January 10, 2018

Racial differences in plasma levels have implications on heart disease

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PankajPankaj Arora, M.D.A new study published in JAMA Cardiology by University of Alabama at Birmingham researchers shows that a key protein, N-terminal pro-B-type-NP (NTproBNP) that is released from the heart is almost 35 percent lower in African-Americans than in Caucasians, and predicts the risk of death, particularly cardiovascular mortality similarly in both races.

Pankaj Arora, M.D., assistant professor in the Division of Cardiovascular Disease, explained that the human heart is an endocrine organ and produces hormones called natriuretic peptides.  Natriuretic peptides are routinely used as “gold-standard” biomarkers for diagnosis and prognosis of cardiovascular diseases, especially heart failure, in clinical practice.

In the current study, the authors tested the hypothesis that African-American race is a natriuretic peptide deficiency state and further explored whether association of natriuretic peptides with all-cause mortality and CV mortality in apparently healthy individuals differ by race. 

To investigate, Arora and his team examined racial differences in NTproBNP levels in the REGARDS study — an ongoing NIH-sponsored observational study of stroke risk factors  assessed by region and race — in more than 30,000 American adults age 45 or older. They pooled their results from the REGARDS study of NTproBNP levels by race with participants from the Dallas Heart Study and Atherosclerosis Risk in Communities study, and studied the association of NTproBNP levels, race, all-cause mortality and cause-specific mortality in the REGARDS participants.

“Decades of work done previously has consistently shown that African-Americans have higher prevalence of high blood pressure and heart failure,” Arora said. “Lower levels of natriuretic peptides may be the reason behind the excess burden of cardiovascular disease seen in African-Americans.”  

The authors summarized by saying natriuretic peptide deficiency is implicated causally in the development of CV disease, whereas elevated natriuretic peptide levels can reflect a consequence of CV disease.

Arora noted that, while using this hormone clinically, one could argue that physicians should be reporting race-specific cutoff values.

“This is where I think our study moves the needle to suggest ‘individualized’ cutoff of laboratory values for natriuretic peptides in different racial/ethnic groups,” he said. “Clinicians taking care of African-American patients with heart failure may not be able to increase natriuretic peptide levels to an extent similar to those individuals with no natriuretic peptide deficiency.”

Arora says one key piece of missing information is whether the natriuretic peptide production from the heart in response to physiological stress is reduced in African-Americans, and this is an important future direction for this work.