Surgical revascularization for acute coronary insufficiency: analysis of risk factors for hospital mortality

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.

The current status of multi-arterial off-pump coronary artery bypass grafting

PURPOSE

Off-pump coronary artery bypass surgery has not become widespread because of its technical difficulty. However, especially in Asia, pioneer surgeons continue with efforts to develop the off-pump technique.

METHOD

By reviewing past studies, mainly retrospective single-center reports, an up-to-date profile of off-pump surgery was assembled.

RESULTS

Many of the past randomized trials failed to demonstrate the advantages of off-pump surgery. Although many of these were single-center retrospective studies, the data presented, mostly from world-famous surgeons, show that off-pump surgery does have advantages in high-risk patients and results in reduced rates of postoperative morbidity and equal rates of mortality in both the short- and long terms. Moreover, almost all experienced off-pump surgeons noted the benefit of multiple uses of arterial grafts, skeletonization harvesting of arterial conduits and the aorta no-touch technique.

CONCLUSION

The off-pump procedure has not become a standard technique performed by the average surgeon in daily practice. However, off-pump surgery will continue to provide a significant benefit to high-risk patients with coronary disease.

Optimal coronary artery bypass grafting strategy for acute coronary syndrome

OBJECTIVE

Conventional coronary artery bypass grafting (CABG) using cardiopulmonary bypass and cardiac arrest is associated with higher mortality and morbidity rates in acute coronary syndrome (ACS) patients undergoing surgery. Although off-pump CABG (OPCAB) is beneficial for high-risk patients, its efficacy for ACS is unknown, with on-pump beating CABG an adjunctive method. We investigated the effects of OPCAB and on-pump beating CABG for ACS.

METHODS

We evaluated 121 consecutive patients with ACS (91 males, 30 females; mean age 69.5 ± 10.3 years) who underwent CABG since 2000. Seventy-five had unstable angina (UA) and 46 acute myocardial infarction (AMI) [non-ST elevation (NSTEMI): 22, ST elevation (STEMI): 24]. We assessed CABG for acute coronary syndrome under our primary OPCAB strategy, and compared perioperative status between UA and AMI patients.

RESULTS

(1) Sixty-five (87 %) with UA underwent OPCAB, 8 on-pump beating CABG, and 2 conventional CABG. Conversion from OPCAB was seen in 4 patients. In-hospital mortality was 1.3 %. (2) All UA patients who had intra-aortic balloon pumping (IABP) underwent OPCAB. No patients with preoperative IABP experienced conversion from OPCAB. (3) In AMI patients, hospital mortality was higher (8.9 %) and the ratios for OPCAB, on-pump beating CABG, and conventional CABG were 39, 57, and 4 %, respectively. Mortality was exclusively seen in patients with STEMI who underwent conventional CABG.

CONCLUSIONS

OPCAB might have beneficial effects for ACS patients with UA, while IABP was found essential for completing OPCAB. In AMI patients, on-pump beating CABG might be reasonable for avoiding conversion from OPCAB and ischemic perfusion injury.

URGENT AND EMERGENCY CORONARY ARTERY BYPASS GRAFTING FOR ACUTE CORONARY SYNDROMES

BACKGROUND

Urgent and emergency coronary artery bypass grafting may be associated with significant mortality and morbidity. We report our recent experience with this group of patients.

METHODS

A retrospective analysis of 441 patients undergoing urgent and emergency surgery over a 3-year period was carried out. Multivariate analysis was used to identify subgroups of patients who were most at risk of death.

RESULTS

The 30-day mortality was 3.3 and 16.3% in the urgent and emergency groups, respectively. Urgent surgery was associated with significantly shorter duration of ventilation (16 h vs 69 h) and stay at the intensive care unit (31 h vs 102 h). The incidence of pneumonia, pulmonary embolism, renal failure and neurological events were also less in the urgent group. The preoperative use of the intra-aortic balloon pump was low (0.8% in the urgent group and 4.8% in the emergency group). Multivariate analysis showed that patients over 70 years of age (odds ratio 3.2, 95% confidence interval 1.1-9.5) with left main stenosis (odds ratio 4.4, 95% confidence interval 1.5-12.4) complicated by cardiogenic shock (odds ratio 17.8, 95% confidence interval 5.2-61.1) were at highest risk of death. Patients transferred directly to theatre from cardiac catheter laboratory following failed percutaneous interventions were found to be most at risk. Mortality in this group was 29%, with 50% patients being in shock and 36% having left main stenosis.

