Effects of off-pump and on-pump coronary-artery bypass grafting at 1 year

AKI associated with cardiac surgery

Approximately 18% of patients undergoing cardiac surgery experience AKI (on the basis of modern standardized definitions of AKI), and approximately 2%-6% will require hemodialysis. The development of AKI after cardiac surgery portends poor short- and long-term prognoses, with those developing RIFLE failure or AKI Network stage III having an almost 2-fold increase in the risk of death. AKI is caused by a variety of factors, including nephrotoxins, hypoxia, mechanical trauma, inflammation, cardiopulmonary bypass, and hemodynamic instability, and it may be affected by the clinician's choice of fluids and vasoactive agents as well as the transfusion strategy used. The risk of AKI may be ameliorated by avoidance of nephrotoxins, achievement of adequate glucose control preoperatively, and use of goal-directed therapy hemodynamic strategies. Remote ischemic preconditioning is an exciting future strategy, but more work is needed before widespread implementation. Unfortunately, there are no pharmacologic agents known to reduce the risk of AKI or treat established AKI.

Contemporary coronary artery bypass grafting

Current evidence clearly demonstrates that coronary artery bypass grafting (CABG) remains the "gold standard" treatment for most patients with multivessel and left main stem disease. This article summarizes the relevant evidence basis demonstrating that CABG, in comparison to stenting, reduces mortality and subsequent myocardial infarction and the need for repeat revascularization. The article also describes the evidence basis to support the use of more arterial grafts during CABG and the current role of off-pump CABG.

Is the evidence from first time off-pump coronary artery bypass graft surgery transferable to re-operative off-pump surgery?

On-pump coronary artery surgery remains the gold standard treatment for multi-vessel disease. The technique of off-pump surgery has evolved since its first use; however, currently less than 20% of all cases worldwide are performed this way. This poor uptake has been both the cause and the effect of widespread scepticism regarding the validity of the data on the technique, as well as criticism regarding the conversion-related adverse outcomes, graft patency and completeness of revascularisation. Consequently, there has been focus on patient selection from subgroups most likely to benefit from the technique. Re-operative patients, by virtue of their advanced age, complex co-morbidities and the technical challenges of re-operation, fall into this category. In this review, the authors will discuss the outcomes of off-pump surgery in comparison to on-pump, explore the potential beneficial effects of off-pump in re-operative surgery and formulate a decision-making strategy in patients undergoing reoperative coronary artery surgery.

A new beating-heart off-pump coronary artery bypass grafting training model

OBJECTIVES

Training models are essential in mastering the skills required for off-pump coronary artery bypass grafting (OPCAB). We describe a new, high-fidelity, effective and reproducible beating-heart OPCAB training model in human cadavers.

METHODS

Human cadavers were embalmed according to the 'Thiel method' which allows their long-term and repeated use. The training model was constructed by bilateral ligation of the pulmonary veins, cross-clamping of the aorta, positioning of an intra-aortic balloon pump (IABP) in the left ventricle (LV) through the apex (tightened with pledget-reinforced purse strings) and finally placing of a fluid line in the LV through the left atrial appendage (tightened with a pledget-reinforced purse string). The LV was filled with saline to the desired pressure through the fluid line and the IABP was switched on and set to a desired frequency [usually 60-80 beats per minute (bpm)].

RESULTS

A high-fidelity simulation has known limitations, but a more complex, realistic training environment with an actual beating (human) heart strengthens the entire training exercise and is of incremental value. All types of coronary artery anastomosis can be trained with this model. Training should be performed under the supervision of an experienced OPCAB surgeon and training progress is best evaluated with serial Objective Structured Assessment of Technical Skills (OSATS). A score of at least 48 points on the final OSATS ('good' on all components) is recommended before trainees can start their training on patients.

CONCLUSIONS

The entire set-up provides a versatile training model to help develop and improve the skills required to safely perform beating heart OPCAB anastomoses.

On-pump versus off-pump coronary artery bypass graft surgery: what do the evidence show?

The main purpose of the off-pump coronary artery bypass surgery is to reduce morbidity and mortality due cardiopulmonary bypass. However, even though many studies have shown that off-pump coronary artery bypass is feasible and provides hospital morbidity and mortality similar to the on-pump coronary artery bypass graft surgery, probably better in some aspects, its long-term results have been questioned, since some trials have shown reduced survival with off-pump coronary artery bypass. It is likely that incomplete revascularization and/or poor graft patency with off-pump coronary artery bypass probably are responsible for such unfavorable outcome.

Neutrophil gelatinase-associated lipocalin after off pump versus on pump coronary artery surgery

CONTEXT

Cardiac surgery.

