What's next if cardioversion didn't work?

AF Ablation & Rx. Intracardia arrythmia ablation. This procedure is done by an electrophysiologist cardiologist. And if that doesn't work the heart rate can be controlled by medication plus a blood thinner.
Medicine. As a large study showed (the affirm) study, people do fine even with atrial fibrillation as long as the heart rate is controlled with drugs and anticoagulants are given if indicated.