In a new study, researchers found that signs of cardiac stress that appear in the blood after exercise can indicate which patients with coronary artery disease are most at risk of heart attack or other issues.
The research was conducted by a team at Emory University,
Identifying patients with otherwise stable coronary artery disease (CAD) who are high-risk and would benefit from more intense or invasive interventions is currently a major theme in cardiology research.
Often CAD patients undergo a treadmill exercise test to look for signs of blockages in their coronary arteries, and the researchers have been examining measurements that could provide additional information on which patients may be at the highest risk of cardiac events.
In this study, the researchers looked at how circulating progenitor cells can disappear from the blood, presumably because they’re needed in the heart.
Circulating progenitor cells (or CPCs), thought of as blood vessel “repair crews,” derive from the bone marrow and circulate in the blood at low levels.
In healthy people, physical exercise causes the cells to leave the bone marrow and enter the blood because their job is repairing blood vessels.
In people with coronary artery disease whose arteries are narrowed enough so that they develop ischemia (restriction of blood flow), more of the cells are diverted to the heart to repair the damage.
In the study, the researchers used the data from the Mental Stress Ischemia Prognosis Study, looking at 454 patients with stable coronary artery disease.
They divided participants into two groups, based on whether CPC counts increased or decreased during a treadmill exercise test.
They found that people whose CPC counts decreased were more than twice as likely to experience a heart attack or die from heart disease over the next three years, even taking standard risk factors into account.
In particular, monitoring the CPC response to exercise provided more information than nuclear imaging for cardiac ischemia (restriction of blood flow).
This was important because imaging procedures can contribute to radiation exposure.
In previous research, the team demonstrated that a decrease in CPC counts is a sign of ischemia. The current study extended the findings to outcomes.
The lead author of the study is Kasra Moazzami, a cardiovascular research fellow at Emory University.
The study is published in JAMA Cardiology.
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