I am glad to know your premature beats are PACs . Unlike PVC's, PAC's generally do not cause hemodynamic compromise because the conduction throughout the AV node and ventricles is normal, and the filling and contraction of the heart is therefore normal. Did your cardiiologist feel the shortness of breath, dizziness and fatigue were caused by the PACs ?
I do not know what your autoimmune disease is or if this could be the source of your symptoms so please do keep in close contact with your physician.
I do not have any expereince with a naturopath but hopefully a member that does will be by to share with you.