Thoracic visceral adipose tissue linked to pulmonary hypertension in transplant candidates

In a new study, lower thoracic visceral adipose tissue was associated with elevated risk for pulmonary hypertension in patients with advanced lung disease undergoing evaluation for lung transplantation.

“Obesity is a heterogeneous disease, so to better understand its effects on the pulmonary circulation and its role in pulmonary hypertension, we need to deep phenotype fat deposits, as they have different metabolic activity,” Nadine Al-Naamani, MD, MS, assistant professor of medicine in the division of pulmonary, allergy and critical care at Perelman School of Medicine at the University of Pennsylvania, told Healio. “We found that the higher the amount of visceral fat in the chest, the less likely these patients had hypertension.”

Researchers performed a cross-sectional analysis of the Lung Transplant Body Composition Study to examine the relationship between thoracic visceral and subcutaneous adipose tissue and pulmonary hypertension. The researchers assessed 399 patients undergoing evaluation for lung transplantation at three centers. Patients had advanced lung diseases such as COPD, interstitial lung disease, sarcoidosis and pulmonary arterial hypertension.

Pulmonary hypertension was defined as mean pulmonary artery pressure greater than 20 mm Hg and pulmonary vascular resistance of at least 3 Wood units. Chest CT was used to measure visceral and subcutaneous adipose tissue and normalized to height squared.

Nadine Al-Naamani

Thirty-four percent of patients had pulmonary hypertension. In these patients, increased thoracic visceral adipose tissue was associated with lower pulmonary vascular resistance (beta = –0.24; 95% CI, –0.46 to –0.02; P = .04), higher pulmonary arterial wedge pressure (beta = 0.79; 95% CI, 0.32-1.26; P = .001) and lower risk for pulmonary hypertension (RR = 0.86; 95% CI, 0.74-0.99; P = .04). Patients without pulmonary hypertension had higher vaspin levels (P < .001) but the researchers said this finding did not mediate the association between visceral adipose tissue and pulmonary hypertension risk.

Thoracic subcutaneous adipose tissue and BMI were not independently associated with pulmonary hypertension risk in this cohort.

“Further research is ongoing to better understand the associations that were observed and to understand the drivers of these associations and to tailor therapy to patients based on their radiographic phenotypes,” Al-Naamani said. “It will be important to replicate these findings in a different cohort of patients and to assess whether adipokines, like vaspin, are mediating these associations.”

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Nadine Al-Naamani, MD, MS, can be reached at nadine.al-naamani@pennmedicine.upenn.edu.