David J. McCormack

A meta-analysis of cognitive outcome following coronary artery bypass graft surgery

Coronary artery bypass graft (CABG) surgery is an established treatment for complex coronary artery disease. There is a widely held belief that cognitive decline presents post-operatively. A consensus statement of core neuropsychological tests was published in 1995 with the intention of guiding investigation into this issue. We conducted a meta-analysis evaluating the evidence for cognitive decline post-CABG surgery. Twenty-eight published studies, accumulating data from up to 2043 patients undergoing CABG surgery, were included. Results were examined at very early (<2 weeks), early (3 months) and late (6-12 months) time periods post-operatively. Two of the four tests suggested an initial very early decrease in psychomotor speed that was not present at subsequent testing. Rather, the omnibus data indicated subtle improvement in function relative to pre-operative baseline testing. Our findings suggest improvement in cognitive function in the first year following CABG surgery. This is contrary to the more negative interpretation of results of some individual publications included in our review, which may reflect poor outcomes in a few patients and/or methodological issues.

Which stages of thymoma benefit from adjuvant chemotherapy post-thymectomy?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was Which stages of thymoma benefit from adjuvant chemotherapy post thymectomy? Altogether more than 150 papers were found using the reported search, of which only eight represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated; these studies have mainly reported the survival and recurrence rates of post-thymectomy patients who received adjuvant radiotherapy or chemoradiotherapy, and adjuvant radiotherapy alone was only used in a small group of patients in these studies. We did not find any randomized controlled trials comparing adjuvant chemotherapy with chemo/radiotherapy and, due to a very small incidence of this tumour, it is unlikely to see any trials in future. Studies were mainly retrospective or institutional reports and showed that, despite the high sensitivity of this tumour to chemotherapy agents and the use of chemotherapy as one of the main treatment modalities in the advanced stages of thymoma, current data are not supporting postoperative chemotherapy as a sole adjuvant treatment in advanced stages of thymoma. We conclude that, in patients with thymoma, surgical resection with or without radiation therapy is the gold standard treatment for early-stage disease (I and II). Adjuvant radiotherapy/chemoradiotherapy should be considered for Masaoka stage III (A and B) or above, and it is also advised to add adjuvant therapy for all patients with cortical fenestration, even in stages I and II. But there is no evidence that chemotherapy alone improves the survival in patients with completely resected stage III and IV thymomas and thymic carcinoma. In patients with extra-radiation field disease, however, the use of chemotherapy can potentially improve survival but no follow-up data on this group of patients are available.

Undiagnosed sleep apnoea syndrome in patients with acute myocardial infarction: potential importance of the STOP-BANG screening tool for clinical practice.

Sleep apnoea hypopnea syndrome (SAHS) has been identified as an independent risk factor for adverse cardiovascular events in patients admitted with an acute coronary syndrome (ACS) [1]. Most people with SAHS, including those with ACS, are undiagnosed. Konecny and colleagues [2] reported a prevalence of previously diagnosed or suspected SAHS (specificall obstructive sleep apnoea) of 14% among 74 patients with acute MI. However, the frequency of SAHS defined by overnight polysomnography (PSG) was 69%, more than half of whom had PSG findings indicative of moderate–severe SAHS. Whilst PSG is the gold standard for the diagnosis of SAHS, it is time consuming and costly to perform, and its routine application to patients with ACS is impractical. By contrast, a simple screening tool capable of stratifying patients into high and low risk groups for SAHS could potentially be applied to this patient group. The STOP-BANG screen for SAHS comprises four binary questions and four items, paraphrased here as: Snore?, Tiredness during daytime?,Observed apnoea?, High Blood Pressure?, Body mass index, Age, Neck circumference and Gender [3]. We applied the STOP-BANG screen to all patients admitted with acute MI within a one month period to a tertiary referral centre, an urban general hospital and a rural general hospital. A total of 135 patients were diagnosed with MI during the study period. 101 (75%) were male, the mean age was 66±14.6 years, and the mean body mass index (BMI) was 28±5.7 kg/m. There was no significant difference in these variables between the three centres. A STOP-BANG score suggestive of SAHS (≥3) was present in 100 (74%) patients. The two patients who had a pre-existing diagnosis of SAHS both had a STOP-BANG score suggesting high risk of SAHS (6,7). The proportion of significant scores was similar across centres (P=0.88). A significant score was more common in males compared with females (83% v 47%; χ=17.3, Pb0.001) and this was not explained by BMI. In this study of patients presenting with ACS to UK hospitals, 74% of those with confirmedMI had a STOP-BANG score suggestive of preexisting SAHS. While this proportion appears surprisingly high, our data are consistent with those from two recent PSG-based studies of patients with acute MI. In these studies, the prevalence of SAHS defined by an apnoea hypopnea index (AHI) >5, was 68.9% and 74.9%, respectively (Fig. 1) [2,4]. For patients with an AHI>5 the sensitivity of the STOP-BANG for SAHS is 83.6%, rising to 92.9% for those with an AHI>15 [3]. In the present study population, the STOP BANG is likely to have identified the majority of patients across the spectrum of SAHS severity but with greatest sensitivity implied for those with moderate–severe SAHS. That only two of our patients who had significant STOP-BANG scores had a prior diagnosis of SAHS reinforces the finding of Konecny and colleagues [2] that this potentially important underlying condition is not well recognised. The high sensitivity of the STOP-BANG makes it a potentially useful screening tool for SAHS and its simplicity means that it is ideal for use in patients presenting with acute MI. Indeed, we were able to apply the STOP-BANG to all patients who presented with MI whereas studies utilising PSG have generally excluded patients with co-morbidities such as diabetes [4], COPD, stroke and valvular heart disease [5], and concomitant treatment with sedatives and narcotics [5].

