Clinical outcomes and resource usage in 100 consecutive patients after off-pump coronary bypass procedures

Effect of Pre-operative Angiotensinconverting Enzyme Inhibitors on Haemodynamic Parameters and Vasoconstrictor Requirements in Patients Undergoing Off-pump Coronary Artery Bypass Surgery

The effects of pre-operative angiotensin-converting enzyme inhibitor (ACEI) treatment on haemodynamic status and vasoconstrictor requirements during off-pump coronary artery bypass surgery (OPCAB) were studied. Eighty patients selected for OPCAB were divided into those who had been treated with ACEIs for 4 weeks or more pre-operatively (ACEI group) (n = 43) and those who had not been treated with ACEIs (control group) (n = 37). Noradrenaline was infused during the operation when the mean systemic arterial pressure (SAP) fell below 60 mmHg. No significant differences in the haemodynamic parameters measured were detected between the two groups, except for cardiac output, which was found to be significantly greater in the control group. During anastomosis of the obtuse marginal branch of the left circumflex artery (OM), a significantly larger amount of noradrenaline was required by the ACEI group compared with the control group. In conclusion, pre-operative treatment with ACEIs significantly increased the amount of vasoconstrictor necessary to maintain the target SAP during OM anastomosis during OPCAB.

The effect of milrinone infusion on right ventricular function during coronary anastomosis and early outcomes in patients undergoing off-pump coronary artery bypass surgery

Background

During coronary anastomosis in off-pump coronary artery bypass surgery (OPCAB), hemodynamic alternations can be induced by impaired diastolic function of the right ventricle. This study was designed to examine the effect of milrinone on right ventricular function and early outcomes in patients undergoing OPCAB.

Methods

Forty patients undergoing OPCAB were randomly assigned in a double-blind manner to receive either milrinone (milrinone group, n = 20) or normal saline (control group, n = 20). Hemodynamic variables were measured after pericardiotomy (T1), 5 min after stabilizer application for anastomosis of the left anterior descending coronary artery (LAD, T2), the obtuse marginalis branch (OM, T3), the right coronary artery (RCA, T4), 5 min after sternal closure (T5), and after ICU arrival. The right ventricular ejection fraction (RVEF) and right ventricular volumetric parameters were also measured using the thermodilution technique. For evaluation of early outcomes, the 30-day operative mortality and morbidity risk models were used.

Results

There was no significant difference in hemodynamic variables, including mean arterial pressure, between the 2 groups, except for the cardiac index and RVEF. The cardiac index and RVEF were significantly greater at T3 in the milrinone group than in the control group.

Conclusions

Continuous infusion of milrinone demonstrated a beneficial effect on cardiac output and right ventricular function in patients undergoing OPCAB, especially during anastomosis of the graft to the OM artery, and it had no adverse effect on early outcomes.

The real-world outcomes of off-pump coronary artery bypass surgery in a public health care system

BACKGROUND

The population-based results of off-pump coronary artery bypass surgery (OPCAB) in a public health care system have not been reported.

OBJECTIVE

The study objective was to compare the one-year outcomes of OPCAB with those of the standard on-pump coronary artery bypass surgery (ONCAB) in the province of Ontario.

METHODS

The present study was a retrospective, population-based study (n=15,172, with 1660 OPCAB patients) undertaken in fiscal years 2000 and 2001 using clinical and administrative data. Multivariate regression modelling for risk adjustment and propensity matching were used to compare OPCAB with ONCAB for one-year outcomes, including death, repeat revascularization and cardiac readmission.

RESULTS

The rate of OPCAB was 11%, with institutional rates ranging from 3% to 51%. OPCAB patients were more likely to be female and older than 79 years of age, with peripheral vascular disease and higher socioeconomic status. OPCAB patients were less likely to have surgically significant coronary disease, poor left ventricular function, an urgent status, congestive heart failure and diabetes. The risk-adjusted one-year composite outcome was higher for OPCAB (11.8%, 95% CI 10.40% to 13.29%) than ONCAB (10.8%, 95% CI 10.23% to 11.27%); however, this difference was eliminated with propensity matching. OPCAB patients had shorter hospital lengths of stay and lower blood product transfusion rates than ONCAB patients.

