In reality, there are many patients who have “chest pain” even after coronary stent implantation, and it is important to distinguish whether it is angina or non-cardiac chest pain first. Many diseases such as gastrointestinal tract, lung, bone and joint, shingles, and anxiety can cause “chest pain”, but not angina, which needs to be carefully distinguished. Possible causes of angina include: 1) in-stent restenosis; 2) acute or subacute thrombosis in the stent; 3) progression of atherosclerotic disease in other segments; 4) incomplete coronary revascularization; 5) diffuse atherosclerotic disease without focal stenosis; 6) myocardial bridges. 7, epicardial vasospasm; 8, coronary microvascular dysfunction; 9, mechanical stretching of the arterial vessel wall associated with stenting. For this purpose, some auxiliary tests are needed to judge, such as electrocardiographic stress test, positron emission tomography, ultrasound stress test, cardiac magnetic resonance imaging, etc. If non-invasive procedures are not satisfactory, this is where invasive coronary angiography is needed, which helps in the diagnosis by measuring the flow reserve fraction. For treatment, if the chest pain is non-cardiogenic, appropriate treatment needs to be given. In case of angina e.g. patients with evidence of epicardial spasm/contraction, they should be treated with calcium antagonists and nitrates, microvascular angina can be treated with beta-blockers etc.