Conversion in off-pump coronary artery bypass grafting: an analysis of predictors and outcomes

Two novel nomograms predict 30-day mortality after off-pump coronary artery bypass grafting

Background

With the development of surgical techniques and medical equipment, the mortality rate of off-pump coronary artery bypass grafting (CABG) has been declining year by year, but there is a lack of convenient and accurate predictive models. This study aims to use two nomograms to predict 30-day mortality after off-pump CABG.

Methods

Patients with isolated off-pump CABG from January 2016 to January 2021 were consecutively enrolled. Potential predictive factors were first screened by lasso regression, and then predictive models were constructed by multivariate logistic regression. To earlier identify high-risk patients, two nomograms were constructed for predicting mortality risk before and after surgery.

Results

A total of 1840 patients met the inclusion and exclusion criteria. The 30-day mortality was 3.97 % (73/1840) in this cohort. Multivariate logistic analysis showed that age, BMI<18.5 kg/m2, surgical time, creatinine, LVEF, history of previous stroke, and major adverse intraoperative events (including conversion to cardiopulmonary bypass or implantation of intra-aortic balloon pump) were independently associated with 30-day mortality. Model 1 contained preoperative and intraoperative variables, and the AUC was 0.836 (p < 0.001). The AUC of the K-fold validation was 0.819. Model 2 was only constructed by preoperative information. The AUC was 0.745 (p < 0.001). The AUC of the K-fold validation was 0.729. The predictive power of Model 1 was significantly higher than the SinoScore (DeLong's test p < 0.001).

Conclusions

The two novel nomograms could be conveniently and accurately used to predict the risk of 30-day mortality after isolated off-pump CABG.

Conversion from off-pump to on-pump coronary artery bypass grafting: impact of surgeon and anaesthetist experience

OBJECTIVES

Intraoperative conversion from off-pump to on-pump coronary artery bypass grafting (CABG) is associated with increased postoperative morbidity and mortality. The aim of this study is to assess the impact of surgeon and anaesthetist experience on the conversion rate.

METHODS

We performed a retrospective analysis of the data of all patients who underwent planned off-pump CABG in a single centre in 2007-2021, some of whom were non-electively converted to on-pump. Surgeon and anaesthetist experience were assessed by the number of off-pump bypass procedures per year. Multivariable logistic regression analysis was used to assess the impact of surgeon and anaesthetist experience on conversion rate.

RESULTS

A total of 2742 patients met the inclusion criteria. Ninety-four (3.4%) patients underwent non-elective conversion to on-pump surgery. Converted patients had significantly higher mortality [11 (11.7%) vs 35 (1.3%), P < 0.0001] in comparison to non-converted patients. Anaesthetist experience was found to be a risk factor for conversion (P = 0.011). Surgeon experience did not significantly affect conversion rate (P = 0.51). Other risk factors for conversion were female gender [odds ratio 2.65 (95% confidence interval 1.65-4.26), P = 0.0001] and left ventricular ejection fraction ≤35% [odds ratio 1.91 (95% confidence interval 1.05-3.49), P = 0.040].

CONCLUSIONS

Conversion from off-pump to on-pump CABG is associated with worse postoperative outcomes. Limited experience of anaesthetists in off-pump bypass surgery is associated with a higher conversion rate.

No association between pulmonary artery catheter use and postoperative complications in off-pump coronary artery bypass grafting: a single-center pilot study

BACKGROUND

A pulmonary artery catheter is often used in cardiac surgery despite its uncertain effectiveness. The aim of this pilot study was to investigate the associations between the use of a pulmonary artery catheter and clinical outcomes in off-pump coronary artery bypass grafting.

METHODS

Patients over 20 years of age who had undergone off-pump coronary artery bypass grafting between December 2018 and November 2021 were enrolled in this single-center retrospective pilot study. The propensity score of pulmonary artery catheterization was calculated. Multivariate analysis including the propensity score as a covariate was performed to assess clinical outcomes. The primary outcome was the composite outcome of in-hospital death, unplanned intraoperative conversion to cardiopulmonary bypass, resuscitated cardiac arrest, mechanical circulatory support, myocardial infarction, stroke, new initiation of renal replacement therapy, inhaled nitric oxide, re-intubation and tracheostomy.

RESULTS

Among the 315 patients who were enrolled, 298 were included in the final analysis. A pulmonary artery catheter was inserted in 131 patients. There were 50 patients with the composite outcome including two in-hospital deaths. Multivariate logistic regression analysis showed that pulmonary artery catheterization was not significantly related to the composite outcome. Clinical outcomes worsened significantly as the number of anastomoses increased (odds ratio: 1.450, 95% confidence interval: 1.040-2.040, P=0.029).

CONCLUSIONS

Pulmonary artery catheterization did not improve the clinical outcomes in off-pump coronary artery bypass grafting in this pilot study.

Off-Pump Coronary Artery Bypass Grafting; is it Still Relevant?

Off-pump Coronary Artery Bypass Grafting (OPCAB) experienced a resurgence in the 1980s -2000s and developed steadily with improvement of the instrumentation and techniques. However questions about graft patency and long-term survival of OPCAB patients still exist. This review attempts to explore the current relevance of OPCAB.

A systematic review and meta-analysis of randomized controlled studies comparing off-pump versus on-pump coronary artery bypass grafting in the elderly

AIM

Comparison of short and mid-term outcomes between off-pump CABG (OPCAB) and on-pump CABG (ONCAB) in patients older than 65 throughout a meta-analysis of randomized clinical trials (RCTs).

EVIDENCE ACQUISITION

A literature search was conducted using 3 databases. RCTs reporting mortality outcomes of OPCAB versus ONCAB among the elderly were included. Data on myocardial infarction, stroke, re-revascularization, renal failure and composite endpoints after CABG were also collected. Random effects models were used to compute statistical combined measures and 95% confidence intervals (CI).

