An elevated level of B-type natriuretic peptide --- particularly of the N-terminal fragment--- accurately predicted mortality risk for patients hospitalized with myocardial infarction or unstable angina, according to an article in the November 12th rapid access issue of Circulation.

“In patients with acute coronary syndromes, measurements of the N-terminal fragment [of the peptide] taken early after admission identified patients at increased risk of early and late death,” said senior author Kenneth Caidahl, M.D., Ph.D.

“This relationship remained significant after adjusting for conventional risk markers. The most important finding was that the N-terminal fragment also predicted mortality among patients without clinical signs of left ventricular failure.”

Blood tests for the peptide have been useful in diagnosing heart failure in the emergency setting. More recently, hormone level has been shown to predict cardiac outcome in patients with myocardial infarction or angina. The current study shows that measurement of the N-terminal fragment may provide prognostic information that is superior to information obtained with the level of intact peptide.

Caidahl and colleagues sought to clarify the role of N-terminal fragment level in assessing acute coronary syndromes with data from 609 patients admitted to the coronary care unit of a Swedish university hospital. Based on records and interviews, patients were classified as positive or negative for a medical history of myocardial infarction, angina, congestive heart failure, diabetes, and hypertension.

All patients had N-terminal fragment levels measured approximately three days after hospital admission, had an echocardiographic study within five days of hospital admission, and had evaluation of left ventricular ejection fraction.

The final study population consisted of 204 patients with ST-elevation infarction, 220 with non-ST segment elevation infarction, and 185 with unstable angina. After 51 months (with follow-up ranging from 19 to 72 months), 86 patients (14 percent) had died.

Median N-terminal fragment levels were significantly lower in long-term survivors than in patients who died (442 vs. 1306 pmol/L). In a statistical analysis that adjusted for patient age, heart failure status, and ejection fraction, the level of N-terminal fragment remained significantly associated with mortality. Those in the highest group had twice the risk as those in the lowest group.

“[N-terminal fragment of B-type natriuretic peptide and intact peptide] appear to be stronger predictors of short- and long-term mortality than conventional biochemical risk markers, including troponins, in acute coronary syndromes,” says Caidahl. “This novel blood test is an important tool for risk stratification in acute coronary syndromes and may be measured routinely in this large and important patient group in the future. A method for rapid measurement [of the fragment] has recently become commercially available.”