Coronary Artery Revascularization (CARE) Registry: An Observational Study of On-Pump and Off-Pump Coronary Artery Revascularization

Development and validation of a model to categorize cardiovascular cause of death using health administrative data

Study objective

Develop and evaluate a model that uses health administrative data to categorize cardiovascular (CV) cause of death (COD).

Design

Population-based cohort.

Setting

Ontario, Canada.

Participants

Decedents ≥ 40 years with known COD between 2008 and 2015 in the CANHEART cohort, split into derivation (2008 to 2012; n = 363,778) and validation (2013 to 2015; n = 239,672) cohorts.

Main outcome measures

Model performance. COD was categorized as CV or non-CV with ICD-10 codes as the gold standard. We developed a logistic regression model that uses routinely collected healthcare administrative to categorize CV versus non-CV COD. We assessed model discrimination and calibration in the validation cohort.

Results

The strongest predictors for CV COD were history of stroke, history of myocardial infarction, history of heart failure, and CV hospitalization one month before death. In the validation cohort, the c-statistic was 0.80, the sensitivity 0.75 (95 % CI 0.74 to 0.75) and the specificity 0.71 (95 % CI 0.70 to 0.71). In the primary prevention validation sub-cohort, the c-statistic was 0.81, the sensitivity 0.71 (95 % CI 0.70 to 0.71) and the specificity 0.75 (95 % CI 0.75 to 0.75) while in the secondary prevention sub-cohort the c-statistic was 0.74, the sensitivity 0.81 (95 % CI 0.81 to 0.82) and the specificity 0.54 (95 % CI 0.53 to 0.54).

Conclusion

Modelling approaches using health administrative data show potential in categorizing CV COD, though further work is necessary before this approach is employed in clinical studies.

Preoperative treatment with clopidogrel and ticagrelor on bleeding complications in off-pump coronary artery bypass grafting

BACKGROUND

Dual antiplatelet therapy (DAPT) consisting of acetylsalicylic acid and clopidogrel or ticagrelor increased bleeding complications in patients undergoing coronary artery bypass grafting (CABG). We aimed to compare the bleeding risks between patients treated with clopidogrel and ticagrelor preoperatively and investigate the influence of discontinuation of clopidogrel and ticagrelor on bleeding risk in off-pump CABG (OPCABG).

METHODS

We conducted a retrospective analysis of patients with DAPT who underwent OPCABG. The propensity score matching was performed given the baseline differences between clopidogrel- and ticagrelor-treated patients. Bleeding was assessed by chest tube drainage volume and universal definition of perioperative bleeding.

RESULTS

This study included 836 patients. Five hundred and fifty patients were treated with clopidogrel and 286 patients treated with ticagrelor before surgery. After matching, 275 patients treated with clopidogrel and 275 patients with ticagrelor were included. There were no significant differences in bleeding between clopidogrel and ticagrelor group. Patients who discontinued clopidogrel before surgery <3 d had a higher risk of severe perioperative bleeding compared with those who discontinued ≥5 d (16.4 % vs. 5.0 %, P = 0.045). By contrast, the risk of severe perioperative bleeding was comparable among patients who discontinued ticagrelor for <3 d, ≥3-5 d and ≥5 d preoperatively (16.2 % vs. 9.1 % vs. 10.1 %, P = 0.317). The multivariable analysis confirmed that time since discontinuation (<3 d vs. ≥5 d: OR = 2.732, 95 % CI: 1.332-5.605, P = 0.006) but not the types of P2Y₁₂ receptor antagonist was an independent predictor for severe perioperative bleeding.

CONCLUSIONS

There were no significant differences in severe perioperative bleeding between clopidogrel and ticagrelor groups. Discontinuation of clopidogrel <3 d before OPCABG increased the risk of severe perioperative bleeding.

Fluid Status After Cardiac Surgery Assessed by Bioelectrical Impedance Vector Analysis and the Effects of Extracorporeal Circulation

OBJECTIVE

Hydration status after cardiac surgery can be difficult to assess, often requiring invasive measurements. Bioelectrical impedance vector analysis (BIVA) is based on patterns of resistance (R) and reactance (Xc), corrected by height, and has been used in various clinical scenarios to determine body composition and monitor its changes over time. The purpose of the present study was to apply this method in cardiac surgery patients to assess the variation in hydration status and to compare its changes according to the use of extracorporeal circulation.