EVIDENCE SYNTHESIS

Five RCTs encompassing 6221 patients were included (3105 OPCAB and 3116 ONCAB). There were no significant differences on mid-term mortality (pooled HR: 1.02, 95%CI: 0.89-1.17, p=0.80) and composite endpoint incidence (pooled HR: 0.98, 95%CI: 0.88-1.09, p=0.72) between OPCAB and ONCAB. At 30-day, there were no differences in mortality, myocardial infarction, stroke and renal complications. The need for early re-revascularization was significantly higher in OPCAB (pooled OR: 3.22, 95%CI: 1.28-8.09, p=0.01), with a higher percentage of incomplete revascularization being reported for OPCAB in trials included in this pooled result (34% in OPCAB vs 29% in ONCAB, p<0.01).

CONCLUSIONS

Data from RCTs in elderly patients showed that OPCAB and ONCAB provide similar mid-term results. OPCAB was associated with a higher risk of early rerevascularization. As CABG on the elderly is still insufficiently explored, further RCTs, specifically designed targeting this population, are needed to establish a better CABG strategy for these patients.

On-pump beating heart versus off-pump myocardial revascularization-a propensity-matched comparison

Objective

On-pump beating heart (OP-BH) coronary artery bypass grafting (CABG) is often undertaken as an alternative between off-pump coronary artery bypass (OPCAB) and conventional on-pump coronary artery bypass grafting (On-pump CABG), especially in India. However, outcome data following OP-BH surgery is sparse. The aim of this study was to compare the outcomes of OP-BH CABG with OPCAB.

Methods

From our institutional database, all patients undergoing OP-BH CABG (n = 531) were identified. A propensity-matched cohort undergoing OPCAB (n = 531) was identified from the database. Nearest neighbor matching technique was used and the groups were matched for variables including age, gender, body mass index, EuroSCORE, history of recent myocardial infarction or unstable angina, hypertension, peripheral vascular disease, chronic obstructive airway disease, diabetes, pre-op renal impairment, pre-op neurological events, and left ventricular function.

Results

The propensity-matched groups were well matched in terms of baseline characteristics. The mean EuroSCORE was 3.17 and 3.20 in the OP-BH and the OPCAB groups. The unadjusted 30-day mortality in the propensity-matched OPCAB group was 2.07% (11/531) while mortality in the on-pump beating heart group was significantly higher at 6.9% (37/531). Multivariate analysis showed that OP-BH CABG was an independent risk factor for 30-day mortality as well as major adverse post-operative outcomes including renal, neurological, and respiratory outcomes and post-operative atrial fibrillation.

Conclusions

OP-BH CABG is associated with worse clinical outcomes compared to patients undergoing OPCAB.

On-pump beating heart versus conventional on-pump coronary artery bypass grafting on clinical outcomes: a meta-analysis

Background

A hybrid surgery method, on-pump beating heart coronary artery bypass graft (ON-BH CABG), is supposed to be a promising technology for coronary artery revascularization. Here, we conducted a comprehensive meta-analysis of the data derived from published studies on ON-BH CABG and conventional on-pump coronary artery bypass graft (C-CABG) to compare their short-term and long-term clinical outcomes.

Methods

We searched major electronic databases and 24 studies incorporating 6,862 patients (1,847 ON-BH CABG and 5,015 C-CABG) were included eventually, and 9 studies of them were focusing on high-risk patients.

Results

Compared with ON-BH CABG, C-CABG was associated with a higher risk in early mortality [odds ratio (OR), 1.45; 95% confidence interval (CI), 1.09 to 1.93; P=0.01], myocardial infarction (MI) (OR, 2.60; 95% CI, 1.41 to 4.78; P<0.01), low output syndrome (LOS) (OR, 2.56; 95% CI, 1.55 to 4.23; P<0.01), renal failure (OR, 1.84; 95% CI, 1.38 to 2.44; P<0.01). In contrast, there was no significant difference in long-term survival [hazard ratio (HR), 1.08; 95% CI, 0.81 to 1.43; P=0.60]. In systematic analysis of the studies in high-risk patients, ON-BH CABG showed a lower risk in terms of early mortality, intra-aortic balloon pump (IABP) usage, renal failure, hemodialysis, MI and pulmonary complication. No significant difference was observed in the long-term survival between ON-BH CABG and C-CABG.

Conclusions

With experienced and adept surgical team and mature ON-BH technology, ON-BH CABG may reduce the risk of postoperative death and complications in some patients. It might be an attractive alternative for high-risk patient populations.

Preoperative right ventricular dysfunction requires high vasoactive and inotropic support during off-pump coronary artery bypass grafting

Objectives

The association of preoperative RV function with hemodynamics during OPCAB or emergency conversion is not clear. The aim of this study was to investigate the association of vasoactive-inotropic score with tricuspid annular plane systolic excursion and tricuspid regurgitation in off-pump coronary artery bypass grafting, and to calculate the optimal cut-off value of tricuspid annular plane systolic excursion to predict emergency conversion to cardiopulmonary bypass.

Methods

Patients over 20 years of age who had undergone off-pump coronary artery bypass grafting between April 2015 and March 2020 were enrolled in this study. We retrospectively assessed the association of intraoperative maximum “vasoactive-inotropic score”, a weighted sum of various inotropes and vasoconstrictors, with tricuspid annular plane systolic excursion and tricuspid regurgitation. A receiver operating characteristic curve of conversion on tricuspid annular plane systolic excursion was also constructed.

Results

135 patients were included in final analysis. Conversion was performed in 10 cases. Multiple regression analysis showed that tricuspid annular plane systolic excursion, mild or more tricuspid regurgitation and experienced surgeon were significantly related to vasoactive-inotropic score. The receiver operating characteristic curve to predict conversion by tricuspid annular plane systolic excursion showed an optimal cut-off value of 15.0 mm and area under the curve of 0.808.

