CTCA useful for risk stratification prior to noncardiac surgery

Use of CT coronary angiography (CTCA) for predicting cardiovascular events following noncardiac surgery has been shown to add value over assessing clinical risk factors alone, according to a study published in the February issue of the Journal of the American College of Cardiology. However, an accompanying editorial stopped short of recommending the approach.

“The CTCA should be considered in patients with poor or unknown functional capacities, high [revised cardiac risk index (RCRI)] score (≥3), and contraindications to noninvasive stress tests,” wrote Jong-Hwa Ahn, MD, of Gyeongsang National University Hospital and Gyeongsang National University School of Medicine, Republic of Korea, and colleagues.

The researchers were interested in CTCA as a reliable and noninvasive method of risk stratification for patients undergoing noncardiac surgery as typical evaluations—treadmill tests, stress myocardial perfusion scintigraphy, stress echocardiography—may not be feasible in all patients.

Ahn and colleagues retrospectively reviewed data from 239 patients who underwent CTCA before intermediate-risk noncardiac surgeries, measuring coronary artery calcium scores (CACS) and the degree of stenosis. RCRI scores also were determined.

Nineteen patients (8 percent) had post-operative cardiac events, and the variables that correlated most with these events were RCRI, CACS, coronary artery stenosis of at least 50 percent and multivessel coronary artery disease, reported the authors. In patients with two or fewer risk predictors, though, RCRI alone was not sufficiently sensitive for estimating risk, and combination models including both CACS of at least 113 and multivessel disease were significantly more predictive than RCRI alone.

The positive predictive value and negative predictive value of a CACS of at least 113 for cardiac death and myocardial infarction were 9 percent and 98 percent, respectively, according to Ahn and colleagues.

Perioperative cardiac events are one of the leading causes of death related to major surgical procedures, explained Richard A. Lange, MD, of the University of Texas Health Science Center in San Antonio in an accompanying editorial. “Accordingly, risk stratification has become an integral part of the evaluation of patients before major surgery.”

Lange acknowledged the work of Ahn et al and said it should not be surprising that patients with elevated CACS or multivessel CAD are at an increased risk of perioperative cardiac events because these CTCA parameters are surrogates for overall coronary plaque burden. He added that the recommendation from Ahn and colleagues that CTCA be used to assess cardiac risk with noncardiac surgery is reasonable and consistent with guidelines.

However, Lange challenged the notion that CTCA is a cost-effective tool as data on its cost-effectiveness for this use have not been published. He also noted that there’s no clear recommendation for how to handle patients who are determined to be at risk for a post-operative cardiac event as beta-adrenergic blockade, perioperative antiplatelet therapy and statin therapy are all either associated with side effects or have not been established as effective.

“Although CTCA may provide additive value to the RCRI in assessing the risk of post-operative cardiac events, until this information can be translated to an intervention that reduces the perioperative risk or mortality, it is not unlike being ‘all dressed up, with nowhere to go,’” wrote Lange.