Nonobstructive coronary artery disease is far from benign: study

By Megan Brooks

NEW YORK (Reuters Health) - Adults with nonobstructive coronary artery disease (CAD) - atherosclerotic plaque not expected to obstruct blood flow or result in angina - have a significantly increased risk of suffering a heart attack, researchers found in a large observational study.

Clinicians need to recognize that non-obstructive CAD "isn't insignificant or benign, but instead confers significant risk for MI and mortality," Dr. Thomas M. Maddox of the VA Eastern Colorado Health Care System in Denver told Reuters Health by email.

"Preventative therapies -- such as aspirin, statins, and lifestyle modifications such as smoking cessation, weight loss, and increased physical activity -- should be considered in all patients with non-obstructive CAD," Dr. Maddox said.

Nonobstructive CAD is relatively common, seen in 10% to 25% patients undergoing coronary angiography, he and his colleagues note in a November 5 JAMA report.

Its presence has been characterized as "insignificant" or "no significant CAD" in the medical literature. But actually little is known about the risk of cardiac events in patients with nonosbstructive CAD, the researchers say.

To investigate, they did a retrospective study of more than 37,600 U.S. veterans who had elective coronary angiography between October 2007 and September 2012; 22% had nonobstructive CAD, 55% had obstructive CAD and 22% had no apparent CAD.

Within one year, 385 were hospitalized for MI and 845 patients died.

The researchers found that that one-year risk of MI increased progressively by the extent of CAD, rather than abruptly increasing between nonobstructive and obstructive CAD.

"Patients with nonobstructive CAD had an associated risk of MI that was 2- to 4.5-fold greater than among those with no apparent CAD," they report. "Similar observations were seen with 1-year mortality and the combined outcome of 1-year MI and death."

Historically, obstructive CAD has been the primary focus in CAD management due its role in causing cardiac ischemia and chest pain, Dr. Maddox and colleagues point out.

"The results of this study support the concept that nonobstructive CAD is not 'insignificant' but rather is associated with a significant and quantifiable risk for cardiovascular morbidity and mortality," they conclude.

The results also highlight the "limitations of a dichotomous characterization of angiographic CAD into 'obstructive' and 'nonobstructive' to predict MI and highlight the importance of preventive strategies such as pharmacotherapy treatments and lifestyle modifications to mitigate these risks," they add.

SOURCE: http://bit.ly/1tAL9fi

JAMA 2014;312:1754-1763.

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