Diagnosing a cardiac cause for palpitations: Five-year service evaluation of a smartphone ambulatory ECG pathway for Emergency Department patients.

Background: Capturing an electrocardiogram (ECG) during transient symptoms remains challenging in emergency department (ED) patients with palpitations. Following the IPED trial, a smartphone-based ambulatory ECG event recorder pathway was integrated into NHS care. We evaluated this service over five years, assessing diagnostic yield, management, one-year outcomes and predictors of cardiac arrhythmia. Methods: Single-centre service evaluation of consecutive patients referred with palpitations to a smartphone-based ambulatory ECG event recorder clinic between 24th July 2019 and 24th July 2024. Patients underwent event-triggered ECG monitoring using the single-lead Kardia Mobile (AliveCor, Inc.) or their own smartwatch with ECG capability. Clinical characteristics, rhythm recordings, investigations, one-year outcomes and management changes were recorded. Multivariable logistic regression identified independent predictors of one-year cardiac arrhythmia diagnosis. Results: 1750 patients attended the clinic, mean age 44.3 +/- 16.1 years, 58.2% female. 1176 patients (67.2%) underwent monitoring with a cardiac arrhythmia directly captured in 67 patients (5.7% of monitored), including atrial fibrillation (n=39), supraventricular tachycardia (13), atrial flutter (9), atrial tachycardia (5) and ventricular tachycardia (1). By one year, 84 (7.1%) who underwent monitoring received a cardiac diagnosis with 79.8% (67/84) established directly via clinic monitoring. Across the entire cohort (n=1750), 114 (6.5%) had a cardiac cause at one year, 1472 (84.2%) had non-cardiac aetiology and 1569 (89.1%) were discharged back to primary care. Medication changes were initiated in 106 patients (6.1%). Independent predictors of a one-year cardiac diagnosis were increasing age (aOR 1.04 per 1-year increase), prior atrial fibrillation/flutter (aOR 5.57) and a presenting symptom of irregular beating (aOR 2.65). Conclusion: Our service provides an effective model for evaluating ED patients with palpitations. Over five years the service reliably detected actionable cardiac arrhythmias while safely discharging nearly 90% of patients to primary care. Clinical characteristics may guide patient selection to maximise clinic efficiency.