A63-34 Pulmonary Vascular Resistance as a Misleading Marker in Group 2 Pulmonary Hypertension: A Cautionary Case of Clinical Stabilization After Vasodilator Withdrawal

Abstract Background World Health Organization (WHO) Group II Pulmonary hypertension (PH) due to left-heart disease (LHD-PH) is the most common and often most misunderstood subtype of PH. LHD-PH pulmonary vascular remodeling can elevate pulmonary vascular resistance (PVR), creating a combined or even isolated precapillary profile on right-heart catheterization (RHC). This may misleadingly suggest a primary syndrome of pulmonary arterial hypertension (PAH), prompting inappropriate initiation of pulmonary vasodilator therapy. However, in patients with pulmonary venous hypertension (PVH), such therapy can worsen pulmonary venous congestion and precipitate clinical deterioration. We present a case illustrating the hazards of overinterpreting PVR as evidence of precapillary disease and the subsequent stabilization that followed vasodilator withdrawal. Case Presentation A 63-year-old woman with severe mitral regurgitation (MR) and a secundum atrial septal defect (ASD) with left-to-right shunt presented with progressive dyspnea. RHC showed a mean pulmonary artery pressure (mPAP) of 62 mmHg, pulmonary capillary wedge pressure (PAWP) of 26 mmHg, and PVR of 3.66 Wood units, consistent with combined pre- and postcapillary PH (CpcPH). She was started on intravenous Treprostinil, subcutaneous Sotatercept, and Tadalafil. Follow-up echocardiography showed a persistently elevated right ventricular systolic pressure (RVSP) of 44 mmHg. Vasodilator therapy was continued, and she subsequently underwent mitral valve repair and ASD closure. Postoperative echocardiography demonstrated a normalized RVSP of 31 mmHg. Shortly thereafter, she developed acute pulmonary edema and hypoxic respiratory failure requiring high-flow nasal cannula. Vasodilators were rapidly withdrawn, resulting in prompt resolution of pulmonary congestion and complete weaning to room air. Discussion This case highlights the physiological hazard of misclassifying LHD-PH as PAH. In this context, vasodilators can worsen pulmonary edema by increasing flow across a noncompliant pulmonary venous system with already elevated hydrostatic pressure. Prior trials, including RELAX and SIOVAC, have shown no benefit and potential harm from such therapies in LHD-PH. In contrast, Sotatercept, mechanistically distinct, may offer a potentially safer profile in selected Group 2 PH phenotypes and is a subject of active research. Conclusion Accurate hemodynamic phenotyping remains essential to prevent treatment-related worsening. Patients with significantly elevated PAWP (18 mmHg) and clear risk factors for PVH should be presumed to have LHD-PH until proven otherwise. Although no approved targeted therapies exist for LHD-PH, emerging data on non-vasodilator agents addressing pulmonary vascular remodeling suggest a promising direction for future treatment. This abstract is funded by: None