The study, “Obesity Is Associated With Pulmonary Hypertension and Modifies Outcomes,” was published in the Journal of the American Heart Association.
Obesity is estimated to affect more than a third of adults in the U.S. and is associated with a higher risk of heart failure with preserved ejection fraction — a type of heart failure in which the heart’s ability to pump blood efficiently to the rest of the body remains intact.
Recent studies suggested that in patients with heart failure with preserved ejection fraction, PH is more prevalent among those with higher body mass index (BMI) and diabetes. Moreover, studies in animal models have shown that obesity-related disorders may trigger precapillary PH, a form of PH in which blood vessel remodeling in the lungs is responsible for increased pulmonary vascular resistance (a measure of heart strain).
“When present, PH confers a worse prognosis among patients with heart failure with preserved ejection fraction. Conversely, obesity is associated with improved survival among patients with heart failure, an observation that has been termed the ‘obesity paradox’,” investigators wrote.
However, it is still unclear if — and how — obesity may affect the association between PH and patient mortality.
To tackle these issues, researchers in the U.S. examined the medical records of adults (ages 18–80) undergoing right‐sided heart catherization — a standard diagnostic procedure for PH that measures blood pressure in the lungs and assesses the heart’s capacity to pump blood — at the Massachusetts General Hospital, from 2005 to 2016.
Statistical analyses were used to evaluate possible associations between BMI and hemodynamic (blood flow) parameters, as well as to examine the effect of obesity and PH on patient mortality.
The study included data from 8,940 patients, with a mean age of 62 years. More than half of the patients in the group were men (60%) and non-obese (52%). Of those who were obese (38% of the total population and BMI of 30 or greater), more than half (69%) showed signs of PH.
Statistical analyses revealed that higher BMI values were associated with a higher risk of PH — 34% increased risk per five-unit increase in BMI. This was true for all PH subtypes, including pre- and postcapillary PH, a form of PH in which there is an increase in blood pressure coming from vessels on the left side of the heart.
Analyses also showed that individuals who had PH had a higher risk of mortality — more than twofold in all PH subtypes — compared to those who did not have the disease.
However, those who were obese and had PH had a 23% lower risk of mortality compared to those who had PH and were not obese. This effect was even more striking among those with precapillary PH, where obesity was associated with a 43% lower risk of mortality.
“Although PH was associated with worse all‐cause mortality, this association was modified by obesity, such that obese patients with PH had lower mortality compared with their non-obese counterparts. This appears particularly pronounced among those with precapillary PH, where obesity appeared to modify the effect of PH on mortality,” the researchers wrote.
“Further studies are needed to elucidate mechanisms underlying obesity‐related PH and factors influencing clinical outcomes,” they added.
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