Key result
Combined post- and pre-capillary PH shows similar mortality risk to isolated post-capillary PH.
Why the study?
Little is known about the clinical or physiological characteristics distinguishing isolated post-capillary PH from combined post- and pre-capillary PH, or whether combined post- and pre-capillary PH shares molecular similarities to pulmonary arterial hypertension.
Cohort (n=2,817)
No
Answers are grounded in this paper and cite their sources.
Cpc-PH shares genetic and biological pathways with PAH and carries a similar mortality risk to Ipc-PH, suggesting it is a distinct and highly morbid subphenotype.
Background Pulmonary hypertension (PH) is a common and morbid complication of left heart disease with 2 subtypes: isolated post-capillary PH (Ipc-PH) and combined post-capillary and pre-capillary PH (Cpc-PH). Little is known about the clinical or physiological characteristics that distinguish these 2 subphenotypes, and if Cpc-PH shares molecular similarities to pulmonary arterial hypertension (PAH). Objectives We sought to test the hypothesis that the hemodynamic and genetic profile of Cpc-PH would more closely resemble PAH than Ipc-PH. Methods We used Vanderbilt’s electronic medical record linked to a DNA biorepository to extract demographics, clinical data, invasive hemodynamics, echocardiography, and vital status for all patients referred for right heart catheterization between 1998 and 2014. We identified shared genetic variants between PAH and Cpc-PH compared with Ipc-PH using pre-existing single-nucleotide polymorphism data. Results We identified 2,817 patients with PH (13% Cpc-PH, 52% Ipc-PH, and 20% PAH). Cpc-PH patients were on average 6 years younger, with more severe pulmonary vascular disease than Ipc-PH patients, despite similar comorbidities and prevalence, severity, and chronicity of left heart disease. After adjusting for relevant covariates, the risk of death was similar between Cpc-PH and Ipc-PH (HR: 1.14, 95% CI: 0.96 to 1.35, p = 0.15) when defined by diastolic pressure gradient. We identified 75 shared exonic single-nucleotide polymorphisms between Cpc-PH and PAH enriched in pathways involving cell structure, extracellular matrix, and immune function. These genes are expressed, on average, 32% higher in lungs relative to other tissues. Conclusions Cpc-PH patients develop pulmonary vascular disease similar to PAH patients, despite younger age and similar prevalence of obesity, diabetes mellitus, and left heart disease compared with Ipc-PH patients. An exploratory genetic analysis in Cpc-PH identified genes and biological pathways in the lung known to contribute to PAH pathophysiology, suggesting that Cpc-PH may be a distinct and highly morbid PH subphenotype.
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Assad et al. (2016) conducted a cohort in Pulmonary hypertension (n=2,817). Combined post-capillary and pre-capillary PH (Cpc-PH) vs. Isolated post-capillary PH (Ipc-PH) was evaluated on Risk of death (HR 1.14, 95% CI 0.96 to 1.35, p=0.15). Combined post- and pre-capillary PH was associated with a similar risk of death compared to isolated post-capillary PH (HR 1.14; 95% CI 0.96-1.35; p=0.15).
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