ACTIONABLE ARRHYTHMIAS IN LOW-RISK STEMI PATIENTS: THE ROLE OF CONTINUOUS ECG MONITORING BEYOND 48 HOURS OF REPERFUSION

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 AND RESULTS 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; additionally, excluded were patients treated medically without reperfusion. The primary outcome included the occurrence of an AA following discharge from the coronary care unit (CCU); an AA was defined as any of the following: >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 was also excluded. Key secondary outcomes included 30-day all-cause mortality and re-hospitalization. Continuous variables are presented as mean (±SD), and categorical variables as proportions. Of the 85 patients meeting eligibility criteria, 82 provided informed consent and their baseline demographics are presented in Table 1. 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. The infarct-related territory was distributed as: anterior 34% and inferior 49%; significant stenoses (>70% non left main or >50% left main) in the non-infarct related territory were identified in 45%. 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 82 patients 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.