There is hardly any risk associated with shock treatment. However, it is mandatory to keep proper INRs for a couple of months before cardioversion and preferable to have a trans-oesophageal (endoscopic) echocardiogram to rule out any clots in your heart before the shock. If you are converted from atrial fibrillation, the atria (the top two chambers of your heart) may start contracting, and this may dislodge any clots from the atria into your blood stream. Even after successful conversion it is advisable to continue Warfarin and maintain proper INR with monthly check-ups. If the valve has narrowed again it may need to be reopened as this will help in maintaining normal rhythm as well as preventing clot formation. Ablation therapy may also be tried if you have not been in atrial fibrillation for a long time. Your doctor will discontinue Cordarone if it does not convert with the shock. If it converts he will keep you on it as long as it works. Cordarone also needs regular monitoring for its side effects.