Similar or Reduced Mortality Risk

Operative mortality rates between OPCAB versus CABG with CPB have been comparable, with studies demonstrating similar and even reduced mortality risks with OPCAB.^8,9,10 In a review of two large databases of 8,499 patients undergoing isolated CABG surgery, OPCAB showed improved early survival in multivessel CABG patients with a 49% reduction in mortality (1.8% OPCAB versus 3.5% CABG with CPB, p=.002).10 A significant reduction in mortality by avoiding the CPB has also been demonstrated in high-risk patients with characteristics known to be predictors of high mortality rates. Several studies suggest that OPCAB improves mortality outcomes for patients with high-risk factors including female gender, atheromatous aortic disease, advanced age > 70 years, renal failure, left main coronary artery disease, acute myocardial infarction, poor left ventricular function with EF < 30%, and reoperations.^4,11,12,13 Mortality Rates

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

Meharwal ZS, Mishra YK, Kohli V, Bapna R, Singh S, Trehan N.

Department of Cardiovascular Surgery, Escorts Heart Institute and Research Centre, New Delhi, India.

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 <> 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. Annals of Thoracic Surgery. 2002 Oct;74(4):S1353-7.

8. Off-pump coronary artery bypass is associated with improved risk-adjusted outcomes

Plomondon ME, Cleveland JC Jr, Ludwig ST, Grunwald GK, Kiefe CI, Grover FL, Shroyer AL.

University of Colorado Health Sciences Center, Denver, USA.

BACKGROUND: The impact of off-pump median sternotomy coronary artery bypass grafting procedures on risk-adjusted mortality and morbidity was evaluated versus on-pump procedures.

METHODS: Using the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Program records from October 1997 through March 1999, nine centers were designated as having experience (with at least 8% coronary artery bypass grafting procedures performed off-pump). Using all other 34 Veterans Affairs cardiac surgery programs, baseline logistic regression models were built to predict risk of 30-day operative mortality and morbidity. These models were then used to predict outcomes for patients at the nine study centers. A final model evaluated the impact of the off-pump approach within these nine centers adjusting for preoperative risk.

RESULTS: Patients treated off-pump (n = 680) versus on-pump (n = 1,733) had lower complication rates (8.8% versus 14.0%) and lower mortality (2.7% versus 4.0%). Risk-adjusted morbidity and mortality were also improved for these patients (0.52 and 0.56 multivariable odds ratios for off-pump versus on-pump, respectively, p < 0.05).

CONCLUSIONS: An off-pump approach for coronary artery bypass grafting procedures is associated with lower risk-adjusted morbidity and mortality Annals of Thoracic Surgery. 2001 Jul;72(1):114-9.

9. Off-pump coronary artery bypass grafting decreases risk-adjusted mortality and morbidity

Cleveland JC Jr, Shroyer AL, Chen AY, Peterson E, Grover FL. Division of Cardiothoracic Surgery, University of Colorado Health Sciences Center, Denver, USA.

BACKGROUND: The purpose of this study was to determine whether coronary artery bypass grafting without cardiopulmonary bypass (off-pump CABG) decreases risk-adjusted operative death and major complications after coronary artery bypass grafting in selected patients.

METHODS: Using The Society of Thoracic Surgeons (STS) National Adult Cardiac Surgery Database, procedural outcomes were compared for conventional and off-pump CABG procedures from January 1, 1998, through December 31, 1999. Mortality and major complications were examined, both as unadjusted rates and after adjusting for known base line patient risk factors.

RESULTS: A total of 126 experienced centers performed 118,140 total CABG procedures. The number of off-pump CABG cases was 11,717 cases (9.9% of total cases). The use of an off-pump procedure was associated with a decrease in risk-adjusted operative mortality from 2.9% with conventional CABG to 2.3% in the off-pump group (p < 0.001). The use of an off-pump procedure decreased the risk-adjusted major complication rate from 14.15% with conventional CABG to 10.62% in the off-pump group (p < 0.0001). Patients receiving off-pump procedures were less likely to die (adjusted odds ratio 0.81, 95% CI 0.70 to 0.91) and less likely to have major complications (adjusted odds ratio 0.77, 95% CI 0.72 to 0.82).

CONCLUSIONS: Off-pump CABG is associated with decreased mortality and morbidity after coronary artery bypass grafting. Off-pump CABG may prove superior to conventional CABG in appropriately selected patients.

Annals of Thoracic Surgery. 2001 Oct;72(4):1282-8; discussion 1288-9.

10. Elimination of cardiopulmonary bypass improves early survival for multivessel coronary artery bypass patients

Magee MJ, Jablonski KA, Stamou SC, Pfister AJ, Dewey TM, Dullum MK, Edgerton JR, Prince SL, Acuff TE, Corso PJ, Mack MJ.

Cardiopulmonary Research Science and Technology Institute, Dallas, Texas, USA.

