Stroke prevention strategies for cardiac surgery: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Stroke is a much-feared complication of cardiac surgery, but existing literature on preventive strategies is fragmented. Hence, a systematic review and meta-analysis of stroke prevention strategies for cardiac surgery was conducted.

METHODS

An electronic literature search was conducted to retrieve randomized controlled trials (RCTs) investigating perioperative interventions for cardiac surgery, with stroke as an outcome. Random-effects meta-analyses were conducted to generate risk ratios (RRs), 95% confidence intervals (95% CI), and forest plots. Descriptive analysis and synthesis of literature was conducted for interventions not amenable to meta-analysis, focusing on risks of stroke, myocardial infarction and study-defined major adverse cardiovascular events (MACE).

RESULTS

Fifty-six RCTs (61 894 patients) were retrieved. Many included trials were underpowered to detect differences in stroke risk. Among pharmacological therapies, only preoperative amiodarone was shown to reduce stroke risk in one trial. Concomitant left atrial appendage closure (LAAC) significantly reduced stroke risk (RR = 0.55, 95% CI = 0.36-0.84, P = 0.006) in patients with preoperative atrial fibrillation, and there was no difference in on-pump versus off-pump coronary artery bypass grafting (CABG) (RR = 0.94, 95% CI = 0.64-1.37, P = 0.735). Much controversy exists in literature on the timing of carotid endarterectomy relative to CABG in patients with severe carotid stenosis. The use of preoperative remote ischemic preconditioning was not found to reduce rates of stroke or MACE.

CONCLUSION

This review presents a comprehensive synthesis of existing interventions for stroke prevention in cardiac surgery, and identifies gaps in research which may benefit from future, large-scale RCTs. LAAC should be considered to reduce stroke incidence in patients with preoperative atrial fibrillation.

Routine preoperative screening computed tomography of the thorax for cardiac surgery

Introduction

This study aimed to evaluate the role of screening computed tomography (CT) of the thorax in cardiac surgery by analysing the presence of CT aortic calcifications in association with changes in operative strategy and postoperative stroke, and the CT features of emphysema with development of pneumonia.

Methods

All patients who underwent cardiac surgery from January 2013 to October 2017 by a single surgeon were retrospectively studied. Patients who underwent screening CT thorax before cardiac surgery (CT group) were compared to those who did not (no CT group). Multivariate subgroup analyses were performed to determine significant association with postoperative outcomes.

Results

A total of 392 patients were included, of which 156 patients underwent preoperative screening CT thorax. Patients in the CT group were older (63.9 vs. 59.0 years, P = 0.001), had fewer recent myocardial infarctions preoperatively (41% vs. 56.4%, P = 0.003) and had better ejection fraction (>30%; P = 0.02). Operative strategy was changed in 4.3% of patients, and 4.9% of patients suffered stroke postoperatively. The presence of CT aortic calcifications was significantly associated with change in operative strategy (P = 0.016) but not with postoperative stroke (P = 0.33). Age was an independent risk factor for change in operative strategy among patients with CT thorax (P = 0.02). Multivariate age-adjusted analysis showed only palpable plaque to be significantly associated with change in operative strategy (P < 0.001). None of the patients with CT emphysema features developed pneumonia.

Conclusion

The results of this study do not support routine use of preoperative screening CT thorax. Contrasted CT may be advisable in older patients and for other operative planning purposes.

N-Acetylcysteine's Renoprotective Effect in Cardiac Surgery: A Systematic Review and Meta-Analysis

OBJECTIVE

To examine N-acetylcysteine's (NAC's) renoprotective effect in adult cardiac surgeryMethods: PubMed, Ovid Medline, and Embase were searched for randomized controlled trials published between January 1990 and May 2021 that investigated the effect of NAC in preventing acute kidney injury (AKI) in patients undergoing cardiac surgery. The inclusion criterion was studies that assessed the effect of NAC in comparison to placebo by measuring the incidence of AKI.

RESULTS

Overall meta-analytic estimates of all 10 included trials showed that NAC did not have a significant effect (odds ratio [OR]: 0.84, 95% confidence interval [CI]: 0.64-1.10) on AKI. Further subgroup analysis did not show a significant benefit of NAC in preventing AKI.

