dot>pulse(AT)/O-2<middle dot>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 SVAT/SVrest. Conclusions CPET detected deficient SV augmentation more accurately than echocardiography. CPET-determined O-2<middle dot>pulse(AT)/O-2<middle dot>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.