Prognostic Value and Reproducibility of Simplified Noninvasive Pulmonary Artery Pressure-Flow Relationships in...

The noninvasive mean pulmonary artery pressure (mPAP) to cardiac output (CO) relationship has been associated with cardiovascular outcomes across various populations. This study compared different methodologies for assessing this noninvasive relationship during exercise, with a dual focus on reproducibility and prognostic value. Specifically, we sought to determine whether simplified 1-point mPAP/CO measurements offer equal reproducibility without compromising prognostic performance in patients with unexplained exertional dyspnea undergoing exercise echocardiography.

This secondary analysis of a prospective, multicenter cohort study included 1619 patients referred for unexplained dyspnea to 6 dedicated clinics in Belgium between January 2016 and March 2023. All patients underwent symptom-limited cardiopulmonary exercise testing with concurrent exercise echocardiography. The mPAP-CO relationship was assessed using 4 approaches: (1) 3-point linear regression, (2) 2-point slope (rest to peak), (3) 1-point mPAP/CO ratio at low-level exercise, and (4) 1-point mPAP/CO ratio at peak exercise. The primary outcome was a composite of all-cause mortality or heart failure hospitalization. The median follow-up was 28.2 months (interquartile range 15.9-45.1 months). Prognostic performance was evaluated by comparing discrimination across methods using receiver operating characteristic curves. Reproducibility was assessed by intraobserver and interobserver agreement. The 1-point method at peak exercise showed the highest discriminative performance (area under the curve [AUC] 0.715), with modest but significant improvement over the 2-point (AUC 0.685, P = 0.019) and 3-point methods (AUC 0.686, P = 0.028). The 1-point at low-level exercise showed similar accuracy (AUC 0.713). Reproducibility was highest for the 1-point ratios, with narrower intraobserver and interobserver limits of agreement (P < 0.001) compared with slope-based approaches.

Simple, 1-point mPAP/CO ratios measured during exercise offer prognostic performance comparable with slope-based methods, with greater reproducibility. This finding supports its adoption as a practical and robust approach for evaluating exercise pulmonary hypertension.