Artemisinin-Quinidine Combination for Suppressing Ventricular Tachyarrhythmia in an Ex Vivo Model of Brugada Syndrome.

Background: The ionic mechanism underlying Brugada syndrome (BrS) arises from an imbalance in transient outward current flow between the epicardium and endocardium. Previous studies report that artemisinin, originally derived from a Chinese herb for antimalarial use, inhibits the Ito current in canines. In a prior study, we showed the antiarrhythmic effects of artemisinin in BrS wedge preparation models. However, quinidine remains a well-established antiarrhythmic agent for treating BrS. Therefore, this study aims to investigate the efficacy of combining artemisinin with low-dose quinidine in suppressing ventricular tachyarrhythmia (VTA) in experimental canine BrS models.

Methods: Transmural pseudo-electrocardiogram and epicardial/endocardial action potential (AP) were recorded from coronary-perfused canine right ventricular wedge preparation. To mimic the BrS model, acetylcholine (3 μM), calcium channel blocker verapamil (1 μM), and Ito agonist NS5806 (6-10 μM) were administered until VTA was induced. Subsequently, low-dose quinidine (1-2 μM) combined with artemisinin (100 μM) was perfused to mitigate VTA. Key parameters, including AP duration, J wave area, notch index, and T wave dispersion, were measured.

Results: After administering the provocation agents, all sample models exhibited prominent J waves and VTA. Artemisinin alone (100-150 μM) suppressed VTA and restored the AP dome in all three preparations. Its infusion resulted in reductions in the J wave area and epicardial notch index. Consequently, low-dose quinidine (1-2 μM) did not fully restore the AP dome in all six sample models. However, when combined with additional artemisinin (100 μM), low-dose quinidine effectively suppressed VTA in all six models and restored the AP dome while also decreasing the J wave area and epicardial notch index.

Conclusion: Low-dose quinidine alone fails to fully alleviate VTA in the BrS wedge model. However, its combination with artemisinin effectively suppresses VTA. Artemisinin may reduce the therapeutic dose of quinidine, potentially minimizing its associated adverse effects.