KCNH2 and atrial flutter: Vanoxerine was later found to have desirable cardiac antiarrhythmic properties (Matsumoto et al. 2010).Patch clamp studies showed that it potently blocked IKr (hERG), L-type calcium and sodium channels (Preti 2000).In a phase II dose-ranging COR-ART study, vanoxerine was highly effective in converting atrial fibrillation and atrial flutter (AF/AFL) to sinus rhythm without evidence of proarrhythmia (Howard et al. 2015).