A troponin level is drawn specifically to see if you have had a heart attack. Your strip looks pretty darn good to me. I see no irrigular beats or PVC's in it at all. Looks normal to me. What we call sinus rythum strip. But, if the doc told you to see a cardiologist, then that is what you do. Maybe he wants a stress test or something.
Let us know how you make out. Personally your ECG is just beautiful.
P.S. I worked on a cardiac unit and did ECG's for 3 years. I think you can ease your mind. Your troponin level came back fine, your ECG to me looks great. I am no doctor by I can read rythum strips.
Carrie