Evaluating the Efficacy of Pressure Microcatheters for Fractional Flow Reserve Measurement in Chronic Thromboembolic Pulmonary Hypertension: A Comparative Study

Background This study aimed to compare the efficacy and procedural performance of pressure microcatheters and pressure guidewires for fractional flow reserve (FFR) measurement in patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing balloon pulmonary angioplasty (BPA). Methods This prospective observational study enrolled patients with CTEPH undergoing BPA between April 2022 and December 2025. FFR was sequentially measured using a pressure microcatheter (PMC) followed by a pressure guidewire (PW). Agreement between methods was evaluated using Bland–Altman analysis. Diagnostic performance of FFR (PMC) was assessed using receiver operating characteristic analysis, with FFR(PW) ≤ 0.80 as the reference standard. Results Seventy-five vessels were included. The mean FFR (PW) was 0.60 ± 0.17; the mean FFR (PMC) was 0.59 ± 0.18. The mean bias between methods was − 0.010, with 95% limits of agreement from − 0.071 to 0.052. FFR (PMC) demonstrated a sensitivity of 98.4% and specificity of 90.9%, with an area under the curve of 0.992 (p < 0.001). Conclusion FFR (PMC) shows excellent agreement and diagnostic accuracy compared with FFR (PW), supporting its use as an alternative physiological assessment during BPA in CTEPH.