OBJECTIVE

To compare plasma and urinary neutrophil gelatinase-associated lipocalin (P-/U-NGAL) in on-pump (n = 43) versus off-pump (n = 40) surgery.

MATERIALS AND METHODS

We obtained perioperative P-/U-NGAL and outcome data.

RESULTS

P-/U-NGAL increased after surgery. P-NGAL was higher post-surgery in on pump patients (139 versus 67 µg L(-1); p < 0.001), but not at 24 h. There were no differences in U-NGAL. Correlation between P-/U-NGAL and plasma creatinine was weak.

DISCUSSION

P-NGAL acts like a neutrophil activation biomarker and U-NGAL like a tubular injury marker.

CONCLUSION

On-pump patients had greater neutrophil activation. On- versus off-pump surgery had similar impact on tubular cells.

Avoiding aortic clamping during coronary artery bypass grafting reduces postoperative stroke

OBJECTIVE

The purpose of this study was to determine whether the incidence of postoperative stroke could be reduced by eliminating aortic clamping during coronary artery bypass grafting.

METHODS

From 2002 to 2013, 12,079 patients underwent primary, isolated coronary artery bypass grafting at a single US academic institution. Aortic manipulation was completely avoided by using in situ internal thoracic arteries for inflow in 1552 patients (12.9%) (no-touch), a clampless facilitating device for proximal anastomoses in 1548 patients (12.8%), and aortic clamping in 8979 patients (74.3%). These strategies were assessed in a logistic regression model controlling for relevant variables.

RESULTS

The overall incidence of postoperative stroke was 1.4% (n = 165), with an unadjusted incidence of 0.6% (n = 10) in the no-touch group, 1.2% (n = 18) in the clampless facilitating device group, and 1.5% (n = 137) in the clamp group (P < .01 for no-touch vs clamp). The ratio of observed to expected stroke rate increased as the degree of aortic manipulation increased, from 0.48 in the no-touch group, to 0.61 in the clampless facilitating device group, and to 0.95 in the clamp group. Aortic clamping was independently associated with an increase in postoperative stroke compared with a no-touch technique (adjusted odds ratio, 2.50; P < .01). When separated by cardiopulmonary bypass use, both the off-pump partial clamp and the on-pump crossclamp techniques increased the risk of postoperative stroke compared with no-touch (adjusted odds ratio, 2.52, P < .01; and adjusted odds ratio, 4.25, P < .001, respectively).

CONCLUSIONS

A no-aortic touch technique has the lowest risk for postoperative stroke for patients undergoing coronary artery bypass grafting. Clamping the aorta during coronary artery bypass grafting increases the risk of postoperative stroke, regardless of the severity of aortic disease.

Effects of on-pump and off-pump surgery in the Arterial Revascularization Trial

OBJECTIVES

The Arterial Revascularization Trial (ART) is a randomized comparison of bilateral internal mammary artery (BIMA) versus single internal mammary artery (SIMA) grafting in coronary artery bypass graft (CABG) surgery and is one of the largest randomized trials of surgery ever conducted. ART is also one of the largest studies of contemporary CABG with a high proportion of off-pump surgeries (41%). The objective of this post hoc analysis was to evaluate the surgical process and 1-year outcomes for surgery performed on-pump compared with off-pump.

METHODS

ART randomized 3102 patients with multivessel coronary artery disease (CAD) to SIMA or BIMA grafts to determine if BIMA grafts have an additional survival advantage at 10 years. The 1-year interim analysis showed an overall very low mortality and major morbidity rate irrespective of whether the procedure was with an SIMA or BIMA. The surgical process and 1-year outcomes were analysed according to whether surgery was performed on-pump or off-pump.

RESULTS

Baseline variables were not statistically significantly different between on- and off-pump surgery within each treatment group after taking account of the effects of clustering by individual surgeons. At both 30 days and 1 year, there was a low incidence of death (1.2%, 2.3%), stroke (1.1%, 1.7%), myocardial infarction (MI) (1.4%, 1.9%), repeat revascularization (0.5%, 1.5%) and wound reconstruction (1.2%). A similar average number of grafts were performed with on- and off-pump surgery (median = 3), but the duration of surgery was 20-30 min and ventilation time ∼ 2 h shorter with off-pump surgery. Blood loss and platelet transfusions were lower in the off-pump group, with no difference in the need for balloon pump or renal support. Sternal wound reconstruction was similar with off-pump surgery in the SIMA group (0.5 vs 0.6%) and lower with off-pump surgery in the BIMA group (1.4 vs 2.2%). Repeat revascularization was marginally higher in off-pump patients at 30 days (0.8 vs 0.3%) and at 1 year (1.7 vs 1.3%).