DESIGN

Single-center, observational, prospective study including patients older than 18 years undergoing elective or urgent cardiac surgery.

SETTING

Intensive cardiac care unit of a tertiary center in a metropolitan area.

PARTICIPANTS

The study comprised 76 patients with a median age of 60 years and mostly undergoing coronary artery bypass grafting (CABG) (n = 47 [61.8%]) with extracorporeal circulation (n = 54 [73%]).

INTERVENTIONS

Bioimpedance was measured with a standard tetrapolar single-frequency bioimpedance meter using a standardized procedure and plotted in an R-Xc graph.

MEASUREMENTS AND MAIN RESULTS

The study demonstrated an increase in total body water immediately after surgery that was sustained until producing hyperhydration 24 hours later. Off-pump CABG was associated with a normal hydration status after surgery, whereas on-pump CABG produced a significant increase in total body water.

CONCLUSIONS

Fluid status assessment with BIVA in cardiac surgery showed an increase in total body water up to 24 hours after surgery. Off-pump surgery prevented overhydration, which partially could explain the reduction in some of the postoperative complications. BIVA could serve as a useful method for monitoring fluid status in the setting of goal-directed therapy to assist in maintaining euvolemia in cardiac surgical patients.

Off-pump versus on-pump coronary artery bypass grafting-a surreal controversy?

As per the findings of the SYNTAX Trial, it has been established that coronary artery bypass grafting (CABG) affords the best long-term results in patients with multivessel disease. However, it is still a point of contention whether 'off-pump' CABG (OPCAB) (on cardiopulmonary bypass) is better. Many studies appear to establish the superiority of one or the other. But there is still no well-planned multi-centre randomised controlled trial looking into all aspects of the issue that can, once and for all, put the controversy to rest. But as long as one is able to give the patient a good result, does it really matter whether the procedure is done off or on pump? This article looks at the available evidence with regard to various parameters comparing OPCAB and conventional CABG in an attempt to answer the question, if at all, it is a question!

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.

Current outcomes of off-pump coronary artery bypass grafting: evidence from real world practice

Coronary artery bypass grafting (CABG) can be performed conventionally using cardiopulmonary bypass (CPB) and aortic clamping or on a beating heart (BH) without the use of CPB, the so-called off-pump CABG. Some surgeons, who are proponents of off-pump CABG, preferentially use this technique for the majority of operations, whereas others use it only in certain situations which warrant avoidance of CPB. Ever since the conception of off-pump CABG, the never-ending debate about which technique of CABG is safe and efficacious continues to date. Several randomized controlled trials (RCTs) have been conducted that have either favored on-pump CABG or have failed to show a significant difference in outcomes between the two techniques. However, these RCTs have been fraught with claims that they do not represent the majority of patients undergoing CABG in real world practice. Therefore, assessment of the benefits and drawbacks of each technique through observational and registry studies would be more representative of patients encountered in daily practice. The present review examines various retrospective studies and meta-analyses of observational studies that compare the early and long-term outcomes of off- and on-pump CABG, which assesses their safety and efficacy. Additionally, their outcomes in older patients, females, and those with diabetes mellitus, renal dysfunction, presence of ascending aortic disease, and/or acute coronary syndrome (ACS) have also been discussed separately. The general consensus is that early results of off-pump CABG are comparable to or in some cases better than on-pump CABG. However, on-pump CABG provides a survival benefit in the long term according to a majority of publications in literature.

Short-term clinical outcomes after hybrid coronary revascularization versus off-pump coronary artery bypass for the treatment of multivessel or left main coronary artery disease: a meta-analysis

Background

Hybrid coronary revascularization (HCR) and off-pump coronary artery bypass grafting (OPCABG) are both feasible, less invasive techniques for coronary revascularization. Although both techniques utilize the left internal mammary artery to left anterior descending artery graft, HCR uses drug-eluting stents instead of saphenous vein bypass. It remains unclear whether HCR is equal to, better or worse than OPCABG.

