Off-pump coronary artery bypass grafting: initial experience at one community hospital

Morphologic Evaluation of the Mitral Annulus During Displacement of the Heart in Off-Pump Coronary Artery Bypass Surgery

OBJECTIVE

To evaluate the morphologic changes of the mitral annulus using 3-dimensional transesophageal echocardiography during heart displacement to expose the anastomosis site in off-pump coronary artery bypass surgery (OPCAB).

DESIGN

Prospective case series.

SETTING

Single center, university hospital.

PARTICIPANTS

The study comprised 34 consecutive patients who underwent OPCAB of the left circumflex artery (LCX) and the right coronary artery (RCA).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Mitral annulus parameters were measured using the Mitral Valve Quantification program after sternotomy (physiologic position) and during displacement of the heart to expose the LCX (LCX position) and the RCA (RCA position). The height of the mitral annulus was significantly lower in the LCX (5.76 ± 0.90 mm) and RCA (5.92 ± 0.97 mm) positions than in the physiologic position (6.96 ± 0.99 mm; both p < 0.0001). The percent change in the height of the mitral annulus was significantly greater in the mitral regurgitation group than in the mitral regurgitation nondeterioration group when in the LCX (-16.3% ± 6.0% v -11.9% ± 3.3%, p = 0.0203) and RCA (-16.9% ± 6.3% v -12.1% ± 3.8%, p = 0.0207) positions. The anteroposterior and intercommissural diameters, annulus perimeter, and surface area of the mitral annulus did not differ significantly among all heart positions.

CONCLUSIONS

The mitral annulus flattened and lost its saddle shape without expanding while in the LCX and RCA positions. The greater percent change in the height of the mitral annulus may aggravate mitral regurgitation.

Neurocognitive outcomes of off-pump versus on-pump coronary artery bypass: a prospective randomized controlled trial

BACKGROUND

Preliminary reports have documented the safety of off-pump coronary artery bypass graft compared with conventional coronary artery bypass graft surgery. Whereas off-pump coronary artery bypass graft surgery may be associated with improvement in some short-term outcomes, longer-term outcomes and influence on neurocognitive function have not been fully assessed. We examined short-term and intermediate-term neurocognitive and index admission morbidity and mortality after coronary artery bypass surgery performed with and without the use of extracorporeal circulation.

METHODS

We prospectively randomly assigned 201 patients undergoing nonemergent isolated coronary artery bypass graft surgery to conventional coronary artery bypass graft surgery (n = 102) or off-pump coronary artery bypass graft surgery (n = 99). The primary end points of the study were neurocognitive function assessed using a 19-test neurocognitive battery at baseline, discharge, and 6 months. Neurocognitive deficit was defined as a 20% or greater reduction from baseline in at least 20% of the tests. Secondary end points included index admission mortality, stroke, low-output cardiac failure, return to the operating room for bleeding, and postoperative troponin release. Risk ratios and 95% confidence intervals were calculated based on intention-to-treat analysis.

RESULTS

There was no difference in neurocognitive deficit at discharge (discharge versus preoperative: risk ratio, 0.83; 95% confidence interval, 0.65 to 1.07) or at 6 months (6 months versus preoperative: risk ratio, 0.94; 95% confidence interval, 0.70 to 1.28). There was no significant difference in mortality or morbidity between the two groups. The off-pump coronary artery bypass graft group had fewer patients with troponin release than the conventional coronary artery bypass graft group.

CONCLUSIONS

Off-pump coronary artery bypass graft surgery did not result in decreased frequency of neurocognitive deficit. Off-pump coronary artery bypass graft surgery was associated with substantially lower levels of troponin release after surgery.

Can the EuroSCORE predict the early and mid-term mortality after off-pump coronary artery bypass grafting?

BACKGROUND

This study evaluated the role of the European System for Cardiac Operative Risk Evaluation (EuroSCORE) in the prediction of early-term and mid-term mortality in patients undergoing isolated off-pump coronary artery bypass grafting (OPCAB).

METHODS

From January 2002 to August 2006, 757 consecutive patients underwent isolated OPCAB. The patients' operative risks were calculated according to the standard and logistic EuroSCORE models. The cohort was classified into four subgroups according to both EuroSCORE scales. To evaluate the predictability, the expected mortality was compared with the observed mortality. The receiver operating characteristic curves were plotted and calibration was assessed. Mean follow-up was 32.8 +/- 13.9 months.

