Treating the unknown: the use of anti-arrhtyhmic drugs in idiopathic ventricular fibrillation

Background After receiving the diagnosis idiopathic ventricular fibrillation (IVF), an implantable cardioverter defibrillator is indicated as secondary prevention of sudden cardiac death. When recurrent ICD discharges or an electrical storm occur, there is a class IIa indication for treatment with quinidine for the prevention of ventricular arrhythmias (VAs). Besides that, pharmacological treatment with anti-arrhythmic drugs is not recommended. However, it appears that in clinical practice primarily beta-blockers are frequently prescribed. Purpose This study aimed to assess the use of pharmacological anti-arrhythmic therapy in patients with IVF in the Netherlands. Methods We included 431 patients from the Dutch IVF registry who remained idiopathic at last follow-up. Data regarding initiation, indication and type of anti-arrhythmic therapy were retrospectively collected. Results For 355 patients (82%), data regarding anti-arrhythmic therapy was retrievable. Among those, 247 (70%) patients received any anti-arrhythmic drug during follow-up (median duration of follow-up 9 [5 – 15] years). In 101/355 (29%) patients anti-arrhythmic therapy was started directly or shortly after the first event. The median time from index event to first prescription was 55 [14-1014] days. Most patients (183/355, 52%) received beta-blockers as their initial therapy (Figure 1). In total, beta-blockers were prescribed in 203/355 (57%) patients during follow-up. Indications varied between index event itself to recurrent VAs (Figure 2). Quinidine was prescribed in 33/355 (9%) patients, for 17 patients it was the initial therapy. Quinidine was started mostly after a recurrence of VAs, 9/17 (53%). In 5/17 (29%) prescriptions, quinidine was started directly after the index event. Conclusions The majority of IVF patients received pharmacological anti-arrhythmic therapy after their index event. Beta-blockers are most often prescribed. Quinidine is mainly prescribed after a recurrence, in accordance with the ESC guideline. Prospective studies are required to assess whether anti-arrhythmic drugs reduce recurrence of VA’s.