Diagnosing post-capillary pulmonary hypertension in the era of mild pulmonary hypertension: what is the optimal threshold of resting pulmonary arterial wedge pressure?

Background The 2022 ESC/ERS guidelines lowered the diagnostic threshold for pulmonary hypertension (PH) to mean pulmonary arterial pressure (mPAP) >20 mmHg, while the pulmonary arterial wedge pressure (PAWP) cutoff for post-capillary PH remains >15 mmHg. Given the positive correlation between mPAP and PAWP in PH due to left heart disease (group 2 PH), this discrepancy may lead to underdiagnosis in patients with mild PH (mPAP 21–24 mmHg). Although additional exercise or fluid challenge is recommended for borderline PAWP, these tests are often impractical. Purpose To determine an optimal resting PAWP cutoff for diagnosing post-capillary PH in mild PH. Methods We retrospectively analyzed consecutive right heart catheterizations performed at our University Hospital between January 2018 and December 2022. Patients who met the current definition of PH (mPAP >20 mmHg) and had available resting PAWP measurements were included. They were classified as pulmonary arterial hypertension (group 1 PH) or group 2 PH by two experienced cardiologists based on clinical data, including echocardiographic findings, without knowledge of PAWP values, and were subsequently categorized as mild PH or conventional PH (mPAP ≥25 mmHg). Diagnostic performance of PAWP for identifying group 2 PH was assessed using receiver operating characteristic (ROC) analysis. A Sankey diagram illustrated changes in hemodynamic subtype according to the ROC-derived cutoff versus the 2022 PH definition. Results Of 391 patients with PH, 342 were diagnosed with group 1 or 2 PH. They were further categorized into two groups: 125 with mild PH and 217 with conventional PH. ROC curve of PAWP for clinically suspected group 2 PH showed that the area under the curve (AUC) was 0.87 for conventional PH, with an optimal PAWP cutoff of 15.5 mmHg (sensitivity 0.85, specificity 0.81, Figure 1). For mild PH, the AUC decreased to 0.77, with an optimal cutoff of 12 mmHg; both sensitivity and specificity were lower compared with conventional PH (0.81 and 0.64, respectively). Application of the guideline-recommended PAWP threshold (>15 mmHg) in patients with mild PH resulted in substantial clinical discordance, accounting for nearly half of the cohort (Figure 2A). In contrast, lowering the cutoff to ≥12 mmHg (ROC-derived) markedly reduced discordance to approximately 20%, primarily by improving sensitivity for group 2 PH (Figure 2B). Conclusions A resting PAWP cutoff of ≥12 mmHg for the diagnosis of post-capillary PH may improve identification of group 2 PH in mild PH. Nevertheless, diagnosis in this population requires careful clinical evaluation, as PAWP-based classification in mild PH may be less reliable than in conventional PH.