Key result
LGL-phenocopy with Hisian extrasystoles signals a potentially lethal inherited arrhythmogenic substrate requiring evaluation.
Why the study?
The short PR interval without preexcitation (Lown-Ganong-Levine-phenocopy) is often considered benign, but its association with malignant arrhythmogenic substrates is underappreciated.
Case Report (n=1)
Surface ECG red flags such as LGL-phenocopy with dual AV nodal physiology should prompt comprehensive genetic and clinical evaluation when associated with a malignant family history.
May support targeted genetic evaluation in select cases with LGL-phenocopy and family SCD history; leaves open broader validation in prospective cohorts.
BACKGROUND: The short PR interval without preexcitation (Lown-Ganong-Levine-phenocopy) is often considered benign, but its association with malignant substrates is underappreciated. CASE SUMMARY: A 45-year-old man with no previous cardiac history presented with palpitations, dyspnea, and diaphoresis. Electrocardiogram (ECG) during symptoms showed supraventricular tachycardia at ∼220 beats/min with a Hisian extrasystole and QRS variability. Postconversion ECG revealed short PR and dual atrioventricular nodal physiology. Echocardiography showed subtle nonterritorial hypokinesia. Family history included sudden cardiac death in 3 siblings. DISCUSSION: This case demonstrates that Lown-Ganong-Levine-phenocopy with dual atrioventricular nodal physiology and Hisian extrasystoles can be a red flag for a lethal inherited arrhythmogenic substrate requiring comprehensive evaluation including cardiac magnetic resonance, genetic testing, and family screening. TAKE-HOME MESSAGES: A short PR pattern with a malignant family history warrants comprehensive evaluation. Surface ECG red flags should not be ignored even when the resting ECG appears benign.
No takes yet. Share an insight, caveat, or question.
Negm et al. (2026) conducted a case report in Lown-Ganong-Levine-phenocopy with malignant supraventricular tachycardia (n=1). Lown-Ganong-Levine-phenocopy with dual atrioventricular nodal physiology was evaluated. Lown-Ganong-Levine-phenocopy with dual AV nodal physiology and Hisian extrasystoles can be a red flag for a lethal inherited arrhythmogenic substrate requiring comprehensive evaluation.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: