Gerald T. O’Connor

Obesity and Risk of Adverse Outcomes Associated With Coronary Artery Bypass Surgery

Background—Obesity is frequently cited as a risk factor for adverse outcomes of major surgery. The results of prior studies of the relationship between obesity and risk of adverse outcomes of coronary artery bypass grafting (CABG) have been contradictory because of insufficient power to assess relatively infrequent outcomes or data to adjust for confounding factors. Methods and Results—Data on patient age, sex, height, weight, medical history, current clinical status, and treatment factors were assessed prospectively among 11 101 consecutive patients undergoing CABG. Body mass index (BMI) was used as the measure of obesity and was categorized as nonobese (1st to 74th percentiles), obese (75th to 94th percentiles), or severely obese (95th to 100th percentiles). Adverse outcomes occurring in-hospital, including mortality, intraoperative/postoperative cerebrovascular accident (CVA), postoperative bleeding, and sternal wound infection, were defined prospectively. Associations between obesity and postoperative...

Survival of patients with diabetes and multivessel coronary artery disease after surgical or percutaneous coronary revascularization: results of a large regional prospective study

OBJECTIVES We sought to assess survival among patients with diabetes and multivessel coronary artery disease (MVD) after percutaneous coronary intervention (PCI) and after coronary artery bypass grafting surgery (CABG). BACKGROUND The Bypass Angioplasty Revascularization Investigation (BARI) demonstrated that diabetics with MVD survive longer after initial CABG than after initial PCI. Other randomized trials or observational databases have not conclusively reproduced this result. METHODS A large, regional database was linked to the National Death Index to assess five-year mortality. Of 7,159 consecutive patients with diabetes who underwent coronary revascularization in northern New England during 1992 to 1996, 2,766 (38.6%) were similar to those randomized in the BARI trial. Percutaneous coronary intervention was the initial revascularization strategy in 736 patients and CABG in 2,030. Cox proportional hazards regression was used to calculate risk-adjusted hazard ratios (HR) and 95% confidence intervals (CI 95%). RESULTS Patients who underwent PCI were younger, had higher ejection fractions and less extensive coronary disease. After adjusting for differences in baseline clinical characteristics, patients with diabetes treated with PCI had significantly greater mortality relative to those undergoing CABG (HR = 1.49; CI 95%: 1.02 to 2.17; p = 0.037). Mortality risk tended to increase more among 1,251 patients with 3VD (HR = 2.02; CI 95%: 1.04 to 3.91; p = 0.038) than among 1,515 patients with 2VD (HR = 1.33; CI 95%: 0.84 to 2.1; p = 0.21). CONCLUSIONS In this analysis of a large regional contemporary database of patients with diabetes selected to be similar to those enrolled in the BARI trial, five-year mortality was significantly increased after initial PCI. This supports the BARI conclusion on initial revascularization of patients with diabetes and MVD.

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 (≥2 competing mechanisms), or unclassified (unknown mechanism). The reliability of the classification system was determined by percent agreement and &kgr; 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.

Effect of Coronary Artery Diameter in Patients Undergoing Coronary Bypass Surgery

BACKGROUND Coronary artery diameter is known to be inversely associated with perioperative mortality related to coronary artery bypass grafting (CABG). This association is believed to be responsible for increased risk among women and smaller people. However, the associations between sex, body size, and coronary size have not been carefully examined because direct information about coronary size is rarely available. Also, whether sex has an independent effect on vessel size is largely unknown. METHODS AND RESULTS Height, weight, sex, age, status at hospital discharge, and luminal diameter of the midleft anterior descending coronary artery (mid-LAD) were recorded prospectively in 1325 patients undergoing CABG. Small vessel size was associated with substantially increased risk of in-hospital mortality (15.8% for 1.0-mm vessels, 4.6% for 1.5- to 2.0-mm vessels, and 1.5% for 2.5- to 3.5-mm vessels, P[trend] < .001). Vessel size was strongly related to both sex and measures of body size. In multiple linear regression analysis, vessel size was positively correlated with body surface area (P[trend] < .01), body mass index (P[trend] = .004), height (P[trend] = .001), and weight (P[trend] = .001). After controlling for differences in age and body size, sex remained an important predictor of coronary size. Within each quartile of each body-size measure, mid-LAD diameter in men was greater than that in women (mean difference [range], 0.14 to 0.23 mm). CONCLUSIONS Small mid-LAD diameter is associated with substantially increased risk of in-hospital mortality with CABG. Although body size is correlated with mid-LAD diameter, women have smaller coronary arteries than men after controlling for differences in body size. These findings further support the hypothesis that smaller coronary arteries explain higher perioperative mortality with CABG in women and smaller people.