Conclusions

Tricuspid annular plane systolic excursion and tricuspid regurgitation were associated with vasoactive-inotropic score in off-pump coronary artery bypass grafting. The optimal cut-off value of tricuspid annular plane systolic excursion to predict emergency conversion was 15 mm.

Effect of Hospital and Surgeon Procedure Volumes on the Incidence of Intraoperative Conversion During Off-Pump Coronary Artery Bypass Grafting

Intraoperative conversion to cardiopulmonary bypass with its subsequent high mortality is a major concern associated with off-pump coronary artery bypass grafting (OPCAB). The impact of procedure volume on the incidence of intraoperative conversion, however, is poorly defined. This study therefore evaluated the effect of procedure volume on the incidence of conversion in OPCAB using nationwide data. We analyzed 31,361 patients who underwent primary, nonemergent, isolated OPCAB during 2013-2016 reported in the Japan Cardiovascular Surgery Database. Hospitals (n = 548) and surgeons (n = 1315) were divided into tertile categories (low-, medium-, and high volumes) based on the total number of isolated coronary artery bypass grafting (CABG). Hierarchical logistic regression analysis, including 22 preoperative factors and hospital and surgeon CABG volumes, was used to assess the relation between procedure volume and the risk of conversion due to bleeding/hemodynamic instability. There were 797 (2.5%) intraoperative conversions due to bleeding/hemodynamic instability. Risk-adjusted odds ratios for conversion were significantly lower in some combined hospital/surgeon CABG volume categories than in the reference category. Hospital/surgeon volumes and their odds ratio (95% confidence interval) were as follows: low/low 1.00 (reference); medium/low 0.62 (0.39-0.96); high/low 0.47 (0.27-0.81); high/high 0.58 (0.38-0.89). There was a lower risk of conversion in medium- and high-volume than low-volume hospitals, especially among low-volume surgeons. Procedure volume is associated with the incidence of conversion during OPCAB. Among low-volume surgeons, hospital CABG volume significantly reduces conversion in a volume-dependent manner. These findings will be useful for safety training of OPCAB surgeons.

Conversion from Off to On-Pump Coronary Artery Bypass Grafting. Is it Avoidable?

Background

With the emergence of new technologies to stabilize the heart off-pump coronary artery bypass grafting (OPCAB), there is an increasing trend that is being observed throughout the world. In certain circumstances, OPCAB needs to be converted to on-pump CABG (ONCAB). In this study, we aim to identify certain risk factors mandating conversions and their associated short-term outcomes.

Methods

After approval from the institutional ethical review committee and exemption from informed consent, retrospective data of 100 patients meeting the inclusion criteria who underwent OPCAB operations at our institution from August 2018 to July 2019 were included. Preoperative, intraoperative, and postoperative variables were recorded and compared in conversion and non-conversion groups. This study was conducted at the National Institute of Cardiovascular Diseases, Karachi, Pakistan.

Results

A total of 100 patients were included in this study, out of which 82% (82) were male, with age ranging between 18 and 77 years with a mean age of 56.34 ± 8.3 years. In nine of the cases, OPCAB was emergently converted to ONCAB due to arrhythmias. In nine (9%) cases, off-pump CABG was emergently converted to on-pump CABG (ONCAB). Emergent conversion was due to arrhythmias in five cases, due to hypotension during OM graft in two cases, and due to hypotension during ramus graft for the remaining two cases. The emergent conversion was significantly associated with higher New York Heart Association (NYHA) functional classification and comorbid conditions such as chronic obstructive pulmonary disease (COPD).

Conclusion

Emergency conversion from off-pump to OPCAB is the most catastrophic event causing higher morbidity and mortality. Conversion rate was observed to be 9% with arrhythmias being the common cause and patients with higher NYHA status and COPD at baseline were found to be at increased risk of emergency conversion. Considering our results in patients with diagnosed COPD and higher NYHA status, the decision for off-pump CABG should be wisely taken carefully weighing the risks and benefits.

Off-Pump versus Conventional Coronary Artery Bypass Grafting: A Meta-Analysis and Consensus Statement from the 2004 ISMICS Consensus Conference

Background

The purpose of this evidence-based consensus statement is to systematically review and meta-analyze the randomized and nonrandomized evidence comparing off-pump (OPCAB) to conventional coronary artery bypass (CCAB) surgery and to provide consensus on the role of OPCAB in low- and high-risk surgical patients.

Methods and Results

This consensus conference was conducted according to the American College of Cardiology (ACC)/American Heart Association (AHA) standards for development of clinical practice guidelines. The Steering Committee collated all published studies of OPCAB versus CCAB through May 2004 and developed six questions central to controversies surrounding OPCAB surgery in mortality, morbidity, and resource utilization. For mixed-risk patient populations, meta-analysis of 37 randomized clinical trials (3,369 patients, Level A) reported across a total of 53 papers, and two meta-analyses of nonrandomized trials (Level B) comparing OPCAB versus CCAB were identified. For high-risk patient populations, we performed a meta-analysis of 3 randomized and 42 nonrandomized trials (26,349 patients, Level B).

Conclusion

Meta-analysis of Level A and B evidence provided the basis for the following consensus statements in patients undergoing surgical myocardial revascularization: (1) OPCAB should be considered a safe alternative to CCAB with respect to risk of mortality [Class I, Level A]; (2) With appropriate use of modern stabilizers, heart positioning devices, and adequate surgeon experience, similar completeness of revascularization and graft patency can be achieved [Class IIa, Level A]; (3) OPCAB is recommended to reduce perioperative morbidity [Class I, Level A]; (4) OPCAB may be recommended to minimize midterm cognitive dysfunction [Class IIa, Level A]; (5) OPCAB should be considered as an equivalent alternative to CCAB in regard to quality of life [Class I, Level A]; (6) OPCAB is recommended to reduce the duration of ventilation, ICU and hospital stay, and resource utilization [Class I, Level A]; (7) OPCAB should be considered in high-risk patients to reduce perioperative mortality, morbidity, and resource utilization [Class IIa, Level B].

