Two Heart Markers Prove Better Together

By Paula Rasich
Reviewed by Elizabeth Klodas, MD, FACC

(CardioSmart) The presence of small amounts of cardiac troponin T (TnT), a protein released in the bloodstream in response to heart muscle injury, can increase your risk of death. A new study finds that also having higher levels of N-terminal pro B-type natriuretic peptide (NP-proBNP), a marker of abnormal heart pumping function, raises those odds even more.

In patients with symptoms, measuring TnT and NP-proBNP levels with a blood test helps doctors determine the severity of a heart attack or heart failure, respectively. Experts now suspect that even low concentrations of these substances in the blood of apparently healthy individuals may be an early warning of heart damage caused by inflammation, abnormal blood vessel function, and other factors.

To investigate the connection, a team of researchers led by Lori B. Daniels, MD, MAS, of the University of California San Diego Medical Center, examined data from the Rancho Bernardo Study. Rancho Bernardo is an ongoing community-based study of heart disease risk factors in older individuals that began in 1972.

In the study, researchers followed 957 otherwise healthy men and women between the ages of 60 and 97 for an average of 6.8 years. They found that those who had even slight elevations in TnT levels in their blood demonstrated a twofold increase in the risk of death from any cause, compared to those with no detectable levels. And people with elevated NT-proBNP levels had a greater risk of dying from a heart attack.

Researchers also found that people who had both elevated TnT and high NT-proBNP fared the worst. That combination increased their risk for death from any cause by more than threefold, compared to study subjects who were TnT-free and had low NT-proBNP levels. 

Dr. Daniels says that it’s too early to recommend this screening routinely because more research needs to be done to clarify and confirm these observations. But these extra blood tests, particularly for people not suspected of having heart disease, will make it possible for doctors to detect heart threats long before damage is done.

“My hope is that someday we can use these tests as a screening tool to identify patients who might be at higher risk and who might benefit from more aggressive treatments and lifestyle changes,” says Dr. Daniels.

The study results are published in the August 5th issue of the Journal of the American College of Cardiology.

Sources:

Daniels LB. et al.  Minimally Elevated Cardiac Troponin T and Elevated N-Terminal Pro B-Type Natriuretic Peptide Predict Mortality in Older Adults.  Results From the Rancho Bernardo Study.  Journal of the American College of Cardiology, 2008.

Lori B. Daniels, MD, MAS, Assistant Professor of Medicine in the Division of Cardiology, University of California San Diego Medical Center, San Diego, California.