Key Points
- Understanding the future risk of myocardial infarction and death for patients with established coronary artery disease is a cornerstone of modern cardiology.
- The PRE18FFIR study attempted to pool PET-CTA images into patients’ established invasive and noninvasive coronary images to predict the risk of future myocardial infarction, death, and coronary revascularization.
- 704 patients from 4 countries were enrolled into this prospective cohort study
- While the technique was not able to accurately demonstrate the risk of future myocardial infarction, the authors were able to find an association with increased coronary activity on PET scans and both all-cause mortality and cardiac mortality.
Risk prediction tools for recurrent cardiac events in patients with established coronary artery disease have historically lacked accuracy. The use of invasive angiography and coronary physiology adds to the fidelity of these risk prediction tools, but come with added procedural risk. The use of a noninvasive PET-CT measurement called coronary microcalcification activity (CMA) had previously been shown to associate with recurrent myocardial infarction. CMA measures the activity of coronary plaque rather than just the overall plaque burden, which was postulated to be a better marker of risk, as highly active plaques are more likely to rupture, causing acute coronary syndrome. From this, the idea of the PRE18FFR study was born.
In a Hot Line Session at the 2022 European Society of Cardiology Congress, Dr. David Newby (University of Edinburgh, United Kingdom), presented the results of this prospective cohort study, in which investigators asked whether CMA could predict recurrent coronary events in patients with recent myocardial infarction. Over 5 years, 704 patients over the age of 50 with a recent myocardial infarction (within 21 days) and multivessel coronary artery disease on invasive angiography were enrolled. All patients underwent PET and CTCA, from which CMA was determined and validated by an independent blinded core laboratory. From this cohort, 421 patients had a CMA > 0, indicating high coronary atherosclerotic plaque activity, and the remaining 421 had a CMA = 0, indicated low activity.
Patients had a mean age of 64 years and 15% were women. Only 4% had one-vessel disease, and 7% had left main coronary artery disease. At four years, the primary composite endpoint of cardiac death, non-fatal MI, or unscheduled coronary revascularization occurred in 18% (51 patients) in the CMA = 0 group and 21% (90 patients) in the CMA >0 group (HR 1.25, 95% confidence interval [CI] 0.89–1.76; p=0.20)). As such, increased plaque activity was not associated with the primary endpoint, likely due to the lac of association with unscheduled coronary revascularization. When assessing the endpoints individually as part of the secondary endpoints, CMA was associated with all cause mortality (HR 2.43; 95% CI 1.15–5.12; p=0.020) as well as cardiac death or nonfatal MI (HR 1.82; 95% CI 1.07–3.10; p=0.028).
The imaging was not without its own procedural risks, as there were 15 adverse events, 2 of which were graded “serious”. Despite this, the authors concluded that CMA was associated with cardiac endpoints, and can be used to tailor lipid-lowering or anti-inflammatory therapies to prevent recurrent events. “The association remained after adjusting for severity of obstructive coronary artery disease or GRACE score,” said Dr. Newby, “indicating that coronary atherosclerotic plaque activity predicts recurrent spontaneous antithrombotic events”.