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Pulmonary arterial hypertension (PAH) is typically distinguished from pulmonary venous hypertension (PVH) by documenting a pulmonary capillary wedge pressure (PCWP) < 15 mm Hg. However, PCWP has uncertain utility in establishing PAH. Other suggests using left ventricular end-diastolic pressure (LVEDP) instead. We aim to compare both parameters to the “gold standard” measurement of direct “mean left atrial pressure (m LAP)” obtained through transeptal access.
We examined hemodynamic data from 25 patients with pulmonary hypertension undergoing simultaneous right-heart and left-heart catheterization with transeptal puncture to evaluate mean left atrial pressure.
Among 25 patients with severe pulmonary hypertension, acquiring a reliable conformed PCWP was not possible in 4 patients (16%). In the remaining cohort of 21 patients, when we used mLAP as the gold standard, the classification of PAH vs. PVH changed in 4/21 (19%) when PCWP was used and in 5/21 patients (24%) when LVEDP was used. PCWP had better correlation with mean mLAP when compared with LVEDP (R2= 0.76 and R2= 0.65 respectively).
A PCWP that can be used to discriminate PAH from PVH is either not easy to be obtained or is unreliable in roughly one-third of patients with severe pulmonary hypertension. LVEDP is even less reliable than PCWP in discriminating PAH and PVH. Reliance on PCWP or LVEDP may result in the dangerous or cost-ineffective use of pulmonary vasodilators for patients with left-heart disease. Direct assessment of mLAP may be beneficial in the classification of pulmonary hypertension and guiding therapeutic decisions.