CONCLUSION

This meta-analysis suggests that NAC does not have a significant effect in reducing the incidence of AKI. However, there is notable heterogeneity among the included studies that could possibly account for the non-significant effect observed. It is worth noting that only one trial administered NAC high dosages perioperatively, and it is the only included trial to show a significant benefit in reducing the incidence of AKI (OR: 0.30, 95% CI: 0.11-0.81). Further studies on this dosage and duration of administration should be conducted to best elucidate the effect of administering NAC.

Optimal vortex formation time index in mitral valve stenosis

Left ventricular vortex formation time (VFT) is a novel dimensionless index of flow propagation during left ventricular diastole, which has been demonstrated to be useful in heart failure and cardiomyopathy. In mitral stenosis (MS), flow propagation in the LV may be suboptimal. We studied VFT in varying degrees of MS. Echocardiography was performed on 20 healthy controls and 50 cases of rheumatic MS. Patients with atrial fibrillation, LV ejection fraction < 50% and other valvular heart diseases were excluded. VFT was obtained using the length-to-diameter ratio (L/D), where L is the continuous-wave Doppler velocity time integral stroke distance, divided by D, the mitral leaflet separation index. This was correlated against varying degrees of MS severity, left atrial (LA) volume and function. In controls, VFT was 3.92 ± 2.00 (optimal range) and was higher (suboptimal) with increasing severity of mitral stenosis (4.98 ± 2.43 in mild MS; 7.22 ± 2.98 in moderate MS; 11.55 ± 2.67 in severe MS, p < 0.001). VFT negatively correlated with mitral valve area (R² = 0.463, p < 0.001) and total LA emptying fraction (R² = 0.348, p < 0.001), and positively correlated with LA volume index (R² = 0.440, p < 0.001) and mean transmitral pressure gradient (R² = 0.336, p < 0.001). More severe MS correlated with suboptimal (higher) VFT. The restricted mitral valve opening may disrupt vortex formation and optimal fluid propagation in the LV. Despite the compensatory increase in LA size with increasingly severe MS, reduced LA function also contributed to the suboptimal LV vortex formation.

Minimally invasive tricuspid valve surgery and concomitant MAZE procedure with closure of LA appendage through an ASD

Utilization of the ASD as a gateway to reach the left heart in tricuspid valve surgery may facilitate the use of a mini right thoracotomy and single atriotomy approach, avoiding the need for bi-atrial incisions and/or median sternotomy.

Meta-analysis of the benefit of beta-blockers for the reduction of isolated atrial fibrillation incidence after cardiac surgery

Objectives

Postoperative atrial fibrillation (POAF) is a common problem of cardiac surgery. Beta-blockers are recognized as effective prophylactic agents available for POAF management. To better understand its effect on isolated atrial fibrillation after cardiac surgery, a meta-analysis was conducted.

Methods

Randomized controlled trials (RCTs) were searched and filtered by comparing the efficacy of beta-blockers and control users in isolated POAF for cardiac surgery. Seventeen RCTs were identified and analyzed by typical meta-analysis methods. The search was performed from inception to May 31, 2020. Subgroup analyses were conducted for type of surgery and beta-blocker, starting time and route of administration of beta-blocker, and dosage of intravenous landiolol hydrochloride.

Results

Beta-blockers were effective in reducing isolated POAF risk (risk ratio [RR], 0.52 [0.41, 0.66], P = .31, I² = 12%). In subgroup analyses, beta-blocker administration during postoperative period (RR, 0.43 [0.29, 0.62], P = .84, I² = 0%) and on-pump coronary artery bypass graft (RR, 0.34 [0.04, 3.15], P = .56, I² = 0%) had lowest risk of isolated POAF incidence. Intravenous landiolol hydrochloride at 2 μg/kg/min also had low risk of isolated POAF occurrence.

