Imaging Tests May Predict Stroke and Heart Attack

MRI and ultrasound gauged risks of serious cardiovascular problems in people with severely clogged arteries

(RxWiki News) If your arteries have dangerous plaque build-up, determining your risks for stroke and heart attack can help guide self-care and medical care. Certain imaging tests may aid in predicting those risks.

In a recent study, magnetic resonance imaging (MRI) and ultrasound revealed the potential for major cardiovascular problems in people with unusual fatty and calcium build-up in the main neck arteries that pump blood to the brain.

Such build-up of plaque was more common in people who underwent those tests and later had a stroke or heart attack than in those who did not have a stroke or heart attack, this study showed.

"See your doctor regularly to track cardiovascular health."

David Bluemke, MD, PhD, director of radiology and imaging sciences at the National Institutes of Health (NIH) Clinical Center in Bethesda, MD, was this study’s lead author.

Dr. Bluemke and his team of investigators performed MRIs and ultrasounds on the carotid arteries — the large vessels located on each side of a person’s neck — of 946 patients from the Multi-Ethnic Study of Atherosclerosis (MESA). None of those individuals showed symptoms of stroke, heart attack or angina (chest pain) or had a history of cardiovascular disease.

The patients ranged in age from 45 to 84 and were enrolled in the MRI-ultrasound study between July 2000 and September 2002. They were from Baltimore, MD; Chicago; Forsythe County, NC; Los Angeles; New York City; and St. Paul, MN.

The MRI identified whether patients’ arteries were clogged with plaque and what was the biological make-up of that plaque. The ultrasound measured plaque thickness. Also, the tests aimed to determine how likely it was that those plaque-hardened arteries would burst.

These researchers monitored the patients' health for 5.5 years after the MRI and ultrasound examinations.

Out of the group of 946, 59 patients had major cardiovascular events. Of the 59, 19 had a stroke, 22 had angina and one had a heart attack. In addition, nine had cerebrovascular disease, which affects blood flow in the brain. One person died of cerebrovascular disease. Four died of heart disease.

The carotid arteries of half (50 percent) of the 59 patients who had a stroke or heart attack were covered with abnormal fat and calcium deposits. Among patients who did not have a stroke or heart attack, 17.8 percent had those dangerous deposits in their carotid arteries. 

Patients who were older, white, male, had diabetes, had high blood pressure and/or were taking medicine to control high blood pressure were more likely than others to have a stroke, heart attack or angina or to die as a result.

Roughly 20 percent of the entire study group had plaque build-up in the carotid arteries.

Using an MRI, the researchers found that the number of patients at risk for heart attack and stroke and who had such an event rose 16 percent over the 5.5 years of study. Among patients who did not have a heart attack or stroke, 7 percent were correctly reclassified as being at higher risk for serious cardiovascular problems, researchers wrote. 

"As risk factor prediction gets better, we'll be able to screen more intelligently and use more intensive treatments in those individuals who face a higher risk of cardiovascular events,” Dr. Bluemke said

Calculating the risk for a major cardiovascular problem will help patients and their doctors better determine which treatments and lifestyle habits might help individuals with clogged arteries prevent a heart attack or stroke.

Smoking and a diet too high in certain fats are leading causes of these cardiovascular disorders.

MRI and ultrasound are non-surgical procedures, the researchers noted. MRIs cost more than ultrasound but may be better at pinpointing dangerous cardiovascular plaque build-up and determining those patients' risks for cardiovascular events, according to these researchers.

"Imaging patients to evaluate for cardiovascular risk is not new," said Jeffrey Schussler, MD, an interventional cardiologist at Baylor University Medical Center's Heart and Vascular Hospital in Dallas.

"We currently have a calcium score which costs less than $80, and can (within a few seconds) estimate your coronary risk. MRI may be helpful as an additional modality to evaluate asymptomatic patients for the presence of plaque," said Dr. Schussler, who was not involved in this study.

When MRIs are too costly — they range widely from a few hundred to several thousand dollars — or unavailable, ultrasound and computed tomography (CT) are good alternatives, Dr. Bluemke said. A carotid intima-media thickness test (CIMT) is an ultrasound ranging from about $150 to $500.

CT is a kind of X-ray. Getting a CT dose that is correct and doesn't needlessly harm patients has been one issue surrounding CT. 

Despite these researchers' conclusions, the American College of Cardiology does not now endorse these kinds of screenings.

This study was published online March 4 in Radiology.

The researchers did not report any non-NIH funding of this study.

The researchers did not report any financial or other involvements that would shape study design, analysis or outcomes.

Review Date: 
February 28, 2014