If a patient has a headache accompanied by tachycardia, there are usually several causes as follows: 1. The most common cause is acute cerebrovascular disease, such as acute transient cerebral insufficiency, TIA attack, acute stroke, or acute cerebral hemorrhage, acute cerebral infarction, or the presence of cerebrovascular accidents, all of which can have headaches accompanied by rapid heartbeat. 2. In cardiogenic diseases, such as coronary atherosclerotic heart disease of un Patients also have headache accompanied by rapid heartbeat in cases of cardiogenic diseases, such as unstable angina attacks, arrhythmias, or the presence of acute coronary syndrome. 3. Headache accompanied by significantly rapid heartbeat also occurs in cases of unstable blood pressure, such as hypertensive encephalopathy, hypertensive crisis, and acute hypertension.