Postoperative stroke after off-pump versus on-pump coronary artery bypass surgery

The Rationalisation of Intra-Operative Imaging During Cardiac Surgery: A Systematic Review

INTRODUCTION

One critical complication of cardiac surgery is cerebrovascular accidents (CVAs). Ascending aorta atherosclerosis poses a significant risk of embolisation to distal vessels and to cerebral arteries. Epi-aortic ultrasonography (EUS) is thought to offer a safe, high-quality accurate visualisation of the diseased aorta to guide the surgeon on the best surgical approach to the planned procedure and potentially improve neurological outcomes post-cardiac surgery.

METHOD

The authors conducted a comprehensive search of PubMed, Scopus and Embase. Studies that reported on epi-aortic ultrasound use in cardiac surgery were included. Major exclusion criteria were: (1) abstracts, conference presentations, editorials, literature reviews; (2) case series with <5 participants; (3) epi-aortic ultrasound in trauma or other surgeries.

RESULTS

A total of 59 studies and 48,255 patients were included in this review. Out of the studies that reported patient co-morbidities prior to cardiac surgery, 31.6% had diabetes, 59.5% had hyperlipidaemia and 66.1% had a diagnosis of hypertension. Of those that reported significant ascending aorta atherosclerosis found on EUS, this ranged from 8.3% of patients to 95.2% with a mean percentage of 37.8%. Hospital mortality ranged from 7% to 13%; four studies reported zero deaths. Long-term mortality and stroke rate varied significantly with hospital duration.

CONCLUSION

Current data have shown EUS to have superiority over manual palpation and transoesophageal echocardiography in the prevention of CVAs following cardiac surgery. Yet, EUS has not been implemented as a routine standard of care. Extensive adoption of EUS in clinical practice is warranted to aid large, randomised trials before making prospective conclusions on the efficacy of this screening method.

Bilateral internal thoracic artery grafting for peripheral arterial disease patients

BACKGROUND

Peripheral arterial disease (PAD) is known to have a poor prognosis. Some reports have also described poor late results after coronary artery bypass grafting (CABG). However, there have been few reports about whether bilateral internal thoracic artery grafting improves the long-term survival of PAD patients after CABG. We performed this study to clarify whether or not this is the case.

METHODS

One hundred and thirty-six PAD patients who underwent elective CABG with two or more grafts were enrolled in this study. Patients were divided into two groups, 71 patients in the bilateral internal thoracic artery (BITA) group and 65 patients in the single internal thoracic artery (SITA) group. The maximum follow-up period was 19 years, with a mean of 5.7 ± 4.4 years.

RESULTS

We investigated the long-term results based on three factors; survival, freedom from cardiac death, and freedom from cardiac events. The 3-, 5- and 10-year survival rates in the BITA group were 83.0, 74.2, and 43.1%, respectively. And those in the SITA group were 79.4, 67.7, and 32.3%, respectively. There were no significant differences between the two groups (p = 0.5843). There were also no statistically significant differences between the two groups in terms of the freedom from cardiac death (p = 0.8589) or in the freedom from cardiac events (p = 0.9445).

CONCLUSION

No long-term advantage was observed for CABG with BITA in comparison to SITA alone in patients with PAD.

Frequency of and determinants of stroke after surgical aortic valve replacement in patients with previous cardiac surgery (from the Multicenter RECORD Initiative)

Surgical aortic valve replacement (S-AVR) after previous cardiac surgery is expected to be associated with a high rate of adverse events. The aim of this study was to estimate the rate and identify the determinants of postoperative stroke in these patients. This is a multicenter study including 741 patients who underwent S-AVR after previous cardiac surgery. Forty-eight patients (6.5%; after isolated AVR, 6.0%) suffered stroke and 10 of them died during the in-hospital stay (20.8%). At multivariate analysis, women (10.2% vs 4.4%, odds ratio [OR] 2.57, 95% confidence interval [CI] 1.36 to 4.86), emergency procedure (15.1% vs 4.8%, OR 2.63, 95% CI 1.12 to 5.78), perioperative use of intra-aortic balloon pump (22.9% vs 5.3%, OR 2.67, 95% CI 1.15 to 6.19), cardiopulmonary bypass time of >210 minutes (15.7% vs 5.0%, OR 2.31, 95% CI 1.13 to 4.71), blood products transfusion (9.3% vs 0.8%, OR 7.75, 95% CI 1.83 to 32.93), and reexploration for bleeding (24.0% vs 5.2%, OR 4.84, 95% CI 2.18 to 10.77) were independent predictors of postoperative stroke. These findings were confirmed by a regression model including CHA2DS2-VASc score of ≥2, which itself was predictive of stroke (8.2% vs 1.6%, OR 4.52, 95% CI 1.34 to 15.28). Survival at 3 years in patients with postoperative stroke was 51.9%, whereas it was 85.0% in control patients (adjusted analysis: relative risk 2.97 and 1.86 to 4.72, respectively). In conclusion, the risk of postoperative stroke after S-AVR in patients with previous cardiac surgery is high and has an impact on the immediate and late mortality. Excessive bleeding requiring blood transfusion and/or reexploration, prolonged cardiopulmonary bypass time, and use of intra-aortic balloon pump were associated with an extremely high rate of stroke.