BACKGROUND: Coronary artery bypass graft (CABG) surgery performed without cardiopulmonary bypass (CPB) is currently increasing in clinical practice. Decreased morbidity associated with off-pump (OP) CABG in selected risk groups examined in relatively small, single institution groups has been the focus of most recent studies. The purpose of this study was to determine the independent impact of CPB on early survival in all isolated multivessel CABG patients undergoing surgery in two large institutions with established experience in OPCABG techniques.

METHODS: A review of two large databases employed by multiple surgeons in the hospitals of two institutions identified 8,758 multivessel CABG procedures performed from January 1998 through July 2000. In all, 8,449 procedures were included in a multivariate logistic regression analysis to determine the relative impact of CPB on mortality independent of known risk factors for mortality. Procedures were also divided into two treatment groups based on the use of CPB: 6,466 had CABG with CPB (CABG-CPB), 1,983 had CABG without CPB (OPCABG). Disparities between groups were identified by univariate analysis of 17 preoperative risk factors and treatment groups were compared by Parsonnet's risk stratification model. Finally, computer-matched groups based on propensity score for institution selection for OPCABG were combined and analyzed by a logistic regression model predicting risk for mortality.

RESULTS: CABG-CPB was associated with increased mortality compared with OPCABG by univariate analysis, 3.5% versus 1.8%, despite a lower predicted risk in the CABG-CPB group. CPB was associated with increased mortality by multiple logistic regression analysis with an odds ratio of 1.79 (95% confidence interval = 1.24 to 2.67). An increased risk of mortality associated with

CPB was also determined by logistic regression analysis of the combined computer-matched groups based on OPCABG-selection propensity scores with an odds ratio of 1.9 (95% confidence interval = 1.2 to 3.1).

CONCLUSIONS: Elimination of CPB improves early survival in multivessel CABG patients. Rigorous attempts to statistically account for selection bias maintained a clear association between CPB and increased mortality. Larger multiinstitutional studies are needed to confirm these findings and determine the most appropriate application of OPCABG.

Annals of Thoracic Surgery. 2002 Apr;73(4):1196-202; discussion 1202-3.

11. Outcomes experience with off-pump coronary artery bypass surgery in women

Brown PP, Mack MJ, Simon AW, Battaglia S, Tarkington L, Horner S, Culler SD, Becker ER.

HCA, Inc, Nashville, Tennesee, USA.

BACKGROUND: It has been well documented that women have higher morbidity and mortality rates than men following coronary artery bypass graft (CABG) surgery. In view of this evidence, we investigated the following question: compared with on-pump CABG surgery, is there benefit to off-pump CABG surgery in women?

METHODS: Our investigation analyzes patient mortality and 13 procedure complications controlling for 35 variables representing patient characteristics and comorbid conditions, and for procedure characteristics for a population of 16,871 consecutive women undergoing off-pump and on-pump CABG surgery at 78 hospitals for the period January 1998 to June 2001.

RESULTS: Mean comparisons reveal that the mortality rate for women undergoing off-pump CABG surgery is nearly a percentage point lower than for women undergoing on-pump surgery (3.12 vs 3.90; p = 0.052). The complication rates for all complications analyzed (shock/hemorrhage, neurologic, cardiac, respiratory, renal, acute renal failure, adult respiratory distress syndrome, implant infection, postoperative infection, septicemia, pneumonia, and peripheral vascular) were lower for women off-pump than women on-pump with the exception of mechanical complications. Logistic regression results reveal, after controlling for 35 relevant patient characteristics, comorbid conditions and procedure characteristics, that women undergoing on-pump CABG surgery experience a 42% higher mortality rate (p = 0.0239) than women undergoing off-pump CABG surgery.

CONCLUSIONS: Evidence suggests that off-pump CABG surgery may be better for women than on-pump CABG surgery because it appears to reduce mortality and respiratory complications, shorten lengths-of-stay, and increases discharges directly home. None of the 12 other complications investigated demonstrated an advantage for women undergoing on-pump surgery relative to those receiving off-pump surgery.

Annals of Thoracic Surgery. 2002 Dec;74(6):2113-9; discussion 2120.

12. Comparison of coronary bypass surgery with and without cardiopulmonary bypass in patients with multivessel disease

Mack MJ, Pfister A, Bachand D, Emery R, Magee MJ, Connolly M, Subramanian V.

Cardiopulmonary Research Science and Technology Institute, Medical City Dallas Hospital, TX, USA.

BACKGROUND: Coronary artery bypass grafting can now be performed with or without cardiopulmonary bypass. Our objective was to determine whether off-pump coronary artery bypass grafting is associated with better early outcomes compared with conventional coronary artery bypass grafting.

METHODS: In 4 centers with off-pump coronary surgery experience, a retrospective analysis of all coronary artery bypass grafting in a 3-year period was performed. Groups were compared to determine selection criteria, mortality, and morbidity, then computer-matched by propensity score to control for selection bias. Multivariate logistic regression identified risk factors predictive of mortality. Specific subgroups most likely to benefit were identified.