RESULTS

Ten (1.3%) in-hospital deaths occurred. The predicted total numbers of deaths by the EuroSCORE models were 34.2 (4.5%) for the standard EuroSCORE and 37.8 (5.0%) for the logistic EuroSCORE. The expected mortality rates were significantly higher than the observed mortality rates in all subgroups, except one. The area under curve (AUC) in in-hospital mortality was 0.72 for the standard EuroSCORE and 0.71 for the logistic EuroSCORE, but the tests of calibration for both EuroSCORE models were significant. Mid-term mortality was 3.6%. The AUC curve in mid-term mortality was 0.71 for the standard or logistic EuroSCORE. The calibration in both EuroSCORE models for mid-term mortality was nonsignificant, indicating good calibration.

CONCLUSIONS

Both EuroSCORE models overestimated the in-hospital mortality; however, both models showed good predictability for mid-term mortality. The EuroSCORE could be helpful in planning resource allocation and tailoring follow-up for patients undergoing isolated OPCAB.

Cardiac troponin T levels in on- and off-pump coronary artery bypass surgery

BACKGROUND

Conventional coronary artery bypass graft surgery (CCAB) has been associated with greater myocardial injury than off-pump surgery (OPCAB). However, the extent of myocardial injury following CCAB and OPCAB has not been assessed by priority of surgery or the number of diseased vessels. We tested the hypothesis that the additional myocardial injury associated with CCAB compared with OPCAB is sustained when patients are stratified by priority and 2- or 3-vessel disease.

METHODS AND RESULTS

In this prospective cohort, we measured 24-hour postoperative cardiac troponin T (cTnT) following CCAB and OPCAB surgery to determine if OPCAB results in less perioperative myocardial damage by priority (urgent or elective). We studied 1511 patients who underwent heart surgery in one hospital in northern New England between 2000 and 2004. Surgeons used either CCAB (778 patients) of OPCAB (733 patients). Unpaired t tests were used to test the mean difference in cTnT between CCAB and OPCAB subgroups. Mean cTnT levels were significantly higher in the CCAB group (0.94 ng/mL) than the OPCAB group (0.18 ng/mL) with P < .001; this difference was consistent across urgent and elective surgeries, and patients with both 2- and 3-vessel disease. CCAB patients consistently demonstrated higher cTnT levels. Similar results were evident when stratified by patient characteristics and surgeon.

CONCLUSIONS

In summary, higher postoperative cTnT levels are associated with CCAB than with OPCAB, regardless of priority, number of diseased vessels, patient characteristics, or surgeon. OPCAB results in less myocardial injury in patients, whether they present with 2- or 3-vessel disease and whether they undergo urgent or elective cardiac surgery.

Neurologic Injury Associated with CABG Surgery: Outcomes, Mechanisms, and Opportunities for Improvement

Neurologic injuries, whether subtle or overt, are a major source of morbidity secondary to coronary artery bypass graft (CABG) surgery. A comprehensive review of research in the area of neurologic injury is provided. We conclude this article by providing insight regarding areas requiring further investigation in order to reduce sustainably the risk of these iatrogenic events among patient undergoing CABG surgery.

[Off-pump versus on-pump coronary artery bypass surgery. Comparison of 270 case-matched elderly patients]

INTRODUCTION

Off-pump versus on-pump coronary artery bypass surgery: it still remains a matter of debate which method results in a lower incidence of perioperative morbidity and mortality. This case-matched study evaluates the outcome of elderly patients in both groups.

METHODS

All patients aged 75 and older, who underwent CABG from 1998 to 2002, were examined retrospectively. They were matched according to Euroscore and the number of diseased vessels. The Student's t-test and chi-square test were used where appropriate.

RESULTS

270 CABG patients were considered: 135 off-pump and 135 on-pump patients. Mean age was 78.4 +/- 3.1 versus 77.5 +/- 2.9 years, respectively. EuroSCORE was 7.11 +/- 2.3 in both groups; number of distal anastomoses per patient 1.7 +/- 0.74 versus 2.6 +/- 0.63 (p < 0.001), operation time 138 versus 177 minutes (p < 0.001). There were no significant differences in postoperative complications including hospital mortality 3.0 versus 3.7%, renal failure 8.9 versus 12.1% (new onset), acute myocardial infarction 1.5 versus 4.4% and cerebral events 0 versus 1.5%, respectively. The number of transfused packed cells was 2.6 +/- 2.8 versus 4.6 +/- 5.3 (p < 0.001). Intubation time and ICU stay were similar in both groups.

