CTA May Guide Primary Prevention Statins in Nonobstructive CAD

Anna Goshua

July 19, 2021

The relative risk of death or myocardial infarction (MI) went down with statin therapy in a cohort study of patients with either nonobstructive coronary artery disease (CAD) or no CAD at computed tomographic angiography (CTA). The absolute benefit of statins was directly proportional to CAD burden at imaging.

The findings speak to the effectiveness of statin therapy in patients without obstructive CAD at CTA and the evaluation of coronary artery calcium (CAC) for suspected CAD, and support a greater role for CTA and CAC scoring in deciding whether to initiate statins for primary prevention, proposes a report published online July 14 in JACC: Cardiovascular Imaging.

"Previously, there was a lack of evidence about how statins could possibly influence the outcomes of these patients," said first author Kristian A. Øvrehus, MD, PhD, Odense University Hospital, Odense, Denmark, in an interview with theheart.org | Medscape Cardiology.

"The higher the cardiovascular risk, the more absolute benefits there are. That could possibly give us a tool in the future to help physicians and patients to decide whether to start preventive therapy not only based on risk factors but also visualized coronary artery disease," Øvrehus said.

The researchers identified 33,552 adult patients with suspected CAD in the Western Denmark Cardiac Computed Tomography registry from 2008 to 2017 who were found not to have obstructive CAD at CTA.

Of the total, 19,669 patients had no CAD at imaging and 13,883 had nonobstructive CAD, defined as an absence of coronary stenoses 50% severity.

Their CAC scores were compared with the cohort's use of statins 90 days before and after the imaging procedure and compared with cardiovascular events over a median follow-up of 3.5 years, with statin use and outcomes based on data from other registries.

Their CAD burden by CAC score was directly proportional to their rate of MI or death, expressed as events per 1000 patient-years:

  • 4.13 in patients with no CAD

  • 7.74 in those with mild CAD (score 0-99),

  • 13.72 in patients with moderate CAD (score 100-399)  

  • 32.47 in those with severe CAD (score 400 and higher)

In multivariate analysis, statin therapy was associated with an about one-half reduction in adjusted risk of MI or death across all categories of CAD, with hazard ratios (HR) of:

  • 0.52 (95% CI, 0.36 - 0.75) in no CAD

  • 0.44 (0.32 - 0.62) in mild CAD

  • 0.51 (0.34 - 0.75) in moderate CAD

  • 0.52 (0.32 - 0.86) in severe CAD

Øvrehus cautioned against overinterpreting the results, given the retrospective nature of the study and the likelihood of unmeasured confounders, such as variations in statin dosage and any lifestyle changes made by the patients. 

"Maybe it's a bit optimistic to talk about a 50% reduction" on statin therapy, Øvrehus said, "but the signal is clearly there."

Steven Nissen

The current findings are unlikely to change clinical practice significantly, Steven Nissen, MD, Cleveland Clinic, Ohio, told theheart.org | Medscape Cardiology.  

"We've known that statins work in primary prevention and we also know that having a higher calcium score increases your risk of cardiovascular events," said Nissen, who was not part of the study. "The fact that the people with higher calcium scores had a higher event rate and that they have a slightly better result is not terribly surprising."

Nissen is also skeptical about the role of CTA for evaluating CAD in patients considered for primary preventive therapy. "It's lower quality and lower reliability" compared with coronary angiography, he said. "This is not the same as having disease proven or disproven by coronary angiography."

Further investigation of the usefulness of CTA in such evaluations for CAD is warranted, said Øvrehus.

"The patients that underwent cardiac CTA had a higher degree of receiving preventive therapy and also a reduction in myocardial infarction," Øvrehus said. "Visualizing the coronary arteries may play a larger role in the future and I think that will be interesting to look into further."

The study was supported by a research grant to Øvrehus by the Faculty of Health Sciences, University of Southern Denmark. Øvrehus and Nissen have disclosed no relevant financial relationships.

JACC: Cardiovascular Imaging. Published online July 14, 2021. Abstract

Anna Goshua is a reporting intern with Medscape. She is a dual medical and journalism student who has previously written for STAT, Scientific American, Slate, and other outlets. She can be reached at  agoshua@webmd.net  or  @AnnaGoshua.


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