RESULTS: In all, 17,401 isolated coronary artery bypass grafts were performed, 7,283 (41.9%) off-pump coronary artery bypass grafts and 10,118 (58.1%) conventional coronary artery bypass with cardiopulmonary bypass. Factors determining selection of patients for off-pump coronary artery bypass grafting included female gender (55.5% vs 44.5%), preexisting renal failure (57.0% vs 43.0%), and reoperations (52.6% vs 47.4%). Operative mortality was 2.8%; off-pump coronary artery bypass grafting versus conventional coronary artery bypass with cardiopulmonary bypass (1.9% vs 3.5%, P <.001) had the same predicted risk. Of the patients with multivessel disease, 11,548 were matched by propensity scoring. Mortality was significantly less in the off-pump coronary artery bypass grafting group (2.8% vs 3.7%, P <.001).> 75 years. Off-pump coronary artery bypass grafting was associated with less morbidity, including reductions in blood transfusion (32.6% vs 40.6%, P <.001), stroke (1.4% vs 2.1%, P =.002), renal failure (2.6% vs 5.2%, P <.001), pulmonary complications (4.1% vs 9.5%, P <.001), reoperation (1.7% vs 3.2%, P <.001), atrial fibrillation (21.1% vs 24.99%, P <.001), and gastrointestinal complications (3.6% vs 4.8%, P =.02).

CONCLUSION: In 4 centers with beating-heart operation experience, there is an overall early benefit in off-pump surgery, especially in patients traditionally considered at high risk for coronary artery bypass grafting.

Journal of Thoracic and Cardiovascular Surgery. 2004 Jan;127(1):167-73.

13. Propensity case-matched analysis of off-pump coronary artery bypass grafting in patients with atheromatous aortic disease

Sharony R, Grossi EA, Saunders PC, Galloway AC, Applebaum R, Ribakove GH, Culliford

AT, Kanchuger M, Kronzon I, Colvin SB.

Department of Surgery, New York University School of Medicine, New York, USA.

OBJECTIVE: Atheromatous aortic disease is a risk factor for excessive mortality and stroke in patients undergoing coronary artery bypass grafting. Outcomes of off-pump coronary artery bypass grafting and coronary artery bypass grafting with cardiopulmonary bypass in patients with severe atheromatous aortic disease were compared by propensity case-match methods.

METHODS: Routine intraoperative transesophageal echocardiography identified 985 patients undergoing isolated coronary artery bypass grafting with severe atheromatous disease in the aortic arch or ascending aorta. Off-pump coronary artery bypass grafting was performed in 281 patients (28.5%). Propensity matched-pairs analysis was used to match patients undergoing off-pump coronary artery bypass grafting (n = 245) with patients undergoing coronary artery bypass grafting with cardiopulmonary bypass.

RESULTS: Univariate analysis revealed decreased hospital mortality (16/245, 6.5% vs 28/245, 11.4%; P =.058) and stroke prevalence (4/245, 1.6% vs 14/245, 5.7%; P =.03) in off-pump coronary artery bypass grafting compared with coronary artery bypass grafting with cardiopulmonary bypass. Freedom from any postoperative complication was higher in off-pump coronary artery bypass grafting compared with coronary artery bypass grafting with cardiopulmonary bypass (226/245, 92.2% vs 196/245, 80.0%; P <.001). Multivariable analysis of preoperative risk factors showed that increased hospital mortality was associated with coronary artery bypass grafting with cardiopulmonary bypass (odds ratio = 2.7; P =.01), fewer grafts (P =.05), acute myocardial infarction (odds ratio = 11.5; P <.001), chronic obstructive pulmonary disease (odds ratio = 2.4; P =.03), previous cardiac surgery (odds ratio = 10.2, P =.05), and peripheral vascular disease (odds ratio = 2.1; P =.05). Cardiopulmonary bypass was the only independent risk factor for stroke (odds ratio = 3.6, P =.03). At 36 months' follow-up, comparable survival was observed in the off-pump coronary artery bypass grafting and coronary artery bypass grafting with cardiopulmonary bypass groups (74% vs 72%). Multivariable analysis revealed that renal disease (P <.001), advanced age (P <.001), previous myocardial infarction (P =.03), and lower number of grafts (P =.02) were independent risks for late mortality.

CONCLUSIONS: Patients with severe atherosclerotic aortic disease who undergo off-pump coronary artery bypass grafting have a significantly lower prevalence of hospital mortality, perioperative stroke, and overall complications than matched patients who underwent coronary artery bypass grafting with cardiopulmonary bypass. Routine intraoperative transesophageal echocardiography identifies severe atheromatous aortic disease and directs the choice of surgical technique.

Journal of Thoracic and Cardiovascular Surgery. 2004 Feb;127(2):406-13.

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