The results from the coronary stress test ("markedly abnormal ST segment response to exercise with 2.5mm ST depression in leads II, III, aVF and V6”) and from the coronary angiography (“LAD had diffuse narrowing of about 50% in the distal segment only”) are evidence that you are experiencing stable angina pectoris. Angina pectoris is a variant of coronary heart disease. Coronary heart disease is due to atherosclerosis. During atherosclerosis, the coronary arteries become narrow due to atherosclerotic plagues. Smoking, high blood pressure, high cholesterol and high blood sugar are the 4 major risk factors for developing atherosclerosis.