Key result
Sodium bicarbonate reverses QRS widening and ventricular dysfunction in a case of propafenone toxicity.
Why the study?
Propafenone is a class Ic antiarrhythmic with a narrow therapeutic window that may cause conduction disturbances.
Case Report (n=1)
In patients on class Ic antiarrhythmics presenting with a new wide-QRS rhythm, sodium channel blocker toxicity should be suspected and treated early with sodium bicarbonate to reverse conduction disturbances and ventricular dysfunction.
Warrants caution with propafenone use; leaves open need for larger studies on toxicity incidence and monitoring.
BACKGROUND: Propafenone, a class Ic antiarrhythmic with a narrow therapeutic window, may cause conduction disturbances. CASE SUMMARY: A 68-year-old man on propafenone presented with dyspnea and dizziness. Electrocardiogram showed QRS widening (160 milliseconds). Angiography excluded occlusion but showed transient ventricular dysfunction. Sodium bicarbonate normalized QRS complex and reversed dysfunction. CONCLUSIONS: New wide-QRS rhythm in patients on class Ic agents suggests sodium channel blocker toxicity. QRS narrowing after bicarbonate is diagnostically important. Early treatment ensures reversibility and prevents arrhythmias. TAKE-HOME MESSAGES: Toxicity in new wide-QRS rhythm on class Ic drugs should be assumed. QRS narrowing after bicarbonate is key. Early treatment prevents fatal complications.
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Lucena et al. (2026) conducted a case report in Propafenone toxicity (n=1). Sodium bicarbonate was evaluated on QRS narrowing and reversal of ventricular dysfunction. Sodium bicarbonate administration successfully normalized QRS widening and reversed transient ventricular dysfunction in a 68-year-old man with propafenone toxicity.
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