Patient: Description of condition (onset, main symptoms, hospital visited, etc.): The disease was discovered 5 years ago and has been asymptomatic and does not affect my life or work. Does the doctor treat it surgically? No treatment Is it surgical treatment? If surgery is not required, what should I pay attention to in my life and work? 1. We encounter many patients with coronary artery disease who also have carotid and/or subclavian artery stenosis and need to be treated at the same time. 2.As far as simple left subclavian artery stenosis and occlusion are concerned, manifestations such as blood-stealing syndrome can cause insufficient blood supply to the vertebrobasilar artery during vigorous activity, even though the collateral circulation is abundant. 3. If the Wills loop is intact, even if the left vertebral artery is completely occluded, it can still supply blood through the right side, and no treatment is needed. When we do thoracic aortic aneurysm stenting, after judging the left vertebral artery well, we can completely close the left subclavian artery without symptoms. 3. It is better to do a carotid + cranial MRA (magnetic resonance angiography) to clarify the condition of carotid artery, subclavian artery and intracranial vessels. Angiography can also be done, after all, it is an invasive examination. 4.No symptoms, you can continue to observe and not operate for the time being. 5.If vertigo, diplopia, sudden collapse without consciousness impairment, etc. occur when the left upper limb is strenuously moving, or accompanied by weakness, heaviness, pain and coldness of the left upper limb, active treatment is needed. 6.Treatment methods: interventional treatment is preferred, followed by surgical bypass surgery. These are very conventional methods.