American College of Cardiology
American College of Cardiology
March 24, 2020
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SCOT-HEART: Low-attenuation plaque burden predicts MI in angina

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Michelle C. Williams

The strongest predictor of nonfatal or fatal MI in patients who presented with stable chest pain was low-attenuation plaque burden, according to a new analysis of the SCOT-HEART trial presented at the American College of Cardiology Scientific Session.

The findings were simultaneously published in Circulation.

“This is an important paper, as for the first time, we have actually measured with noninvasive CT imaging the types of plaques which cause heart attacks, the lipid-rich necrotic core,” Michelle C. Williams, MBChB, PhD, senior clinical research fellow at University of Edinburgh, U.K., told Healio. “The quantitative assessment that we have performed in this paper provides us with a more repeatable, reliable, comprehensive assessment of the plaque burden throughout the coronary artery tree, and it has led to some important insights.”

SCOT-HEART trial data

As Healio previously reported in 2015, the main findings from the SCOT-HEART trial were that the use of coronary CT angiography-aided physicians in clarifying diagnoses, enabled targeting of interventions and was associated with a trend toward lower MI compared with standard care in patients presenting with suspected angina due to CHD. Several analyses were performed since then, most recently in October, which found that the beneficial effect of a coronary CT angiography-based strategy on clinical outcomes vs. standard care was consistent across subgroups.

In this analysis, researchers analyzed coronary CT angiographic data from 1,769 patients (mean age, 58 years; 56% men; mean 10-year CV risk score, 18%) with suspected angina from CAD. Several calculations were assessed including CV risk with the ASSIGN CV risk score, coronary artery calcium score and coronary artery stenosis assessments.

The primary event of interest was fatal or nonfatal MI, which was monitored for a median follow-up of 4.7 years.

Low attenuation plaque burden strongly correlated with CAC score (r = 0.62; P < .001) and very strongly with severity of luminal coronary stenosis (r = 0.83; P < .001). A weak correlation was observed for CV risk score (r = 0.34; P < .001).

During follow-up, the primary event of interest occurred in 2.3% of patients. Compared with patients without MI, those who had nonfatal or fatal MI had a higher CAC score (336 Agatston units vs. 19 Agatston units; P < .001), low attenuation plaque burden (7.5% vs. 4.1%; P < .001) and presence of obstructive coronary CAD (54% vs. 25%; P < .001).

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The strongest predictor of MI was low attenuation plaque burden (adjusted HR per doubling = 1.6; 95% CI, 1.1-2.34) regardless of CAC score, CV risk score or coronary artery area stenosis.

Compared with those without low attenuation plaque burden, those who had a burden greater than 4% were nearly five times more likely to have a subsequent MI (HR = 4.65; 95% CI, 2.06-10.5).

“This method could be used to identify patients who would benefit from more aggressive management of their modifiable cardiovascular risk factors and more aggressive medical therapy,” Williams said in an interview.

Additional research

Williams said she and colleagues plan on conducting additional research. “We are going to validate these findings using CT imaging from other research studies, which we and collaborators have performed. We will also look at these plaque measurements in the SCOT-HEART2 trial, which we have recently started recruitment for.” – by Darlene Dobkowski

References:

Williams MC, et al. Highlighted Original Research: Acute and Stable Ischemic Heart Disease and the Year in Review. Presented at: American College of Cardiology Scientific Session; March 28-30, 2020 (virtual meeting).

Williams MC, et al. Circulation. 2020;doi:10.1161/CIRCULATIONAHA.119.044720.

Disclosures: Williams reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.