ANSiscope™: Can it be the crystal ball of cardiac anesthesia?

Background

: Autonomic dysfunction (AD) is infrequently evaluated preoperatively despite having profound perioperative implications. The ANSiscope™ is a monitoring device that quantifies AD. This study aims to determine the potential of the device to predict hypotension following anesthetic induction, occurrence of arrhythmias, and inotrope requirement for patients undergoing off-pump coronary artery bypass surgery (OPCAB).

Study Design

: Prospective observational double-blinded study.

Materials and Methodology

Seventy-five patients undergoing OPCAB had their autonomic function assessed by ANSiscope™. They were classified into four groups based on their AD and compared to perioperative adverse events.

Results

Patients with diabetes had a higher ANSindex (P = 0.0263). They had a greater decrease in systolic blood pressure (P = 0.001) and mean arterial pressure (P = 0.004) postinduction, had an increased incidence of arrhythmias (P = 0.009), required higher inotropic support immediately (P = 0.010) and at 24 h after surgery (P = 0.018), and longer duration of postoperative ventilation (P < 0.001). They also had a higher incidence of emergency conversion of OPCAB to on-pump surgery (P = 0.009).

Conclusions

An increased association between AD as quantified by the ANSiscope™ and perioperative adverse outcomes was observed. An increased rate of emergency conversion of OPCAB to on-pump surgery with higher dysfunction was noted. The authors opine that the threshold for conversion must be lower in patients deemed to be at a higher risk. Proper evaluation of the autonomic nervous system empowers the anesthesiologist to anticipate and adequately prepare for complications.

Early outcomes in patients undergoing off-pump coronary artery bypass grafting

Background

In spite of general decline worldwide, off-pump coronary artery bypass grafting (CABG) surgery is performed in more than 60% of patients undergoing CABG in India; mainly because of shorter operative time and reduced procedure cost. However, paucity of data exists in literature about early outcomes following off-pump CABG from India.

Methodology

We conducted a prospective observational study of 800 consecutive cases that underwent off-pump CABG (OPCAB) from August 2015 to October 2017. Primary end point of the study was the 30-day/in-hospital mortality from any cause.

Results

On multivariate analysis, emergency surgery (OR 9.72; CI 1.96-48.21, p value 0.005), severe left ventricular dysfunction (OR 2.28; CI 1.25-4.76, p value 0.026), postoperative atrial fibrillation (OR 9.95; CI 3.12-32.01, p value 0.05), and dialysis-dependent renal failure (OR 29.7, CI 10.02-87.99, p value 0.006) were the factors associated with mortality. The observed mortality was 1.6%, and the expected mortality by EuroSCORE II was 2.6%. The median EuroSCORE II of expired patients was 3.03 and of entire cohort was 1.54 (p value 0.001). Stroke rate was 0.9%. Deep sternal wound infection occurred in 0.9%, and 3.8% patients were readmitted to the hospital after discharge.

Conclusion

Early outcome of off-pump CABG was excellent in this study. Increased incidence of deep sternal wound infection remains a concern. Multicenter study with a larger sample size is required for a dependable evaluation of the efficacy of off-pump CABG in Indian population.

Major adverse cardiac and cerebrovascular event and patients' quality of life after endoscopic vein harvesting as compared with open vein harvest (MAQEH): a pilot study

Background

This is a prospective, comparative, pilot and follow-up (2-year postoperatively) study in patients undergoing coronary artery bypass graft surgery where the long saphenous vein was harvested either by the endoscopic vein harvest (EVH) technique or open vein harvest (OVH) technique. Quality of life (QOL) and major adverse cardiac and cerebrovascular events (MACCE) were assessed.

Methods

Alive patients who were initially part of a pilot study when EVH was introduced in our institution were included (n=48 EVH, n=49 OVH). Patients were sent a QOL questionnaire (SF12v2; 12-item medical outcomes study short form health survey version 2.0), and their cardiologist and general practitioner were contacted to assess MACCE.

Results

Median follow-up was 32 and 33 months, respectively. Three patients died (2 EVH, 1 OVH). Of the remaining 97 patients who were sent a questionnaire, 76% patients returned the form. More patients from the EVH group returned the QOL questionnaire (82% vs 71%). Time taken to return to normal daily activities was much shorter in EVH (median 6 (2–30) weeks) compared with OVH (median 9 (2–50) weeks) (P<0.05). QOL questionnaire revealed significant difference in physical score at follow-up: 45.3 (10.2) for EVH group and 40.7 (11.0) for OVH group (P<0.05). There was no difference in mental scores (46.9 (10.5) vs 49.2 (9.1), P=0.4). There were no significant differences in MACCEs including death between the two groups (12.2% vs 13.9%, P=0.5).

Conclusion

EVH patients returned to normal daily activities faster than OVH patients and experienced better physical QOL even after 2 years postoperatively with no increase in MACCE during follow-up.

Conversion after off-pump coronary artery bypass grafting: the CORONARY trial experience

Objectives

Emergent and late conversions form OFF-to-ON pump coronary artery bypass grafting (CABG) have been associated with worse outcomes, however, it remains unclear as to which risk factors are associated with conversion and how to prevent them.

Methods

Among 4718 patients who randomly underwent off- or on-pump CABG, the incidence of off-pump to on-pump cross-over, or 'OFF-to-ON conversion', was 7.9% (186/2356). The primary outcome was a composite of death, stroke, myocardial infarction, or new renal failure requiring dialysis. We assessed the risk factors and outcomes of converted patients.

