Rapid rule out for suspected myocardial infarction: is the algorithm appropriate for all?

Area of Science:

• Cardiology
• Emergency Medicine
• Clinical Risk Stratification

Background:

• Patients with cardiac chest pain and low high-sensitive troponin I (HsTnI) levels (< 5 ng/L) generally have a favorable prognosis.
• European Society of Cardiology (ESC) guidelines suggest discharging patients with normal HsTnI, no chest pain, and a Global Registry of Acute Coronary Events (GRACE) score < 140 for outpatient evaluation.
• The current guideline-based approach may not adequately identify all patients at risk for adverse cardiovascular events.

Purpose of the Study:

• To evaluate the hypothesis that not all patients with a GRACE score < 140 and undetectable HsTnI should be discharged for ambulatory testing.
• To assess the risk of major adverse cardiovascular events (MACE) in patients with chest pain, low HsTnI, and varying GRACE scores.
• To refine risk stratification protocols for patients presenting with chest pain in the emergency department.

Main Methods:

• A population-based retrospective cohort study was conducted at a large tertiary care center.
• Included patients were discharged between February 2016 and February 2019 after a rule-out myocardial infarction (MI) protocol.
• Data analysis focused on HsTnI levels, GRACE risk scores, and subsequent adverse events, including death, revascularization, and readmission for acute coronary syndrome (ACS).

Main Results:

• Of 13,800 patients discharged after MI rule-out, 9,236 (67%) had HsTnI < 5 ng/L.
• Among those with HsTnI < 5 ng/L, 7,705 patients met criteria for low (n=7,162) or moderate (n=543) GRACE risk scores.
• Moderate-risk patients (GRACE score < 140) experienced significantly higher rates of adverse events (4.6% vs. 2.1%, P < 0.001), including death (0.5% vs. 0.1%), revascularization (3.9% vs. 1.8%), and ACS readmission (1.1% vs. 0.4%).

Conclusions:

• Patients with chest pain, HsTnI < 5 ng/L, and GRACE score < 140 have a 2-4% risk of adverse events within 60 days.
• The observed differences in adverse events suggest that rapid rule-out algorithms should be reserved for low-risk patients with a GRACE score < 73.
• Current risk stratification may need refinement to better identify patients who can be safely discharged for outpatient workup.