Cardiovascular Testing and Clinical Outcomes in Emergency Department Patients With Chest Pain

Reviewed by Dr. Grace Liu
Sandhu AT, et al. JAMA Int Med. 2017;177(8):1175-1182

SUMMARY
This study sought to determine whether noninvasive cardiac testing (exercise ECG, stress echocardiography, nuclear stress test, CT angiography) in patients presenting with atypical chest pain (“without evidence of ischemia”) leads to improved cardiovascular outcomes. The authors used national claims data to perform a retrospective cohort analysis of 926,633 privately insured patients between ages 18 to 64 who presented to the ED with chest pain between 2011 and 2012. All patients had initial findings that excluded the diagnosis of myocardial ischemia. The analysis used an instrumental-variables approach to adjust for potential selection bias and confounders. The primary endpoints were coronary revascularization (PCI or CABG) and acute myocardial infarction (AMI) admission at 7, 30, 180, and 365 days.

Noninvasive cardiac testing was performed within 30 days of presentation in 224,973 patients (24%). In multivariate analyses, patients undergoing noninvasive cardiac testing within 30 days had significantly higher rates of coronary angiography (36.5 per 1,000 patients tested; 95% CI, 21.0 – 52.0) and revascularization (22.8 per 1,000 patients tested; 95% CI, 10.6 – 35.0) at 1 year as compared to those who did not receive testing; however, there was no significant change in AMI admissions (7.8 per 1,000 patients tested; 95% CI, -1.4 to 17.0) at 1 year. Subgroup analysis of high-risk patients similarly showed higher rates of revascularization, with lower risk of CABG surgery, but no change in AMI admissions in patients who received noninvasive cardiac testing as compared to those who did not receive testing (data in supplementary material).

COMMENTARY
As physicians, we are often faced with the question of what to do next in a patient with chest pain once AMI has been ruled out with serial biomarker testing and ECG. The current ACC/AHA guidelines recommend noninvasive testing or coronary angiography prior to discharge or within 72 hours in such patients (moderate strength recommendation).1 This study, as well as previous observational studies, challenges these recommendations by showing that although noninvasive testing increases revascularization, it is not associated with reduction in AMI admissions.2, 3

We should always weigh the risks and benefits of cardiac testing and strive to avoid testing in low-risk patients, but the management of moderate- to high-risk patients is less clear. This study reported that testing those with greater baseline risk did not decrease AMI admission. However, we should also be cautious against viewing AMI as the sole important outcome. Notably, this study did not provide mortality data. There were also potential benefits that were not analyzed – negative test results may be reassuring to patients, and positive test results leading to coronary revascularization may provide relief of anginal symptoms and improvement in exercise tolerance.

In the absence of better risk assessment tools for identification of patients most likely to benefit from cardiac testing, the best course may be to strive for patient-physician shared decision-making to balance resource utilization and improve care.

REFERENCES
1. Amsterdam EA, et al. 2014 AHA/ACC Guideline for the Management of Patients with Non-ST-Elevation Acute Coronary Syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2014; 64(24):e139-e-228.
2. Foy AJ, et al. Comparative effectiveness of diagnostic testing strategies in emergency department patients with chest pain: an analysis of downstream testing, interventions, and outcomes. JAMA Intern Med. 2015;175(3):428-436.
3. Prasad V, et al. Chest pain in the emergency department: the case against our current practice of routine noninvasive testing. Arch Intern Med. 2012;172(19):1506-1509.

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