Noninvasive CT angiography and stress tests help predict heart attacks
March 14, 2017
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OAK BROOK, Ill. — Noninvasive CT angiography and stress tests can help predict which patients are likely to suffer a heart attack or other adverse cardiovascular event, according to a new study appearing online in the journal Radiology.
Cardiovascular disease is a leading cause of death worldwide. Bypass surgery or stent placement is often recommended in people with certain degrees of coronary arterial narrowing, or stenosis, but recent studies have shown that many of these patients do just as well with medical therapy. A key factor in treatment decisions is the hemodynamic significance of the lesion, meaning the degree to which the lesion is blocking blood from getting to areas of the heart. 
“Previous studies show that a lesion is hemodynamically significant if there is a significant blood pressure drop corresponding to a big reduction in blood flow across the stenosis,” said study author João A.C. Lima, M.D., from Johns Hopkins Hospital and School of Medicine in Baltimore. “If plaque has those characteristics, the patient should be targeted for intervention, be it with a stent or downstream bypass surgery.”
A combination of invasive coronary angiography (ICA) and stress tests with single photon emission tomography (SPECT) myocardial imaging has been the gold standard for making these determinations, with ICA showing the blockages and SPECT the perfusion, or penetration of the blood into the tissue. However, ICA requires the use of a catheter that is threaded from a puncture point in the groin all the way up to the heart.
“Invasive angiography is generally safe, but it can cause vascular problems in a significant number of patients, most commonly at site of the puncture,” Dr. Lima said. “In rare cases, it can cause strokes or heart attacks. These risks are not trivial.”
The ICA/SPECT approach can also be expensive, as it often necessitates hospitalization for the patient.
“The traditional approach with invasive catheterization requires that patients go to the hospital, get a catheter inserted into their leg and go in for the nuclear SPECT study on a different day,” said study coauthor Marcus Chen, M.D., from the National Institutes of Health in Bethesda, Md. “Now with just one noninvasive test we can get two important but different pieces of information about the coronary arteries.”
The researchers set out to determine if combined CT angiography (CTA) and CT myocardial stress perfusion imaging (CTP) could demonstrate similar or superior ability to ICA/SPECT in predicting future adverse events.