CONCLUSION

Satisfactory results have been obtained in urgent coronary artery bypass grafting, but acute coronary syndromes complicated by cardiogenic shock remain a high-risk group. Further studies are needed to define the optimal operative management in this group of patients.

Emergency Coronary Artery Bypass Graft Surgery for Acute Coronary Syndrome: Beating Heart Versus Conventional Cardioplegic Cardiac Arrest Strategies

BACKGROUND

Aim of this study was to compare the outcome of beating heart versus conventional coronary artery bypass graft (CABG) strategies in acute coronary syndromes for emergency indications.

METHODS AND RESULTS

638 consecutive patients with acute coronary syndrome (ACS) receiving emergency CABG surgery via midline sternotomy from January 2000 to September 2005 were evaluated. Propensity score analysis was used to predict the probability of undergoing beating heart (BH) (n=240) versus cardioplegic cardiac arrest (CA) (n=398) strategies. Patients presented with stable hemodynamics (n=531) or in cardiogenic shock (CS) (n=107). Hospital and follow-up outcome was compared by propensity score adjusted multiregression analysis. BH included 116 on-pump and 124 off-pump (OPCAB) procedures. There was a propensity to operate CS patients on the beating heart (multivariate odds ratio [OR], 3.8; P=0.001). Under stable hemodynamics significant predictors for BH selection were logEuroSCORE >20% (OR, 2.05), creatinine >1.8 mg/dL (OR, 4.12), complicated percutaneous coronary intervention (OR, 1.88), ejection fraction <30% (OR, 2.64), whereas left main disease (OR, 0.68), circumflex artery (OR, 0.32), and 3-vessel disease (OR, 0.67) indicated preference for cardioplegic arrest. Time from skin incision to culprit lesion revascularization was significantly reduced in BH patients. BH surgery led to a significant benefit in terms of less drainage loss, less transfusion requirement, less inotropic support, shorter ventilation time, lower stroke rate, and shorter intensive care unit stay. In CS, BH was associated with lower incidence of stroke, inotropic support, acute renal failure, new atrial fibrillation and sternal wound healing complications. In CS patients, hospital mortality rate was reduced when using beating heart strategies (P=0.048). Overall survival, major adverse cerebral and cardiovascular event rate, and repeated revascularization was comparable during a 5-year follow-up.

CONCLUSIONS

Beating heart strategies are associated with an improved hospital outcome and comparable long-term results for high-risk patients presenting acute coronary syndrome with or without CS.

Clinical outcomes of nonelective coronary revascularization with and without cardiopulmonary bypass

BACKGROUND

Patients who undergo emergent coronary artery bypass grafting pose a greater challenge in terms of intraoperative and postoperative mortality and morbidity compared to elective coronary artery bypass. Coronary artery bypass without cardiopulmonary bypass (off-pump coronary artery bypass) might benefit these high-risk patients by eliminating the cardiopulmonary bypass and therefore decreasing the systemic inflammatory response associated with it. The aim of this study was to compare the early clinical outcome after nonelective off-pump coronary artery bypass with a matched set of patients undergoing coronary artery bypass with cardiopulmonary bypass (on pump).

METHODS

Between January 2000 and October 2003, 2273 patients underwent nonelective (urgent or emergent) off-pump coronary artery bypass and were compared with a contemporaneous control group of 3487 patients undergoing on-pump coronary artery bypass. Logistic regression analysis was used to compare operative mortality, postoperative stroke, length of stay, postoperative placement of intra-aortic balloon pump, postoperative renal failure, and hemorrhage-related re-exploration between the groups, controlling for preoperative risk factors. The patients undergoing off-pump coronary artery bypass were matched to patients undergoing on-pump bypass by propensity scores.

