RAPID-CTCA Finds No Advantage to CT Angiography in Mid- to High-Risk Suspected ACS

November 19, 2020

A strategy of routine coronary CT angiography (CTA) made little difference to treatment decisions or 1-year outcomes, compared with standard care, in intermediate- to high-risk patients with chest pain and suspected acute coronary syndromes (ACS), a randomized trial shows.

The RAPID-CTCA trial is only the latest attempt to nail down the most appropriate coronary CTA candidates among patients coming to the emergency department for evaluation of acute chest pain.

Routine coronary CTA also prompted greater use of invasive angiography than did standard care, in contrast to earlier trials conducted in lower-risk patients with stable or acute chest pain that saw fewer trips to the cath lab among those undergoing coronary CTA.

That group also showed a modest increase in length of hospital stay and healthcare costs, observed Alasdair J. Gray, MBChB, MD, Royal Infirmary of Edinburgh, United Kingdom, when presenting RAPID-CTCA November 16 during the American Heart Association (AHA) Scientific Sessions 2020 virtual meeting. 

The primary endpoint in the trial with more than 1700 patients, death from any cause or new type 1 or type 4b myocardial infarction (due to thrombosis from plaque rupture or stent thrombosis), was seen in 5.8% of those assigned to routine coronary CTA, statistically on par with the standard-care group's rate of 6.1%.

As the trialists also concluded, "these findings do not support the routine use of early coronary CTA in intermediate- or high-risk patients with suspected acute coronary syndrome in this era of using rapid troponin tests to make the diagnosis," said Judith S. Hochman, MD, NYU Langone Medical Center, New York City.

"And there was equal use of revascularization, which suggests that clinicians selected patients appropriately in both groups," said Hochman as the invited discussant following Gray's presentation.

"Coronary CTA is an excellent test for patients that don't have known coronary heart disease. It may not always be as helpful in patients that have prior coronary heart disease, which in this study was a third of the patients," Ron Blankstein, MD, told theheart.org | Medscape Cardiology.

"This is why when you're dealing with a patient population such as this, the use of CTA may be helpful, but only in carefully selected patients," said Blankstein, who is director of Cardiac Computed Tomography at Brigham and Women's Hospital, Boston, Massachusetts.

Generally, he said, a trial designed to determine which patients with suspected ACS are likely to benefit from coronary CTA, given the trials to date, would best exclude those with previously known coronary heart disease (CHD). "As a group, those are patients that may be better evaluated by functional testing," said Blankstein, who was not part of RAPID-CTCA. "I would be really curious to know if you took those patients out, would there perhaps have been more of an advantage for CT."

The trial entered symptomatic patients who were evaluated for suspected ACS and had at least one of three additional risk markers: ECG abnormalities such as ST-segment depression; a confirmed history of ischemic heart disease; or elevated troponins in the top 1% of normal range or higher. It excluded anyone with signs of high-risk ACS such as acute heart failure or shock and those with ST-segment elevation MI.

During the trial, they added an additional criterion. "If the treating clinician felt that the patient's underlying condition mandated invasive angiography, they were also excluded," Gray said.

"We were thoughtful about the relative heterogeneity of the inclusion criteria in this pragmatic trial," he said, so a subgroup analysis was prespecified to compare outcomes by age, sex, CHD history, troponin levels, GRACE risk scores, whether there were ECG abnormalities and whether the hospital offered on-site invasive angiography. In no subgroup was either strategy superior to the other.

The trial randomly assigned 1748 patients, mean age 62 and 64% male, to routine early coronary CTA or to standard care (877 and 871, respectively) at 37 centers in the UK between 2015 and 2019. There was a known personal history of CHD in 34%, 31% had a CHD family history, and 18% had diabetes. Elevated troponins were a qualifying risk factor in 57% and ECG abnormalities in 61%.

Coronary CTA was performed in 87.5% of patients in CTA group a median 4.2 hours after randomization; it showed obstructive coronary disease in 47%, nonobstructive disease in 29%, and normal coronaries in 23%.

The adjusted hazard ratio (HR) for the primary endpoint in the CTA group compared with those assigned to standard care was nonsignificant at 0.91 (95% CI, 0.62 - 1.35, P = .65). Nor were there significant differences in death from any cause, CHD death, or nonfatal MI.

The rate of invasive coronary angiography went down with coronary CTA, for an HR of 0.81 (95% CI, 0.72 - 0.92, P = .001), but the rate of coronary revascularization was similar in both groups: HR, 1.03 (95% CI, 0.87 - 1.21).

In RAPID-CTCA "roughly half the patients didn't have any obstructive disease. That's actually a larger proportion than I would have expected for a high-risk acute chest-pain population," Blankstein said.

"And as a result, it's not surprising that when you start with CTA, fewer patients ended up in the cath lab. I think that is a potential benefit of coronary CTA. If you select the right patients, you can avoid invasive angiography."

Gray reports no conflicts. Hochman discloses significant relationships with Amgen, Abbott Vascular, Medtronic, St Jude Medical, Volcano, Merck, and Omron Healthcare; and receiving research support from AstraZeneca and Arbor Pharmaceuticals. Blankstein discloses receiving research grants from Amgen and Astellas.

American Heart Association Scientific Sessions 2020: Abstract LBS.07 Daily Recap & Late-Breaking Science: Randomized Trials – Brain, Kidney, and Heart. Presented November 16, 2020.

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