Sustained-release quinidine (Kinidin Durules) in maintaining sinus rhythm after electroversion of atrial dysrhythmias.

mean relapse time being 3-75 months after DC shock. A second electroversion preceded and followed by maintenance Kinidin was performed, and the mean electrical energy for conversion to sinus rhythm remained unchanged at 142joules. The dose of slow-release quinidine was controlled by frequent quinidine blood levels. A careful follow-up study was maintained for 26 months. Twelve patients have remained in sinus rhythm for a sirnificantly longer period while taking Kinidin, in whom the mean quinidine blood level was 2-I ug./ml., eight reverted in a shorter time despite the same mean quinidine blood levels, and in four the length of time of maintained sinus rhythm was unchanged. Complications to the quinidine preparation occurred in four (25%) and included unduegain in weight, skin sensitivity,gastrointestinal bleeding, and severe diarrhoea. The results of the trial when analysed statistically show a small benefit in the use of this preparation in maintaining sinus rhythm for an additional four months after electroversion, when the optimal dose controlled by frequent blood levels is administered, but thereafter there is little evidence that Kinidin Durules are beneficial long term. It is concluded that Kinidin Durules may be worth while in selected patients in whom the drug is well tolerated, particularly if relapse to atrial fibrillation or flutter has occurred within the first few months after electroversion and in whom sinus rhythm is haemodynamically important.