CONCLUSIONS

The outcomes of contemporary CABG are excellent with low mortality, stroke, myocardial infarction and need for wound reconstruction and repeat revascularization whether performed on-pump or off-pump.

CLINICAL TRIAL REGISTRATION

Controlled-trials.com (ISRCTN46552265).

Effects of Dexamethasone on Cognitive Decline after Cardiac Surgery

Background:

Cardiac surgery can be complicated by postoperative cognitive decline (POCD), which is characterized by impaired memory function and intellectual ability. The systemic inflammatory response that is induced by major surgery and cardiopulmonary bypass may play an important role in the etiology of POCD. Prophylactic corticosteroids to attenuate the inflammatory response may therefore reduce the risk of POCD. The authors investigated the effect of intraoperative high-dose dexamethasone on the incidence of POCD at 1 month and 12 months after cardiac surgery.

Methods:

This multicenter, randomized, double-blind, placebo-controlled trial is a preplanned substudy of the DExamethasone for Cardiac Surgery trial. A total of 291 adult patients undergoing cardiac surgery with cardiopulmonary bypass were recruited in three hospitals and randomized to receive dexamethasone 1 mg/kg (n = 145) or placebo (n = 146). The main outcome measures were incidence of POCD at 1- and 12-month follow-up, defined as a decline in neuropsychological test performance beyond natural variability, as measured in a control group.

Results:

At 1-month follow-up, 19 of 140 patients in the dexamethasone group (13.6%) and 10 of 138 patients in the placebo group (7.2%) fulfilled the diagnostic criteria for POCD (relative risk, 1.87; 95% CI, 0.90 to 3.88; P = 0.09). At 12-month follow-up, 8 of 115 patients in the dexamethasone group (7.0%) and 4 of 114 patients (3.5%) in the placebo group had POCD (relative risk, 1.98; 95% CI, 0.61 to 6.40; P = 0.24).

Conclusion:

Intraoperative high-dose dexamethasone did not reduce the risk of POCD after cardiac surgery.

Myocardial protection and early outcome of different coronary surgical techniques for diabetic patients with triple vessels

BACKGROUND AND OBJECTIVES

For patients with diabetes and triple-vessel disease, coronary artery bypass grafting (CABG) surgery is a well-established procedure, but cardiopulmonary bypass support may also lead to severe complications to these patients. The aim of this study was to compare myocardial protection and early outcomes in patients with diabetes and triple-vessel disease following different coronary surgical techniques.

DESIGN AND SETTINGS

Prospective randomized trial of patients treated at the First Affiliated Hospital of China Medical University over a 3-year period (2011- 2013).

METHODS

In a single-center randomized trial, 668 patients with diabetes and triple-vessel disease were randomly assigned to off-pump (OPCAB) (number [n]=222), on-pump beating heart (OnP-BH) (n=223), and conventional CABG (OnP) (n=223) between January 2011 and October 2013. Myocardial injury was assessed by measuring the serial release of cardiac troponin I (cTnI) preoperatively, 1 hour, 12 hours, 24 hours, and 72 hours postoperatively. The early outcomes were compared among these 3 groups.

RESULTS

Preoperative characteristics of the patients in all 3 groups were similar. No significant difference was found regarding the number of anastomoses, the use of the internal thoracic artery, postoperative new-onset atrial fibrillation, hemodialysis, stroke, reoperation for bleeding, and infective complications in the 3 groups (P > .05). The complete revascularization, postoperative drainage loss, intra-aortic balloon pump support, blood requirements, postoperative myocardial infarction, pulmonary complications, gastrointestinal complications, inotropic requirements > 24 hours, ventilation > 24 hours, intensive care unit stay > 24 hours, and in-hospital stay > 7 days were significantly lower in the OPCAB group than in the other 2 groups (P < .05). In-hospital mortality was lower in the OPCAB group than in the other 2 groups, but no statistical difference was observed (P > .05). Preoperative cTnI in the 3 groups was similar (P > .05); however, the lowest cTnI value was noted in the OPCAB group, followed by the OnP group, and it was highest in the OnP-BH group 1 hour, 12 hours, 24 hours, and 72 hours postoperatively (P < .05).

CONCLUSION

OPCAB is superior to the OnP-BH and OnP techniques in terms of postoperative complications and myocardial protection in patients with diabetes and triple-vessel disease. Myocardial injury in the OnP-BH group was significantly higher than that in the OnP group.

