B-type natriuretic peptide (BNP) levels predicted mortality risk better than some traditional risk factors, even in patients without heart failure, a recent study found.
Researchers used data from the Vanderbilt University Medical Center electronic health record to identify 30,487 patients who had a first plasma BNP measurement between 2002 and 2013. Their median age was 63 years, 50% were men, 17% were black, and 38% were diagnosed with heart failure. Follow-up continued through 2015, and results were published in the May 15 Journal of the American College of Cardiology.
Over 90,898 person-years of follow-up, 31% of the patients without heart failure and 53% of those with heart failure died. BNP levels were lower in patients without heart failure than in those with heart failure (median, 89 pg/mL [interquartile range, 34 to 238 pg/mL] vs. 388 pg/mL [interquartile range, 150 to 940 pg/mL]; P<0.0001). However, the risk for death according to BNP level was similar regardless of whether patients had heart failure. For example, a BNP level of 400 pg/mL was associated with a three-year risk for death of 21% (95% CI, 20% to 23%) in patients with heart failure and 19% (95% CI, 17% to 20%) in those without.
This increase in mortality was observed whether patients' elevated BNP level was found in an acute care or outpatient setting. Higher BNP level was the strongest predictor of mortality risk among patients without heart failure, even in multivariate models including traditional risk markers such as age, renal function, diabetes, vital signs, left ventricular mass, and left ventricular ejection fraction. The authors noted that the latter two factors were found to be strongly associated with higher BNP levels. “Thus, finding an elevated BNP level in a patient without [heart failure] may warrant additional investigation, including assessment of cardiac structure and function,” the authors said.
They cautioned that as an observational analysis, the study is susceptible to residual confounding, and that other potentially predictive factors, such as C-reactive protein and troponin, were not compared to BNP. Variability in treatment, such as high diuretic doses for patients with acute heart failure decompensation, may also have affected BNP levels, they noted.
An accompanying editorial called the results “stimulating” and offered several possible explanations for the prognostic value of BNP in patients without heart failure. Elevated BNP levels could be a sign of asymptomatic cardiac disease, an effect of noncardiac conditions such as sepsis or chronic obstructive pulmonary disease, or a sign of vascular aging. Based on the study's findings, the editorialists recommended more extensive cardiovascular evaluation for patients found to have BNP levels above 35 pg/mL in outpatient settings or above 100 pg/mL in acute care. They noted that the next question for researchers will be how to treat patients who have an elevated BNP level without heart failure.