{'fraction_non_alphanumeric': 0.02005597014925373, 'fraction_numerical': 0.012593283582089552, 'mean_word_length': 5.430284857571214, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
I Perioperative beta-blockade , 2008 : What does POISE tell

In the early days of patients presenting for surgery while on beta-blockers, it was customary to stop their administration 2 weeks before elective surgery because of the perceived risk of cardiovascular collapse that could result from blockade of compensatory mechanisms. This view was supported by mostly anecdotal evidence, and seemed illogical as surgery constitutes a high stress situation during which the heart may need to be protected by blockade from the effects of exaggerated sympathetic activity. In 1973, the first detailed haemodynamic study of betablockade in surgical patients showed that beta-blockade was compatible with anaesthesia and surgery, reduced the risk of hypertension on laryngoscopy and intubation, and decreased the incidence of both ventricular arrhythmias and myocardial ischaemia. Further evidence for protection against perioperative myocardial ischaemia by acute beta-blockade was observed in a number of subsequent studies. 4 A significant improvement in cardiac outcome at 2 yr after non-cardiac surgery was reported by Mangano and colleagues in a randomized controlled trial (RCT) in 1996. In this trial, the event-free survival was 91% for those given atenolol for 1 week postsurgery and 81% for those given a placebo. However, in their analysis, the authors did not include events occurring during hospitalization, and in contrast to the published results, an intention-to-treat analysis does not show longterm mortality benefit. Despite the limitations of the data from this trial, the American College of Medicine proposed in 1997 that atenolol should be given before operation to all patients with coronary artery disease or risk factors for that condition. Such an approach was indirectly supported by the data available at the time related to the efficacy of betablockade in the treatment of acute myocardial infarction, and its secondary prevention, hypertension, and later in the management of patients with cardiac failure. In 1999, another RCT of patients with reversible ischaemia, on dobutamine echocardiography, presenting for major elective vascular surgery showed a 100% reduction in the incidence of myocardial infarctions and an 80% reduction in cardiac deaths in the patients treated before and after operation with bisoprolol. Although there were also limitations in this trial (e.g. it was unblinded and stopped at the first interim analysis, despite only randomizing 112 patients and the presence of 20 events), these data strengthened the case for beta-blockade. Our previous editorial in the British Journal of Anaesthesia expressed enthusiasm for the use of these drugs, but cautioned the reader against injudicious use! The American College of Cardiology/American Heart Association (ACC/AHA) guideline of 2002 stated: ‘current studies suggest that appropriately administered betablockers reduce perioperative ischaemia and may reduce the risk of myocardial infarction and death in high risk patients’. Nevertheless, these guidelines categorized the use of beta-blockers in patients undergoing vascular surgery with ischaemia detected during preoperative testing as a class I recommendation, and they gave a class IIa recommendation to the use of perioperative beta-blocker therapy in patients with preoperative untreated hypertension, known coronary artery disease, or major risk factors for coronary disease. The acknowledgement of some degree of uncertainty about the efficacy of beta-blockade in surgical patients was appropriate, as some other studies failed to show early or short-term outcome benefits. 12 When data from these and other studies were combined, early systematic reviews of acute beta-blockade with a meta-analysis of RCTs, based on a relatively small number of patients, showed evidence of cardiac protection. 14 However, more recent and much larger meta-analyses of their use in non-cardiac and in cardiac and non-cardiac surgery indicate only a trend towards protection. The findings from these systematic reviews express uncertainties that are reflected in the 2006 and 2007 ACC/AHA guidelines which state ‘current studies suggest that beta-blockers reduce perioperative ischaemia and may reduce the risk of myocardial infarction and death