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

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.

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.

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.