2024 Top Story in Cardiology: The Continuing Evolution of Coronary CT Angiography

Several PracticeUpdate commentaries in 2024 have highlighted technical advances in the analysis of CCTA. This imaging technique has been clinically available for approximately 20 years. During its early evolution, publications primarily focused on its ability to identify anatomic coronary stenoses and quantify coronary calcium. Over time, the capability to identify stenoses improved significantly, culminating in the 2016 recommendation by the National Institute for Health and Care Excellence in the UK, which declared CCTA the first-line test for individuals with chest pain and suspected coronary artery disease (CAD), to be performed before considering functional stress testing with or without imaging.¹ More recently, US guidelines elevated CCTA to a class I recommendation, equivalent to other forms of stress testing for individuals with chest pain and suspected CAD.² These recommendations were driven by two pivotal trials: the PROMISE trial, which demonstrated similar outcomes when patients with suspected CAD were managed based on CCTA versus functional stress testing,³ and the SCOT-HEART trial, where management guided by CCTA results following exercise electrocardiography led to a lower long-term risk of nonfatal myocardial infarction compared with management based solely on exercise electrocardiography results.⁴

The next phase of CCTA's evolution involved assessing the physiologic significance of stenoses. Trials demonstrated that incorporating CT-derived fractional flow reserve (CT-FFR) into CCTA assessments reduced the need for invasive angiography referrals.⁵ The large observational FISH&CHIPS study associated management based on CCTA and CT-FFR data with improved catheterization lab efficiency and reduced the need for additional noninvasive testing.⁶

In 2024, PracticeUpdate commentaries explored the latest advancements in CCTA. Leveraging artificial intelligence (AI) and machine learning, researchers have been able to perform deeper analyses of plaque characteristics using CCTA imaging datasets.

One study utilized the ADVANCE Registry, involving more than 4000 patients undergoing CCTA with adjudicated 1-year outcomes.⁷ Researchers evaluated whether AI-enabled measurements of plaque volume and atheroma burden offered incremental risk-stratification benefits beyond traditional metrics such as luminal stenosis, CT-FFR, and high-risk plaque features. They found that both total plaque volume and percent atheroma volume, as assessed by a fully automated algorithm, were associated with 1-year outcomes, including major adverse events and late revascularization. These findings suggest that the transition from chronic to acute coronary syndromes may involve a complex interplay of plaque characteristics and their effects.

In another study, detailed analysis of CCTA images was carried out using AI techniques to evaluate “radiomic” features — plaque image details such as texture and density — to generate numerous markers presumably related to plaque characteristics from patients enrolled in the SCOT-HEART trial, with a 5-year follow-up of clinical outcomes.⁸ The authors found that combining some radiomic markers with anatomic data and plaque characteristics provided a small but detectable improvement in the area under the curve for predicting acute events during follow-up.

Whether these impressive advances in imaging and plaque characterization will eventually translate into targeted therapeutics that improve clinical outcomes remains uncertain. It appears that the incremental information provided by these cutting-edge analytic tools currently surpasses our ability to respond therapeutically. In the future, lesion-specific therapies may enable interventions tailored to patients and plaques at the highest risk of instability. Until then, these scientific advancements deepen our understanding of CAD and offer insights into the mechanisms that transform stable plaques into unstable ones. We await the day when precise risk estimation can be paired with therapeutic intensification to meaningfully reduce that risk.