Methods and results

A meta-analysis was carried out using a random-effects model. Seven observational studies were included. There was no significant difference either in in-hospital mortality [relative risk (RR) 0.57, 95% confidence interval (CI) 0.13–2.59, P=0.47] or in the MACCE rate (RR 0.63, 95% CI 0.24–1.64, P=0.34) between the HCR group and the OPCABG group. A significant difference was observed between the two groups in the length of hospitalization (RR 0.55, 95% CI 0.13–0.97, P=0.01), length of ICU stay (RR 0.45, 95% CI 0.10–0.80, P<0.05), intubation time (RR 0.48, 95% CI 0.13–0.84, P<0.01), need for red blood transfusion (RR 0.67, 95% CI 0.56–0.82, P<0.001), and total in-hospital costs (RR 0.90, 95% CI 0.39–1.42, P<0.01).

Conclusion

Compared with OPCABG, HCR did not improve early survival but decreased the length of hospitalization, length of ICU stay, intubation time, and need for red blood transfusion, and increased total in-hospitalcosts.

Off-pump surgery: is it beneficial in patients with left ventricular dysfunction?

On-pump coronary artery bypass surgery remains the gold standard for complex multivessel disease. Off-pump revascularization has matured as a technique over the last twenty years, but is used in less than 20% of cases worldwide. The poor uptake has been attributed to the significant learning curve in learning the procedure and conflicting evidence reports, together with concerns over mortality related conversion, graft patency and completeness of revascularization. Given these concerns, patient selection continues to be paramount and the subgroups that benefit most are hotly debated. Patients with left ventricular dysfunction constitute a high-risk subgroup which is enlarging in size. There is some evidence to suggest that avoidance of cardiopulmonary bypass in this group may lead to superior results in terms of early mortality, non-cardiac complications and organ dysfunction. Even with the theoretical risk of incomplete revascularization, the technique may be an attractive option in managing high-risk patients.

Less invasive coronary artery revascularization with a minimized extracorporeal circulation system: preliminary results of a comparative study with off-pump-procedures

BACKGROUND

Coronary-artery-bypass-grafting (CABG) with conventional extracorporeal circulation (CECC) is associated with adverse effects such as systemic inflammatory response leading to a decrease in systemic vascular resistance and hemodynamic instability. Modern "less invasive" procedures have been established recently which potentially avoid negative side effects of CECC. The aim of this study was to compare perioperative outcome following coronary revascularization using either a minimized extracorporeal circuit (Mini-HLM) or off-pump technique (OPCAB).

METHODS

In this prospective ethics-approved trial, 120 patients referred for CABG were randomly assigned either to off-pump coronary artery bypass (OPCAB) or to a Mini-HLM procedure. Patient demographics, preoperative characteristics and extensive postoperative outcome were analyzed for both groups. Hemodynamic data were measured at seven time points perioperatively.

RESULTS

Operation-time was longer in the Mini-HLM group (178,3 ± 32,9 min) compared to OPCAB (133,2 ± 32,7 min, p < 0,001) with higher graft numbers in Mini-HLM group (3,11 ± 0,7 vs. 1,78 ± 0,7, p < 0.001). There were no significant differences in perioperative hemodynamic criteria, catecholaminergic support, hospital (p = 0,534) and intensive care unit stay (p = 0,880), ventilation time (p = 0,113), blood loss (p = 0,570), transfusion requirements, postoperative atrial fibrillation rate (p = 0,706) and neurocognitive disturbance (p = 0,297). No deaths and no myocardial infarctions were observed.

CONCLUSIONS

Coronary revascularisation with Mini-HLM represents a suitable and "less invasive" procedure which achieves all benefits of OPCAB but may allow for less demanding revascularisation than OPCAB in special patients with complex coronary anatomy and can therefore be used both on a routine basis and in all "conversion" cases of OPCAB.

Perioperative heart-type fatty acid binding protein levels in atrial fibrillation after cardiac surgery

BACKGROUND

Postoperative atrial fibrillation (POAF) is common and associated with poor outcomes. Perioperative ischemia can alter arrhythmic substrate.

OBJECTIVE

To demonstrate an association between perioperative measurements of heart-type fatty acid binding protein (HT-FABP), a sensitive marker of ischemic myocardial injury.

METHODS

Blood samples from 63 inpatients undergoing coronary artery bypass surgery, valve surgery, or both were obtained before and up to 4 days after surgery. Continuous telemetry monitoring was used to detect POAF. Fifty-nine patients had at least 3 HT-FABP measurements. The relationship of enzyme-linked immunosorbent assay-measured HT-FABP with POAF was assessed by using joint logistic regression adjusted for age and surgery type.

