Questions are:

What is your current protocol for dealing with possible paroxysmal or transient arrhythmias where a recent ECG showed no apparent anomaly? You'll want some kind of positive indication that he/she will want you on a monitor like a Loop Recorder that you will have for some time that will have a record over weeks, not a few days. Also, you'll want to hear that he/she will not be averse to exercise, or if he/she is, to what target zone should you try to take your heart?

Would he/she attempt a stress test, possibly a MIBI stress test with contrast and CT scan?

Is ischemia a potential culprit? If so, how would he/she recommend a definitive assessment? Angiogram, Doppler, MIBI...?

Should you be on a statin if you are not already? Why? Are your lipids in a good ratio, triglycerides in normal range?

The thing is, maggie, you are intermittently in tachycardia, and apparently mostly/only during exercise of a certain intensity or type. It could be that you will simply have to desist if you don't want interventions of any kind, whether drugs or some kind of intrusive diagnostic (MIBI and angiography).

Secondly, you really do want to nail down what KIND of tachycardia it is. If it is ventricular, it must be dealt with aggressively. If it's supraventricular (meaning originates and takes place above the ventricles), then it's only worrisome to the extent that you don't like how it feels, you don't like the not knowing, you don't like the potential for progression (yes, arrhythmias tend to progress) and what an evolution to a more intractable type of arrhythmia means for morbidity. Yours.

Lastly, how does your cardiologist feel about catheter ablation if that procedure is ever indicated? Will he/she refer you to a (really crackerjack) electrophysiologist, a specialist in electrical conductivity and disorders of the myocardium? If you are highly symptomatic, and would like this nipped as soon as possible, then you should get into line for an EP as soon as he/she can refer you to one. A good one. A very busy, highly sought one. If you know somebody in the health sciences locally, ask that person to sleuth around for a great EP, but be open to traveling at least a full days' drive if that person is not local. You want THE BEST!!