CaseStudy-06112016 - chest pain

A middlle aged gentleman, with background history of hypercholesterolaemia, type 2 diabetes mellitus, increased in body mass index, smoker of 20 pack years history, attended casualty due to an episodes of central chest pain in the morning. He woke up in the morning, and went to do some gardening. After around 15-20 minutes of doing some heavy task in his garden, he suddenly experienced sharp central chest pain, did radiated to his jaw, associated with some shortness of breath. He took a rest for 5 minute and the pain slowly went away. He never experience such chest pain. He denied any cough, no calf swelling, and the pain was not pleuritic in nature. He was very concerned about the pain. There is no family history of ischaemic heart disease. Patient is pain free when he was in casualty, and the initial ECG and cardiac enzyme were normal, with a normal chest x-ray. The rest of his blood tests were normal. What other invetsigations you plan to do next?? What is your possible diagnosis ??