Some therapies - e.g. bosentan or prostacyclin- are only indicated and approved for PAH but not for pulmonary venous hypertension (PVH). A diagnosis of PAH implies a mean pulmonary arterial pressure (mPAP) >25 mmHg at rest and a normal left ventricular (LV) filling pressure (<15 mmHg) to exclude PVH. A PCWP <15 mmHg is generally assumed to exclude PVH but a rigorous comparison of PCWP with the “gold standard” LVEDP < 15 mmHg in patients with PAH is lacking. We hypothesized that sole reliance on PCWP might erroneously misclassify a significant number of patients with PVH as PAH.
We reviewed the records and raw catheterization data from 131 patients who underwent simultaneous right and left catheterization as part of their evaluation for suspected pulmonary hypertension (PH) and in whom PH was confirmed. The diagnostic performance of PCWP vs. LVEDP was evaluated using a 2 x 2 contingency table. A chi-square test was used to compare those results. Linear regression analysis was used for comparison of continuous variables.
Our patients were 60 years of age, mostly women (76%) and predominantly white (75%). The most common etiologies of PH were collagen vascular disease (24%), LV diastolic dysfunction (20%) and idiopathic PAH (18%). LVEDP suggested PVH in 59% of patients vs. 37% by PCWP (p= <0.0001). Up to 37% of patients with PVH would have been misclassified as PAH by PCWP measurement alone.
We report limitations to the use of PCWP as the only method of assessing LV filling pressures in patients with suspected PAH, especially when PCWP is >10. We found that LVEDP measurement was important to accurately differentiate between PAH and PVH.
Since the current data support the benefit of certain therapies in PAH only, careful assessment of LV filling pressures is indicated before such therapies are initiated. PAH-specific therapies are not only expensive but can lead to higher morbidity and mortality when used in PVH.
Francisco Soto, None.