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The Ultimate Chest Pain Pathway? Not Quite

June 10, 2024

Written by Laura Murphy

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This was a validation study for the recently published American College of Cardiology (ACC) Expert Consensus Decision Pathway for chest pain. Results suggest this pathway is safe and efficacious for use in patients without known CAD; however, performance was not as good for patients with known CAD.

The ultimate chest pain pathway? Not quite..
This was a validation study for the American College of Cardiology (ACC) Expert Consensus Decision Pathway for Chest Pain (more on that here). This pathway uses a 12-lead ECG, serial high-sensitivity troponin (hs-cTn) measures (0 and 2 hours) to risk stratify patients presenting with possible acute coronary syndrome (ACS). Thus far, studies of hs-cTn algorithms have been derived and validated mostly in Europe and have had mixed results in US populations.

This was a multicenter observational cohort study of 14,395 adults with possible acute coronary syndrome (ACS) from November 2020 to July 2022 from 5 US EDs in a single state (North Carolina). Primary safety outcome was 30-day all-cause death or myocardial infarction (MI), and efficacy was defined as the proportion of patients stratified to the rule-out zone. Negative predictive value for 30-day death or MI was assessed among the entire cohort and a subgroup of 3,386 patients with known CAD (defined as prior MI, coronary revascularization or >70% coronary stenosis on cardiac catheterization).

48.1% of patients were stratified to the “rule-out” zone, and among these patients, 0.3% had death or MI at 30 days (NPV of 99.7%, 95%CI 99.5-99.8%), which is above the commonly used 99% NPV safety threshold for acute coronary syndrome risk stratification pathways and risk tools.  However, in patients with CAD, efficacy was lower (20% of cohort stratified to rule-out zone), and the pathway did not meet 99% NPV safety threshold (1.5% had death or MI within 30 days; NPV 98.5% for 30-day death or MI and 96.0% for 30-day MACE), largely due to missed MIs. Interestingly, many of the 30-day MACE events (rate of 4.0%) in this cohort were revascularization without MI (2.5%).

Authors conclude that patients with CAD require further risk stratification and that the ACC pathway may benefit from further revisions to include known CAD as a branch point in the algorithm given higher risk in this group. 

One limitation of this study was that it was conducted in a single state. Furthermore, event rates were low, and adjustment was only possible for composite events of death or MI and MACE, and follow-up only extended to 30 days beyond index visit (one year follow-up data is coming). This study also did not address what to do with observation zone patients (41.3% of patients in total cohort and 54.7% in known CAD cohort). The ACC pathway advises additional risk stratification and use of noninvasive testing, and optimal pathways for these patients are still being explored.

How will this change my practice?
This study reinforces that additional risk stratification is likely indicated for patients with known CAD who are higher risk for MACE. I emphasize to many of my patients with known CAD (or other significant risk factors) that a “rule-out” in the ED is not necessarily sufficient; additional stratification and cardiac testing may be needed. Ultimately, admission vs close outpatient follow up may vary by site, but it is important that we acknowledge higher risk in these patients, even with negative high-sensitivity troponins. 

Editor’s note: So much to say, for my rant please listen to the podcast. ~ Nick Zelt

Validation of the ACC Expert Consensus Decision Pathway for Patients With Chest Pain. J Am Coll Cardiol. 2024 Apr 2;83(13):1181-1190. doi: 10.1016/j.jacc.2024.02.004. Epub 2024 Mar 25. PMID: 38538196.

What are your thoughts?