On-pump versus off-pump coronary artery bypass surgery in patients older than 60 years: five-year follow-up of MASS III trial

BACKGROUND

We aim to evaluate in-hospital events and long-term clinical outcomes in patients over 60 years of age with stable coronary artery disease and preserved left ventricular ejection fraction undergoing off-pump or on-pump coronary artery bypass grafting.

METHODS

The MASS III was a single-center randomized trial that evaluate 308 patients with stable coronary artery disease and preserved ventricular function assigned for: 155 to off-pump and 153 to on-pump CABG. Of this, 176 (58.3%) patients were 60 years or older at the time of randomization (90 of-pump and 86 on-pump). The primary short-term end point was a composite of myocardial infarction, stroke, and overall mortality occurring within 30 days after surgery or before discharge, whichever was later. The primary long-term end point was death from any cause within 5 years, non-fatal myocardial infarction between 30 days and 5 years, or additional revascularization between 30 days and 5 years.

RESULTS

On-pump CABG had a higher incidence of 30-day composite outcome than off-pump CABG (15,1% and 5.6%, respectively; P = 0.036). However, after the multivariate analysis, this association lost statistical significance, P = 0.05. After 5-year follow-up, there were no significant differences between both strategies of CABG in the composite end points 16.7% and 15.1%; Hazard Ratio 1.07; CI 0.41 - 1.82; P = 0.71, for off-pump and on-pump CABG respectively.

CONCLUSIONS

On-pump and off-pump CABG achieved similar results of combined events at short-term and 5-year follow-up.

TRIAL REGISTRATION

Clinical Trial Registration Information-URL: http://www.controlled-trials.com.

REGISTRATION NUMBER

ISRCTN59539154.

Intra-operative Graft Blood Flow Measurements for Composite and Sequential Coronary Artery Bypass Grafting

Objectives

Intraoperative assessment of coronary artery bypass grafts (CABG) anastomotic quality can be performed using transit-time flowmetry (TTF). The aim of this study was to compare on- versus off-pump coronary graft TTF and early postoperative outcomes.

Materials and methods

Between January 2009 and January 2010, 521 distal graft flows were assessed using TTF measurements in 253 consecutive patients undergoing primary isolated CABG surgery. Data were analyzed using multilevel models accounting for clustering among surgeons and grafts performed in the same patient.

Results

Mean age was 66 ± 10 years and 22% were female (n = 55) with 34% diabetics (n = 86) and 40% pre-operative myocardial infarction (MI) (n = 101). The surgeries were performed off-pump in 67% (n = 170) with sequential vein grafts in 57% (n = 144) of patients. Off-pump patients had higher pre-operative left ventricular ejection fractions (LVEF), fewer urgent surgeries, fewer distal anastomoses, and fewer sequential vein grafts (all p<0.001). Intra-operative coronary graft TTF measurements were lower in sequential vein grafts performed off-pump versus on-pump. More patients in the on-pump group needed milrinone or dobutamine 24-48 h postoperatively (p = 0.005). Independent predictors of lower TTF included female gender and off-pump surgery, whereas predictors of better TTF were pre-operative MI, larger coronary diameter at the site of the distal anastomosis, and sequential vein grafting.

Conclusions

Lower intra-operative TTF measurements were found in sequential vein grafts in offpump CABG. However, off-pump patients experienced similar short-term outcomes compared to on-pump patients.

Advances in clinical cardiology

Multiple, potentially practice-changing cardiology trials have been presented or published over the past year. In this paper, we summarize and place in clinical context, new data regarding management of acute coronary syndrome and ST-elevation myocardial infarction (copeptin assessment, otamixaban, cangrelor, prasugrel, sodium nitrite, inclacumab, ranolazine, preventive coronary intervention of non-culprit lesions, immediate thrombolytic therapy versus transfer for primary intervention), new coronary intervention data (thrombectomy, radial access, pressure wire fractional flow reserve, antiplatelet therapy duration and gene-guidance, permanent and biodegradable polymers, coronary bifurcation and strategies), and coronary artery bypass data (off pump vs. on pump). Latest trials in trans-aortic valve implantation, heart failure (eplerenone, aliskiren, spironolactone, sildenafil, dopamine, nesiritide, omecamtiv mecarbil, the algisyl left ventricular augmentation device, and echo-guided cardiac resynchronization), atrial fibrillation (edoxaban, dabigatran, and ablation), cardiac arrest (hypothermia, LUCAS™ mechanical chest compression), and cardiovascular prevention (vitamins, renal denervation for resistant hypertension, renal artery stenting, saxagliptin, alogliptin, and gastric banding) are also discussed.

