Background: Following reperfusion in ST segment elevation myocardial infarction (STEMI), continuous ECG monitoring is strongly recommended for the first 24-48 hours, the highest at-risk period for an actionable arrhythmia (AA). Beyond this time-frame, the incident rate of an AA and the role of continued telemetry is unclear.
Methods: Between Dec 2019 and Mar 2020 (interrupted by COVID-19), we aimed to prospectively quantify the risk of an AA in a consecutive low-risk STEMI cohort treated within a single PCI-network of care (Royal University Hospital, Saskatoon). Patients presenting with cardiogenic shock, cardiac arrest or acute decompensated heart failure were excluded. The primary outcome was defined as an AA occurring following coronary care unit (CCU) discharge. AAs included: >3 seconds asystole; high grade block; ventricular fibrillation; >15 beats ventricular tachycardia; atrial fibrillation with rapid ventricular response; and >15 beats supraventricular tachycardia. Patients with a history of any of these arrhythmias were excluded. Key secondary outcomes included 30-day all-cause mortality and re-hospitalization.
Results: Of 85 patients meeting eligibility criteria, 82 consented. The mean (±sd) durations of CCU and cumulative in-hospital length of stays were 2 (±0.81) days and 3.8 (±1.4) days, respectively. Two-thirds (n=54) had been treated with primary PCI, the rest with a fibrinolytic pharmaco-invasive strategy. Only 1/82 (1.2%) had an AA following CCU discharge, new onset atrial fibrillation not identified within the first 48 hours of presentation. All survived to hospital discharge, and the 30-day rates of all-cause mortality and re-hospitalization were 1% and 10%, respectively.
Conclusion: In this small, single-center, observational analysis of contemporarily treated low-risk STEMI patients, the risk of an AA beyond 48 hours appears to be very small. The practice of universally monitoring all low-risk STEMI patients until hospital discharge needs to be better defined.