Conclusions

Beta-blocker treatment helps to reduce isolated atrial fibrillation incidence after cardiac surgery. Our subgroup analyses also reveal postoperative beta-blocker administration after on-pump coronary artery bypass graft surgery is most effective in reducing isolated POAF risk. Intravenous landiolol hydrochloride at a dosage of 2 μg/kg/min has also displayed favorable results. Further trials may be required to explore these factors.

An Asian Perspective on Gender Differences in Clinical Outcomes and Echocardiographic Profiles of Patients With Medically Managed Severe Aortic Stenosis

BACKGROUND

Gender differences in valvular heart disease are increasingly recognised. A prior study has suggested better surgical outcomes in women with symptomatic aortic stenosis (AS). We investigate gender differences in medically managed severe AS.

METHOD

We studied 347 patients with severe AS (aortic valve area index <0.6 cm²/m²) in terms of baseline clinical background, echocardiographic characteristics, and clinical outcomes. Appropriate univariate and multivariate models were employed, while Kaplan-Meier curves were constructed to compare mortality outcomes.

RESULTS

In total, 205 (59%) patients were women. Despite higher incidences of hypertension (75.6% vs 47.3%) and diabetes mellitus (46.5% vs 29.5%) in women, women had improved survival (Kaplan-Meier log-rank = 6.24, p = 0.012). After adjusting for age (hazard ratio [HR], 1.034; 95% confidence interval [CI], 1.014-1.054), hypertension (HR, 1.469; 95% CI, 0.807-2.673), diabetes (HR, 1.219; 95% CI, 0.693-2.145), and indexed aortic valve area (HR 0.145, 95% CI 0.031-0.684) on multivariate analyses, female gender remained independently associated with lower mortality (HR, 0.561; 95%, CI 0.332-0.947). Women tended to have smaller body surface area (BSA), left ventricular (LV) internal diastolic diameter, and smaller LV outflow tract diameter but were similar to men in terms of LV ejection fraction, AS severity, and patterns of LV remodelling.

CONCLUSIONS

Women appeared to have better outcomes compared to men in medically managed severe AS. These gender differences warrant further study and may affect prognosis, follow-up, and timing of valve surgery.

Five-year experience with congenital cardiac surgery at National University Heart Centre, Singapore

INTRODUCTION

Surgical procedures performed for congenital heart disease are usually complex and variable. The aims of this paper were to analyse patient demographics in a centre that caters to congenital cardiac surgery, compare departmental standards to international centres, and investigate the relationship between patient volume and clinical outcome.

METHODS

A total of 163 patients who presented to the Cardiac, Thoracic and Vascular Surgery Department of the National University Hospital , Singapore between 2002 and 2006 were identified and studied retrospectively. Patient demographics were analysed. The mortality rates and patient volume were compared with those observed at international centres.

RESULTS

The mean annual patient volume was 32.6 cases. The mean age of the patients was 15.7 years, with the oldest patient being 73 years old. 57.1 percent of the patients were Chinese, 23.3 percent were Malay and 19.6 percent were Indian and other races. Foreigners made up nearly half of the patient cohort (45.4 percent). Atrial septal defect was found to be the most common diagnosis (n is 64), with the secundum being most commonly involved (76.9 percent). The commonest postoperative morbidities encountered were arrhythmias and pleural effusions. Patient volume was not found to be a significant factor affecting clinical outcomes.

CONCLUSION

With a growing population of adults with congenital heart disease and a significant number of foreign patients, improvements to our resources and infrastructure need to be considered in order to cope with the increasing demands. Despite having a low patient volume, the centre is still able to provide congenital heart surgery with good clinical outcomes that are comparable to those of international centres with similar or higher patient volumes.

Assessment, management and spatial distribution of ground water for irrigation in Rupnagar district of Punjab (India)

Ground water samples for geo-referenced sites were collected and analyzed for various chemical constituents for assessing their quality for irrigation. These waters were categorized as good and marginal sodic based upon the values of EC and RSC. The ground water quality map of the area was prepared and digitized using GIS software and blockwise area under different categories was commuted, which indicates that Kharar block (46.7 percent of the TGA) has maximum area under marginally sodic water as compared to the Anandpur Sahib block with 8.5 percent of its TGA under marginally sodic waters.