A simple ratio-based approach for power and sample size determination for 2-group comparison using Rasch models

BACKGROUND

Despite the widespread use of patient-reported Outcomes (PRO) in clinical studies, their design remains a challenge. Justification of study size is hardly provided, especially when a Rasch model is planned for analysing the data in a 2-group comparison study. The classical sample size formula (CLASSIC) for comparing normally distributed endpoints between two groups has shown to be inadequate in this setting (underestimated study sizes). A correction factor (RATIO) has been proposed to reach an adequate sample size from the CLASSIC when a Rasch model is intended to be used for analysis. The objective was to explore the impact of the parameters used for study design on the RATIO and to identify the most relevant to provide a simple method for sample size determination for Rasch modelling.

METHODS

A large combination of parameters used for study design was simulated using a Monte Carlo method: variance of the latent trait, group effect, sample size per group, number of items and items difficulty parameters. A linear regression model explaining the RATIO and including all the former parameters as covariates was fitted.

RESULTS

The most relevant parameters explaining the ratio's variations were the number of items and the variance of the latent trait (R2 = 99.4%).

CONCLUSIONS

Using the classical sample size formula adjusted with the proposed RATIO can provide a straightforward and reliable formula for sample size computation for 2-group comparison of PRO data using Rasch models.

On-pump with beating heart or cardioplegic arrest for emergency conversion to cardiopulmonary bypass during off-pump coronary artery bypass

BACKGROUND AND OBJECTIVES

Intraoperative conversion, especially under emergent circumstances during off-pump coronary artery bypass (OPCAB), is associated with a significantly higher rate of hospital mortality. This study compared the clinical early outcomes of patients emergently converting to cardiopulmonary bypass (CPB) with or without cardioplegic arrest and evaluated the efficacy of an on-pump beating heart technique for these critically ill patients.

DESIGN AND SETTING

A retrospective study of patients treated at The First Affiliated Hospital of China Medical University over an 8-year period (2005 to 2013).

PATIENTS AND METHODS

Between January 2005 and September 2013, 104 patients were emergently converted to CPB during OPCAB. In the first 55 patients (53%), the cardioplegic arrest was performed. In the most recent 49 patients (47%), the on-pump beating heart procedure was used without cardioplegic arrest.

RESULTS

There were no significant differences in their baseline clinical characteristics, number of anastomoses performed per patient, and reasons for conversions (P > .05). A significant reduction occurred in the observed mortality between the cardioplegic arrest group and the on-pump beating heart group (25.6% vs 6.1%, P=.008). A statistical difference was found between the cardioplegic arrest group and the on-pump beating heart group in the time of CPB, peak cardiac troponin I, duration of inotropic support, time to extubation, intensive care unit stay, postoperative hospital stay, incidence of new intra-aortic balloon pump support, and pulmonary complications (P < .05). The incidence of blood requirements, postoperative myocardial infarction, new-onset atrial fibrillation, hemodialysis, stroke, infective complications, and resurgery for bleeding were lower in on-pump beating heart group, but the difference did not reach statistical significance (P > .05).

CONCLUSION

The on-pump beating heart technique is the preferred method of emergency conversion to CPB during OPCAB. It has lower postoperative mortality and morbidity than the cardioplegic arrest.

Does off-pump coronary revascularization confer superior organ protection in re-operative coronary artery surgery? A meta-analysis of observational studies

Off-pump coronary artery bypass surgery (OPCAB) has been hypothesised to be beneficial in the high-risk patient population undergoing re-operative coronary artery bypass graft surgery (CABG). In addition, this technique has been demonstrated to provide subtle benefits in end-organ function including heart, lungs and kidney. The aims of this study were to assess whether OPCAB is associated with a lower incidence of major adverse cardiovascular and cerebrovascular events (MACCE) and other adverse outcomes in re-operative coronary surgery. Twelve studies, incorporating 3471 patients were identified by systematic literature review. These were meta-analysed using random-effects modelling. Primary endpoints were MACCE and other adverse outcomes including myocardial infarction, stroke, renal dysfunction, low cardiac output state, respiratory failure and atrial fibrillation. A significantly lower incidence of myocardial infarction, stroke, renal dysfunction, low cardiac output state, respiratory failure and atrial fibrillation was observed with OPCAB (OR 0.58; 95% CI (confidence interval) [0.39-0.87]; OR 0.37; 95% CI [0.17-0.79]; OR 0.39; 95% CI [0.24-0.63]; OR 0.14; 95% CI [0.04-0.56]; OR 0.36; 95% CI [0.24-0.54]; OR 0.41; 95% CI [0.22-0.77] respectively). Sub-group analysis using sample size, matching score and quality score was consistent with and reflected these significant findings. Off-pump coronary artery bypass grafting reduces peri-operative and short-term major adverse outcomes in patients undergoing re-operative surgery. Consequently we conclude that OPCAB provides superior organ protection and a safer outcome profile in re-operative CABG.