RESULTS

Thirty-five patients (55%) developed POAF; these were, on average, older (69.3±10 years vs 60±11 years; P = .0019), with a higher prevalence of heart failure (43% vs 17%; P = .034), chronic obstructive lung disease (26% vs 4%; P = .017), preoperative calcium channel blocker use (29% vs 7%; P = .031), and more likely to undergo combined surgery (21% vs 11%, P = .049). The joint age- and coronary artery bypass surgery-adjusted model revealed that postoperative but not preoperative HT-FABP levels predicted POAF (coefficient 1.9±0.87; P = .03). Longer bypass time, prior infarction, and worse renal function were all associated with higher postoperative HT-FABP.

CONCLUSIONS

A greater rise of HT-FABP is associated with atrial fibrillation after cardiac surgery, suggesting that ischemic myocardial damage is a contributing underlying mechanism. Interventions that decrease perioperative ischemic injury may also decrease the occurrence of POAF.

Off-pump coronary artery bypass grafting--the current state

The optimal strategy for coronary revascularization remains controversial. Currently, most surgical revascularizations are performed with the use of cardiopulmonary bypass (ONCAB), yet over the past 20 years off-pump coronary artery bypass grafting (OPCAB) has been increasingly used because of the increased awareness of the deleterious effects of cardiopulmonary bypass (CPB) and aortic manipulation. Small, prospective, randomized controlled trials have lacked sufficient sample size to demonstrate differences in early and long-term outcomes. Larger observational studies that are better powered to statistically compare outcomes have shown more favorable in-hospital outcomes and equivalent long-term outcomes with OPCAB and ONCAB. The benefits of OPCAB techniques may be more apparent for patients at high risk for complications associated with CPB and aortic manipulation. Recent studies have demonstrated improved outcomes in higher-risk patients undergoing OPCAB, as well as improved neurological outcomes. The purpose of this review is to outline the recent literature comparing OPCAB with ONCAB, and to demonstrate efficacy of OPCAB as a useful technique for coronary revascularization.

Comparison of long-term outcome of off-pump coronary artery bypass grafting versus drug-eluting stents in triple-vessel coronary artery disease

After the introduction of drug-eluting stents (DESs), percutaneous coronary intervention with DESs has challenged coronary artery bypass grafting as the gold standard for the treatment of 3-vessel coronary artery disease. The purpose of this study was to compare the long-term clinical results between percutaneous coronary intervention with DESs and off-pump coronary artery bypass grafting (OPCAB) in 3-vessel coronary artery disease. Two hundred ninety propensity-score matched patients with 3-vessel coronary artery disease treated by DESs or OPCAB were included. Mean follow-up duration was 58.8 ± 11.5 months (2 to 73) and follow-up rate was 97.9%. Five-year survival rates were 94.8 ± 2.1% in the DES group and 96.5 ± 1.5% in the OPCAB group (p = 0.658). Five-year rates of freedom from major adverse cardiac and cerebrovascular event were 71.6 ± 4.1% in the DES group and 89.6 ± 2.5% in the OPCAB group (p < 0.001). Freedom from nonfatal myocardial infarction and target vessel revascularization rates were the determining factors between the 2 groups (p = 0.018 and p < 0.001, respectively). The OPCAB group showed better clinical outcomes compared to the DES group in 3-vessel coronary artery disease after 5-year follow-up. Freedom from major adverse cardiac and cerebrovascular event rate was significantly higher in the OPCAB group mainly because of the lower incidence of target vessel revascularization and nonfatal myocardial infarction. Longer follow-up with randomization will clarify our present conclusions.

Have improvements in myocardial protection influenced a surgeon's choice of coronary artery bypass surgery?

The aim of this study is to determine whether improvements in myocardial protection strategy have influenced the surgeon's choice of coronary artery bypass surgery. Between February 2002 and April 2009, a total of 662 patients underwent coronary artery bypass surgery under the provision of a single consultant surgeon. Operative mortality was defined as in-hospital death and comparison was made based on both the observed and expected mortalities as derived from the logistic EuroSCORE. Of the 662 patients who underwent cardiac surgery, 155 had off-pump whilst 507 had conventional coronary artery bypass surgery. The observed mortalities improved over the years in line with the improvements in myocardial protection strategy despite the increasing risk as predicted by the logistic EuroSCORE, with a reduction in the ratio of observed to expected mortalities of 1.2 in the off-pump group to 0.4 in the conventional group who had better myocardial protection. This has lead to a change in practice being predominantly off-pump at the beginning to that of conventional surgery in the later part of the study. As the case mix of patients gets worse with the increasing severity of multi-vessel disease and poor ventricular function, myocardial protection becomes crucial to the surgeon's preoperative assessment.