Risks of Morbidity and Mortality in Dialysis Patients Undergoing Coronary Artery Bypass Surgery

Background—Although dialysis patients are undergoing CABG with increasing frequency, large studies specifically comparing patient characteristics and procedure-related risks in this population have not been performed. Methods and Results—We conducted a regional prospective cohort study of 15 500 consecutive patients undergoing CABG in northern New England from 1992 to 1997. We used multiple logistic regression analysis to examine associations between preoperative dialysis-dependent renal failure and postoperative events and to adjust for potentially confounding variables. The 279 dialysis-dependent renal failure patients (1.8%) were 4.4 times more likely to experience in-hospital mortality than were other CABG patients (12.2% versus 3.0%, respectively;P <0.001). Dialysis-dependent renal failure patients were older and had more comorbidities and more severe cardiac disease than did other CABG patients. After adjusting for these factors in multivariate analysis, however, dialysis-dependent renal failure patients remained 3.1 times more likely to die after CABG (adjusted odds ratio [OR] 3.1, 95% CI 2.1 to 4.7;P <0.001). Dialysis-dependent renal failure patients compared with other CABG patients also had a substantially increased risk of postoperative mediastinitis (3.6% versus 1.2%, respectively; adjusted OR 2.4, 95% CI 1.2 to 4.7;P =0.011) and postoperative stroke (4.3% versus 1.7%, respectively; adjusted OR 2.1, 95% CI 1.1 to 3.9;P =0.016), even after controlling for potentially confounding variables. Risks of reexploration for bleeding were similar for patients with and without dialysis-dependent renal failure. Conclusions—Preoperative dialysis-dependent renal failure is a strong independent risk factor for in-hospital mortality and mediastinitis after CABG.

Is ε-Aminocaproic Acid as Effective as Aprotinin in Reducing Bleeding With Cardiac Surgery? A Meta-Analysis

Background—Although aprotinin is known to be effective in reducing postoperative hemorrhage after cardiac surgery, e-aminocaproic acid, an alternative antifibrinolytic, is considerably less expensive. Because the results of 3 small randomized clinical trials comparing these 2 agents directly were inconclusive, we performed a meta-analysis to compare the relative effectiveness and adverse-effect profile of these 2 agents against placebo. Methods and Results—Data from 52 randomized clinical trials published between 1985 and 1998 involving the use of e-aminocaproic acid (n=9) or aprotinin (n=46) in patients undergoing cardiac surgery were abstracted. Our primary outcomes were total blood loss, red blood cell transfusion rates and amounts, reexploration, stroke, myocardial infarction, and mortality. The meta-analysis revealed substantial reductions in total blood loss with e-aminocaproic acid and low-dose aprotinin (each with a 35% reduction versus placebo, P<0.001) and high-dose aprotinin (53% reduction, P<0...

Predicting vascular complications in percutaneous coronary interventions

OBJECTIVES Using a large, current, regional registry of percutaneous coronary interventions (PCI), we identified risk factors for postprocedure vascular complications and developed a scoring system to estimate individual patient risk. BACKGROUND A vascular complication (access-site injury requiring treatment or bleeding requiring transfusion) is a potentially avoidable outcome of PCI. METHODS Data were collected on 18,137 consecutive patients undergoing PCI in northern New England from January 1997 to December 1999. Multivariate regression was used to identify characteristics associated with vascular complications and to develop a scoring system to predict risk. RESULTS The rate of vascular complication was 2.98% (541 cases). Variables associated with increased risk in the multivariate analysis included age >or=70, odds ratio (OR) 2.7, female sex (OR 2.4), body surface area <1.6 m(2) (OR 1.9), history of congestive heart failure (OR 1.4), chronic obstructive pulmonary disease (OR 1.5), renal failure (OR 1.9), lower extremity vascular disease (OR 1.4), bleeding disorder (OR 1.68), emergent priority (OR 2.3), myocardial infarction (OR 1.7), shock (1.86), >or=1 type B2 (OR 1.32) or type C (OR 1.7) lesions, 3-vessel PCI (OR 1.5), use of thienopyridines (OR 1.4) or use of glycoprotein IIb/IIIa receptor inhibitors (OR 1.9). The model performed well in tests for significance, discrimination, and calibration. The scoring system captured 75% of actual vascular complications in its highest quintiles of predicted risk. CONCLUSION Predicting the risk of post-PCI vascular complications is feasible. This information may be useful for clinical decision-making and institutional efforts at quality improvement.

