CTA Doesn’t Add Value in At-Risk Patients Thought to Have ACS

Patients who are at intermediate or high risk with suspected or provisionally diagnosed ACS don’t benefit from undergoing early coronary CT angiography (CTA), new data from the RAPID-CTCA trial confirm.

The pragmatic, multicenter trial found that—in this particular population—adding CTA to standard of care made no difference when it came to outcomes but it did improve diagnostic certainty and patient satisfaction. This came at the cost of slightly longer hospital stays and higher healthcare costs, Alasdair Gray, MBChB, MD (Edinburgh Emergency Medicine, Scotland), told attendees of the virtual American Heart Association (AHA) 2020 Scientific Sessions this week.

“It’s well determined that in stable chest pain that the use of CT increases coronary artery disease diagnosis [and] increases invasive angiography and coronary revascularization,” he said. And in SCOT-HEART, a chest-pain workup strategy using CTA offered a long-term reduction in MI. For low-risk acute chest pain, similar short-term effects are seen, Gray pointed out, “but the data on subsequent long-term clinical outcomes is equivocal.”

Certainly in the UK, there’s a creep towards higher-risk patients being investigated by using CT early on in their investigation process. Alasdair Gray

Current guidelines say that CTA may be useful, too, in intermediate-risk patients. “And certainly in the UK, there’s a creep towards higher-risk patients being investigated by using CT early on in their investigation process,” he continued. “However, there is limited or no evidence for use of CT in intermediate- or high-risk patients. The RAPID-CTCA trial aims to fill that gap.”

Its findings, Gray concluded at the end of his presentation, “do not support the routine use early coronary CT angiography in intermediate- or high-risk patients with acute chest pain.”

Jonathon Leipsic, MD (St. Paul's Hospital, Vancouver, Canada), who commented on the results for TCTMD, emphasized that “these are patients who’ve been ‘ruled in,’ so to speak, with heart attack.”

Despite the overall negative result of RAPID-CTCA, he said, it does hint at some ways CT might still prove useful if targeted to an even more narrow segment of that population. Imaging those without known CAD prior to admission, for example, would likely have a higher yield in terms of identifying the patients who have normal arteries and allow them to skip a trip to the cath lab, said Leipsic, as was found in the VERDICT trial.

RAPID-CTCA

RAPID-CTCA investigators looked at 1,748 adults (mean age 62 years; 64% men) with suspected or provisional diagnosis of ACS who had prior history of coronary heart disease (34%), troponin > 99th percentile (57%), and/or abnormal 12-lead ECG (61%). Participants were enrolled at 37 UK hospitals between 2015 and 2019.

Mean GRACE score was 115, with 44% of patients having a score below 109, 23% having a score greater than 140, and the remaining 32% falling in the middle.

Of the 767 patients randomized to CTA, 87% underwent the testing, which occurred at a median of 4.2 hours. Ninety percent were diagnostic quality. These showed normal coronary arteries in 23%, nonobstructive CAD in 29%, and obstructive CAD in 47%.

It’s very appealing to imagine, especially in the era of COVID, that you could avoid an invasive angiogram. Jonathon Leipsic

CTA patients were slightly less likely than standard-of-care patients to then undergo invasive angiography (adjusted HR 0.81; 95% CI 0.72-0.92) but equally likely to undergo revascularization (adjusted HR 1.03; 95% CI 0.87-1.21). Overall ACS treatment and use of preventive therapies were similar between groups, as well.

Mean diagnostic certainty increased from 7.1 to 8.5 on a 10-point scale with CTA, however, and patients randomized to the added imaging reported higher satisfaction (83.3% vs 79.7%). Hospital stays post-CTA averaged about 5 hours longer, with higher mean healthcare costs ($9,494 vs $8,776) than standard of care alone. Both groups were equally likely to return to the hospital or be admitted with chest pain.

Most importantly, the primary endpoint of all-cause death or MI (spontaneous or due to stent thrombosis) at 1 year did not differ between CTA and standard of care alone (adjusted HR 0.91; 95% CI 0.62-1.35), with no differences across patient subgroups.

Targeted CT

Judith S. Hochman, MD (NYU School of Medicine, New York, NY), discussing Gray’s presentation during the late-breaking session, observed that the RAPID-CTCA trialists had achieved their goal of enrolling a higher-risk cohort compared with earlier studies, as evidenced by the 1-year all-cause death rate of 6%.

There are, however, limitations to RAPID-CTCA, Hochman said, citing the wide confidence intervals around the primary endpoint as well as the fact that one in 10 patients randomized to CTA didn’t actually undergo the imaging test.

And finally, she called for more details on whether the slice of CTA patients found to have nonobstructive disease had started preventive therapy as a result. This might be a means to improve outcomes, Hochman stressed. “SCOT-HEART was a landmark that actually showed that that was the case: patients visualized with nonobstructive disease had more statin and aspirin prescribed, which led to a lower death and MI event rate.”

All that said, this trial convincingly demonstrates that in an era where troponin can rapidly diagnose MI, there’s no need for routine CTA in the higher-risk, acute patients studied here, Hochman agreed. “There was equal use of revascularization, which suggests that clinicians selected patients appropriately in both groups,” she added.

Moving ahead, both RAPID-CTCA and the HARP trial, also presented at AHA, reinforce the need for clinicians to be aware of MI in nonobstructive disease—otherwise known as MINOCA—particularly when treating women, Hochman stressed. “They have a high event rate and should not be dismissed.”

Both she and Leipsic drew attention to the GRACE score and its ability to tease out who will benefit most from revascularization. At a very high GRACE score, he said, CT isn’t going to discourage intervention, so is unnecessary. More useful would be homing in on lower-score individuals, where the CT results might guide care. Leipsic added that he has reached out to the RAPID-CTCA investigators for further information on treatment and outcomes within the latter group.

“I think it’s clear that if you take all patients with known disease, without known disease, that come in with non-ST segment elevation MI and say you have to do a CT on all of them, it’s not going to add value. But it’s very appealing to imagine, especially in the era of COVID, that you could avoid an invasive angiogram” in many cases, he said, suggesting that CT perfusion or CT-derived fractional flow reserve might provide complementary information.