|Prichard BNC et al.|
Beta-blockers in the third millennium - when are they really indicated
Journal of Clinical and Basic Cardiology 2001; 4 (1): 3-9
Keywords: Betablocker, Diabetes mellitus, Hypertonie, Morbiditšt, Mortalitšt, beta-blocker, Diabetes, hypertension, morbidity, mortality
Beta-blockers have come a long way in development since the first two used clinically, pronethalol and propranolol, were evaluated in angina pectoris, cardiac arrhythmias and phaeochromocytoma. Pharmacological development has been directed to improving both selectivity and more recently agents with additional vasodilator activity, either by alpha-receptor blockade or by other mechanisms. Therapeutic development has led to the use of beta-blockers in a wide variety of indications, principally in the cardiovascular system, but also elsewhere. Numerous studies have confirmed the value of beta-blockers in ischaemic heart disease. They remain a most efficacious treatment for symptom relief in angina pectoris although evidence that prognosis is improved is mainly indirect. Many studies have demonstrated that beta-blockers improve prognosis post myocardial infarction; benefit being demonstrated in many categories, particular value has been shown in patients with poor left ventricular function. The first non-predicted use of beta-blockers demonstrated was their antihypertensive effect. They are now accepted by major international guidelines as first line therapy. Beta1-selective agents are more effective than non-selective agents, and contrary to some earlier evidence based on non-selective agents, they are often effective in younger (under 65) black patients. Beta-blockers have been shown to improve prognosis in younger patients while in the elderly, diuretics appear superior in primary prevention. Since early reports of propranolol precipitating heart failure, studies with bisoprolol, carvedilol and metoprolol have established that beta-blockers carefully titrated even when added to a treatment regimen including ACE-inhibitors give a dramatic improvement in survival. Diabetes was another area where beta-blockers were considered to have disadvantages. While beta2-blockade should be avoided in patients on insulin, hypoglycaemic episodes are not rendered more of a problem by beta1-selective blockade. A recent important study in type 2 diabetes has shown that tight control of blood pressure resulted in an improvement of various prognostic indicators, with results with atenolol treated patients throughout being at least as good as with the captopril treated subjects. Some supposed contra-indications to beta-blockade have been previously over-emphasised. Notably, patients with chronic airways obstructive disease frequently tolerate beta-blockade well and will benefit, eg, post infarction, although beta1-selective agents should be used. Quality of life investigations show that beta1-selective drugs are well tolerated when compared to other drugs including ACE-inhibitors. J Clin Basic Cardiol 2001; 4: 3-9.