Pulmonary vascular reactivity in pulmonary hypertension due to left heart disease

Abstract

Purpose: Pulmonary hypertension (PH) due to left heart disease (LHD) is the most common subset of PH. It is defined by an increase of mean pulmonary artery pressure (mPAP) ≥25mmHg in the presence of a mean pulmonary capillary wedge pressure (mPCWP) >15mmHg. In the current guidelines PH due to LHD with a TPG >12mmHg is labeled as out-of-proportion PH, as opposed to what is labeled as passive PH, i.e. PH as the consequence of elevated left ventricular filling pressures. Recent data have shown that patients with out-of-proportion PH and a diastolic pulmonary vascular pressure gradient (DPG) ≥7mmHg have an increased mortality and significant pulmonary vascular disease. We hypothesize that these patients may benefit from vasodilator treatment. The aim of this study was to compare the degree of acute vasoreactivity to inhaled nitric oxide (NO) in out-of-proportion PH with a DPG ≥7mmHg to that of passive PH and out-of-proportion PH with a DPG <7mmHg. Methods: A prospective data set of 73 patients with PH due to LHD undergoing first diagnostic right and left heart catheterizations at rest and after inhalation of 40ppm NO was analyzed. 22 patients were classified as passive PH, 25 as out-of-proportion PH with a DPG <7mmHg and 26 as out-of-proportion PH with a DPG ≥7mmHg. Changes were expressed as the differences between hemodynamics at baseline and after vasoreactivity testing. Results: The strongest decrease of mPAP was observed in patients with out-of-proportion PH and a DPG ≥7mmHg (-4.1±5.9mmHg, p=0.003). In contrast there was no significant change in mPAP in patients with out-of-proportion PH and a DPG <7mmHg (-2.1±5.3mmHg, p=0.07). In passive PH a significant increase in mPAP could be observed (2.3±4.8mmHg, p=0.045) upon NO inhalation. View this table: Table 1. Hemodynamics at rest and after Conclusion: DPG identifies patients with out-of-proportion PH who have significant pulmonary vascular disease that is reactive to inhaled NO.