Results

Emergent OFF-to-ON conversions, defined as conversions for hypotension or ischaemia, were required for 3.2% of patients ( n  = 75), while most elective conversions were due to small or intramuscular coronaries ( n  = 83). OFF-to-ON converted patients required increased surgery time, blood transfusions, intensive care unit stay, and presented a higher incidence at 1 year of the composite outcome compared with non-converted off-pump patients (all P < 0.01), especially if the conversion was emergent. Conversely, elective conversions outcomes were no different compared with non-converted off-pump patients ( P  = 0.35). Independent predictors of emergent conversions included higher heart rate or chronic atrial fibrillation, urgent surgery, more grafts planned and surgeon experience with off-pump CABG.

Conclusions

Emergent OFF-to-ON conversion is associated with worse outcomes compared with elective conversion or no conversion. In the presence of risk factors for emergent conversion, an early and elective conversion approach is a judicious strategy.

Risk Factors of On-Pump Conversion during Off-Pump Coronary Artery Bypass Graft

Background

Off-pump coronary artery bypass grafting (OPCABG) procedures can avoid the complications of an on-pump bypass. However, some cases unexpectedly require conversion to cardiopulmonary bypass during OPCABG. The risk factors associated with a sudden need for cardiopulmonary bypass were analyzed.

Methods

This retrospective study included 283 subjects scheduled for OPCABG from 2001 to 2010. These were divided into an OPCABG group and an on-pump conversion group. Preoperative, operative, and postoperative variables were compared between the 2 groups.

Results

Of the 283 patients scheduled for OPCABG, 47 (16%) were switched to on-pump coronary artery bypass grafting (CABG). The mortality of the both the OPCABG and on-pump conversion groups was not significantly different. The major risk factors for conversion to on-pump CABG were congestive heart failure (CHF) (odds ratio [OR], 3.5; p=0.029), ejection fraction (EF) <35% (OR, 4.4; p=0.012), and preoperative beta-blocker (BB) administration (OR, 0.3; p=0.007). The use of intraoperative (p=0.007) and postoperative (p=0.021) inotropics was significantly higher in the conversion group. The amount of postoperative drainage (p<0.001) and transfusion (p<0.001) also was significantly higher in the conversion group. There were no significant differences in stroke or cardiovascular complications between the groups over the course of short-term and long-term follow-up.

Conclusion

Patients who undergo OPCABG and have CHF or a lower EF (<35%) are more likely to undergo on-pump conversion, while preoperative BB administration could help prevent conversions from OPCABG to on-pump CABG.

Assessment of deformation of the mitral valve complex during off-pump coronary artery bypass surgery using three-dimensional echocardiography in a porcine model

BACKGROUND

This study aimed to assess the deformation of the mitral valve complex during the displacement of the beating heart by using three-dimensional echocardiography in a porcine off-pump coronary artery bypass grafting (OPCAB) model.

METHODS

In nine healthy swine, we positioned the beating heart as an OPCAB model, i.e. control, left anterior descending artery (LAD), right coronary artery (RCA), and left circumflex artery (LCX) positions. In each position, three-dimensional echocardiography was performed to assess the mitral valve complex with hemodynamic parameters. We analyzed the deformation of the mitral valve and the three-dimensional coordinates of the papillary muscles.

RESULTS

There was a significant increase in maximum tenting length and tenting volume (control 0.70±0.30, LAD 0.65±0.27, RCA 0.79±0.23, LCX 0.95±0.34cm³, p<0.05) in the LCX position compared with the other positions. The posterior papillary muscle (PPM) angle had a significant relationship with the tenting volume (r=-0.643, p<0.001). The PPM was displaced to the medial side in the LAD and LCX positions (p<0.01).

CONCLUSIONS

The prime cause of the deformation of the mitral leaflets is suggested to be the displacement of the PPM associated with the change in geometry of the left ventricle in a porcine model.

Myocardial revascularization without extracorporeal circulation; Why hasn't it convinced yet?

Extracorporeal circulation has led to a great development in cardiovascular surgery during the last five decades. Its time-proven efficacy and safety have made on-pump coronary artery bypass grafting (CABG) the gold standard method of surgical revascularization. However, coronary revascularization on cardiopulmonary bypass and the accompanying aortic manipulation are related to plenty of deleterious complications. Therefore, off-pump CABG surgery was established to avoid complications. Nevertheless, despite the initial enthusiasm on this technique, only 20% of myocardial revascularization procedures worldwide are performed off-pump. Not only are off-pump cardiac procedures more technically difficult but also they do not provide better results in terms of graft patency, completeness of revascularization, repeat revascularization requirement, cost, and quality of life. Completeness of revascularization and anastomotic quality should not be compromised to avoid cardiopulmonary bypass.

Intraoperative conversion to on-pump coronary artery bypass grafting is independently associated with higher mortality in patients undergoing off-pump coronary artery bypass grafting: A propensity-matched analysis

Context:

One of the main limitations of off-pump coronary artery bypass grafting (OPCAB) is the occasional need for intraoperative conversion (IOC) to on-pump coronary artery bypass grafting. IOC is associated with a significantly increased risk of mortality and postoperative morbidity. The impact of IOC on outcome cannot be assessed by a randomized control design.

Aims:

The objective of this study was to analyze the incidence, risk factors, and impact of IOC on the outcome in patients undergoing OPCAB.

Settings and Design:

Three tertiary care level hospitals; retrospective observational study.

Subjects and Methods:

This retrospective observational study included 1971 consecutive patients undergoing OPCAB from January 2012 to October 2015 at three tertiary care level hospitals by four surgeons. The incidence, patient characteristics, cause of IOC, and its impact on outcome were studied.

