Herbert B. Ward

Radial Artery Grafts vs Saphenous Vein Grafts in Coronary Artery Bypass Surgery: A Randomized Trial

CONTEXT Arterial grafts are thought to be better conduits than saphenous vein grafts for coronary artery bypass grafting (CABG) based on experience with using the left internal mammary artery to bypass the left anterior descending coronary artery. The efficacy of the radial artery graft is less clear. OBJECTIVE To compare 1-year angiographic patency of radial artery grafts vs saphenous vein grafts in patients undergoing elective CABG. DESIGN, SETTING, AND PARTICIPANTS Multicenter, randomized controlled trial conducted from February 2003 to February 2009 at 11 Veterans Affairs medical centers among 757 participants (99% men) undergoing first-time elective CABG. INTERVENTIONS The left internal mammary artery was used to preferentially graft the left anterior descending coronary artery whenever possible; the best remaining recipient vessel was randomized to radial artery vs saphenous vein graft. MAIN OUTCOME MEASURES The primary end point was angiographic graft patency at 1 year after CABG. Secondary end points included angiographic graft patency at 1 week after CABG, myocardial infarction, stroke, repeat revascularization, and death. RESULTS Analysis included 733 patients (366 in the radial artery group, 367 in the saphenous vein group). There was no significant difference in study graft patency at 1 year after CABG (radial artery, 238/266; 89%; 95% confidence interval [CI], 86%-93%; saphenous vein, 239/269; 89%; 95% CI, 85%-93%; adjusted OR, 0.99; 95% CI, 0.56-1.74; P = .98). There were no significant differences in the secondary end points. CONCLUSION Among Veterans Affairs patients undergoing first-time elective CABG, the use of a radial artery graft compared with saphenous vein graft did not result in greater 1-year patency. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00054847.

A fifteen-year wound surveillance study after coronary artery bypass☆

Wound infections after coronary artery bypass operations have been continuously monitored at the Minneapolis Veterans Affairs Hospital for 15 years. All patients were followed up for 30 days. From 1977 to 1991, 2,402 coronary artery bypass operations were performed, and wound infections developed in 125 (5%) patients. There were 71 (3%) chest infections of which 33 (1.4%) were major and 38 (1.6%) superficial. Greater than 94% of these grew only a single organism, of which 74% were Staphylococcus species. There were 63 (2.6%) leg wound infections. More than 50% of these grew multiple organisms, of which 68% were enteric in origin. Nine (0.4%) patients had simultaneous chest and leg infections. Wound infections were diagnosed an average of 15.3 +/- 6.7 (range, 4 to 30) days postoperatively, with 50% occurring after discharge from the hospital. Of 14 variables evaluated by multivariate logistic regression analysis, only steroids (p = 0.005) and diabetes (p = 0.003) were identified as independent risk factors for wound infections. Patients taking steroids or with diabetes tended to have chest infections, whereas obese patients tended to have more leg infections (p = 0.08). During an interval in the surveillance program, a trend toward increasing infections was identified and successfully reversed.

Percutaneous coronary intervention versus coronary bypass graft surgery for diabetic patients with unstable angina and risk factors for adverse outcomes with bypass: Outcome of diabetic patients in the AWESOME randomized trial and registry

OBJECTIVES This study compared survival after percutaneous coronary intervention (PCI) with survival after coronary artery bypass graft surgery (CABG) among diabetics in the Veterans Affairs AWESOME (Angina With Extremely Serious Operative Mortality Evaluation) study randomized trial and registry of high-risk patients. BACKGROUND Previous studies indicate that CABG may be superior to PCI for diabetics, but no comparisons have been made for diabetics at high risk for surgery. METHODS Over five years (1995 to 2000), 2,431 patients with medically refractory myocardial ischemia and at least one of five risk factors (prior CABG, myocardial infarction within seven days, left ventricular ejection fraction <0.35, age >70 years, or an intra-aortic balloon being required to stabilize) were identified. A total of 781 were acceptable for CABG and PCI, and 454 consented to be randomized. The 1,650 patients not acceptable for both CABG and PCI constitute the physician-directed registry, and the 327 who were acceptable but refused to be randomized constitute the patient-choice registry. Diabetes prevalence was 32% (144) among randomized patients, 27% (89) in the patient-choice registry, and 32% (525) in the physician-directed registry. The CABG and PCI survival rates were compared using Kaplan-Meier curves and log-rank tests. RESULTS The respective CABG and PCI 36-month survival rates for diabetic patients were 72% and 81% for randomized patients, 85% and 89% for patient-choice registry patients, and 73% and 71% for the physician-directed registry patients. None of the differences was statistically significant. CONCLUSIONS We conclude that PCI is a relatively safe alternative to CABG for diabetic patients with medically refractory unstable angina who are at high risk for CABG.

