Acute peri-operative beta-blockade in South Africa

No Abstract. Southern African Journal of Anaesthesia and Analgesia Vol. 12(1) 2006: 32-3

Predicting outcome

No Abstract

The new American Heart Association algorithm: is it progress?

The new 2014 American College of Cardiology (ACC) and American Heart Association (AHA) guideline for the perioperative cardiovascular evaluation and management of patients undergoing non-cardiac surgery was published in 2014.1 There are a number of fundamental changes to this guideline, of which the practising anaesthetist should be aware. Furthermore, the changes in the guideline give an idea of the change in the philosophy of cardiovascular risk stratification and risk reduction in the USA. This paper reviews the changes to the algorithm, and the publications that resulted in these recommendations.Keywords: AHA algorithm, ACC, guideline, non-cardiac surgery, acute coronary syndrome

Postoperative risk stratification for cardiovascular complications

No Abstract

Statins in cardiac surgery

Background: Recent studies on the utility of statins in cardiac surgery appear to show conflicting results. Most studies are either retrospective or prospective observational, with small sample sizes. In order to address these limitations, we systematically reviewed studies from 2008 to the present, in order to determine the clinical utility of perioperative statin use in cardiac surgery.Method: We searched PubMed for studies reporting the use of statin therapy in cardiac surgery. The outcomes of interest were postoperative mortality, non-fatal myocardial infarction, acute renal injury,  cerebrovascular events, and atrial fibrillation. An a priori decision was taken to conduct a subgroup analysis of coronary artery bypass surgery (CABG) and valve replacement surgery.Results: Statins were associated with a reduction in all-cause mortality at 30 days in cardiac surgical patients (odds ratio (OR) 0.65, [95% confidence interval (CI) 0.60-0.71]), and this was consistent in both subgroups. Statins were associated with a reduction in myocardial infarction in the CABG group [OR 0.73, (95% CI 0.48-1.13)], but not in the valve group [OR 1.14, (95% CI 0.80-1.63)]. Statins were not associated with protection from acute renal injury post-cardiac surgery [OR 1.20, (95% CI 1.10-1.31)]. Statins were associated with significantly less postoperative cerebrovascular events [OR 0.83, (95% CI 0.71-0.97)], and this was consistent for both CABG and valve surgery. Statins were associated with significantly less postoperative atrial fibrillation [OR 0.78, (95% CI 0.70-0.98)], which was evident following CABG. However, there were insufficient data to determine its efficacy in valve surgery.Conclusion: Statins were associated with improved outcomes for mortality, myocardial infarction, cerebrovascular accident, and atrial fibrillation, following CABG. In valve surgery, statins were only associated with  improved outcomes for mortality and cerebrovascular accident. The associated increase in acute renal injury needs further investigation

The impact of acute preoperative beta-blockade on perioperative cardiac morbidity and all-cause mortality in hypertensive South African vascular surgery patients

Background. Acute β-blockade has been associated with poor perioperative outcomes in non-cardiac surgery patients, probably as a result of β-blocker-induced haemodynamic instability during the perioperative period, which has been shown to be more severe in hypertensive patients.Objective. To determine the impact of acute preoperative β-blockade on the incidence of perioperative cardiovascular morbidity and allcause mortality in hypertensive South African (SA) patients who underwent vascular surgery at a tertiary hospital.Methods. We conducted two separate case-control analyses to determine the impact of acute preoperative β-blockade on the incidence of major adverse cardiovascular events (MACEs, a composite outcome of a perioperative troponin-I leak or all-cause mortality) and perioperative troponin-I leak alone. Case and control groups were compared using χ2, Fisher’s exact, McNemar’s or Student’s t-tests, where applicable. Binary logistic regression was used to determine whether acute preoperative β-blocker use was an independent predictor of perioperative MACEs/troponin-I leak in hypertensive SA vascular surgery patients.Results. We found acute preoperative β-blockade to be an independent predictor of perioperative MACEs (odds ratio (OR) 3.496; 95% confidence interval (CI) 1.948 - 6.273; p<0.001) and troponin-I leak (OR 5.962; 95% CI 3.085 - 11.52; p<0.001) in hypertensive SA vascular surgery patients.Conclusions. Our findings suggest that acute preoperative β-blockade is associated with an increased risk of perioperative cardiac morbidity and all-cause mortality in hypertensive SA vascular surgery patients

The South African Surgical Outcomes Study: A seven-day prospective observational cohort study: preliminary results