Effect of preoperative aspirin use on mortality in coronary artery bypass grafting patients

BACKGROUND Discontinuing aspirin use in patients before coronary artery bypass grafting (CABG) has focused on bleeding risks. The effect of aspirin use on overall mortality with this procedure has not been studied. METHODS We performed a case patient-control patient study of the 8,641 consecutive isolated CABG procedures performed between July 1987 and May 1991 in Maine, New Hampshire, and Vermont. Patients included all 368 deaths. Each case patient was paired with approximately two matched survivors (control patients). Aspirin use was defined by identification of ingestion within 7 days before the operation. RESULTS CABG patients using preoperative aspirin were less likely to experience in-hospital mortality in univariate (odds ratio [OR] = 0.73, 95% confidence interval [0.54, 0.97]) and multivariate [OR = 0.55, (0.31, 0.98)] analysis compared to nonusers. No significant difference was seen in the amount of chest tube drainage, transfusion of blood products, or need for reexploration for hemorrhage between patients who did and did not receive aspirin. CONCLUSIONS Preoperative aspirin use appears to be associated with a decreased risk of mortality in CABG patients without significant increase in hemorrhage, blood product requirements, or related morbidities.

Comparing long-term survival of patients with multivessel coronary disease after CABG or PCI: Analysis of BARI-like patients in Northern New England

Background—Randomized trials comparing coronary artery bypass graft surgery (CABG) with percutaneous coronary interventions (PCIs) for patients with multivessel coronary disease (MVD) report similar long-term survival for CABG and PCI. These studies used a highly selected population of patients and providers, and their results may not be generalizable to actual care. Our goal in this study was to compare long-term survival of MVD patients treated with CABG vs PCI in contemporary practice. Methods and Results—From our northern New England registries of consecutive coronary revascularizations, we identified 10 198 CABG and 4295 PCI patients with MVD who may have been eligible for either procedure between 1994 and 2001. Vital status was obtained by linkage to the National Death Index. Proportional-hazards regression was used to calculate hazard ratios (HRs) for survival in CABG vs PCI patients after adjustment for comorbidities and disease characteristics. CABG patients were older; had more comorbidities, more 3-vessel disease, and lower ejection fractions; and were more completely revascularized. Adjusted long-term survival for patients with 3-vessel disease was better after CABG than PCI (HR, 0.60; P<0.01) but not for patients with 2-vessel disease (HR, 0.98; P=0.77). The survival advantage of CABG for 3-vessel disease patients was present in all patient populations, including women, diabetics, and the elderly and in the era of high stent utilization. Conclusions—In contemporary practice, survival for patients with 3-vessel coronary disease is better after CABG than PCI, an observation that patients and physicians should carefully consider when deciding on a revascularization strategy.

Association of bacterial infection and red blood cell transfusion after coronary artery bypass surgery

BACKGROUND Previous studies have shown an association between red blood cell transfusions (RBC) and bacterial infections following coronary artery bypass graft (CABG) surgery. We sought to assess whether there is an independent effect of RBC on the incidence of bacterial infections. METHODS This was a prospective cohort study of 533 CABG patients over a 7-month period. Subjects were followed from time of CABG until 30 days postoperatively. Data were collected on patient and treatment characteristics, surgical management, and transfusion incidence. RESULTS Seventy-five (14.1%) of 533 patients developed a bacterial infection. After controlling for patient and disease characteristics, invasive treatments, surgical time, and the transfusion of other substances, the adjusted rates of bacterial infection were 4.8% for no RBC transfusion, 15.2% with one to two units, 22.1% with three to five units, and 29.0% with greater than or equal to six units, (p(trend) < 0.001). Diabetes was the only patient or disease factor significantly associated with bacterial infection (p < 0.001). CONCLUSIONS RBC transfusions were independently associated with a higher incidence of post-CABG bacterial infections. The risk of infection increased in proportion to the number of units of RBC transfused.