A multicentre Spanish study for multivariate prediction of perioperative in-hospital cerebrovascular accident after coronary bypass surgery: the PACK2 score

OBJECTIVES

To develop a multivariate predictive risk score of perioperative in-hospital stroke after coronary artery bypass grafting (CABG) surgery.

METHOD

A total of 26 347 patients were enrolled from 21 Spanish hospital databases. Logistic regression analysis was used to predict the risk of perioperative stroke (ictus or transient ischaemic attack). The predictive scale was developed from a training set of data and validated by an independent test set, both selected randomly. The assessment of the accuracy of prediction was related to the area under the ROC curve. The variables considered were: preoperative (age, gender, diabetes mellitus, arterial hypertension, previous stroke, cardiac failure and/or left ventricular ejection fraction<40%, non-elective priority of surgery, extracardiac arteriopathy, chronic kidney failure and/or creatininemia≥2 mg/dl and atrial fibrillation) and intraoperative (on/off-pump).

RESULTS

Global perioperative stroke incidence was 1.38%. Non-elective priority of surgery (priority; OR=2.32), vascular disease (arteriopathy; OR=1.37), cardiac failure (cardiac; OR=3.64) and chronic kidney failure (kidney; OR=6.78) were found to be independent risk factors for perioperative stroke in uni- and multivariate models in the training set of data; P<0.0001; AUC=0.77, 95% CI 0.73-0.82. The PACK2 stroke CABG score was established with 1 point for each item, except for chronic kidney failure with 2 points (range 0-5 points); AUC=0.76, 95% CI 0.72-0.80. In patients with PACK2 score≥2 points, off-pump reduced perioperative stoke incidence by 2.3% when compared with on-pump CABG.

CONCLUSIONS

PACK2 risk scale shows good predictive accuracy in the data analysed and could be useful in clinical practice for decision making and patient selection.

Blood-brain barrier disruption after cardiac surgery

BACKGROUND AND PURPOSE

CNS complications are often seen after heart surgery, and postsurgical disruption of the BBB may play an etiologic role. The objective of this study was to determine the prevalence of MR imaging-detected BBB disruption (HARM) and DWI lesions after cardiac surgery.

MATERIALS AND METHODS

All patients had an MRI after cardiac surgery. For half the patients (group 1), we administered gadolinium 24 hours after surgery and obtained high-resolution DWI and FLAIR images 24-48 hours later. We administered gadolinium to the other half (group 2) at the time of the postoperative scan, 2-4 days after surgery. Two stroke neurologists evaluated the images.

RESULTS

Of the 19 patients we studied, none had clinical evidence of a stroke or delirium at the time of the gadolinium administration or the scan, but 9 patients (47%) had HARM (67% in group 1; 30% in group 2; P = .18) and 14 patients (74%) had DWI lesions (70% in group 1; 78% in group 2; P = 1.0). Not all patients with DWI lesions had HARM, and not all patients with HARM had DWI lesions (P = .56).

CONCLUSIONS

Almost half the patients undergoing cardiac surgery have evidence of HARM, and three-quarters have acute lesions on DWI after surgery. BBB disruption is more prevalent in the first 24 hours after surgery. These findings suggest that MR imaging can be used as an imaging biomarker to assess therapies that may protect the BBB in patients undergoing heart surgery.

Use of blood products and risk of stroke after coronary artery bypass surgery

BACKGROUND

The impact of blood transfusion on the development of post-operative stroke after coronary artery bypass grafting (CABG) is not well established. We, therefore, investigated this issue.

MATERIALS AND METHODS

Complete data on peri-operative blood transfusion were available for 2,226 patients who underwent CABG in three Finnish hospitals.