Statistical Analysis Used:

The cohort was divided into two groups according to IOC. Univariate logistic regression was performed to describe the predictors of IOC. Variables that were found to be significant in univariate analysis were introduced into multivariate model, and adjusted odds ratio (OR) was calculated. To further assess the independent effect of IOC on mortality, propensity score matching with a 5:1 ratio of non-IOC to IOC was performed.

Results:

The overall all-cause in-hospital mortality was 2.6%. IOC was needed in 128 (6.49%) patients. The mortality in the IOC group was significantly higher than non-IOC group (21 of 128 [16.4%] vs. 31 of 1843 [1.7%], P = 0.0001). The most common cause for IOC was hemodynamic disturbances during grafting to the obtuse marginal artery (51/128; 40%). On multivariate logistic regression analysis, left main disease, pulmonary hypertension, and mitral regurgitation independently predicted IOC. We obtained a propensity-matched sample of 692 patients (No IOC 570; IOC 122), and IOC had OR of 16.26 (confidence interval 6.3–41; P < 0.0001) for mortality in matched population.

Conclusions:

Emergency IOC increases odds for mortality by 16-fold. Hence, identification of patients at higher risk of IOC may improve the outcome.

Early clinical outcomes of on-pump beating-heart versus off-pump technique for surgical revascularization in patients with severe left ventricular dysfunction: the experience of a single center

Background

Limited experiences of applying an on-pump beating-heart technique for surgical revascularization in patients with severe left ventricular dysfunction have been reported. Which strategy, either off-pump coronary artery bypass grafting (CABG) or on-pump beating-heart CABG surgery, is the best strategy for surgical revascularization in patients with severe left ventricular dysfunction is still controversial. This single-center study aimed to evaluate the impacts of an on-pump beating-heart versus an off-pump technique for surgical revascularization on the early clinical outcomes in patients with a left ventricular ejection fraction (LVEF) of 35% or less to explore which technique would be more suitable for surgical revascularization in patients with severe left ventricular dysfunction.

Methods

A total of 216 consecutive patients with an echocardiographic estimated LVEF of 35% or less who underwent non-emergency, primary, isolated CABG from January 2010 to December 2014 were included in this study and were divided into either an ONBEAT group (patients who received on-pump beating-heart CABG surgery, n = 88) or an OFF group (patients who received off-pump CABG surgery, n = 128). The early clinical outcomes were investigated and compared.

Results

Patients in the ONBEAT group compared to the OFF group had a significant higher early postoperative LVEF (35.6 ± 2.9 vs. 34.8 ± 3.3%, p = 0.034) but shared a similar baseline LVEF (31.0 ± 2.8 vs. 31.0 ± 2.9%, p = 0.930). Patients in the ONBEAT group compared to the OFF group received a greater number of grafts and an increased amount of drainage during the first 24 h (3.7 ± 0.8 vs. 2.8 ± 0.6, p <0.001; 715 ± 187 ml vs. 520 ± 148 ml, p <0.001, respectively), without evidence of worse in-hospital mortality or major postoperative morbidity. Additionally, logistic regression analysis showed that surgical technique (on-pump beating-heart CABG vs. off-pump CABG) had no independent influence on in-hospital mortality or major postoperative morbidity in patients with preoperative LVEF of 35% or less.

Conclusions

The on-pump beating-heart technique may be an acceptable alternative to the off-pump technique for surgical revascularization in patients with an estimated LVEF of 35% or less.

Analysis of Risk Factors for Conversion from Off-Pump to On-Pump Coronary Artery Bypass Graft

BACKGROUND

Off-pump coronary artery bypass (OPCAB) is performed worldwide, but significant risks are associated with conversion to on-pump surgery. Therefore, we evaluated the composite outcomes between an OPCAB group and a conversion group.

METHODS

From January 2008 to December 2012, 100 consecutive patients underwent OPCAB at Hallym University Sacred Heart Hospital, of whom 84 underwent OPCAB without adverse events (OPCAB group), and 16 were converted to on-pump surgery (conversion group). Early morbidity, early and long-term mortality, and major adverse cardiac and cerebrovascular events (MACCEs) were the primary and long-term composite endpoints.

RESULTS

The mean follow-up period was 55±26 months, with 93% of the patients completing follow-up. The composite outcomes in the OPCAB and conversion groups were as follows: early morbidity, 2.3% versus 12.5%; early mortality, 4.7% versus 0%; long-term mortality, 14.3% versus 25.0%; and MACCEs, 14.3% versus 18.8%, respectively. No composite endpoints showed statistically significant differences. Preoperative acute myocardial infarction (AMI) was identified as an independent risk factor for conversion (p=0.025).

CONCLUSION

The conversion group showed no statistically significant differences in early mortality and morbidity, MACCEs, or long-term mortality compared with the OPCAB group. The preoperative diagnosis of AMI was associated with an increased number of conversions to on-pump surgery.

Off Pump Coronary Artery Bypass Graft Surgery Versus Conventional Coronary Artery Bypass Graft Surgery: A Systematic Review of the Literature

The recent development of off-pump coronary artery bypass (OPCAB) graft surgical techniques has led to numerous observational and several randomized trials that have investigated outcomes compared with the current gold standard of conventional on-pump coronary bypass (CCAB) graft surgery. This systematic review assesses the current randomized trials that compare OPCAB and CCAB. Numerous end points were investigated, including mortality, stroke, myocardial infarction, atrial fibrillation, blood transfusions, wound infections, and renal failure. In addition to these important outcomes, resource utilization markers were also examined such as hospital length of stay, intensive care unit length of stay, and duration of intubation/ventilation. Finally, when level I evidence from randomized trials was unavailable, level II evidence was examined. This was done for subgroup analysis, where currently no randomized trials exist, looking at OPCAB in high-risk patients. Recommendations were made as to who should receive OPCAB and the potential benefits in this patient population.

