Retrospective chart review of 198 ED patients with triage heart rate <50 bpm across two academic EDs (July 2024–June 2025), comparing outcomes and ECG-to-intervention times across primary bradycardia (requiring permanent pacemaker, n=62), secondary bradycardia (requiring treatment of underlying cause, n=68), and neither (n=68).
Secondary bradycardias had significantly higher mortality (25.0% vs 4.8%, p<0.05) and more frequent hypotension (BP <90 mmHg: 19.1% vs 6.5%, p<0.05) than primary bradycardias. ECG-to-intervention delays were notable for hyperkalemia (111 min to calcium) and MI (76 min to aspirin) despite ECG changes, while opioid overdose had near-immediate response (1 min to naloxone).
Single-centre quality improvement design at two affiliated academic EDs limits generalizability. Retrospective chart review is subject to documentation bias. No control group or pre/post intervention comparison was performed.
Treat secondary bradycardia as a high-acuity emergency — it carries ~5× the mortality of primary bradycardia. Prioritize rapid calcium administration in hyperkalemia and early warming in sepsis-related hypothermia, as ECG-to-intervention times for these conditions lagged well behind opioid overdose and intracranial emergencies.