CONCLUSION

OPCAB is not associated with a reduction of perioperative mortality and morbidity in patients aged 75 and older.

A prospective, randomized study of endothelin and postoperative recovery in off-pump versus conventional coronary artery bypass surgery

OBJECTIVE

The objectives are 2-fold: (1). to serially determine endothelin (ET) levels in arterial vascular compartments in patients undergoing coronary artery bypass surgery using either cardiopulmonary bypass or off-pump techniques, and (2). to define potential relationships between endothelial levels and specific perioperative parameters of patient recovery.

METHODS

In a prospective, randomized study, endothelin plasma content was measured from patients undergoing coronary artery bypass grafting using either off-pump techniques (OPCAB group, n = 25) or conventional cardiopulmonary bypass (CPB group, n = 25) before surgery, before and after coronary artery anastomosis, and 6 and 24 hours postoperatively. Specific indices of patient recovery including pulmonary artery pressures, ventilation requirement, and hospital stay were documented for patients in both study groups.

RESULTS

Postoperative systemic arterial ET levels were significantly increased by 200% in the CPB group and 50% in the OPCAB group. ET levels remained significantly higher in the CPB group relative to the OPCAB group throughout the postoperative period of observation (p < 0.05). Pulmonary artery pressures, ventilation requirement, and hospital stay were significantly increased in patients in the CPB group.

CONCLUSIONS

Postoperative ET levels were higher in patients who underwent CPB for coronary artery bypass surgery. Increased ET in the postoperative period may contribute to a more complex recovery from coronary artery bypass surgery in patients undergoing cardiopulmonary bypass.

Meta-analysis of short-term and mid-term outcomes following off-pump coronary artery bypass grafting

BACKGROUND

Uncertainty continues to surround the relative benefits and harms of conventional coronary artery bypass grafting (CABG) and off-pump coronary artery bypass grafting (OPCABG). Possible reasons are that high-quality studies have not comprehensively examined relevant patient outcomes and have enrolled a limited range of patients. Some studies may have been too small to detect clinically important differences in patient outcomes. The present study addresses these issues using meta-analysis.

METHODS

We comprehensively retrieved randomized and nonrandomized controlled studies according to predetermined criteria. We performed meta-analyses for each outcome and empirically determined whether potential biases that might result from differences in study design or patient characteristics actually biased a study's results. We also conducted sensitivity analyses and tested for publication bias.

RESULTS

Rates of perioperative myocardial infarction, stroke, reoperation for bleeding, renal failure, and mortality were lower after OPCABG than after CABG. Reductions in length of hospital stay, atrial fibrillation, and wound infection were also associated with OPCABG, but statistically significant differences among study results for these outcomes could not be explained by available information. Midterm (3 to 25 months) angina recurrence did not appear to differ between treatments; a trend was noticed toward lower reintervention rates with CABG, and a trend toward lower overall mortality with OPCABG, at least when performed at experienced centers. These midterm outcome results require confirmation.

CONCLUSIONS

Off-pump coronary artery bypass grafting appears to reduce length of hospital stay, operative morbidity, and operative mortality relative to on-pump CABG. More studies are required before firm conclusions can be drawn concerning the effect of OPCABG on midterm mortality, angina recurrence, and repeat intervention.

Determination of etiologic mechanisms of strokes secondary to coronary artery bypass graft surgery

BACKGROUND AND PURPOSE

Current research focused on stroke in the setting of coronary artery bypass graft (CABG) surgery has missed important opportunities for additional understanding by failing to consider the range of different stroke mechanisms. We developed and implemented a classification system to identify the distribution and timing of stroke subtypes.

METHODS

We conducted a regional study of 388 patients with the diagnosis of stroke after isolated CABG surgery in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Stroke etiology was classified into 1 of the following: hemorrhage, thromboembolic (embolic, thrombotic, lacunar), hypoperfusion, other (subtype not listed above), multiple (>or=2 competing mechanisms), or unclassified (unknown mechanism). The reliability of the classification system was determined by percent agreement and kappa statistics.

RESULTS

Embolic strokes accounted for 62.1% of strokes, followed by multiple etiologies (10.1%), hypoperfusion (8.8%), lacunar (3.1%), thrombotic (1.0%), and hemorrhage (1.0%). There were 54 strokes with unknown etiology (13.9%). There were no strokes classified as "other." Nearly 45% (105/235) of the embolic and 56% (18/32) of hypoperfusion strokes occurred within the first postoperative day.

