A bad heart may cause dizziness and headaches. Usually the mechanism of heart disease causing dizziness and headache includes cardiac insufficiency of cardiac output due to impairment of cardiac function and reduction of cerebral blood supply, which causes tissue hypoxia and leads to dizziness and headache in patients. Common diseases that typically cause cardiac insufficiency and low cardiac output include hypertrophic cardiomyopathy, heart failure, myocardial infarction, etc. Hypertension caused by arteriovenous leakage and hyperthyroidism may also cause dizziness and headaches. However, not all heart conditions, such as supraventricular tachycardia, can cause dizziness and headaches. Dizziness and headaches may only occur when the disease has progressed to a certain level. Patients who experience dizziness and headache should seek prompt medical attention and undergo relevant examinations and treatments under the guidance of a medical professional.