What effect do beta-blockers have on heart rate?

Beta-blockers have a significant effect on heart rate and myocardial oxygen demand. They work primarily by blocking the effects of adrenaline (epinephrine) and other stress hormones on beta-adrenergic receptors in the heart. As a result, beta-blockers decrease the heart rate, which leads to a reduction in the workload of the heart. When the heart beats more slowly, it requires less oxygen, thus reducing myocardial oxygen demand. This is particularly beneficial in conditions like hypertension, heart failure, and angina, where lowering the heart rate and oxygen consumption can help alleviate stress on the heart and improve overall cardiac function.

The reduction in heart rate helps in managing a variety of cardiovascular conditions by improving the efficiency of the heart muscle and allowing more time for the heart to fill with blood, enhancing its performance during periods of increased demand. This mechanism is also why beta-blockers are often prescribed post-myocardial infarction, as they can help prevent further ischemic events while improving cardiac output and oxygen supply to the myocardial tissue.