Current practice and outcomes of off-pump multivessel coronary artery bypass

Outcomes of off-pump multivessel coronary artery bypass were compared with those of the on-pump procedure. From July 2001 to June 2006, 3,637 patients with multivessel coronary disease underwent off-pump coronary artery bypass, and 3,586 patients had on-pump coronary artery bypass in our center. The rates of operative mortality, permanent stroke, renal failure and perioperative myocardial infarction were significantly lower in the off-pump group, and these patients required fewer blood transfusions, shorter durations of ventilatory support, and shorter hospital stays. However, the patients who underwent on-pump coronary artery bypass were considered more high-risk and tended to have more complex procedures.

Fewer grafts performed in off-pump bypass surgery: patient selection or incomplete revascularization?

BACKGROUND

Comparisons of off-pump (OPCAB) versus conventional on-pump coronary artery bypass (CCAB) consistently report fewer grafts per patient with OPCAB. Performing fewer grafts than indicated based on angiographic assessment could result in incomplete revascularization. We questioned whether OPCAB influenced surgeons to perform fewer grafts than needed.

METHODS

Preoperative angiographic and surgical data were collected prospectively on 945 patients undergoing coronary artery bypass grafting (370 OPCAB, 575 CCAB) at 8 hospitals between February 1, 2004, and July 31, 2004. The number of grafts needed per patient was determined from the reported number of vessels with angiographic stenoses of 50% or greater, and compared with the number received per patient, stratified by coronary artery bypass grafting technique.

RESULTS

The OPCAB and CCAB groups were demographically similar. The mean number of grafts needed per patient was significantly less in the OPCAB group (2.95 versus 3.48), accounting for fewer grafts received in that group (2.75 versus 3.36). The ratio of grafts (received/needed) was the same in both groups. Patients receiving more than three grafts were more likely to have CCAB (71.2%), whereas those receiving fewer than three grafts were almost as likely to have OPCAB as CCAB (55.5%). The rate of 1-year major adverse events (death, myocardial infarction, repeat revascularization) was the same in OPCAB and CCAB (15.5% versus 14.1%; p = 0.57).

CONCLUSIONS

Completeness of revascularization, determined by comparing the number of grafts performed to the number needed, was equivalent in OPCAB and CCAB patients, and 18-month clinical outcomes were equivalent. Preferential selection of patients needing more bypass grafts to CCAB results in the lower mean number of grafts per patient with OPCAB.

The choice of on- or off-pump coronary bypass grafting--a surgeon's dilemma

BACKGROUND

Off-pump coronary bypass grafting (OPCAB) is a routine method of heart revascularization. This study was designed to compare the results of OPCAB and ONCAB performed by a single surgeon at our institution over a 3-year period.

METHODS

The study enrolled 345 patients undergoing elective myocardial revascularization procedures, of which 173 (50.1%) were OPCAB and 172 (49.9 %) were ONCAB. The postoperative outcomes of both groups were analyzed, retrospectively.

RESULTS

The mean number of grafts was significantly lower in the OPCAB group (2.9) than in the ONCAB group (3.7). There were no postoperative myocardial infarctions or hospital deaths in any of the patients. The postoperative total blood loss was significantly higher in the ONCAB group. The frequencies of postoperative confused states, strokes, postoperative transfusions, reoperations for bleeding, and atrial fibrillation, and the durations of intubation, ICU stay, and hospital stay did not differ significantly between the two groups.

CONCLUSIONS

The OPCAB procedures are safe and provide good clinical outcomes, similar to those of ONCAB operations. The outcomes of this study favor neither of the compared techniques.

Coagulation and fibrinolytic protein kinetics in cardiopulmonary bypass

The development of Cardiopulmonary Bypass (CPB) catopulted the field of cardiothoracic surgery into a new dimension--one that changed the lives of individuals with congenital and acquired heart disease worldwide. Despite its contributions, CPB has clear limitations and creates unique challenges for clinicians and patients alike, stemming from profound hemostatic pertubations and accompanying risk for bleeding and possibly thrombotic complications.