Clinical impact of circulating miR-133, miR-1291 and miR-663b in plasma of patients with acute myocardial infarction

Background

Acute myocardial infarction (AMI) is one of the leading causes for death in both developed and developing countries and it is the single largest cause of death in the United States, responsible for 1 out of every 6 deaths. The objective of this study was to determine microRNA (miRNA) expression in AMI and determine whether miR-133, miR-1291 and miR-663b could be measured in plasma as a biomarker for recurrence.

Methods

Patients with AMI and those without AMI were retrospectively recruited for a comparison of their plasma miR-133, miR-1291 and miR-663b expression.

Results

miR-133, miR-1291 and miR-663b levels were significantly overexpressed in AMI compared with Non-AMI. MiR-133 showed an AUC of 0.912, with a sensitivity of 81.1% and a specificity of 91.2%. The AUC for miR-1291 was 0.695, with a sensitivity of 78.4% and a specificity of 89.5%. The AUC for miR-663b was 0.611, with a sensitivity of 72.4% and a specificity of 76.5%.

Conclusions

This study demonstrated that the levels of miR-133, miR-1291 and miR-663b are associated with AMI. The potential of these miRNAs as biomarkers to improve patient stratification according to the risk of AMI and as circulating biomarkers for the AMI progonos warrants further study.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/8183629061241474

Neurological complications of cardiac surgery

As increasing numbers of elderly people undergo cardiac surgery, neurologists are frequently called upon to assess patients with neurological complications from the procedure. Some complications mandate acute intervention, whereas others need longer term observation and management. A large amount of published literature exists about these complications and guidance on best practice is constantly changing. Similarly, despite technological advances in surgical intervention and modifications in surgical technique to make cardiac procedures safer, these advances often create new avenues for neurological injury. Accordingly, rapid and precise neurological assessment and therapeutic intervention rests on a solid understanding of the evidence base and procedural variables.

Coronary artery bypass grafting: Part 1--the evolution over the first 50 years

Surgical treatment for angina pectoris was first proposed in 1899. Decades of experimental surgery for coronary artery disease finally led to the introduction of coronary artery bypass grafting (CABG) in 1964. Now that we are approaching 50 years of CABG experience, it is appropriate to summarize the advancement of CABG into a procedure that is safe and efficient. This review provides a historical recapitulation of experimental surgery, the evolution of the surgical techniques and the utilization of CABG. Furthermore, data on contemporary clinical outcomes are discussed.

Coronary artery bypass grafting: Part 2--optimizing outcomes and future prospects

Since first introduced in the mid-1960s, coronary artery bypass grafting (CABG) has become the standard of care for patients with coronary artery disease. Surprisingly, the fundamental surgical technique itself did not change much over time. Nevertheless, outcomes after CABG have dramatically improved over the first 50 years. Randomized trials comparing percutaneous coronary intervention (PCI) to CABG have shown converging outcomes for select patient populations, providing more evidence for wider use of PCI. It is increasingly important to focus on the optimization of the short- and long-term outcomes of CABG and to reduce the level of invasiveness of this procedure. This review provides an overview on how new techniques and widespread consideration of evolving strategies have the potential to optimize outcomes after CABG. Such developments include off-pump CABG, clampless/anaortic CABG, minimally invasive CABG with or without extending to hybrid procedures, arterial revascularization, endoscopic vein harvesting, intraprocedural epiaortic scanning, graft flow assessment, and improved secondary prevention measures. In addition, this review represents a framework for future studies by summarizing the areas that need more rigorous clinical (randomized) evaluation.

A Brief History of Cardiopulmonary Bypass

The development and application of cardiopulmonary bypass (CPB) to permit open heart surgery is considered among the most important clinical advances in medicine during the last half of the 20th century. The birth of CPB for cardiac surgery is attributed to its first successful clinical use by John Gibbon Jr, 51 years ago but its practical clinical use really began in the spring and summer of 1955 when 2 groups led by John Kirklin at the Mayo Clinic and C Walton Lillehei at the University of Minnesota, initiated the routine use of CPB for open heart surgery. However, considerable developments were necessary and preceded the clinical accomplishment of CPB, and much has followed to make it the remarkably safe and effective procedure that it has become today. Many currently practicing cardiac anesthesiologists, cardiac surgeons, and perfusionists are unaware of how brief its history is and how much the practice of CPB has changed during its short existence. The aim of this article is to review this fascinating history and the lessons that can be learned from this review, and to indicate the opportunities that still exist for advancement.