CONCLUSIONS

Despite the minimal use of OPCAB in Canada's public health care system, outcome rates are similar to those of ONCAB. The benefits of OPCAB observed in randomized trials, including shorter hospital lengths of stay and lower transfusion rates, remained true in the investigators' real-world experience. The results OPCAB were at least equivalent to those of ONCAB.

Short-Term Complications and Resource Utilization in Matched Subjects After On-Pump or Off-Pump Primary Isolated Coronary Artery Bypass

• Background Studies suggest that patients who undergo off-pump coronary artery bypass grafting (OPCABG) have fewer short-term complications and use fewer inpatient resources than do patients who undergo standard coronary artery bypass grafting (CABG) with extracorporeal circulation. However, dissimilarity between groups in risk factors for complications has hindered interpretation of results.

• Objectives To compare the prevalence of selected complications (atrial fibrillation, stroke, reoperation, and bleeding) and inpatient resource utilization (length of stay, discharge disposition, total charges) between subjects undergoing primary isolated CABG or OPCABG who were matched with respect to key risk factors.

• Methods Retrospective, causal-comparative survey conducted in 1 center for 18 months. Patients who underwent primary isolated CABG or OPCABG were matched for sex, age (within 2 years), left ventricular ejection fraction (within 0.05), and graft-patient ratio (exact match) and compared for prevalence of new-onset atrial fibrillation, stroke, reoperation within 24 hours, and bleeding. Statistical analysis included Wilcoxon and t tests for paired comparisons.

• Results The sample (107 matched pairs) was 63% male, with a mean age of 66 (SD 9.5) years, a mean left ventricular ejection fraction of 0.51 (SD 0.13), and a mean graft-patient ratio of 3.41 (SD 0.74). The 2 groups did not differ significantly in New York Heart Association class (P = .43), Acute Physiology and Chronic Health Evaluation III score (P = .22), postoperative β-blocker use (P = .73), or comorbid conditions. None of the complications examined differed significantly between pairs.

• Conclusion Patients with comparable risk profiles have similar prevalences of selected complications after CABG and OPCABG.

Comparison of off-pump and on-pump coronary artery bypass grafting in midterm results

OBJECTIVE

Off-pump coronary artery bypass grafting (OPCAB) has become a procedure of choice for surgical treatment of coronary artery disease. Although early advantages of OPCAB were confirmed in comparison with conventional on-pump coronary artery bypass grafting (CABG), late cardiac complications are still controversial. We examined midterm results of OPCAB compared with standard CABG.

METHODS

Between July 1997 and April 2002, 736 consecutive patients who underwent isolated CABG were retrospectively reviewed. The OPCAB group (Group I) comprised 357 patients (49%), and the on-pump CABG group (Group II) 379 patients (51%). Their preoperative, intraoperative, and follow-up data were analyzed.

RESULTS

The mean number of distal anastomoses and the early graft patency were not greatly different between the two groups. The actuarial survival rate at 3 years was not significantly different between Group I (98.3%) and Group II (98.2%) (p = 0.71). The frequency of cardiac events was 4.2%/patient-year in Group I and 2.6%/patient-year in Group II (p = 0.12). The actuarial event free rates were not different between the two groups (p = 0.61). The cardiac event free rates at 3 years were significantly (p = 0.011) higher in patients with complete revascularization (96.7%) than without complete revascularization in Group I (69.2%) and in Group II (92.7% versus 85.9%, p = 0.026).

CONCLUSIONS

Midterm clinical outcome in OPCAB is as good as conventional on-pump CABG. Incomplete revascularization caused cardiac events more frequently than complete revascularization both in OPCAB and on-pump CABG in the intermediate follow-up.

