Value of quinidine in maintenance of sinus rhythm after electric conversion of atrial fibrillation.

Abstract

Onehundred andseventy-five patients withatrial fibrillation treated forthefirst timewithDC shock weredivided into twogroupsaccording toyearofbirth. GroupIreceived a long-acting quinidine bisulphate preparation, thedosage ofwhich was adjusted togive serumlevels of1-3mg./l. Side-effects wererarewiththis dosage. Group 2received noquinidine. Ofthe88patients ofgroup I,sinus rhythm was restored in75(85%). Whenleaving thehospital 64(73%) still hadsinus rhythm, andafter 3 months 52(59%). Thecorresponding figures forthe87patients ofGroup2 were 73(84%), 54(62%), and30(34%). Thedifference at3 months isstatistically highly significant. Because ofthese results itisconcluded thatelectric conversion ofatrial fibrillation should beperformed forthefirst timewithout quinidine prophylaxis. Ifthere isfailure orearly recurrence,however, a second electric conversion withsubsequent quinidine treatmentshould be considered.