Off-pump coronary artery bypass: past, present and future of a controversial technology

PURPOSE OF REVIEW

This review will examine the current role of off-pump coronary artery bypass (OPCAB) surgery compared with on-pump coronary artery bypass (ONCAB) surgery for the revascularization of ischemic myocardium.

RECENT FINDINGS

Recent studies have confirmed earlier findings that OPCAB is associated with less grafts per patient and less complete revascularization, and increased incidence of recurrent angina and need for repeat revascularization procedures, and more frequent rehospitalization for cardiac-related issues. OPCAB does not prevent postoperative renal dysfunction and is associated with worse long-term outcomes. Hospital costs are not reduced and are increased in those OPCAB patients who require intraoperative conversion to ONCAB procedures; however, when multiple arterial grafts are used and a complete revascularization is performed, OPCAB outcomes are equivalent to those of ONCAB procedures.

SUMMARY

OPCAB should only be performed by surgeons experienced in this technique in patients in whom a complete revascularization can be achieved; preferably with multiple arterial grafts.

Developments in surgical revascularization to achieve improved morbidity and mortality

Coronary artery bypass graft surgery remains the main treatment modality for multivessel coronary artery disease and has consistently been demonstrated to have significantly lower rates of major adverse cardiac and cerebrovascular events in comparison to percutaneous coronary intervention. In this article we will explore the advances over time and the recent refinements in the techniques of surgical revascularization and how these contribute to the superior outcome profile associated with coronary artery bypass graft surgery. These include the current outcome status of coronary artery bypass grafting; the major landmark trials, registries and meta-analyses comparing coronary artery bypass grafting and percutaneous coronary intervention; the developments in coronary artery disease lesion classification; the techniques for the physiological assessment of coronary artery lesions; bypass grafting using arterial conduits; the role of off-pump coronary artery surgery; the outcomes of reoperative surgery; hybrid techniques for coronary revascularization; minimally invasive coronary artery surgery and finally robotic surgery.

Risk Stratification in Off-Pump Coronary Artery Bypass (OPCAB) Surgery—Role of EuroSCORE II

OBJECTIVES

To evaluate the EuroSCORE II for risk stratification in patients undergoing off-pump coronary artery bypass (OPCAB) surgery.

DESIGN

A retrospective observational study.

SETTING

Two tertiary care hospitals.

PARTICIPANTS

Participants were 1,211 patients undergoing OPCAB surgery.

INTERVENTIONS

No interventions were implemented.

MEASUREMENTS AND MAIN RESULTS

The EuroSCORE II estimated the operative risk for each patient. The calibration of the scoring system was assessed using the Hosmer Lemeshow test, and the discriminative capacity was estimated with area under receiver operating characteristic curves. The incidence, patient characteristics, causes of intraoperative conversion to on-pump coronary artery bypass (ONCAB), and outcome were studied. The all-cause in-hospital mortality was 2.39%. Predicted mortality with the EuroSCORE II was 2.03±1.63. Using the Hosmer Lemeshow test, a C statistic of 8.066 (p = 0.472) was obtained, indicating satisfactory model fit. The calculated area under the receiver operating characteristic curve was 0.706 (p = 0.0002), indicating good discriminatory power. Emergency intraoperative conversion to ONCAB occurred in 6.53% of patients. The mortality in the ONCAB group was significantly higher compared with patients who underwent successful OPCAB surgery (15.18% v 1.5%, p<0.0001). On multiple regression analysis with conversion to ONCAB as the endpoint, associated factors were patients with a higher EuroSCORE II (odds ratio = 1.13, confidence interval = 1.03-1.27) and more-than-trivial mitral regurgitation (odds ratio = 1.84, confidence interval = 1.07-3.06). Net reclassification improvement of 0.714 (p<0.0001) was obtained when on-pump conversion was added to the EuroSCORE II.

CONCLUSIONS

The EuroSCORE II has satisfactory calibration and discrimination power to predict mortality after OPCAB surgery. Intraoperative conversion to ONCAB is a major complication of OPCAB surgery. A higher EuroSCORE II also predicts higher probability of conversion to ONCAB.

Prophylactic application of an intra-aortic balloon pump in high-risk patients undergoing off-pump coronary artery bypass grafting

BACKGROUND

An intra-aortic balloon pump (IABP) is the most commonly used circulatory assist device in cardiac surgery. We hypothesized that prophylactic application of an IABP improves early clinical outcome of high-risk patients undergoing scheduled off-pump coronary artery bypass grafting (OPCABG).

METHODS

From January 2010 to December 2013, hemodynamically stable, high-risk patients undergoing scheduled OPCABG with preincision use of an IABP were recruited to the IABP group. Using the propensity score-matching method, every patient in the IABP group was matched with another patient (the control group) with a similar propensity score who received an IABP on an as-needed basis during or after OPCABG. Surgical mortality and major morbidity rates were compared between groups.

RESULTS

A total of 116 patient pairs were included in this study. In patients in the IABP group, postoperative low cardiac output and respiratory as well as renal failure were less frequent, intensive care unit stay was shorter, and surgical mortality was lower compared to patients in the control group. In multivariate logistic regression, timing of IABP implantation, as an independent risk factor, was associated with postoperative low cardiac output (OR=2.02, 95% CI 1.28-5.76), respiratory failure (OR=1.86, 95% CI 1.19-4.27), renal failure (OR=2.96, 95% CI 1.51-6.63) and surgical mortality (OR=2.45, 95% CI 1.42-6.07).

CONCLUSIONS

Prophylactic application of an IABP improves postoperative cardiac performance, reduces respiratory and renal complications, and consequently lowers surgical mortality in high-risk patients undergoing scheduled OPCABG.

