Potential Clinical Impact of Revised Pulmonary Hypertension Definitions at Moderate Altitude

Abstract

Background

Pulmonary hypertension (PH) and precapillary PH definitions have been revised. Before 2018, PH was defined by a mean pulmonary arterial pressure ≥ 25 mm Hg, and precapillary PH was defined by a pulmonary vascular resistance ≥ 3 Wood units and a pulmonary arterial wedge pressure ≤ 15 mm Hg. In 2018, the mean pulmonary arterial pressure threshold dropped to 20 mm Hg. In 2022, the diagnostic threshold of pulmonary vascular resistance dropped from ≥ 3 to > 2 Wood units. The implications of the revised definitions at altitude remain unclear.

Research Question

Do revised definitions capture similar patients at altitude and sea level?

Study Design and Methods

We analyzed hemodynamic data from patients’ right heart catheterization procedures at 1,609 m. We extracted clinical data on PH diagnosis, progression, and mortality from the electronic medical record and the National Death Index.

Results

A total of 2,382 patients were analyzed. Mean resident altitude ± SD was 1,631.1 ± 674 m. Pre-2018, 1,412 patients (59.2%) had PH and 508 patients (21.3%) had precapillary PH. Applying the post-2018 definition resulted in 307 patients (12.8%) being diagnosed with PH, including 86 (3.6%) with a diagnosis of precapillary PH. Applying the post-2022 definition resulted in 306 patients (12.8%) being diagnosed with precapillary PH (P < .05). Patients newly diagnosed with PH had age- and sex-adjusted mortality lower than patients with pre-2018 PH (hazard ratio [HR], 0.67; 95% CI, 0.54-0.83; P < .001) and higher than patients without PH (HR, 0.46; 95% CI, 0.39-0.56). Compared with patients with pre-2018 precapillary PH, patients with post-2022 precapillary PH demonstrated mortality (HR, 0.7; 95% CI, 0.53-0.91; P = .009). There was no significant difference in mortality or progression between patients with post-2018 and pre-2018 precapillary PH.

Interpretation

In this study, at moderate altitude, revised definitions of PH identified patients with a greater likelihood of mortality, similar to sea level findings. The post-2022 definition of precapillary PH increased the prevalence of precapillary PH, identifying a population with lower mortality, without progressive disease. Further research on this population is needed.