Perioperative outcomes after on- and off-pump coronary artery bypass grafting

Although numerous reports describe the results of off-pump coronary artery bypass grafting (CABG) at specialized centers and in select patient populations, it remains unclear how off-pump CABG affects real-world patient outcomes. We conducted a large, multicenter observational cohort study of perioperative death and morbidity in on-pump (ON) versus off-pump (OFF) CABG. We reviewed Veterans Affairs Surgical Quality Improvement Program data for all patients (N=65,097) who underwent isolated CABG from October 1997 through April 2011 (intention-to-treat data were available from 2005 onward). The primary outcome was perioperative (30-day or in-hospital) death; the secondary outcomes were perioperative stroke, dialysis dependence, reoperation for bleeding, mechanical circulatory support, myocardial infarction, ventilator support ≥ 48 hr, and mediastinitis. Propensity scores calculated from age, 17 preoperative risk factors, and year of surgery were used to match 8,911 OFF with 26,733 ON patients. In the complete cohort, compared with the ON patients (n=53,468), the OFF patients (n=11,629) had less perioperative death (2.02% vs 2.53%, P=0.0012) and lower incidences of all morbidities except perioperative myocardial infarction. In the matched cohort, perioperative death did not differ significantly between OFF and ON patients (1.94% vs 2.28%, P=0.06), but the OFF group had lower incidences of all morbidities except for perioperative myocardial infarction and mediastinitis. A subgroup intention-to-treat analysis yielded similar but smaller outcome differences between the ON and OFF groups. Off-pump CABG might be associated with decreased operative morbidity but did not affect operative death, compared with on-pump CABG. Future studies should examine the effect of off-pump CABG on long-term outcomes.

Off-pump coronary artery bypass grafting: Misperceptions and misconceptions

Coronary artery bypass grafting (CABG) continues to be one of the most commonly performed cardiac surgical procedures worldwide. Conventional CABG performed on cardiopulmonary bypass termed on-pump CABG is regarded as the gold standard. However, on-pump CABG results in several physiologic derangements including but not limited to thrombocytopenia, activation of complement factors, immune suppression, and inflammatory responses leading to organ dysfunction. Furthermore, manipulating an atherosclerotic ascending aorta during cannulation and cross-clamping can predispose to embolization and stroke risk. Recognition of these detrimental effects of on-pump CABG resulted in resurgence of off-pump CABG nearly two decades ago. Off-pump CABG since its resurgence has been a subject of intensive scrutiny and speculation. Despite numerous retrospective nonrandomized studies, prospective randomized trials, and meta-analyses validating the safety and efficacy of off-pump CABG, opponents of the technique have persistently demanded abandonment of off-pump CABG. Several misconceptions and misperceptions are used as an excuse for such demands. This review article examines published scientific evidence to evaluate these misperceptions and misconceptions about off-pump CABG.

Off-pump coronary artery bypass prevents visceral organ damage

OBJECTIVES

Visceral malperfusion after coronary artery bypass grafting (CABG) results in high morbidity and mortality. This study was designed to evaluate the effect of CABG performed by surgical techniques on visceral perfusion and function.

METHODS

Pigs (n = 28) were studied in four groups: I. Sham; II. Off-pump coronary artery bypass grafting (OPCAB): 1 h stabilizer with 40 min intracoronary shunt; III. Extracorporeal circulation (ECC): 1 h ECC with 40 min aortic cross-clamping and cardioplegic arrest; IV. Impella: 1 h left ventricular blood-pump support and stabilizer with 40 min intracoronary shunt. A left internal mammary to left anterior descending coronary artery bypass was performed in Groups II-IV. All animals were observed for a further 240 min. During the experiment haemodynamics, creatinine clearance, intestinal fatty acid binding protein (iFABP), pancreatic (lipase and amylase) and liver enzymes (α-glutathione s-transferase, glutamate-oxaloacetate transaminase (GOT), gamma-glutamyl transferase (GGT), glutamate dehydrogenase and glutamate-pyruvate transaminase (GPT)) were measured. Visceral perfusion (VP) was assessed in both kidneys, intestine, pancreas, liver and spleen with 15 µm fluorescent microspheres.

RESULTS

During OPCAB surgery, VP decreased slightly. Renal functional parameters, iFABP, pancreatic and liver enzymes remained unchanged. ECC and Impella led to significantly reduced renal, pancreatic and intestinal blood flow (P < 0.05). Creatinine clearance, pancreatic and liver (GPT, GGT) enzymes were significantly decreased only after ECC (P < 0.05). ECC and Impella resulted in a significantly increased iFABP level (P < 0.05). GOT was elevated significantly after surgery in Groups II, III and IV (P < 0.05).