RESULTS

Stroke occurred post-operatively in 53 patients (2.4%). Logistic regression showed that pre-operative creatinine (OR 1.003, 95% CI 1.000-1.006), extracardiac arteriopathy (OR 2.344, 95% CI 1.133-4.847), pre-operative atrial fibrillation (OR 2.409, 95% CI 1.149-5.052), and the number of packed red blood cell units transfused (OR 1.121, 95% CI 1.065-1.180) were significantly associated with post-operative stroke. When the various blood product transfusions instead of transfused units were included in the multivariable analysis, solvent/detergent treated plasma (Octaplas) transfusion (OR 2.149, 95% CI 1.141-4.047), but not red blood cell transfusion, was significantly associated with postoperative stroke. Use of blood products ranging from no transfusion (stroke rate 1.6%) to combined transfusion of red blood cells, platelets and Octaplas was associated with a significant increase in post-operative stroke incidence (6.6%, adjusted analysis: OR 1.727, 95% 1.350-2.209). Patients who received >2 units of red blood cells, >4 units of Octaplas units and >8 units of platelets had the highest stroke rate of 21%. CART analysis showed that increasing amount of transfused Octaplas, platelets and history of extracardiac arteriopathy were significantly associated with post-operative stroke.

CONCLUSIONS

Transfusion of blood products after CABG has a strong, dose-dependent association with the risk of stroke. The use of Octaplas and platelet transfusions seem to have an even larger impact on the development of stroke than red blood cell transfusions.

Postoperative stroke in patients on oral anticoagulation undergoing coronary artery bypass surgery

OBJECTIVE

Patients on long-term warfarin treatment have an inherent high risk of stroke and here we aimed to identify the determinants of postoperative stroke after coronary artery bypass grafting (CABG) in these patients.

METHODS

A consecutive series of 270 patients on long-term warfarin treatment who underwent isolated CABG in two university hospitals was assessed by logistic regression as well as classification and regression tree (CART) analysis.

RESULTS

Postoperative stroke occurred in 10 patients during in-hospital stay (3.7%). Logistic regression showed that CHADS(2) > 2 (p = 0.036), recent thrombolysis (p < 0.0001) and history of deep vein thrombosis (p = 0.025) were independent predictors of postoperative stroke (area under the ROC curve 0.77). CART analysis showed that CHADS(2) > 2, history of stroke/TIA, no preoperative use of aspirin and preoperative use of low molecular weight heparins were associated with an increased risk of stroke (area under the ROC curve of 0.77).

CONCLUSIONS

Both CART and logistic regression analyses showed that the patient characteristics included in CHADS(2) score are important also in the prediction of postoperative stroke risk. Preoperative antiplatelet treatment may be beneficial in the high risk patients and the preoperative bridging with low molecular weight heparins may even be harmful in this respect.

Meta-analysis on the use of the Heartstring anastomotic device to prevent stroke in patients undergoing off-pump coronary artery bypass grafting

OBJECTIVE

Postoperative stroke is the Achilles' heel of coronary artery bypass surgery compared with percutaneous coronary intervention. In this meta-analysis, we sought to determine the efficacy of the Heartstring proximal anastomotic device to reduce the risk of postoperative stroke after off-pump coronary artery bypass grafting (OPCAB).

METHODS

Studies on the Heartstring device were identified by searching PubMed, Cochrane Library and Scopus up to November 2010. The results were expressed as pooled proportions (%) with 95% confidence interval (95% CI). Heterogeneity across the studies was evaluated by the I(2) test and a random effects model was used.

RESULTS

Eighteen articles were pertinent with this issue and we were able to retrieve data on the Heartstring anastomotic device in OPCAB from eight studies. Three studies were prospective and routine epi-aortic ultrasound was used in three studies. A total of 819 patients were enrolled in these eight studies and six of them suffered stroke postoperatively. Cumulative analysis showed a pooled rate of immediate postoperative stroke after OPCAB with the use of Heartstring of 1.9% (95% CI 0.8-4.5, I(2)=23%). Sensitivity analysis including the only three studies evaluating patients with diseased ascending aorta as detected at epi-aortic ultrasound showed that a pooled rate of stroke was 3.2% (95% CI 0.8-11.9, I(2)=0%). Six studies reported on immediate postoperative mortality and the pooled mortality rate was 1.9% (95% CI 0.1-3.4).

CONCLUSIONS

The results of this meta-analysis suggest that the risk of stroke after OPCAB may not be markedly reduced by the use of Heartstring device. On the other hand, a rather low rate of stroke was observed among patients with diseased ascending aorta indicating its potential value in these patients. Most of studies included in this meta-analysis were of poor methodological quality, and properly conducted prospective studies are needed to get more conclusive results on the safety and efficacy of Heartstring anastomosis device.

Jugular bulb desaturation during off-pump coronary artery bypass surgery

PURPOSE

Off-pump coronary artery bypass grafting surgery (OPCAB) frequently results in significant jugular bulb desaturation. Although jugular bulb desaturation during OPCAB may be associated with postoperative cerebral injury, routine jugular bulb oximetry appears to be invasive and expensive. We hypothesized that intraoperative hemodynamic compromise during OPCAB due to cardiac displacement is associated with jugular bulb desaturation which correlates with specific hemodynamic and physiological changes.