Off-pump coronary artery bypass surgery: physiology and anaesthetic management †

Increasing interest is being shown in beating heart (off-pump) coronary artery surgery (OPCAB) because, compared with operations performed with cardiopulmonary bypass, OPCAB surgery may be associated with decreased postoperative morbidity and reduced total costs. Its appears to produce better results than conventional surgery in high-risk patient populations, elderly patients, and those with compromised cardiac function or coagulation disorders. Recent improvements in the technique have resulted in the possibility of multiple-vessel grafting in all coronary territories, with a graft patency comparable with conventional surgery. During beating-heart surgery, anaesthetists face two problems: first, the maintenance of haemodynamic stability during heart enucleation necessary for accessing each coronary artery; and second, the management of intraoperative myocardial ischaemia when coronary flow must be interrupted during grafting. The anaesthetic technique is less important than adequate management of these two major constraints. However, experimental and recent clinical data suggest that volatile anaesthetics have a marked cardioprotective effect against ischaemia, and might be specifically indicated. OPCAB surgery requires team work between anaesthetists and surgeons, who must be aware of each other's constraints. Some surgical aspects of the operation are reviewed along with physiological and anaesthetic data.

Perfusion-assisted direct coronary artery bypass provides early reperfusion of ischemic myocardium and facilitates complete revascularization

BACKGROUND

Perfusion-assisted direct coronary artery bypass (PADCAB) was developed to initiate early reperfusion of grafted coronary artery segments during off-pump operations to resolve episodes of myocardial ischemia and avoid its sequelae. This case series outlines intraoperative findings and clinical outcomes of our first year clinical experience with PADCAB.

METHODS

From November 1999 to November 2000, 169 PADCAB and 358 off-pump coronary artery bypass procedures were performed at the Emory University Hospitals. The decision to use PADCAB was predicated on surgeon preference. Perfusion pressure and flow, amount of intracoronary nitroglycerin, and total perfusion time and volume were recorded at the time of operation.

RESULTS

One off-pump coronary artery bypass patient required emergent conversion to cardiopulmonary bypass. Two PADCAB patients had ischemic ventricular arrhythmias during target vessel occlusion that resolved once active perfusion had begun. Perfusion pressure in PADCAB grafts was on average 44% higher than mean arterial pressure (p < 0.001). Nitroglycerin, infused locally by PADCAB, was used in 67 patients to resolve ischemic episodes and increase initial coronary flows. The mean number of diseased coronary territories and grafts placed was 2.8 +/- 0.5 and 3.4 +/- 0.7, respectively, in the PADCAB group, and 2.3 +/- 0.8 and 2.7 +/- 1.0, respectively, in the off-pump coronary artery bypass group (p < 0.001 for both comparisons). More PADCAB patients received lateral wall grafts than off-pump coronary artery bypass patients (83.4% vs 59.4%; p < 0.001). Hospital death and postoperative myocardial infarction were not different between groups.

CONCLUSIONS

PADCAB can provide suprasystemic perfusion pressures and a means to add vasoactive drugs to target coronary vessels. PADCAB provides early reperfusion of ischemic myocardium and facilitates complete revascularization of severe multivessel coronary artery disease.