RESULTS

Patients undergoing off-pump coronary artery bypass had comparable operative mortality (odds ratio, 0.8; 95% confidence interval, 0.57-1.15; P = .24) and stroke rate (odds ratio, 0.6; 95% confidence interval, 0.33-1.08; P = .09) with the patients undergoing on-pump coronary artery bypass after controlling for preoperative risk factors through matching. Off-pump coronary artery bypass was associated with an abbreviated length of stay (odds ratio, 0.5; 95% confidence interval, 0.47-0.64; P < .01), lower rate of postoperative renal failure (odds ratio, 0.5; 95% confidence interval, 0.37-0.72; P < .01), intra-aortic balloon pump placement (odds ratio, 0.5; 95% confidence interval, 0.3-0.71; P < .01), and hemorrhage-related re-exploration rate (odds ratio, 0.70; 95% confidence interval, 0.5-1.0; P = .5) compared with on-pump coronary artery bypass after matching by propensity scores.

CONCLUSIONS

Nonelective coronary revascularization without cardiopulmonary bypass is associated with comparable operative mortality and stroke and abbreviated length of stay. Off-pump coronary artery bypass might also decrease the need for intra-aortic balloon pump placement and lower the rate of postoperative renal failure and hemorrhage-related re-exploration compared with that of conventional on-pump coronary artery bypass in this subset of patients.

Off-Pump Coronary Artery Bypass Grafting for Acute Myocardial Infarction

BACKGROUND

The aim of this study was to evaluate the surgical results of off-pump coronary artery bypass grafting (OPCAB) for patients with acute myocardial infarction (AMI) within 14 days of the infarction.

METHODS AND RESULTS

From April 2000 to January 2005 among 841 patients who underwent OPCAB, 43 consecutive patients (5.1%) were examined. Mean age at operation was 69.5 years and mean time from the onset of AMI to surgery was 4.6 days. Seventeen patients (39.5%) had left main trunk disease. Three patients (7.0%) underwent OPCAB following unsuccessful percutaneous coronary intervention, and 1 patient (2.3%) underwent redo procedure 9 years after previous coronary artery bypass grafting (CABG). Six patients (14%) were admitted in cardiogenic shock. Intraaortic balloon pumping was inserted preoperatively in 20 patients (46.5%). The average maximum creatine kinase-myocardial band was 139+/-181 (U/L). The mean number of grafts was 3.2 and the rate of complete revascularization was 91%. Two of six patients with preoperative cardiogenic shock were converted to on-pump beating CABG due to ventricular arrythmia. The early graft patency rate was 98%. All patients survived except 2 with preoperative cardiogenic shock.

CONCLUSIONS

OPCAB can be performed after AMI as a relatively low-risk procedure with an acceptable mortality rate, even within 14 days of the infarction.

Cardiac surgery in an Iranian teaching hospital: outcome and risk factors

Cardiac surgery in Iran has been associated with different facilities, equipment and patient populations in comparison to countries from which most of the academic papers used for identification of risk factors related to outcome and subsequent establishment of risk stratification models originate from. During a 15-month period all patients admitted for adult cardiac surgery using cardiopulmonary bypass (CBP) in a university affiliated teaching hospital were enrolled in a prospective study. Appropriate statistical tests were used to analyze data for mortality and morbidity. There were 730 adults (63% male, 37% female), with age ranged from 16 to 82 (mean, 51.4 +/- 14.4). A mortality rate of 5.3% and morbidity of 14.8% (major + minor) were observed in the whole group. Factors correlated with mortality were: age (p = 0.019), emergency surgery (p < 0.0001), redo cardiac surgery (p = 0.01), left ventricular (LV) aneurysm (p < 0.001), presence of catastrophic states (p < 0.001), low ejection fraction (p = 0.04), history of hypertension (p = 0.05), the individual surgeon (p < 0.0001), and CPB duration (p < 0.0001). Factors affecting morbidity included: female gender (p = 0.04), age (p = 0.03), emergency surgery (p = 0.001), redo surgery (p = 0.008), and catastrophic states (p < 0.001). The mortality in our study group may be compared with reports presented in the literature. Factors such as age, emergency surgery, redo cardiac surgery, and catastrophic states are statistically related to both mortality and morbidity.

