Po-05-151 a combination of low-dose quinidine and verapamil for multifocal ectopic purkinje-related premature contractions in a case with scn5a mutation

Multifocal ectopic Purkinje-related premature contractions (MEPPC) which generally caused by the mutation in the SCN5A is characterized by dilated cardiomyopathy and hyperexcitability of the fascicular-Purkinje system-mediated multifocal premature ventricular contraction (PVC) and polymorphic ventricular tachycardia (PMVT). Administration of quinidine has been reported to remarkably suppress PVC/PMVT. However, quinidine administration, especially in high dose, is associated with side effects. We report the first case of a patient with MEPPC in whom the combination of low-dose quinidine and verapamil was effective for both arrhythmia and heart failure. N/A A 32-year-old male patient was admitted due to frequent multiform PVCs (84371/day; 60% of total heartbeats on the 24-hour Holter ECG) and left ventricular dysfunction in 2022 (Figure 1). In this patient, frequent PVCs and non-sustained ventricular tachycardia (NSVT) were observed from around 15 years of age. PVC accounted for 39% to 63% of the total heartbeats on the Holter ECG during the course of the disease. Two times catheter ablation procedures for PVC/NSVT were performed with no or limited effect. Propranolol, bisoprolol, mexiletine, pilsicainide, verapamil, bepridil, and sotalol have failed to suppress PVCs. Genetic analysis revealed a previously reported SCN5A mutation (exon5, c.611C>A, p.A204E), which led to the diagnosis of MEPPC. A third ablation during this admission revealed severe conduction impairment of right bundle-branch and left posterior fascicle associated with previous ablation. Because the sequence of ectopic His and left anterior fascicular (LAF) discharges were quite variable (Figure 2), we considered that multifocal His-Purkinje discharges from both ventricles demonstrate multiple PVC/NSVT. Ablation was abandoned due to concerns about complete atrioventricular block. Quinidine sulfate was administered. Although quinidine was effective, the dose of quinidine was up to 300 mg/day due to diarrhea. Finally, combination of 300 mg/day of quinidine and 240 mg/day of verapamil remarkably suppressed PVC/NSVT (Figure 3). A Holter ECG showed that the number of PVCs was 4040/day (4% of the total heartbeats). The BNP level decreased from 145.0 to 11.2 pg/mL. The quinidine blood concentration was as low as 0.9 μg/mL. This is the first report showing that the combination of low-dose quinidine and verapamil was effective in treating MEPPC despite low blood concentrations of quinidine.