Severe cibenzoline toxicity in hypertrophic obstructive cardiomyopathy successfully managed with extracorporeal membrane oxygenation and percutaneous transluminal septal myocardial ablation — A case report

Abstract

Cibenzoline (CBZ), a class I antiarrhythmic drug, is used for patients with hypertrophic obstructive cardiomyopathy (HOCM). However, it requires careful monitoring in patients with renal dysfunction for potential toxicity. We present a case of severe CBZ toxicity in a 72-year-old woman with HOCM, previous ascending aortic dissection repair, and renal dysfunction. She was maintained on CBZ 300 mg daily despite fluctuating renal function. She presented with acute respiratory distress. On presentation, she was found to have bradycardia with QRS prolongation (340 ms) and markedly elevated CBZ levels (1973 ng/mL, therapeutic range: 200-800 ng/mL). She developed sudden cardiac arrest in the emergency room. Following cardiac arrest, venoarterial extracorporeal membrane oxygenation (VA-ECMO) was initiated. Direct hemoperfusion yielded minimal reduction in CBZ levels. With increased urine output, CBZ levels normalized, accompanied by electrocardiographic improvement. After VA-ECMO withdrawal, percutaneous transluminal septal myocardial ablation (PTSMA) was performed as definitive treatment to eliminate CBZ dependency. This case illustrates the complex interaction between HOCM, renal impairment, and CBZ toxicity, emphasizing the importance of careful drug monitoring in patients with renal impairment. Additionally, it demonstrates the potential role of PTSMA as a definitive treatment for selected patients with HOCM at high risk of medication-related complications.

Learning objectives: •Understand the pharmacokinetics of cibenzoline and its need for monitoring in elderly patients with hypertrophic obstructive cardiomyopathy (HOCM) and impaired renal function.•Recognize the mechanisms of cibenzoline toxicity and its acute management strategies, including mechanical circulatory support and direct hemoperfusion.•Identify the acute management strategies and long-term treatment options for complications arising from medical therapy in patients with HOCM.