CONCLUSIONS

We used a locally developed classification system to determine the etiologic mechanism of 388 strokes secondary to CABG surgery. The principal etiologic mechanism was embolic, followed by stroke having multiple mechanisms and hypoperfusion. Regardless of mechanism, strokes predominantly occurred within the first postoperative day.

Off-pump coronary artery bypass graft surgery: the incidence of postoperative atrial fibrillation

Atrial fibrillation (AF) occurs in one quarter to one third of patients after coronary artery bypass graft surgery (CABG). Conventional CABG uses cardiopulmonary bypass, a process that is itself associated with a systemic vascular inflammatory response that contributes to postoperative morbidity. The avoidance of cardiopulmonary bypass is associated with a significant reduction in the inflammatory response and in the release of markers of myocardial necrosis when compared with conventional CABG. There is speculation that off-pump CABG may reduce the incidence of postoperative AF through reduced trauma, ischaemia, and inflammation. Current data, however, do not emphatically answer the question of whether the incidence of post-CABG AF is reduced by off-pump surgery. The evidence from both observational and randomised studies is conflicting and many studies have weaknesses in design, conduct, or interpretation. It remains an attractive hypothesis that postoperative AF is reduced by off-pump CABG but more robust data are required.

A comparison of bleeding and transfusion in patients who undergo coronary artery bypass grafting via sternotomy with and without cardiopulmonary bypass

OBJECTIVE

To determine whether there is a difference between on-pump cardiopulmonary bypass (CABG) and off-pump coronary artery bypass grafting (OPCAB) without heparin reversal with regard to bleeding, transfusion requirements, and incidence of surgical re-exploration of the mediastinum.

DESIGN

Retrospective chart review.

SETTING

A large academic medical center.

PARTICIPANTS

Two hundred adult patients undergoing cardiac surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred CABG patients were compared with 100 OPCAB patients. Statistical significance was measured with P values of <or=0.05. The heparin was not reversed in the OPCAB patients. CABG patients received more intraoperative allogeneic red blood cells (median 250 mL v 0 mL, p = 0.002), intraoperative autotransfusion (IAT) (550 mL v 425 mL, p = 0.001), platelets (9% v 1%, p = 0.009), and less albumin (0 mL v 250 mL, p = 0.001) than OPCAB patients. Postoperatively, CABG patients were more likely to receive fresh-frozen plasma (19% v 8%, p = 0.03) and less likely to receive IAT than the OPCAB group. During the initial 4-hour postoperative period, OPCAB patients exhibited greater blood loss via chest tube (290 mL v 385 mL, p = 0.003); however, at 12 hours and 24 hours postoperatively, there was no statistical difference in blood loss between the 2 groups. There were no statistically significant differences in surgical re-exploration of the mediastinum between the CABG and OPCAB groups.

CONCLUSION

Despite not reversing the heparin at the end of the OPCAB surgery, OPCAB surgery was associated with an overall reduction in allogeneic transfusion requirements.

Mitral annulus distortion during beating heart surgery: a potential cause for hemodynamic disturbance--a three-dimensional echocardiography reconstruction study

BACKGROUND

Positioning for access to the coronary arteries leads to hemodynamic instability during off-pump cardiac surgery. External changes have been well described, but a description of the intracardiac structures in humans has not been described.

METHODS

With multiplane intraoperative echocardiography, the mitral annulus at end diastole was reconstructed in the different positions and correlated with hemodynamic changes in the right heart and left atrium.

RESULTS

Significant distortion of the mitral annulus with enlargement of the left atrium and pulmonary veins was demonstrated, which correlated with high left atrial pressures.

CONCLUSIONS

Mitral valve distortion can significantly contribute to hemodynamic instability during positioning for off-pump cardiac surgery.

