The simple answer is no best one anti arrhythmic available to treat all kinds of post-CPB arrhythmias. The first rule is all anti-arrythmics are negative inotropes and it is not beneficial to use these drugs in this time of the operation so as not to affect the overall outcome of patient. Second rule is do not treat arrhythmias except if they affect the hemodynamics. Third rule is if you think about using amiodarone for a patient, just remember the "delayed" and "serious" side effects e.g. hepatitis, hypothyroidism and keratitis. Fourth rule, other available anti-arrhythmic drugs may include beta-blockers e.g. propranolol and esmolol (may induce bradycardia and hypotension that needs time and expertise to treat) and calcium channel blockers e.g. verapamil (although a cardio-protective drug but hypotension may be severe). Fifth rule is that many arrhythmia are treated with other maneuvers than giving a drug, e.g. treating hypothermia, deepening anesthesia, decrease cardiac manipulation by the surgeon.

In conclusion, if no marked hemodynamics affection, search for another thing to benefit your patient other than giving an anti arrhythmic.