Assessment of the EuroSCORE II in a New Zealand Tertiary Centre

BACKGROUNDnThe updated European System for Cardiac Operative Risk Evaluation (EuroSCORE II) is a well-established cardiac surgery risk scoring tool for estimating operative mortality. This risk stratification system was derived from a predominantly European patient cohort. No validation analysis of this risk model has been undertaken for the New Zealand population across all major cardiac surgery procedures. We aim to assess the efficacy (discrimination and calibration) of the EuroSCORE II for predicting mortality in cardiac surgical patients at a large New Zealand tertiary centre.nnnMETHODSnData was prospectively collected on patients undergoing cardiac surgery from September 2014 to September 2017 at Waikato Hospital, New Zealand. Patient demographic information, preoperative clinical risk factors and outcome data were entered into a national database. Included patients received either isolated coronary artery bypass grafting (CABG), isolated valve surgery, isolated thoracic aortic surgery, or a combination of these procedures. The primary outcome was the discrimination and calibration of predicted EuroSCORE II risk scores compared with observed 30-day mortality events.nnnRESULTSn1666 cardiac surgery patients were included during the study period, with an average EuroSCORE II of 2.97% (95% confidence interval (CI): 2.76-3.18). 933 patients underwent isolated CABG, 384 underwent isolated valve surgery, 48 received isolated thoracic aortic surgery and 301 received combination procedures. Thirty-day mortality events in each of these groups was 7, 4, 2 and 13 deaths respectively. There were 26 deaths across the total cohort at 30-days (observed mortality rate 1.56%). Discrimination analysis using receiver operating characteristic curves demonstrated the area under the curve (AUC) of the EuroSCORE II in each of these groups as 93.4% (95% CI: 91.6-94.9, p<0.0001), 66.3% (95% CI: 61.3-71.0, p=0.37), 37.0% (95% CI: 15.7-58.2, p=0.23) and 74.8% (95% CI: 69.5-79.6, p<0.0001) respectively. The total cohort AUC was 83.1% (95% CI: 81.2-84.9, p<0.0001). Calibration analysis using Hosmer-Lemeshow tests for the subgroups revealed p-values of 0.848, 0.114, 0.638 and 0.2 respectively. The total cohort Hosmer-Lemeshow p-value was 0.317.nnnCONCLUSIONSnEuroSCORE II showed a strong discriminative ability for isolated CABG 30-day mortality in a New Zealand patient cohort. However, the scoring system discriminated poorly across valvular, thoracic aortic or complex combination cardiac surgical procedures. Good calibration of the EuroSCORE II was achieved across both the total cohort and subgroups. It is important to consider the performance of other cardiac surgery risk stratification models for the New Zealand population.