CONCLUSIONS

CABG with ECC or Impella leads to impaired visceral blood flow and function. OPCAB minimizes these procedure associated alterations.

Off-pump coronary artery bypass grafting in India

Off-pump Coronary Artery Bypass Grafting (OPCAB) is the latest innovation in cardiac surgery. However OPCAB is not adopted universally. Even there have been suggestions of abandoning OPCAB in a special report. In India, OPCAB has been successfully adopted across the board. There are various evidences which favor OPCAB and are discussed in this review. The purpose of this review is to put forward the perspective of the OPCAB surgeons of our country and critically look at the suggestion of abandoning OPCAB.

Impact of renal function in patients with multi-vessel coronary disease on long-term mortality following coronary artery bypass grafting compared with percutaneous coronary intervention

BACKGROUND

Comorbidities, such as diabetes, affect revascularization strategy for coronary disease. We sought to determine if the degree of renal impairment affected long-term mortality after percutaneous coronary intervention (PCI) compared to coronary artery bypass grafting (CABG) in patients with multi-vessel coronary disease (MVD).

METHODS AND RESULTS

8970 patients with MVD undergoing revascularization between 2004 and 2008, in two multi-center parallel PCI and CABG Australian registries were assigned to three groups based on their estimated glomerular filtration rate (eGFR)≥60 mL/min/1.73 m2 (n=1678:839), 30-59 mL/min/1.73 m2 (n=452:226) and <30 mL/min/1.73 m2 (n=74:37). We used 2:1 propensity matching to compare 3306 patients undergoing primary CABG versus PCI. Shock, myocardial infarction (MI)<24 h, previous CABG, valve surgery or PCI were exclusions. Long-term mortality (mean 3.1 years) was compared with Cox-proportional hazard-adjusted modeling. Observed long-term mortality rates (CABG vs. PCI) were 4.5% vs. 4.3% p=0.84, 12.8% vs. 17.3% p=0.12, and 23.0% vs. 40.5% p=0.05 in the three strata, respectively. In patients with eGFR≥60 mL/min/1.73 m2, long-term mortality between PCI and CABG (HR 0.99, 95% CI 0.65-1.49, p=0.95) was similar. However, amongst patients with eGFR 30-59 mL/min/1.73 m2, there was a significant mortality hazard with PCI (HR 2.00, 95% CI 1.32-3.04, p=0.001). In patients with eGFR<30 mL/min/1.73 m2, there was a trend for hazard with PCI (HR 1.66, 95% CI 0.80-3.46, p=0.17).

CONCLUSION

Long-term mortality in MVD patients with preserved renal function was very low and similar between PCI and CABG. However there was a long-term mortality hazard associated with PCI amongst patients with moderate renal impairment.

Improved Short-Term Outcomes with Off-Pump Reoperative Coronary Artery Bypass Grafting

Objective

Reoperative coronary surgery patients are usually sicker and older, and the procedure is more technically demanding. Comparisons between coronary surgery with (coronary artery bypass [CAB] surgery on cardiopulmonary bypass [CPB]) and without (off-pump CAB [OPCAB]) the pump have been conducted; however, few studies showed results in reoperative cases. We investigate the potential superiority of one technique over the other in redo coronary surgeries.

Methods

Our institutional Society of Thoracic Surgery database was used to gather the data for 266 isolated reoperative coronary artery surgeries from January 2004 to July 2011. These were divided into the CAB surgery in CPB group (n = 204) and the OPCAB group (n = 62).

Results

Baseline characteristics of the two groups were similar, except for a significantly higher prevalence of cerebrovascular disease among the off-pump group ( P = 0.01). There was also a trend toward fewer vessels bypassed among the same group ( P = 0.07). Risk adjustment was done using multivariable analyses for detection of independent effects. The use of CPB was an independent predictor of increased rates of postoperative events (odds ratio, 3.9; P = 0.004) and atrial fibrillation (odds ratio, 5.9; P < 0.005) and longer intensive care unit (0.006) and hospital stay (0.004).

Conclusions

Redo OPCAB seems to offer favorable short-term outcomes compared with redo CAB. Our results suggest a reduced rate of overall postoperative events, decreased new postoperative atrial fibrillation, reduced hours stayed in the intensive care unit, and fewer days stayed from surgery to discharge. This was not associated with an increase in morbidity and mortality. A randomized study with a larger number of patients and with a longer follow-up is needed.