I agree with @cmcg. Maybe you can research doctors, read reviews and so on. It sounds like that cardiologist was worried about liability.

You wrote that you monitor at home but do you use a Kardia or other device that tells you about atrial flutter as well as heart rate? Smart watch?

Some of us have episodes of arrhythmias or tachycardia but it sounds like yours- whether SVT or atrial fluttter is continuous. I am surprised noone suggested a beta blocker or diltiazem to bring the rate down.

It sounds like the doc was worried about stroke. The fast heartbeat could be to compensate for the flutter-? So if it is flutter, the main problem is the flutter and the fast heartbeat is a result of that.

Atrial flutter is treated with anticoagulation apparently- and meds, cardioversion, ablation, depending....
https://www.uptodate.com/contents/embolic-risk-and-the-role-of-anticoagulation-in-atrial-flutter
"Most patients with atrial flutter should be considered for chronic anticoagulation in a manner similar to those with atrial fibrillation (AF). This recommendation is based not only on the fact atrial flutter carries a risk for systemic embolization but also that these patients usually have episodes of AF. (See "Atrial fibrillation in adults: Use of oral anticoagulants", section on 'Summary and recommendations'.)
Our approach to anticoagulation applies to all types of atrial flutter, whether it is typical or atypical. (See "Electrocardiographic and electrophysiologic features of atrial flutter".)"

More info, including on ablation and meds:
https://my.clevelandclinic.org/health/diseases/22885-atrial-flutter#SnippetTab
https://www.mayoclinic.org/tests-procedures/atrial-flutter-ablation/pyc-20385002