AJC: Blood test could trump clinical judgment in HF discharge management

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A routine blood test could hold the key to why some patients with congestive heart failure (HF) do well after being discharged from the hospital and why others risk relapse, readmission or death within a year, according to a single-center study published online Feb. 8 in the American Journal of Cardiology.

Henry J. Michtalik, MD, MPH, and his colleagues from Johns Hopkins School of Medicine in Baltimore tested HF patients on admission and discharge for levels of N-terminal pro-B-type natriuretic peptide, or NT-proBNP, a protein that is a marker for heart stress. In previous studies, the levels of this protein have been correlated with heart failure symptoms and have been associated with an increase in adverse outcomes.

The researchers found that patients whose protein levels dropped by less than 50 percent over the course of their hospital stay were 57 percent more likely to be readmitted or die within a year than those whose levels dropped by a greater percentage.

"Testing for NT-proBNP at the beginning and end of hospitalization could help doctors and hospitals make better decisions about which patients are truly ready to be released and which ones are at higher risk for relapse, readmission or worse," according to the authors, who added that these patients are already tested for this marker upon admission.

While these patients may feel and look better, the level of NT-proBNP suggests many of them may not be completely better, the authors said.

"Even though a doctor has determined the patient is ready to go home, a change in this biological marker of less than 50 percent means the patient is at much higher risk and would likely benefit from more intensive treatment, monitoring or outpatient follow up," said Michtalik, a research and clinical fellow in the division of general internal medicine at Johns Hopkins.

The investigators studied 241 HF patients admitted to the Johns Hopkins Hospital between June 2006 and April 2007 who were treated with intravenous diuretics to remove fluid from the body.

Within the first 24 hours, blood was drawn from the patients and tested for NT-proBNP, and patients were treated for their symptoms by their individual physicians. Though the patients' NT-proBNP levels were tested again at discharge, the decision for or against discharge was determined by clinical judgment alone and the treating physicians were not aware of the protein's level at discharge.

Analysis showed that patients whose protein levels decreased by less than 50 percent over the course of the several days to a week that they were in the hospital were at the highest risk for readmission or death.

"Our research suggests that maybe clinical judgment isn't enough to decide whether a heart failure patient is ready to be discharged," he said. "These patients may benefit from being treated until their NT-proBNP decreases by a certain percentage, something that is not considered now."

Michtalik said an appropriate next step would be a prospective randomized trial that examines whether hospitalized HF patients do better when their doctors work intensively to decrease NT-proBNP over the course of their hospital stays.