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Noninvasive testing after ED visit for chest pain may reduce event rates
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Patients who underwent noninvasive diagnostic testing after evaluation for chest pain in the ED had a lower observed rate of CV death or MI, according to a retrospective cohort study published in the Journal of the American Heart Association.
“As far as we are aware, it’s the first [study] to evaluate a strategy of any testing vs. not testing in patients being worked up for coronary artery disease,” Idan Roifman, MD, MSc, FRCPC, assistant professor of medicine at the University of Toronto and adjunct scientist for ICES (formerly the Institute for Clinical Evaluative Sciences) in Toronto, told Cardiology Today. “This question of the utility of noninvasive testing for CAD in contemporary populations arose after two large clinical trials (PROMISE and SCOT-HEART) reported very low rates of cardiac events regardless of the specific type of noninvasive test chosen. This led to the question of whether any noninvasive testing is warranted and, if so, under what circumstances do patients benefit the most? Neither of the trials have no-testing arms that would have helped answer this question. While the overall cohort that we studied showed a small benefit that was attributable to noninvasive testing, the results were driven by the high-risk patient subgroup. Those are patients who had a prior heart attack, or prior angioplasty or bypass surgery. Our results actually show that a risk-based strategy may be beneficial for testing these patients because the vast majority of patients (those at low and intermediate risk) didn’t actually benefit. Finding the optimal ways to test patients noninvasively for coronary artery disease is important. Our findings may be applied to reduce unnecessary testing in the low and intermediate risk patients. The flip side to that is that in that high-risk population, ... those patients right now might be undertested a little bit because physicians may think they already have coronary disease, so it’s not worthwhile testing them, but those are actually the patients that we found benefitted the most from noninvasive testing.”
ED visits for chest pain
Researchers analyzed data from 370,863 patients who were evaluated for chest pain in the ED and were discharged home after evaluation between April 2010 and November 2015. Patients also underwent an ECG within 1 day of the ED visit. These patients were followed for 30 days after the initial visit to the ED for chest pain to determine if they underwent one of four noninvasive diagnostic tests: stress echocardiography, graded exercise stress test, coronary CTA or myocardial perfusion imaging.
After propensity score matching, 96,457 patients underwent noninvasive diagnostic testing (mean age, 57 years; 50% women) and 96,457 patients did not (mean age, 57 years; 49% women).
The main outcome was defined as a composite of time to hospitalization for CV death or acute MI. Follow-up was conducted for 1 year after presenting with chest pain.
At 90 days, the rate of the composite outcome was low for both the nontesting and the noninvasive diagnostic testing groups (0.29% vs. 0.34%, respectively). Low rates were also seen at 1 year for both groups (0.78% vs. 0.68%, respectively).
Patients who underwent noninvasive diagnostic testing had a small yet significantly lower hazard of developing the composite outcome vs. those who did not undergo testing (HR = 0.87; 95% CI, 0.78-0.96). This was primarily driven by patients who were high risk (HR = 0.75; 95% CI, 0.61-0.92).
“That [high-risk] group was only about 10% of patients, whereas 90% of the patients or so, there was actually no statistically significant improvement at all in downstream MI or mortality,” Roifman said in an interview.
Clinical implications
Roifman mentioned that this may have some important clinical implications. He added, “It may allow ED physicians and consultant cardiologists to risk stratify their patients prior to sending them home in order for them to get a better idea of which of their patients would benefit the most from noninvasive testing.” – by Darlene Dobkowski
For more information:
Idan Roifman , MD, MSc, FRCPC, can be reached at University of Toronto, 2075 Bayview Ave., Room M315, Toronto, ON M4N-3M5; email: idan.roifman@sunnybrook.ca
Disclosures: The authors report no relevant financial disclosures.
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