Heart attacks can prove deadly even when telltale narrowing and dangerous calcium deposits don’t show up on imaging studies.
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Now, a study in which Cleveland Clinic took part finds that a biomarker — the perivascular fat attenuation index (FAI) — identifies patients at high risk of death from heart attacks, above and beyond other known risk factors.
“We have a biomarker that predicts cardiovascular risk better than any other scoring or testing method — and it is derived from a fairly routine, noninvasive heart imaging study,” says cardiologist Milind Desai, MD, co-leader of the study.
“This could transform our ability to predict future heart attacks.”
The Cardiovascular Risk Prediction using Computed Tomography (CRISP-CT) study, involving the University of Oxford, UK; Cleveland Clinic; and University of Erlangen, Germany, was published in August 2018 in The Lancet.
The problem: inflammation
The new biomarker highlights inflammation in fat-storing cells that surround key coronary arteries.
When high amounts of inflammation are present, a growing number of experts recognize that heart disease should be treated more aggressively, the researchers say.
“Half of all heart attacks occur without substantial narrowing of the coronary arteries,” notes Dr. Desai.
“This biomarker identifies those who have plaques that may not be large but are highly inflamed — and flags these patients for potentially early, intensive prevention efforts.”
The imaging involved — coronary CT angiography, more commonly called cardiac CT — uses intravenous dye and X-rays to create moving 3D images of the heart and blood vessels.
A theory to prove
The study builds upon the Oxford researchers’ earlier finding that coronary artery inflammation halts fat-cell formation in surrounding tissues.
“We theorized that when patients undergo cardiac CT, the perivascular FAI might be able to predict their risk of adverse coronary events,” explains Dr. Desai.
“We hoped to flag those at high risk of fatal heart attacks, who stand to benefit from more aggressive therapies.”
Key study findings
To test their theory, the researchers looked at data from patients having cardiac CT:
- 2,040 patients from Cleveland Clinic (median age 62) were followed eight years.
- 1,872 patients from the University of Erlangen (median age 53) were followed four years.
“We found that when patients’ perivascular FAI rose above a certain cutoff point, their risk for cardiac death was five to nine times greater,” says Dr. Desai. “Using the biomarker, we were able to identify these patients more accurately.”
Future trials could determine whether certain heart attack survivors might benefit from highly intensive, aggressive therapies, based on the inflammation detected on their scans, he says.
Dr. Desai adds that this study proves the value of cross-continent collaboration in developing technologies that may have a major impact on care and survival.