Although the absolute numbers were small – 48 clinical events in the intervention group and 81 among patients who had standard care – the difference was significant and wasn’t associated with any increase in invasive coronary procedures, David E. Newby, MD, said at the annual congress of the European Society of Cardiology.
The study, presented August 25, was published simultaneously in the New England Journal of Medicine (NEJM 2018; DOI: 10.1056/NEJMoa1805971
The data suggest that 63 patients with stable chest pain would need to undergo CTA to prevent one fatal or nonfatal myocardial infarction over 5 years, said Dr. Newby, the BHF John Wheatley professor of cardiology at the University of Edinburgh, Scotland.
He presented 5-year results of the SCOT-HEART study, an open-label trial that randomized 4,146 patients with stable chest pain to standard care plus CTA, or standard care alone. The primary endpoint was nonfatal myocardial infarction or death from coronary heart disease at 5 years. The 3-year results were previously reported.
“This is one of the most impactful studies in cardiovascular medicine. It’s a groundbreaking trial,” commented Todd C. Villines, MD, a designated discussant for the report at the meeting. SCOT-HEART “looked at the additive value of CTA compared with usual care using functional testing with an exercise stress test. It showed that when you visualize coronary atherosclerosis [with CTA] and change medical management based on whether or not plaque is present it drove a significant decrease in MIs,” noted Dr. Villines, a cardiologist affiliated with Georgetown University Medical School in Washington, and immediate past president of the Society of Cardiovascular CT.
Patients were recruited from 12 cardiology centers across Scotland and followed for a mean of 4.8 years, amassing 20,254 patient-years of follow-up. They were a mean of 57 years old; 41% had nonanginal chest pain, 35% typical angina, and 24% atypical angina About half were current or former smokers, a third had hypertension, and half had hypercholesterolemia. Resting EEG was normal in 85%.
Patients who underwent CTA were more likely to start preventive therapies (19% vs. 14.7%; odds ratio, 1.4) and antianginal therapies (13% vs. 10.7%; hazard ratio, 1.27). And although there were more revascularizations in that group early on, the numbers were similar by the end of follow-up (13.5% vs. 13%). After 12 months, CTA patients were 30% less likely to undergo invasive coronary angiography (HR, 0.70) and 41% less likely to undergo a coronary revascularization (HR, 0.59).
“This would be consistent with both the emergence of unrecognized disease and nonfatal myocardial infarction in the standard-care group and the reduction in disease progression in the CTA group owing to the implementation of lifestyle modifications and preventive therapies,” Dr. Newby and colleagues wrote in the NEJM paper.
The composite clinical endpoint occurred in 2.3% of the CTA group and 3.9% of the standard care group – a significant risk differential of 41% (HR, 0.59). The primary driver of this benefit was a significantly lower rate of nonfatal myocardial infarction (HR, 0.60) among CTA patients.
There was no evidence of a subgroup effect, Dr. Newby noted. Among the 48 CTA patients who experienced a clinical event, 22 had obstructive disease, 17 had nonobstructive disease, and three had normal coronary arteries (six patients assigned to the procedure didn’t return for it).
There was a slightly higher event rate among patients with possible angina than among those with nonanginal pain (3.1% vs. 1.8%), but the 5-year difference between the treatment groups was not significantly different.
“Our findings suggest that the use of CTA resulted in more correct diagnoses of coronary heart disease than standard care alone, which, in turn, led to the use of appropriate therapies and this change in management resulted in fewer clinical events in the CTA group than in the standard-care group,” Dr. Newby noted. “Patients who receive a correct diagnosis are also more likely to receive appropriate preventive therapies and may have greater motivation to implement healthy lifestyle modification.”
“The SCOT-HEART data solidify coronary CTA as the best first-line test for patients without established coronary disease,” especially now that a report documented that clinicians worldwide are performing coronary CTA using lower levels of radiation exposure to patients, commented Dr. Villines in an interview. During the same session where Dr. Newby reported the SCOT-HEART results, an international team of researchers reported results of a survey of CTA methods used at 61 centers in 32 countries, including several U.S. sites. The results from the survey showed that in 2017 patients undergoing coronary CTA received a median radiation dose of 2.7 mSv and a median dose-length product of 195 mGy*cm, both representing a 78% relative reduction compared with the median doses received during CTA when a similar survey ran in 2007 (Eur Heart J. 2018 Aug 25; doi:10.1093/eurheartj/ehy546).
In contrast, for patients with established coronary artery disease functional tests using stress imaging remain best, Dr. Villines said. “What SCOT-HEART said was that when you use coronary CTA in a population without established coronary disease you can identify not only whether the patient has obstructive disease but do they have coronary atherosclerosis, and that is prognostic and valuable. You miss that with functional testing.”
The Chief Scientist Office of the Scottish Government funded the study. Dr. Newby has received grants from Seimens. Dr. Villines had no relevant commercial disclosures.
Updated 8/27/18: Mitchel L. Zoler contributed commentary by Dr. Todd C. Villines, and additional data and discussion from the presentation, to this article.
SOURCE: Newby DE et al. NEJM 2018; DOI: 10.1056/NEJMoa1805971.