Background: Non-cardiac surgical morbidity and mortality is a major global public health burden. Data from sub-Saharan African countries on perioperative outcomes are sparse. South Africa presents a unique public health problem simultaneously engulfed by four epidemics of poverty-related diseases,  noncommunicable diseases, human immunodeficiency virus and related diseases, and injury and violence. Understanding the effects of these epidemics on perioperative outcomes may provide an  important perspective on both South African and surgical global health.Objectives: The objective was to understand the associations with perioperative mortality and critical care admission in South Africa.Method: A seven-day national, multicentre, prospective, observational cohort study was conducted in 50 government-funded hospitals in South Africa. This study is known as the South African Surgical Outcomes Study (SASOS). Participants included patients ≥ 16 years of age undergoing inpatient, non-cardiac surgery between 19 May and 26 May 2014.Outcomes: The primary outcome was in-hospital mortality. Secondary outcomes included duration of hospital stay, admission to the critical care unit after surgery and the duration of the critical care stay. The proportional contribution of noncommunicable diseases, communicable diseases and injuries to perioperative mortality and critical care admission were calculated using population attributable risk statistics.Results: Data on nearly 98% of all eligible patients were submitted from recruiting hospitals. Crude in-hospital mortality was 3.1%, with a postoperative admission to critical care figure of 6.5%. Over 40% of critical care admissions were unplanned. Over half the surgeries in South Africa were classified as urgent or emergent surgery. Urgent or emergent surgery has a population attributable risk for mortality of 26%, and for admission to critical care of 24%.Conclusion: Most patients in South Africa undergo urgent and emergent surgery, which has a strong association with mortality, unplanned critical care admissions and longer critical care stay. Noncommunicable diseases have a larger proportional contribution to morbidity and mortality than infections and injuries. This study was registered on ClinicalTrials.gov (NCT02141867).Funding: This study was funded by the South African Society of Anaesthesiologists and the Vascular Society of Southern Africa.Keywords: The South African Surgical Outcomes Study, SASOS, preliminary result

Are lipophilic beta-blockers preferable for peri-operative cardioprotection?

Atenolol has been proposed as a peri-operative cardioprotective agent in patients with coronary disease. However, recent reports have cast doubt over the cardioprotective efficacy of atenolol in patients with hypertension and coronary artery disease. There is therefore doubt whether atenolol is the correct cardioprotective drug in the surgical setting. It is possible that some of the physiochemical properties of atenolol (hydrophilic and cardioselective) may decrease it's efficacy in comparison to its more lipophilic congeners (such as propranolol, metoprolol, bisoprolol and carvedilol). The issue of prevention of perioperative cardiac events is complicated by many confounders. As a result, the role of the physicochemical properties of beta-blockers can only be determined in the simpler setting of myocardial infarction. Therefore, we conducted a restricted systematic review to evaluate the effect of initiating atenolol and metoprolol on the prevention of ventricular fibrillation following acute myocardial infarction. Neither atenolol nor metoprolol significantly decreased the incidence of in-hospital ventricular fibrillation following acute myocardial infarction. The number-needed-to-treat to prevent in-hospital ventricular fibrillation equals or exceeds 200 with metoprolol and atenolol respectively. Based on the findings of this systematic review and the recently published Clopidogrel and Metoprolol in Myocardial Infarction Trial (COMMIT), it can be concluded that the prevention of peri-operative myocardial ischaemia with a betablocker is clinically more important to peri-operative cardioprotection than whether the beta-blocker is lipo- or hydrophilic. Keywords: atenolol, metoprolol, myocardial infarction, ventricular fibrillation Southern African Journal of Anaesthesia and Analgesia Vol. 12(4) 2006: 141-14

The pharmaco-economics of peri-operative beta-blocker and statin therapy in South Africa

We conducted a pharmaco-economic analysis of the prospective  peri-operative  studies of beta-blocker and statin administration for major  elective non-cardiac surgery, using the Discovery Health claims costs for 2004. This analysis shows that acute peri-operative beta-blockade and statin  therapy could result in a cost saving through a reduction in major   perioperative cardiovascular complications in patients with an expected  peri-operative major cardiovascular complication rate exceeding 10% following elective major non-cardiac surgery. The validity of these findings is dependent on whether the incidence of cardiovascular complications following major  noncardiac surgery reported in the international literature is found to be similar in South Africa

Predictors of Peri-Operative Risk Acceptance by South African Vascular Surgery Patients at a Tertiary Level Hospital

Background: Vascular surgical patients have an elevated cardiac risk following non-cardiac surgery. The decision whether to proceed with surgery is multidimensional. Patients must balance the considerations in favour of surgery with those favouring conservative treatment, which requires weighing peri-operative risk against morbidity associated with non-surgical treatment.Methods: The aim of this prospective correlational study was to determine the proportional contributions of (i) pain, (ii) impulsivity, (iii) patients’ perception of the benefits of surgery, (iv) patients’ perception of peri-operative risk and (v) the predicted peri-operative risk on acceptance of peri-operative risk by vascular surgical patients. Sixty patients were prospectively recruited by convenience sampling from the Inkosi Albert Luthuli Central Hospital vascular surgery clinic between April 2014 and June 2014. Written informed consent was obtained. Patients completed a questionnaire which documented demographics, pain assessment, impulsivity screen (Barratt Impulsiveness Scale 11), patients’ perception of surgery, predicted peri-operative risk (South African Vascular Surgical Cardiac Risk Index) and acceptance of peri-operative risk. Data were analysed using descriptive statistics and linear regression (SPSS version 22).Results: The patients’ perception of the benefits of surgery (β 0.36, 95% CI 0.14–0.70, p = 0.005) was the only predictor of peri-operative risk acceptance. The associations between the other potential predictors and the outcome were insignificant.Conclusion: The perceived benefit of surgery was the most important predictor of acceptance of peri-operative risk in this cohort.Keywords: Pain, Peri-operative Risk, Shared Decision-making, Vascular Surger