Routine cardiac testing may not be warranted for patients who present to the emergency department (ED) for chest pain without a diagnosis consistent with acute coronary syndrome (ACS). The findings of the retrospective cohort analysis were published June 26 in JAMA Internal Medicine.

Alex Sandhu, MD, et al., analyzed national claims data for 926,633 privately insured patients using Truven MarketScan. The patients were aged 18-64 years (average age, 44 years; 59 percent women) who visited an ED between 2011 and 2012.

Results showed an increase in the use of downstream testing and treatment in patients who underwent noninvasive testing and coronary angiography for chest pain in the ED – but no reduction in hospital admissions for an acute myocardial infarction (AMI).

Previously, cardiac testing rates were assumed to be higher on weekdays due to differences in resource availability. To address unmeasured cofounding in the observational data, the researchers used the day of presentation, weekday (Monday through Thursday) vs. weekend (Friday through Sunday), as an instrumental variable in their analysis.

While similar baseline comorbidities were found between the two groups, patients who presented to the ED on a weekday (n = 571,988) were more likely than those who presented over the weekend (n = 354,645) to receive testing within two days (18.1 percent vs. 12.3 percent) or 30 days (26.1 percent vs. 21.35 percent).

After risk factor adjustment, testing within 30 days was associated with an increase in coronary angiography (36.5 per 1000 patients tested) and revascularization (22.8 per 1000 patients tested) at one year, while AMI admissions was not. Similar results were seen in patients who received testing within two days.

The study authors conclude that "further analysis of the effect of testing on health care utilization and costs will refine future practice recommendations and guide patient-physician shared decision-making." They state that "the current evidence supports a shift in the treatment of these patients; shared decision-making with patients should be considered a viable alternative to routine cardiac testing in the absence of robust evidence to support its benefit."

Benjamin C. Sun, MD, and Rita F. Redberg, MD, MSc, FACC, comment, "this study represents the next logical step in assessing the value of cardiac testing after an ED evaluation for suspected ACS. It is important to emphasize that the IVA [instrumental variable] approach depends on strong assumptions that cannot be directly verified." In an editorial comment, they highlight that "the findings of this report are consistent with a rapidly expanding evidence base that challenges the current paradigm of early noninvasive testing after an ED evaluation for suspected ACS," and "strongly advocate for randomized clinical studies that will provide definitive guidance for this prevalent, high-risk, vexing clinical problem."

Keywords: Acute Coronary Syndrome, Chest Pain, Comorbidity, Coronary Angiography, Emergency Service, Hospital, Myocardial Infarction, Research Personnel, Retrospective Studies, Risk Factors

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