A significant proportion of patients undergoing non-cardiac surgery suffer from adverse cardiovascular events in the post-operative period. 1,2 The most common is myocardial injury, which is defined as an isolated troponin elevation due to myocardial ischaemia. 3,4 Even though the majority of patients with myocardial injury are asymptomatic, the event has been associated with an increased risk of post-operative mortality primarily shown in large observational studies investigating a heterogenic non-cardiac surgical population. 1,5 Post-operative complications are frequent after major emergency abdominal surgery. 6-8 While 30-day mortality is estimated between 10% and 20%, the risk of medical and

BACKGROUND Postoperative atrial fibrillation (POAF) occurs frequently following cardiothoracic surgery and is associated with a higher mortality and a longer hospital stay. The condition is less studied following noncardiothoracic surgery as well as emergency surgery. OBJECTIVE The aim of this systematic review was to investigate the occurrence of atrial fibrillation following emergency noncardiothoracic surgery and associated risk factors and mortality. DESIGN We conducted a systematic review according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Observational studies and randomised controlled trials were assessed for risk of bias using the Downs and Black checklist and Cochrane Handbook for Systematic reviews of intervention. DATA SOURCES A systematic literature search of PubMed, EMBASE and Scopus was carried out in August 2019. No publication date- or source restrictions were imposed. ELIGIBILITY CRITERIA Observational and randomised controlled trials were included if data on POAF occurring after an emergency, noncardiothoracic, surgical intervention on adult patients could be extracted. RESULTS We identified 15 studies eligible for inclusion covering orthopaedic-, abdominal-, vascular-, neuro- and miscellaneous noncardiothoracic surgery. The occurrence of POAF after emergency noncardiothoracic surgery ranged from 1.5 to 12.2% depending on type of surgery and intensity of cardiac monitoring. Studies that investigated risk factors and associated mortality found emergency surgery and increasing age to be associated with risk of POAF. Moreover, POAF was generally associated with an increase in long-term and short-term mortality. CONCLUSION In this study, atrial fibrillation occurred frequently, especially following emergency orthopaedic, vascular and neurosurgery. Emergency surgery and age were independent risk factors for developing atrial fibrillation. POAF seems to be related to a higher risk of postoperative complications and mortality, though further studies with long-term follow-up are needed. TRIAL REGISTRATION CRD42019112090.

Background Remote ischaemic preconditioning (RIPC) has been shown to have a protective role on vital organs exposed to reperfusion injury. The aim of this systematic review was to evaluate the effects of non-invasive RIPC on clinical and biochemical outcomes in patients undergoing non-cardiac surgery Methods A systematic literature search of PubMed, EMBASE, Scopus, and Cochrane databases was carried out in February 2020. RCTs investigating the effect of non-invasive RIPC in adults undergoing non-cardiac surgery were included. Meta-analyses and trial sequential analyses (TSAs) were performed on cardiovascular events, acute kidney injury, and short- and long-term mortality. Results Some 43 RCTs including 3660 patients were included. The surgical areas comprised orthopaedic, vascular, abdominal, pulmonary, neurological, and urological surgery. Meta-analysis showed RIPC to be associated with fewer cardiovascular events in non-cardiac surgery (13 trials, 1968 patients, 421 events; odds ratio (OR) 0.68, 95 per cent c.i. 0.47 to 0.96; P = 0.03). Meta-analyses of the effect of RIPC on acute kidney injury (12 trials, 1208 patients, 211 events; OR 1.14, 0.78 to 1.69; P = 0.50; I2 = 9 per cent), short-term mortality (7 trials, 1239 patients, 65 events; OR 0.65, 0.37 to 1.12; P = 0.12; I2 = 0 per cent), and long-term mortality (4 trials, 1167 patients, 9 events; OR 0.67, 0.18 to 2.55; P = 0.56; I2 = 0 per cent) showed no significant differences for RIPC compared with standard perioperative care in non-cardiac surgery. However, TSAs showed that the required information sizes have not yet been reached. Conclusion Application of RIPC to non-cardiac surgery might reduce cardiovascular events, but not acute kidney injury or all-cause mortality, but currently available data are inadequate to confirm or reject an assumed intervention effect.