Hello, Sinus bradycardia can happen to healthy or sick people. Most people with practice sport or exercise a lot may have sinus bradycardia. Abnormal Sinus Bradycardia cause from hypothyroidism, hypothermia, use some of the drugs such as beta blocker (atenolol), Adenosine, Calcium channel blocker, seizure disorder, infection, Acute Myocardial Infarction. Do you have have any history of chronic diseases like diabetes or Hypertension? How old are you? Do you have any chest pain? you may experience squeeze pain, heavy or tightness and radiation to the other area or may only one area. Chest pain with exertion or with shortness of breath. Because those two diseases make me more concerning to Myocardial Infarction. Stress Test Echo can confirm if your heart muscle is working to pump blood to your body. It is often used to detect if your blood flows to the heart decrease or not, and to detect the narrowing of the coronary artery in your heart. It is good to do Stress Test Echo to confirm if you have a heart problem or not. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Heang Chan Raksmey, General & Family Physician