Off-pump multivessel coronary artery surgery in high-risk patients

BACKGROUND

Coronary artery bypass surgery on cardiopulmonary bypass is associated with significant morbidity and mortality, which may be more marked in high-risk patients. We evaluated our results of off-pump coronary artery bypass (OPCAB) in high-risk patients with multivessel coronary artery disease and compared them with results in similar patients who underwent operation on cardiopulmonary bypass.

METHODS

A total of 1,075 patients who underwent OPCAB between October 1996 and June 2001 and who had one or more of the following risk factors were included in the study: poor left ventricular function (EF < or = 30%), advanced age (> 70 years), left main stenosis, acute myocardial infarction, and redo coronary artery surgery. These patients were compared with 2,312 similar patients who underwent coronary artery bypass grafting on cardiopulmonary bypass during the same period. Preoperative risk factors, intraoperative variables, and postoperative results were analyzed and compared between two groups.

RESULTS

The average number of grafts was 3.0 +/- 0.4 and 3.2 +/- 0.3 in the off-pump (OPCAB) and on-pump (CCAB) groups, respectively. Hospital mortality was 3.2% and 4.5% in OPCAB and CCAB groups respectively (p = 0.109). Perioperative myocardial infarction, requirement of inotropic agents, stroke, and renal dysfunction were comparable in two groups. Intubation time (19 +/- 5 vs 24 +/- 6 hours, p < 0.001), mean blood loss (362 +/- 53 vs 580 +/- 66 mL, p < 0.001), atrial fibrillation (14.3 vs 19.7%, p < 0.001), and prolonged ventilation (4.6 vs 7.6%, p = 0.002) were less in OPCAB group. Intensive care unit stay (20 +/- 8 hours) and hospital stay (6 +/- 3 days) were significantly less in the OPCAB group (p < 0.001).

CONCLUSIONS

Off-pump coronary artery surgery can be safely performed in high-risk patients with multivessel coronary artery disease. Operative mortality is comparable to that associated with on-pump surgery, and avoidance of cardiopulmonary bypass is associated with reduced postoperative morbidity in these patients.

Evaluation of coronary artery bypass grafting in acute myocardial infarction

OBJECTIVES

We evaluated coronary artery bypass grafting (CABG) in acute myocardial infarction (AMI) within 14 days of onset.

METHODS

Of 1,450 patients undergoing isolated CABG in the last 12 years we retrospectively analyzed operative risk factors and studied the use of CABG in treating AMI in 66 undergoing surgery during the AMI phase. We divided them into 2 groups: Group D (deceased: n = 8) and Group S (survivors: n = 58).

RESULTS

Total operative mortality was 12.1% (8/66). Univariate analysis showed the following preoperative parameters to be significant in Group D: diabetes mellitus, cardiogenic shock, shortness of the interval between AMI onset and surgery, mean peak creatine phosphokinase-MB, AMI of the left main trunk, and failed recanalization of the infarcted artery. Multivariate analysis showed diabetes mellitus, cardiogenic shock, and AMI of the left main trunk as independent risk factors for hospital mortality. Intra-operative parameters between groups showed no statistical difference. Mortality in patients who did not suffer cardiogenic shock was zero.

CONCLUSION

Maintenance of hemodynamics in the early phase is vital in treating AMI. The most important element in surgical intervention is revascularization of main branches. We concluded that CABG in AMI involves relatively low risk.

