<s>[INST] I have Afib along with CAD & today I exercised for about 45 minutes. I try to exercise on a regualer basis, but aftertodays work-out. I could tell I messed up because I felt & feel like I may have over done it because  my heart is just straining to beat, thats the last time I exercise like that,is this normal or is it this possible cause ?I know I need towork-out but now this scares me ??? [/INST] Hello! Welcome and thank you for asking on Chat Doctor! I carefully passed through your question and would explain that your symptoms seem to be related to coronary artery disease. I would recommend consulting with your attending physician for a careful physical exam and some tests: - a resting ECG- a cardiac ultrasound to examine your cardiac function and structure- a cardiac stress tests-some blood lab tests (complete blood count, fasting glucose, blood electrolytes). A coronary angiography would be the test of choice to examine better the blood flow in the coronary arteries and determine the grade of arterial stenosis. Hope to have been helpful! Kind regards,  </s>