Even Without Blockage, Artery Disease May Still Be a Threat

Nonobstructive coronary artery disease may raise the risk of heart attack and death

(RxWiki News) With coronary artery disease, plaque may block blood vessels. Sometimes, however, plaque that does not restrict blood flow may develop. But even this type of plaque buildup may raise the risk of heart attack.

In the case of nonobstructive coronary artery disease (CAD), plaque may not cause any obstruction or cause only a partial blockage of a blood vessel. The authors of a recent study wanted to study whether this type of CAD raised patients' risk of heart problems.

They found that nonobstructive CAD was tied to a significant increase in risk for major cardiac events like heart attack or death.

Plaque is a buildup of cholesterol, cells and other substances in the blood vessels. Even when it does not create a complete blockage, plaque may weaken blood vessels. Plaque deposits can still rupture and put a patient's heart in jeopardy, the study authors noted.

Thomas M. Maddox, MD, of the VA Eastern Colorado Health Care System in Denver, and colleagues wrote the study.

They followed 37,674 patients. Almost a quarter had nonobstructive CAD, and over half had obstructive CAD. The remainder had no apparent CAD.

Dr. Maddox and his team found that those with nonobstructive CAD faced a heart attack risk that was 2 to 4.5 times greater than those with no apparent CAD one year after screening. They found similar results for the death rates among these patients.

To establish the condition of patients' arteries, the researchers used coronary angiograms. These special X-ray tests may detect blockages, narrowing and lesions in blood vessels.

The authors found that coronary angiography may detect nonobstructive plaque in 10 to 25 percent of patients undergoing this type of imaging. They added that this type of plaque has been characterized as “insignificant” or “not significant CAD” in some past research.

In this study, nonobstructive CAD was defined as blood vessels that were less than 70 percent blocked and less than 50 percent blocked in the left main coronary artery.

The authors said that the heart attack rate over one year increased according to the severity of the disease. For instance, the heart attack rate was 0.11 percent among patients with no apparent CAD. It was 0.24 percent for those with one-vessel nonobstructive CAD — meaning one major blood vessel was narrowed — and 0.56 percent for those with three-vessel nonobstructive CAD. For those with obstructive CAD, this heart attack rate was 1.18 percent in a one-vessel blockage and 2.47 percent in a three-vessel blockage.

“These findings suggest clinical importance of nonobstructive CAD and warrant further investigation of interventions to improve outcomes among these patients,” the authors wrote.

Patients with nonobstructive CAD may be advised to ask their doctor about preventive therapies. These include quitting smoking, following healthy diets, getting regular exercise, losing weight, and taking preventive medications like aspirin and statins.

The study was published Nov. 5 in JAMA.

VA Health Services Research and Development funded the study. Some study authors had potential conflicts of interest that included ties to pharmaceutical companies like Amarin, AstraZeneca, Bristol-Myers Squibb, Johnson and Johnson and Sanofi-Aventis.


Review Date: 
November 4, 2014