Authors
Dr. Harikrishnan S, MD, DM Cardiology, DNB Cardiology, Associate Professor, Department of Cardiology, SCTIMST, Thiruvananthapuram
Abstract
Background: Beta-blockers (BBs), pioneered by Sir James Whyte Black with propranolol, represent a cornerstone in cardiovascular pharmacology. This review explores their diverse applications, emerging controversies, and side effects.
Indications and Efficacy: BBs are vital in Coronary Artery Disease (CAD), improving outcomes in acute coronary syndromes (oral BBs) and significantly reducing mortality in secondary prevention. They are effective for chronic stable angina. In Heart Failure (HF) with reduced ejection fraction (<40%), BBs (bisoprolol, metoprolol succinate, carvedilol, nebivolol) reverse remodeling, improve symptoms, and prolong life, requiring careful up-titration. BBs are also crucial for managing various Arrhythmias, including rate control in atrial fibrillation, termination of supraventricular tachycardias, and prevention of ventricular arrhythmias, contributing to a 30% reduction in Sudden Cardiac Death (SCD). Additionally, they are beneficial in Mitral Valve Prolapse and Hypertrophic Obstructive Cardiomyopathy.
Controversies in Hypertension: While historically used for Systemic Hypertension (HTN), traditional BBs like atenolol are now less favored as first-line agents due to concerns about their efficacy in preventing cardiovascular events compared to other classes, and specific issues like less left ventricular hypertrophy reduction and increased risk of new-onset diabetes. Newer vasodilatory BBs (nebivolol, carvedilol) show promise in HTN management but require further validation.
Side Effects: Common adverse effects include bradycardia, fatigue, and impotence. The beta-blocker withdrawal syndrome necessitates gradual tapering. Cardioselective BBs are generally safe in mild-to-moderate peripheral arterial disease and chronic obstructive pulmonary disease.
Conclusion: BBs remain indispensable in post-myocardial infarction care, left ventricular dysfunction, and SCD prevention. Their role in hypertension, especially with traditional agents, is re-evaluated, favoring newer vasodilatory agents or their use as later-line therapy.