Tough situation. Without the amiodarone, your heart rhythm problems are worse. With amiodarone, you are more hyperthyroid - which will worsen cardiac condition.
Thyroid surgery would be the quickest solution, but the risk of anesthesia with your heart condition are too high. Also, the hyperthyroidism (by numbers) is not that severe at this point.
Now that you have been off amio for a few months, I would do an I-123 uptake and consider ablating the thyroid with I-131 IF there is any uptake. This option may be best if there is a plan to need amiodarone again in the future. The warning here is that sometimes the thyroid gets a little worse before it gets better - so coreg or betapace or similiar heart meds would need to be titrated appropriately to protect you.
Alternatively, and most simply, could try Tapazole to normalize the thyroid prior to ICD placement. This is the most attractive option IF amiodarone is not going to be restarted as it would be a short-term use of Tapazole.