Thank you for your query at DoctorSpring.com
You have paroxysmal atrial fibrillation. Rate control with dilzem is an option. However rhythm control with amiodarone would be a better option in your case. Dilzem is usually contraindicated if heary rate is below 60 pm. But you have intelligently monitored your heart rate and so in your case it may be taken upto heart rates of 50 to 55 per min. Discontinue below 55 till it picks to 60 to 65 per min. Permanent af ablation would be a good option for you.
Feel free to discuss further,
Dr Vivek Mahajan