Coronary CT angiography (CCTA) has revealed that coronary artery disease (CAD) can occur in the absence of typical risk factors such as hypertension, hyperlipidemia, diabetes, and smoking, researchers have reported.
A team led by Seiyon Sivakumar, MD, of Monash University in Melbourne, Australia, found that “in patients undergoing clinically indicated CCTA, patients without [risk factors] exhibited a similar degree of coronary inflammation to those with [them], despite having a lower plaque burden and stenosis severity.” The results were published September 11 in Heart and Lung Circulation.
Clinicians have made progress in preventing CAD by targeting modifiable risk factors, the team explained, but the incidence of CAD occurring in the absence of these factors has increased, prompting a need to identify biomarkers and mechanisms for this kind of CAD so that effective treatment strategies can be developed.
To this end, Sivakumar and colleagues assessed coronary inflammation in patients with typical risk factors and those without, tracking pericoronary adipose tissue (PCAT) attenuation, a new, specific biomarker of coronary inflammation that can be quantified on CCTA. The group conducted a study that included 309 patients who underwent serial CCTAs for suspected stable CAD between 2010 and 2016 at Monash Health in Melbourne, Australia. It tracked PCAT attenuation around the proximal right coronary artery (PCATRCA) using semiautomated software and assessed plaque using the segment involvement score and segment stenosis score. Finally, the investigators assessed coronary artery diameter stenosis severity using the Coronary Artery Disease – Reporting and Data System (CAD-RADS) classification.
Of the total patient cohort, 26.9% did not have cardiovascular disease risk factors. Those study participants with these risk factors were more frequently on statins, angiotensin-converting enzyme inhibitor/angiotensin receptor blockers, and aspirin.
The team reported the following:
- Patients without risk factors had a similar PCATRCA mean attenuation compared to those with the risk factors (Hounsfield units, or HU, of -77.5 vs. -78.4, respectively; p = 0.481) — despite having a lower coronary plaque burden and stenosis severity.
- The mean segment involvement score and segment stenosis score were 18.7% and 39.5% lower, respectively, in patients without risk factors than in those with them (SIS of 1.78 vs. 2.72, p = 0.01, and SSS of 2.22 vs. 3.67, p = 0.004).
- Patients with risk factors were more likely to have obstructive CAD than patients without them (odds ratio of 2.8; p = 0.006).
“In patients undergoing clinically indicated [CCTA], patients without [risk factors] exhibited a similar degree of coronary inflammation to those with [them], despite having a lower plaque burden and stenosis severity,” the group noted.
The study offers “early mechanistic insights into why patients without [risk factors] still develop CAD and subsequent cardiovascular events,” according to the team.
“Further research is needed to validate these findings,” the group concluded. “If confirmed, the therapeutic target of inflammation could be explored further in patients without [risk factors].”
The complete study can be found here.