The efficacy of pharmacotherapy in preventing ventricular fibrillation has only been studies in patients with SQT1.  Given the limited number of patients studied, and the limited duration of follow-up, pharmacotherapy as primary or secondary preventive therapy for patients with SQT1 cannot be recommended at this time.  AICD implantation remains the mainstay of therapy in these patients.  Pharmacotherapy may play an adjunctive role in reducing the risk of events in patients with an AICD as described below in the indications section.
Patients with<unk> <unk><unk>  1 (SQT1) have a mutation in KCNH2 (HERG).  Class IC and III antiarrhythmic drugs do not produce any significant<unk>  interval prolongation  . Flecainide has not been shown to consistently reduce the inducibility of ventricular fibrillation. Although it does not prolong the<unk>  interval in SQT1 patients, propafenone reduces the risk of recurrent atrial fibrillation in SQT1 patients.
Quinidine in contrast may be effective in patients with SQT1 in so far as it blocks both potassium channels (IKr, IKs, Ito, IKATP and IK1) and the inward sodium and calcium channels.  In four out of four patients, Quinidine prolonged the<unk>  interval from 263 +/- 12 msec to 362 +/-25 msec, most likely due to its effects on prolonging the action potential and by virtue of its action on the IK channels. Although Quinidine was successful in preventing the inducibility of ventricular fibrillation in 4 out of 4 patients, it is unclear if the prolongation of the<unk>  interval by quinidine would reduce the risk of sudden cardiac death.
Although pharmacotherapy can be used to suppress the occurrence of atrial fibrillation in patients with SQT1, AICD implantation is the mainstay of therapy, and pharmacotherapy to prevent sudden death should is only indicated if AICD implantation is not possible.
Among patients with SQT1, Qunidine also:
Prolongs the ST segment and T wave durations
Restores the heart rate dependent variability in the<unk>  interval
Decreases repolarization dispersion
Short QT syndrome medical therapy
AVNRT medical therapy
Bradycardia medical therapy
Ventricular fibrillation medical therapy
Junctional bradycardia medical therapy
Ventricular tachycardia medical therapy
Third degree AV block medical therapy
Second degree AV block medical therapy