Dear patient, One of the possibilities that could be contemplated from a heart standpoint would be that of endothelial dysfunction, a tendency of the heart vessels to suffer spasm at rest usually; episodes can be more frequent at night time. A stress test would not precipitate it usually, and to do that, an angiogram with a provocative spasm phase can be recommended. Nonetheless, horses being more common than zebras, other causes of non cardiac chest pain include esophageal reflux or spasm, gastritis, costochondritis or muscle sprains from the thoracic wall. I encourage you to talk to your cardiologist about appropiate referrals and workup if one of these possibilities is contemplated higher in the differential. Yours truly, Dr Brenes-Salazar MD Cardiology Mayo Clinic MN