Pilsicainide Toxicity-Induced Brugada-Like ST Segment Elevation and Increased Pacing Voltage Threshold

Area of Science:

• Cardiology
• Clinical Pharmacology

Background:

• Pilsicainide, a Class Ic antiarrhythmic, is widely used for atrial fibrillation rhythm control in Japan.
• It is primarily renally excreted, suggesting a risk of accumulation in patients with impaired kidney function.

Observation:

• A 90-year-old woman presented with fatigue, loss of appetite, bradycardia, and Brugada-type ECG changes.
• Dehydration exacerbated her renal insufficiency, leading to a significant increase in plasma pilsicainide concentration (2.67 µg/mL).
• The patient experienced pacing failure requiring a temporary pacemaker, indicative of pilsicainide toxicity.

Findings:

• Discontinuation of pilsicainide resulted in improved renal function, resolution of heart failure symptoms (pulmonary edema, cardiomegaly), and normalization of ECG abnormalities.
• Ventricular backup pacing was no longer necessary within 48 hours of drug cessation.

Implications:

• High plasma pilsicainide concentrations can precipitate life-threatening arrhythmias and lead to pacemaker dysfunction.
• Caution is advised when prescribing pilsicainide, especially in elderly patients or those with compromised renal function.
• Therapeutic drug monitoring and dose adjustment may be crucial in specific patient populations to prevent toxicity.