I Am A 67 Year Old Female Who Underwent Open

I am a 67 year old female who underwent open heart surgery in 1993 to repair a congenital atrial septal defect. After that, I developed atrial fibrillation and was placed on Flecanide 100 mg. twice daily, in 2010, I had an afib ablation performed and, subsequently, the Flecanide was reduced until now I am taking 100 mg. every other day. I am very active. Recently, I have experienced heart rate spikes with dizziness during my treadmill workouts. Yesterday, the spike went to 207 - so I reduced my speed from 4.0 to 3.0 and it took about a minute or two for my rate to drop back down to 124. Should I contact my electrophysiologist or is this not a concern?