Blockers will reduce perioperative myocardial ischemia and s

β-Blockers will reduce perioperative myocardial ischemia and studies published in the 1990s suggested that their routine administration before surgery provided protection against perioperative CV complications.31., 32., 33. Based on these early studies, several national organizations endorsed the perioperative use of β-blockers as a best practice in certain patients.34., 36. However, more recent evidence has been accumulating to suggest that routine use of β-blockers may not benefit as many patients as was once hoped, and may actually cause harm in some individuals.36., 37., 38. The benefit of β-blockers may be only present in high-risk CV patients undergoing high-risk surgery. Currently the best evidence supports their use in two patient groups: patients undergoing vascular surgery who have known IHD or multiple risk factors for it, and for those patients who are already receiving β-blockers for CV conditions.31., 32., 33., 34., 35., 36.
Adverse effects and contraindications Most β-blockers, at least in the usual antiHTN dose range, should not be used in patients with asthma, reactive airway disease, acute decompensated HF with systolic dysfunction, heart block (greater than first degree), and sick sinus syndrome. However, there are new data to suggest a mortality benefit with β-blocker use in patients having chronic obstructive pulmonary disease. β-blockers have been documented to increase the risk of new onset Darunavir Ethanolate (DM) and this risk increases with the duration of therapy. The drugs should be used with caution in insulin-dependent DM, because they may worsen glucose intolerance, mask the symptoms of hypoglycemia or prolong recovery from hypoglycemia, or increase the magnitude of the HTN response to hypoglycemia. There is probably a shorter recovery period from hypoglycemia with β1-selective adrenergic blockers. β-Blockers should not be discontinued abruptly in patients with known IHD. If a patient has serious contraindications to β-blockers, unacceptable side effects, or persistent angina, calcium antagonists should be administered. Long-acting dihydropyridine and nondihydropyridine agents are generally as effective as β-blockers in relieving angina. β-Blockers may increase levels of plasma triglycerides and reduce those of high density lipoprotein cholesterol. β-blockers with ISA and/or α blocking-vasodilator activity have little or no adverse effect on plasma lipids. GEMINI, a study comparing the effects of carvedilol versus metoprolol tartrate on glycemic and metabolic control in participants with HTN and DM already receiving renin-angiotensin system blockade demonstrated that carvedilol improved insulin sensitivity and glycemic control and reduced progression to microalbuminuria and with equivalent BP lowering. Based on this study, it appears that the pharmacological differences among the β-blockers can affect the clinical utility of these agents in HTN patients with DM. Of note, weight gain was less with carvedilol than with metoprolol in GEMINI.
Drug–drug interactions There are special considerations when β-blockers are combined with other drugs. Combinations of diltiazem or verapamil with β-blockers may have additional depressant effects on the sinoatrial and atrioventricular nodes and may also promote negative inotropy. The addition of H2-blocking agents to the combination of verapamil and β-blockers can also lead to myocardial depression. Combinations of β-blockers and reserpine may cause marked bradycardia and syncope. Combination with phenylpropanolamine, pseudoephedrine, ephedrine, and epinephrine can cause elevations in BP due to unopposed α-receptor–induced vasoconstriction.
Controversies The Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure did not recommend β-blockers as a potential first-line treatment for HTN. They reasoned that benefits of β-blockade related to secondary CV protection (in established disease) rather than in the primary prevention of CV events. However, the most recent European guidelines state that large-scale meta-analyses of available trial data confirm that diuretics, β-blockers, ACEI, ARBs, and CCBs do not differ significantly in their ability to lower BP and to exert CV protection both in elderly and younger patients. The apparent lack of β-blocker benefit in primary prevention, especially in reducing strokes in the elderly, has been attributed to the use of atenolol, and is probably not generalizable to all β-blockers. In this regard, almost all clinical trials have employed atenolol, once daily, a significant problem in study design because the half-life of the drug is only 6–9 hours. In contrast to IHD and HF where heart rate reduction by β-blockade diminishes the mortality risk, in uncomplicated HTN, heart rate reduction with β-blockers may cause less CV mortality benefit than with other anti-HTN drugs.47., 48., 49.