VANCOUVER, B.C. – B-type natriuretic peptide elevations above 1,000 pg/mL may herald worse prognosis in patients with diastolic heart failure but normal renal function, according to a retrospective database analysis from the University of California, Davis.
Among 421 hospitalized patients with diastolic heart failure – heart failure (HF) with ejection fractions above 45% – investigators found that 117 (28%) patients had B-type natriuretic peptide (BNP) levels above 1,000 pg/mL.
Fifty of those patients (43%) had stage IV or V chronic kidney disease, compared with 7 (13%) of the 54 diastolic HF patients with BNPs below 100 pg/mL. The team also found a significant relationship between estimated glomerular filtration rate (eGFR) and BNP (R = 0.39). In most cases, BNP levels above 1,000 pg/mL "were likely due to reduced [renal] clearance and associated factors. The degree of renal dysfunction is related to the degree of BNP elevation," said senior investigator Dr. Saul Schaefer, professor at the university and also chief of cardiology at the Veterans Affairs Medical Center in Sacramento.
Dr. Saul Schaefer
But 25 patients (21%) with BNPs above 1,000 pg/mL "actually had normal renal function; that is, an [eGFR] greater than 60 mL/min per 1.73 m2. It’s unclear why these patients would have such an elevated BNP. They were older [mean age 70.2 years vs. 67.7 years] and had slightly reduced ejection fractions in comparison to the overall group," he said at the 18th World Congress on Heart Disease.
"My guess is that these patients with high BNPs and normal renal function have more severe abnormalities and diastolic failure. It’s a potential marker of higher risk. We could potentially follow these patients more closely and treat them more aggressively," he said.
Before that happens, however, "we need to prospectively look at these patients and see if they can be distinguished from the lower-BNP patients, and track them to see whether their prognosis is adversely affected," Dr. Schaefer said.
Compared with diastolic HF patients in the study with BNPs below 100 pg/mL, the 117 with levels above 1,000 pg/mL tended to be older (68 vs. 61.4 years), have higher troponin levels (0.2 vs. 0 ng/mL), and have greater use of antihypertensive medications, suggesting that they had more chronic hypertension. There were no associations between markedly elevated BNP and gender, diabetes, or ischemic heart disease. Echo parameters did not predict BNP.
Dr. Schaefer said that he had no relevant disclosures.