CCTA Tops Functional Tests for Suspected CAD in Real-world Diabetic Patients

WASHINGTON, DC—Coronary CT angiography (CCTA) seems to have the edge over functional testing for the assessment of suspected CAD in patients with newly diagnosed type 2 diabetes, real-world data show.

In an analysis of a national South Korean insurance claims database, patients initially evaluated with CCTA versus functional testing had a significantly lower risk of acute MI or death from CAD during follow-up (1.0% vs 1.4%; HR 0.72; 95% CI 0.58-0.89), a difference driven by fewer acute MIs, according to Haechan Cho, MD (Seoul National University Hospital, South Korea).

CCTA evaluation also was associated with lower rates of invasive angiography and PCI overall, although among those who underwent angiography, the rate of revascularization was higher compared with initial evaluation with functional testing, he reported here at the 2024 Society of Cardiovascular Computed Tomography (SCCT) meeting.

That finding, commented Andrew Choi, MD (George Washington University School of Medicine, Washington, DC), who was not involved in the study, indicates that “CT better identified those patients that needed revascularization. It's a very nice, I think, confirmation of what we have been seeing in these CT trials around the world.”

It also aligns, he told TCTMD, with an analysis published last year showing that growing use of CCTA in the United Kingdom after the test was prioritized by the National Institute for Health and Care Excellence (NICE) was associated with lower rates of death from cardiovascular and ischemic causes.

Choosing a Test for Suspected CAD

Although invasive coronary angiography provides a definitive assessment of the presence of CAD, it comes with the potential for complications. Thus, guidelines recommend using a noninvasive option as a first-line test, either an anatomic assessment with CCTA or a functional assessment, such treadmill testing, SPECT imaging, or stress echocardiography.

The debate continues about which option—anatomic or functional testing—is better. The SCOT-HEART trial showed that adding CCTA to a standard chest pain workup significantly improved outcomes over standard care alone, whereas the earlier PROMISE trial showed no difference between use of CCTA and functional testing as a first-line approach. In an analysis of PROMISE based on diabetes status, however, CCTA was associated with a lower rate of CV death or MI in patients with—but not without—diabetes.

To explore a potential difference in the type of testing in patients with diabetes further, Cho and his colleagues turned to the database of South Korea’s National Health Insurance Service. After propensity-score matching, they compared 14,895 patients with newly diagnosed type 2 diabetes and suspected CAD who were evaluated with CCTA against an equal number of patients evaluated with functional testing, mostly treadmill tests. Overall, mean patient age was about 60 years, and more than half (63%) were men.

The lower rate of acute MI or death from CAD after CCTA assessment was attributed to a significantly lower rate of acute MI compared with functional testing (0.9% vs 1.4%; HR 0.67; 95% CI 0.54-0.84), with no significant difference in death from CAD (0.2% vs 0.1%; HR 1.7; 95% CI 0.97-2.97).

The rate of invasive angiography was lower in the CCTA group (10.6% vs 16.0%; P < 0.0001), with a numerically, but nonsignificantly, lower rate of any revascularization (5.4% vs 6.2%; P = 0.068). There was, however, less PCI performed after CCTA than after functional testing (4.9% vs 5.7%; P = 0.0313); CABG was performed in 0.6% of patients in each arm.

Among the subset of patients who underwent invasive angiography, those initially assessed with CCTA were more likely to go on to revascularization (51.5% vs 38.5%).

Unleashing CCTA’s Potential

Cho acknowledged that the study is limited in that it relied on diagnostic codes to assess comorbidities and clinical outcomes, there was a lack of information on patient symptoms, and the results “reflect patterns of clinical practice and outcomes in South Korea.”

Choi, too, highlighted some limitations, including some differences between the healthcare system in South Korea and other countries. In addition, the overall event rate was relatively low, which could be related to the symptom status of the patients, which is unknown. “That may be because there was a significant number—we don't know—of asymptomatic patients, whereas the PROMISE trial included symptomatic chest pain patients. And that might account for those differences,” Choi said.

Moreover, the researchers lacked information on the types of treatments patients received in each group. But presumably, Choi said, outcomes were better in the CCTA group because the plaque was seen and then treated.

“Diabetes leads to a diffuse atherosclerotic process, and if we have an approach, CT, that allows us to uniquely identify this process, especially at the earlier ages, then we can modify that disease process,” he said, adding, “I think the data continues to have strong directionality that use of CT angiography is improving outcomes around the world.”

And that, Choi said, touches on a broader theme of the SCCT meeting: the global importance of identifying coronary disease before it progresses too far. “We're still at an early point for CT as a technology,” he said. “We've done a lot of trials, but we haven't fully unleashed the potential of the modality to be able to treat disease and treat it at an earlier stage.”