METHODS

Hemodynamic and physiological data were measured at the following points: (1) before anastomosis of the coronary artery (baseline); (2) during anastomosis of the left anterior descending artery; (3) during anastomosis of the circumflex branch or posterior descending artery; and (4) after chest closure. Arterial, mixed venous, and jugular venous bulb blood gas analyses were performed serially.

RESULTS

Jugular bulb desaturation (<or=50%) frequently occurred during surgical displacement of the heart. Mixed venous oxygen saturation (S(VO2)), partial pressure of carbon dioxide (Pa(CO2)), and central venous pressure (CVP) showed a significant relationship with jugular bulb oxygen saturation (r = 0.45) by multivariate linear regression analysis. Multivariate logistic regression analysis also demonstrated that S(VO2) <or= 70%, Pa(CO2) <or= 40 mmHg, and CVP >or= 8 mmHg were likely predictors of the occurrence of jugular bulb desaturation.

CONCLUSION

Changes in S(VO2) and Pa(CO2) were associated with jugular bulb oxygen saturation, and S(VO2) <or= 70%, Pa(CO2) <or= 40 mmHg, and CVP >or= 8 mmHg had a significant odds ratio for jugular bulb desaturation. We suggest that achieving normal values of S(VO2), Pa(CO2) and CVP may be important to prevent cerebral desaturation during OPCAB.

Epiaortic ultrasound assessment of the aorta in cardiac surgery

The dislodgement of atheroma from the ascending aorta and proximal arch is a major cause of stroke and neurological injury following cardiac surgery. The accurate detection of atheroma prior to aortic manipulation is necessary to facilitate surgical strategies to reduce the risk of embolisation. The traditional method for atheroma detection is manual palpation by the surgeon. This technique misses about half the number of the atheroma lesions, as the soft (non-calcified) lesions offer little resistance to the surgeon's fingers. Trans-oesophageal echocardiography (TOE) is commonly used in cardiac surgery, but the interposition of the bronchus between the aorta and the oesophagus causes an ultrasound 'blind spot' in the ascending aorta and proximal arch, such that it does not offer improved detection compared to manual palpation. Accurate detection of atheroma requires direct ultrasound assessment using epiaortic scanning, with a high-frequency, linear-array probe. This allows the surgeon to correctly assess and localise any atheroma. In this article, a suggested epiaortic examination sequence is described and strategies for surgeons to avoid atheroma are discussed.

Neurological complications of cardiac surgery

Neurological injury resulting from cardiac surgery has a range of manifestations from focal neurological deficit to encephalopathy or coma. As the safety of drug-eluting stents comes into question, more patients will likely undergo coronary artery bypass graft surgery. These projections, along with the growing proportions of elderly patients and those with comorbidities, portend the potential for rising rates of perioperative neurological complications. The risk for neurological injury may be determined by the type of procedure, by patient-specific characteristics, and by the extent of cerebral embolization and hypoperfusion during and after surgery. Changes in surgical techniques, including the use of off-pump surgery, have not decreased rates of brain injury from cardiac surgery. When appropriate, modern neuroimaging techniques should be used in postoperative patients to confirm diagnosis, to provide information on potential etiology, to direct appropriate therapy, and to help in prognostication. Management of postoperative medications and early use of rehabilitation services is a recommended strategy to optimize the recovery for individuals with neurological injury after cardiac surgery.

Brain protection in cardiac surgery

Brain injury is a major source of patient morbidity after cardiac surgery, and is associated with prolonged hospitalization, excessive operative mortality, high hospital costs, and altered quality of life. Frequency and the clinical manifestations depend on multiple factors, including the completeness and timing of neurologic testing. Ischemic brain infarctions may or may not be associated with stroke or postoperative neurocognitive dysfunction, but the long-term implications of these lesions on neurologic function have not yet been extensively evaluated. This article reviews the current views on the pathophysiologic basis of cerebral injury after cardiac surgery and provides a summary of measures aimed at reducing its occurrence.

Mechanisms of cerebral injury from cardiac surgery

Cerebral injury is a frequent complication of cardiac surgery, and it has been associated with high mortality, morbidity, hospital costs; an increased likelihood of admission to a secondary care facility after hospital discharge; and impaired quality of life. This article examines postulated mechanisms for cerebral injury from cardiac surgery. Most emphasis has been placed in the past on the intraoperative interval as being the period of highest cerebral vulnerability. Many clinical cerebral events, however, occur in the postoperative period.