No Benefit of Routine CT Angiography After Ruling Out a Heart Attack

After ruling out a myocardial infarction (MI) in patients with suspected acute coronary syndrome (ACS), routine use of CT coronary angiography to guide management did not reduce subsequent cardiac events compared with standard care, results of a randomized trial showed.

Over a median of 3 years in the TARGET-CTCA study, the primary composite outcome of MI or death from a cardiac cause occurred in 7.1% of patients randomized to CT coronary angiography and in 7.3% of those in the standard-care group (adjusted HR 0.95, 95% CI 0.73-1.23, P=0.71), reported Nicholas Mills, MD, PhD, of the University of Edinburgh in Scotland.

The findings suggest that once an MI has been ruled out, “routine CT angiography may not be required in this setting,” said Mills at the European Society of Cardiology (ESC) Congress in Munich. “Implementation of these trial findings could reduce healthcare costs and simplify care for patients without compromising future outcomes.”

The results were published simultaneously in the New England Journal of Medicine.

ESC discussant Christoph Grani, MD, PhD, from Bern University Hospital in Switzerland, concluded that the results don’t support routine CT after MI is ruled out, but added that “CT is a diagnostic test, not a treatment.”

“The clinical scenario is very important, and I think in the acute setting, it didn’t change very much,” Grani said. While CT still can be used, “it’s a maybe,” he added. Future trials should “include contemporary coronary CT phenotyping, going beyond diagnosis, and assess cost-effectiveness.”

Across Europe, about 30 million people present with acute chest pain to emergency departments (EDs) each year, but only about one in 10 of those have acute MI, Mills noted. Diagnostic pathways have been implemented to promote early discharge, he said, but some patients return and may remain at risk for future MI. Prior to their study, it was unclear whether further investigation would help to reduce that risk.

TARGET-CTCA included patients presenting with acute chest pain to EDs at 14 hospitals across the United Kingdom in whom MI had been ruled out but who had high-sensitivity cardiac troponin levels indicating an intermediate risk of cardiovascular events, with a maximum troponin I or T concentration of greater than 5 ng/L.

A total of 3,170 patients were randomly assigned 1:1 to receive either outpatient CT coronary angiography-guided care or standard care.

At 90 days after randomization, CT coronary angiography had been performed in 92.1% of participants in the CT coronary angiography group and in 2.2% of the standard-care group. Of these, 0.4% had a CT coronary angiography–related adverse event.

PREC1SE-MI

In a separate study also looking at patients presenting to the ED with acute chest pain, researchers showed that serial troponin measurements to help diagnose or rule out MI at 0 and 1 hours (0/1-hour pathway) matched blood draws at 0 and 3 hours (0/3-hour pathway) in terms of safety. But getting the second troponin result earlier didn’t shorten ED stays.

At 30 days, a primary safety event occurred in 1.1% of presentations in the 0/1-hour group versus 1.2% in the 0/3-hour group (adjusted OR 0.93, 95% CI 0.77-1.13, P=0.0004 for noninferiority), Christian Mueller, MD, from the University of Basel in Switzerland, reported at ESC.

A divergence between the groups was observed in the two components of the primary safety outcome — new type 1 MIs and deaths from any cause — and will require more study, Mueller noted. While there were more new MIs in the 0/1-hour group, for each extra MI there were three fewer deaths, he said.

Despite the second troponin result about 2 hours earlier, the trial did not meet the primary efficacy endpoint of shorter ED lengths of stay, with a median of 309 minutes in each group (P=0.65), according to the findings, which were published simultaneously in The Lancet.

This indicates that the rate-limiting step was not the availability of the troponin results but rather “the workload of the physician and nurses,” Mueller said.

Based on data from early-adopting hospitals, ESC guidelines in 2023 gave a preferred recommendation that MI can be safely ruled out with the 0/1-hour pathway, but uncertainty remained about the safety at late-adopting hospitals.

PREC1SE-MI was a pragmatic, stepped-wedge, cluster-randomized, controlled, masked-endpoint trial at 19 hospitals that had not yet adopted the newer strategy. They were randomly allocated to implement the 0/1-hour pathway after 6 months (early implementation), or after 12 months (late implementation).

In all, 31,160 patients were managed using the 0/1-hour pathway, and 36,464 with the 0/3-hour pathway. Direct discharge from the ED, a secondary endpoint, occurred in 74% and 71% of the two groups, respectively.

Lori Daniels, MD, from the University of California San Diego, said PREC1SE-MI provides “exactly the kind of real-world data we need on efficacy and safety” for the 0/1-hour pathway. Together with a meta-analysis combining findings of four smaller trials with the PREC1SE-MI data, “this gives us the most complete picture yet of the 0/1-hour pathway,” said Daniels.

The finding of divergence in safety outcomes with fewer deaths but more new type 1 MIs with the 0/1-hour pathway “deserves vigilance, not necessarily alarm,” she said, and deserves further study.

Overall, the 0/1-hour pathway is “safe enough to keep using for fast rule out, but don’t expect it alone to fix ED overcrowding,” she noted.