Long-term follow-up of off-pump and on-pump coronary artery bypass grafting

OBJECTIVE

Despite increasing recognition of the benefits of off-pump coronary artery bypass grafting (CABG), concerns persist regarding its impact on long-term mortality and freedom from reintervention. In this study, we assessed the impact of off-pump CABG on long-term outcomes.

METHODS

From January 2002 to December 2002, a total of 307 consecutive patients who underwent isolated multivessel off-pump CABG at our institution were compared with a control group of 397 patients who underwent multivessel on-pump CABG during the same period. Perioperative data were prospectively collected and compared. In addition, univariate and risk-adjusted comparisons between the two groups were performed at 10 years.

RESULTS

After adjusting for clinical covariates, off-pump CABG did not emerge as a significant independent predictor of long-term mortality [hazard ratio (HR), 0.91; 95% confidence interval (CI), 0.70-1.12], readmission to hospital for cardiac cause (HR, 0.96; 95% CI, 0.78-1.10), or the need for reintervention (HR, 0.93; 95% CI, 0.87-1.05).

CONCLUSIONS

At long-term follow-up, off-pump CABG remains a safe and effective myocardial revascularization strategy with no adverse impact on survival or freedom from reintervention.

Role of Left Main Coronary Artery Stenosis on Intraoperative Conversion and Mortality in Off-Pump Coronary Artery Bypass

BACKGROUND

Intraoperative conversion is a major threat in off-pump coronary artery bypass (OPCAB). The conversion rate depends on patient selection and surgeon experience. Previous studies have demonstrated the feasibility of OPCAB for patients with left main coronary artery stenosis (LMCAS) ≥ 50%. However, no studies have focused on the role of LMCAS ≥ 90%. We sought to assess the impact of LMCAS ≥ 90% on the conversion rate and mortality in OPCAB.

METHODS

We conducted a retrospective review of 1055 consecutive unselected patients undergoing OPCAB between 2000 and 2012. The patients in our study were divided into 3 groups by the severity of LMCAS.

RESULTS

LMCAS was < 50% in 704, 50-90% in 266, and ≥ 90% in 85 patients. LMCAS was not associated with major postoperative complications and hospital mortality, although preoperative cardiogenic shock was present in 6.3%. Overall, the conversion rate was 10.1%:11.4% in LMCAS < 50%, 5.6% in LMCAS 50-90%, and 14.1% in LMCAS ≥ 90%. Operation status, cardiogenic shock, left ventricular ejection fraction < 30% and operation before 2007 were noted as independent predictors of conversion. The overall hospital mortality rate was 5.1%: 4.8% in LMCAS < 50%, 4.5% in LMCAS 50-90%, and 9.4% in LMCAS ≥ 90%. Operation status, cardiogenic shock, left ventricular ejection fraction < 30% and intraoperative conversion were observed to be independent predictors of mortality. However, LMCAS did not predict either conversion or hospital mortality.

CONCLUSIONS

LMCAS ≥ 90% was not an independent predictor of intraoperative conversion or hospital mortality in OPCAB.

KEY WORDS

Conversion; Left main coronary artery stenosis; Off-pump coronary artery bypass.

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.

On-pump beating-heart versus conventional coronary artery bypass grafting for revascularization in patients with severe left ventricular dysfunction: early outcomes

BACKGROUND

We sought to evaluate the effects of on-pump beating-heart versus conventional coronary artery bypass grafting techniques requiring cardioplegic arrest in patients with coronary artery disease with left ventricular dysfunction.

METHODS

We report the early outcomes associated with survival, morbidity and improvement of left ventricular function in patients with low ejection fraction who underwent coronary artery bypass grafting between August 2009 and June 2012. Patients were separated into 2 groups: group I underwent conventional coronary artery bypass grafting and group II underwent an on-pump beating-heart technique without cardioplegic arrest.

RESULTS

In all, 131 patients underwent coronary artery bypass grafting: 66 in group I and 65 in group II. Left ventricular ejection fraction was 26.6% ± 3.5% in group I and 27.7% ± 4.7% in group II. Left ventricular end diastolic diameter was 65.6 ± 3.6 mm in group I and 64.1 ± 3.2 mm in group II. There was a significant reduction in mortality in the conventional and on-pump beating-heart groups (p < 0.001). Perioperative myocardial infarction and low cardiac output syndrome were higher in group I than group II (both p < 0.05). Improvement of left ventricular function after the surgical procedure was better in group II than group I.

CONCLUSION

The on-pump beating-heart technique is the preferred method for myocardial revascularization in patients with left ventricular dysfunction. This technique may be an acceptable alternative to the conventional technique owing to lower postoperative mortality and morbidity.

Does off-pump coronary artery bypass grafting negatively impact long-term survival and freedom from reintervention?

Recently published evidence has raised concerns about worse late mortality and increasing need for reintervention after off-pump coronary artery bypass grafting. We undertook this study to assess the impact of off-pump coronary artery bypass grafting on survival and freedom from reintervention at 10 years. From January 2002 to December 2002, 307 consecutive patients who had isolated multivessel off-pump coronary artery bypass grafting at our institution were compared to a control group of 397 patients that underwent multivessel on-pump coronary artery bypass grafting during the same period. In addition, univariate and risk-adjusted comparisons between the two groups were performed at 10 years. Kaplan-Meier survival was similar for the two cohorts. After adjusting for clinical covariates, off-pump coronary artery bypass grafting did not emerge as a significant independent predictor of long-term mortality (Hazard Ratio 0.91; 95% Confidence Interval 0.70-1.12), readmission to hospital for cardiac cause (Hazard Ratio 0.96; 95% Confidence Interval 0.78-1.10), or the need for reintervention (Hazard Ratio 0.93; 95% Confidence Interval 0.87-1.05). Off-pump coronary artery bypass grafting compared with on-pump coronary artery bypass grafting does not adversely impact survival or freedom from reintervention at a 10-year follow-up.