Clinical outcomes of on-pump coronary bypass using heparin-bonded circuits and reduced anti-coagulation compare favorably with off-pump approach

Coronary artery bypass grafting (CABG) without cardiopulmonary bypass (CPB), or off pump, has gained popularity by avoiding the postoperative morbidity related to the use of CPB. Previously, we have demonstrated that CABG done on pump using heparin-bonded cardiopulmonary bypass circuits (HBC) with a lower anti-coagulation protocol (LAP) attenuates these effects, reduces homologous blood product requirement, and improves clinical outcome when compared with conventional CPB circuits. Our purpose in this study was to compare off-pump CABG clinical outcomes to on-pump CABG using HBC with LAP. We retrospectively analysed preoperative and postoperative variables of all primary CABG (n=1214) performed at this institution from 1 January 1997 to 28 July 2000. These patients were divided into the on-pump (n=1152) and off-pump groups (n=62). HBC with LAP were used in all on-pump CABG cases. There was no statistical difference in preoperative comorbid risk factors except percentage of females (on pump, 30% vs. off pump, 44%; p=0.02) and body surface area (on pump, 1.94 +/- 0.25 ml vs. off pump, 1.85 +/- 0.22 ml; p=0.02). There was no difference in intraoperative and postoperative complications, risk-adjusted mortality, total blood product usage, or length of stay. The mean number of distal anastomoses performed was significantly different (on pump, 3.5 +/- 0.82 vs. off pump 1.8 +/- 0.82; p < 0.001). Despite similar preoperative risk factors, clinical outcomes and homologous blood requirements were not statistically different between the off-pump and on-pump groups. These endpoints should not be the only criteria to justify performing off-pump CABG.

Off-pump coronary artery bypass grafting: new developments but a better outcome?

Off-pump coronary artery surgery is now performed safely and effectively without cardiopulmonary bypass. This review includes indications, approaches, anaesthetic and haemodynamic management, and compares the occurrence of postoperative complications and multiorgan dysfunction with conventional cardiac surgery.

The coronary artery bypass conduit: II. Assessment of the quality of the distal anastomosis

The outcome of coronary artery bypass grafting procedures is highly dependent on the technical adequacy of the distal anastomosis. Various methodologies, including flow measurement and imaging techniques, have been used by the cardiothoracic surgeon to assess the adequacy of the distal anastomosis. The limitations of these techniques outweigh their advantages and limit their widespread clinical applicability. Recent improvements in the technique for online measurement of regional myocardial pH provide a promising new metabolic approach to assessing the adequacy of the distal anastomosis in cardiac surgery.

In-hospital outcomes of off-pump versus on-pump coronary artery bypass procedures: a multicenter experience

BACKGROUND

Concern about the possible adverse effects of the cardiopulmonary bypass (CPB) pump and advances in retractors and operative techniques to access all coronary segments have resulted in increased interest in off-pump coronary artery bypass (OPCAB) procedures. Four of the Northern New England Cardiovascular Disease Study Group centers initiated OPCAB programs in 1998. We compared the preoperative risk profiles and in-hospital outcomes of patients done off-pump with those done by conventional coronary artery bypass (CCAB) with CPB.

METHODS

Between 1998 and 2000, 1,741 OPCAB and 6,126 CCAB procedures were performed at these four medical centers. Minimally invasive direct coronary artery bypass grafting procedures were excluded. Data were available for patient and disease risk factors, extent of coronary disease and adverse in-hospital outcomes.

RESULTS

The OPCAB and CCAB groups were somewhat different in their preoperative patient and disease characteristics. The OPCAB patients were more likely to be female and to have peripheral vascular disease. The CCAB patients were more likely to have an ejection fraction less than 0.40 and be urgent or emergent at operation. However, overall predicted risk of in-hospital mortality, based on preoperative factors, was similar in the OPCAB and CCAB groups; the mean predicted risk was 2.6% (p = 0.567). Crude rates of mortality (2.54% OPCAB versus 2.57%, CCAB), intraoperative or postoperative stroke (1.33% versus 1.82%), mediastinitis (1.10% versus 1.37%), and return to the operating room for bleeding (3.46% versus 2.93%) did not differ significantly. The OPCAB patients did have a statistically significant reduction in the need for intraoperative or postoperative intraaortic balloon pump support (2.31% versus 3.41%; p = 0.023) and in the incidence of postoperative atrial fibrillation (21.21% versus 26.31%; p < 0.001). Adjustment for preoperative risk factors and extent of coronary disease did not substantially change the crude results. Median postoperative length of stay was significantly shorter (5 days versus 6 days, p < 0.001) for OPCAB patients than for CCAB patients.

CONCLUSIONS

This multicenter study showed that patients having OPCAB are not exposed to a greater risk of short-term adverse outcomes. These data also provided evidence that patients having OPCAB have significantly lower need for intraoperative or postoperative intraaortic balloon pump, lower rates of postoperative atrial fibrillation, and a shorter length of stay.