Routine use of bilateral skeletonized internal mammary arteries for myocardial revascularization

BACKGROUND

Complete arterial myocardial revascularization without the use of saphenous veins grafts was primarily performed on selected patient populations such as the young and nondiabetic. In a recently developed surgical technique, the internal mammary artery is dissected gently as a longer skeletonized artery, providing greater versatility for complete arterial revascularization, without saphenous veins grafts.

METHODS

We prospectively evaluated the impact of the routine use of double skeletonized internal mammary artery in 472 patients who underwent coronary artery bypass grafting between April 1996 and June 1997. Their average age was 65 years (30 to 87 years), 383 (83%) were men, and 89 (17%) women. One hundred sixty-nine (36%) of the patients were older than 70 years, and 145 (31%) were diabetic. The average number of grafts was 3.2 per patient (two to six grafts).

RESULTS

Operative mortality was 1.7% (n = 8). The mortality of urgent and elective patients was 0.7% (3 of 410 patients), and that of emergency operations was 8.1% (5 of 62 patients; p < 0.01). There were three (0.6%) perioperative infarcts, and 6 patients (1.3%) sustained strokes. Sternal wound infection occurred in 8 patients (1.7%). Postoperative follow-up (1 to 25 months) was available in 462 patients (99%). Two-year actuarial survival was 96.8%, and 92% of the surviving patients are well and free of angina. Neither diabetes mellitus nor old age (>70 years) were significant independent predictors of any early or late untoward events. None of the 70 diabetic patients more than 65 years of age developed sternal wound infection. Chronic lung disease was found to be the only independent predictor for sternal infections.

CONCLUSIONS

Routine use of bilateral skeletonized internal mammary artery is a safe replacement for the current myocardial revascularization technique even in the old and diabetic patients.

Risk factors and outcome in European cardiac surgery: analysis of the EuroSCORE multinational database of 19030 patients

OBJECTIVE

To assess risk factors for mortality in cardiac surgical adult patients as part of a study to develop a European System for Cardiac Operative Risk Evaluation (EuroSCORE).

METHODS

From September to November 1995, information on risk factors and mortality was collected for 19030 consecutive adult patients undergoing cardiac surgery under cardiopulmonary bypass in 128 surgical centres in eight European states. Data were collected for 68 preoperative and 29 operative risk factors proven or believed to influence hospital mortality. The relationship between risk factors and outcome was assessed by univariate and logistic regression analysis.

RESULTS

Mean age (+/- standard deviation) was 62.5+/-10.7 (range 17-94 years) and 28% were female. Mean body mass index was 26.3+/-3.9. The incidence of common risk factors was as follows: hypertension 43.6%, diabetes 16.7%, extracardiac arteriopathy 2.9%, chronic renal failure 3.5%, chronic pulmonary disease 3.9%, previous cardiac surgery 7.3% and impaired left ventricular function 31.4%. Isolated coronary surgery accounted for 63.6% of all procedures, and 29.8% of patients had valve operations. Overall hospital mortality was 4.8%. Coronary surgery mortality was 3.4% In the absence of any identifiable risk factors, mortality was 0.4% for coronary surgery, 1% for mitral valve surgery, 1.1% for aortic valve surgery and 0% for atrial septal defect repair. The following risk factors were associated with increased mortality: age (P = 0.001), female gender (P = 0.001), serum creatinine (P = 0.001), extracardiac arteriopathy (P = 0.001), chronic airway disease (P = 0.006), severe neurological dysfunction (P = 0.001), previous cardiac surgery (P = 0.001), recent myocardial infarction (P = 0.001), left ventricular ejection fraction (P = 0.001), chronic congestive cardiac failure (P = 0.001), pulmonary hypertension (P = 0.001), active endocarditis (P = 0.001), unstable angina (P = 0.001), procedure urgency (P = 0.001), critical preoperative condition (P = 0.001) ventricular septal rupture (P = 0.002), noncoronary surgery (P = 0.001), thoracic aortic surgery (P = 0.001).

CONCLUSION

A number of risk factors contribute to cardiac surgical mortality in Europe. This information can be used to develop a risk stratification system for the prediction of hospital mortality and the assessment of quality of care.