Cost comparisons of pharmacological strategies in open-heart surgery

Open-heart surgery (OHS) is performed to bypass occluded arteries, replace malfunctioning cardiac valves or correct congenital abnormalities. The average cost of OHS varies from $US25 057-$US79 795 (1997 values). The objective of this paper was to review economic studies of pharmacological strategies in open-heart surgery. Pharmacological strategies studied include the prevention of postoperative complications such as atrial fibrillation (AF), bleeding and infection. Modifications in anaesthetic technique have been attempted by using agents that promote early extubation. In addition, strategies for postoperative management of sedation, analgesia and AF and use of neuromuscular blockers have also been compared. The majority of studies in this area have been cost analyses with few cost-effectiveness studies performed. Prophylaxis against AF with amiodarone is associated with a reduction in AF and was cost-neutral compared with placebo. Compared with placebo, prevention of bleeding with antifibrinolytics reduces transfusion costs. In direct comparative studies, lysine analogues, due to lower drug acquisition costs, offset transfusion costs to a greater extent than aprotinin. However, safety concerns with the lysine analogues remain. Erythropoietin decreases transfusion requirements and is cost effective compared with no intervention when the cost of postoperative bacterial complications is included. First- and second-generation cephalosporins prevent postoperative infections. Based on drug acquisition cost, the first-generation agents are less expensive although when administration costs are included, both classes have similar costs. Modifications in anaesthetic technique with short-acting anaesthetic agents, results in higher drug costs although nursing and total hospital costs are typically reduced. For neuromuscular blockers, drug acquisition costs are lowest with pancuronium but administration costs and the cost of adverse events have not been included in existing analyses. Midazolam provides an equivalent level of postoperative sedation to propofol but the acquisition cost is lower. The combined use of propofol and midazolam warrants further investigation, as its use is associated with lower sedative agent costs compared with either agent alone. There is limited data on the economics of postoperative analgesia and the management of AF. As the majority of studies to date are partial cost analyses, additional studies that include length of stay and other hospitalisation data are warranted. In future, cost-effectiveness and cost-utility studies, which incorporate quality of life and the cost of adverse effects and other longer term costs, should be undertaken.

Is Off-pump Coronary Artery Bypass Graft Surgery Cost-Saving?

One of the challenges in comparing the cost of off-pump coronary artery bypass surgery to conventional coronary artery bypass graft surgery with cardiopulmonary bypass is that most data are from observational studies, not randomized controlled trials. Thus, cost differences observed between groups may not be attributable to the difference in surgical technique, but to the underlying patient characteristics that ultimately led the patient to be selected to receive one procedure or another. The purpose of this study was to control for patient selection effects in observational data and estimate reductions in costs and length of stay attributable to the off-pump coronary artery bypass procedure. We studied 1172 patients (245 off-pump coronary artery bypass and 927 coronary artery bypass graft) undergoing coronary bypass graft surgery via a median sternotomy at the Lehigh Valley Hospital between January 1, 1999 and June 30, 2000. Propensity scores were used to match patients who received off-pump coronary artery bypass surgery to similar coronary artery bypass graft surgery patients. Logistic regression was used to estimate propensity scores and select 181 patients from the coronary artery bypass graft group for comparison to patients in the off-pump coronary artery bypass group. Statistical comparisons of continuous outcomes were made using the Student t test after a transformation to natural log scale to correct skewness. Patients in the off-pump group tended to be treated by surgeons with more experience with off-pump surgery (p=0.0001), relatively older (p-0.001), had fewer diseased vessels (p=0.0001), did not have previous coronary artery bypass graft surgery (p=0.01), and had elective (p=0.0002) or urgent (p=0.002) surgery rather than emergent or salvage surgery. Propensity score matched coronary artery bypass graft patients had significantly longer total LOS (p=0.02), postoperative length of stay (p=0.03), and total costs (p=0.016) than patients who underwent off-pump coronary artery bypass surgery. After correcting for selection effects, off-pump coronary artery bypass surgery was associated with 12% lower total costs, 14% fewer total and postoperative hospital days. This suggests that coronary artery bypass surgery without cardiopulmonary bypass is cost-saving at a large academic community medical center. Future research should consider whether off-pump coronary artery bypass surgery is also cost-effective.

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.

Off-Pump Coronary Artery Bypass Surgery: Revival of an Old Technique

The ability to perform surgical procedures on the heart was one of the greatest accomplishments of the 20th century. What was once considered an impossible task has become a routine in daily clinical activity. The in troduction of extracorporeal circulation and myocardial protection strategies opened the doors to what was considered by most an insurmountable barrier— unhin dered access to the coronary circulation and intracar diac structures. In the United States, approximately 85% of coronary artery bypass graft procedures are performed with the use of cardiopulmonary bypass (CPB). CPB was and remains the gold standard for this type of cardiac surgical intervention. Over the years, investigators have struggled to find ways of lessening or eliminating the adverse physiologic effects of CPB. These efforts have focused on pharmacologic interven tion, monitoring procedures, blood gas management, and temperature management. Another way of avoid ing these effects is inherently obvious — eliminate the main source of the problem.