BERN, SWITZERLAND—In patients with pulmonary embolism (PE), accurate risk stratification could permit abbreviated hospital stays or outpatient care for low-risk patients. A recent study of 73 patients with acute PE found that N-terminal pro-brain natriuretic peptide (proBNP) levels below 500 pg/mL are highly predictive of favorable outcomes.[1]

ProBNP and troponin T levels were measured at hospital admission. PE was classified as massive, submassive, or nonmassive, depending on the initial hemodynamic presentation of the patient and the presence or absence of right ventricular dysfunction on echocardiography. Adverse outcomes were defined as in-hospital death or escalation of therapy, with the need for cardiopulmonary resuscitation, mechanical ventilation, pressors, thrombolytics, catheter fragmentation, or surgical embolectomy.

Patients with proBNP levels of 500 pg/mL or higher were older and more likely to have dyspnea or syncope as a presenting symptom. They also had more severe right ventricular strain than did those with proBNP levels below 500 pg/mL.

Twenty patients experienced adverse outcomes a median of eight hours after hospital admission. Of these, 12 had massive PE, six had submassive PE, and two had nonmassive PE. There were five deaths, all due to right ventricular failure.

In the 53 patients with benign outcomes, proBNP levels were lower (median, 121 pg/mL) than those in patients with adverse outcomes (median, 4,250 pg/mL). All but one of the 31 patients with proBNP levels below 500 pg/mL had benign outcomes. In a multivariate analysis, elevated proBNP remained an independent predictor of adverse outcomes after adjusting for troponin T levels, submassive or massive PE, age older than 70, sex, and history of congestive heart failure.

As shown by its high negative predictive value of 97%, proBNP’s strength is identifying patients at low risk for adverse outcomes. “However,” said Nils Kucher, MD, a research fellow with the Venous Thromboembolism Research Group at Brigham and Women’s Hospital in Boston, “elevated proBNP levels should not be interpreted in isolation, due to the limited positive predictive value for adverse outcomes. Indeed, any heart disease associated with an increase in cardiac pressure may lead to proBNP elevation.”

Dr. Kucher, the study’s primary author, added that a novel strategy combining cardiac troponin and proBNP levels with echocardiography will help identify high-risk as well as low-risk patients with acute PE.

In the future proBNP levels could be used to monitor hemodynamic effects of thrombolysis, surgical embolectomy, or anticoagulation alone, Dr. Kucher said. “A rapid decrease in proBNP after initiation of therapy might indicate successful recanalization of the pulmonary arteries with recovery of right ventricular dysfunction.”

“For now,” said Dr. Kucher, “the main conclusion is that very low proBNP levels can be used for risk stratification. [This would help] determine which patients with PE can be discharged earlier from the hospital or even treated on a completely outpatient basis.”

—Gale Jurasek

Reference
1. Kucher N, Printzen G, Doernhoefer T, et al. Low pro-brain natriuretic peptide levels predict benign clinical outcome in acute pulmonary embolism. Circulation. 2003;107:1576-1578.

Return to table of contents