For decades β-blockers have been used in cardiovascular medicine. They have proved to reduce morbidity and mortality. In acute coronary syndrome, β-blockers have been recommended as a class I-A indication in clinical practice guidelines, because the treatment decreases the mortality rate. β-blockers, along with calcium channel blockers, reduce the workload of the heart and its oxygen requirement. β-blockers are sometimes used in a combination therapy to treat angina, if a β-blocker doesn't work well enough on its own. They are used as anti-arrhythmic drugs in patients with hyperthyroidism, cardiac dysrhythmia, atrial fibrillation, atrial flutter and ventricular tachycardia. The treatment with β-blockers reduces the incidence of sudden heart failure when the patient has already had a myocardial infarction. The reason is probably because of their anti-arrhythmic effects and also anti-ischemic effects.  A β-blocker therapy is also useful in myocardial infarction, independent to heart failure. The therapy has been very helpful for high-risk patients.  Although beta-blockers effectively lower blood pressure, they are not recommended as a first-line agent in the treatment of hypertension, as thiazides diuretics, ACE inhibitors, and calcium channel blockers show greater benefit. Therefore, β-blockers are usually used alongside other blood pressure medications such as calcium channel blockers. They also have an effect on cardiomyopathy, postural orthostatic tachycardia syndrome and portal hypertension, to name a few.