Predictors and outcomes of a perioperative myocardial infarction following elective vascular surgery in patients with documented coronary artery disease: results of the CARP trial.

AIMS The predictors and outcomes of patients with a peri-operative elevation in cardiac troponin I above the 99th percentile of normal following an elective vascular operation have not been studied in a homogeneous cohort with documented coronary artery disease. METHODS AND RESULTS The Coronary Artery Revascularization Prophylaxis (CARP) trial was a randomized trial that tested the benefit of coronary artery revascularization prior to vascular surgery. Among 377 randomized patients, core lab samples for peak cardiac troponin I concentrations were monitored following the vascular operation and the blinded results were correlated with outcomes. A peri-operative myocardial infarction (MI), defined by an increase in cardiac troponin I greater than the 99th percentile reference (> or =0.1 microg/L), occurred in 100 patients (26.5%) and the incidence was not dissimilar in patients with and without pre-operative coronary revascularization (24.2 vs. 28.6%; P = 0.32). By logistic regression analysis, predictors of MI (odds risk; 95%CI; P-value) were age >70 (1.84; 1.14-2.98; P = 0.01), abdominal aortic surgery (1.82; 1.09-3.03; P = 0.02), diabetes (1.86; 1.11-3.11; P = 0.02), angina (1.67; 1.03-2.64; P = 0.04), and baseline STT abnormalities (1.62; 1.00-2.6; P = 0.05). At 2.5 years post-surgery, the probability of survival in patients with and without the MI was 0.73 and 0.84, respectively (P = 0.03, log-rank test). Using a Cox proportional hazards regression analysis, a peri-operative MI in diabetic patients was a strong predictor of long-term mortality (hazards ratio: 2.43; 95% CI: 1.31-4.48; P < 0.01). CONCLUSION Among patients with coronary artery disease who undergo vascular surgery, a peri-operative elevation in cardiac troponin levels is common and in combination with diabetes, is a strong predictor of long-term mortality. These data support the utility of cardiac troponins as a means of stratifying high-risk patients following vascular operations.

Percutaneous coronary intervention versus coronary bypass surgery in United States veterans with diabetes.

OBJECTIVES This study sought to determine the optimal coronary revascularization strategy in patients with diabetes with severe coronary disease. BACKGROUND Although subgroup analyses from large trials, databases, and meta-analyses have found better survival for patients with diabetes with complex coronary artery disease when treated with surgery, a randomized trial comparing interventions exclusively with drug-eluting stents and surgery in patients with diabetes with high-risk coronary artery disease has not yet been reported. METHODS In a prospective, multicenter study, 198 eligible patients with diabetes with severe coronary artery disease were randomly assigned to either coronary artery bypass grafting (CABG) (n = 97) or percutaneous coronary intervention (PCI) with drug-eluting stents (n = 101) and followed for at least 2 years. The primary outcome measure was a composite of nonfatal myocardial infarction or death. Secondary outcome measures included all-cause mortality, cardiac mortality, nonfatal myocardial infarction, and stroke. RESULTS The study was stopped because of slow recruitment after enrolling only 25% of the intended sample size, leaving it severely underpowered for the primary composite endpoint of death plus nonfatal myocardial infarction (hazard ratio: 0.89; 95% confidence interval: 0.47 to 1.71). However, after a mean follow-up period of 2 years, all-cause mortality was 5.0% for CABG and 21% for PCI (hazard ratio: 0.30; 95% confidence interval: 0.11 to 0.80), while the risk for nonfatal myocardial infarction was 15% for CABG and 6.2% for PCI (hazard ratio: 3.32; 95% confidence interval: 1.07 to 10.30). CONCLUSIONS This study was severely underpowered for its primary endpoint, and therefore no firm conclusions about the comparative effectiveness of CABG and PCI are possible. There were interesting differences in the components of the primary endpoint. However, the confidence intervals are very large, and the findings must be viewed as hypothesis generating only. (Coronary Artery Revascularization in Diabetes; NCT00326196).

Utility of N-acetylcysteine to prevent acute kidney injury after cardiac surgery: A randomized controlled trial

BACKGROUND Acute kidney injury (AKI) after heart surgery is associated with increased mortality. We sought to determine whether prophylactic perioperative administration of N-acetylcysteine (NAC) prevents postoperative AKI in patients with chronic kidney disease undergoing cardiac surgery (clinical trials.gov identifier NCT00211653). METHODS In this prospective, randomized, placebo-controlled, double-blinded clinical trial, 102 patients with chronic kidney disease who underwent heart surgery at the Minneapolis Veterans Affairs Medical Center were randomized to either NAC (n = 50) 600 mg PO twice daily or placebo (n = 52) for a total of 14 doses (3 preoperative). The primary outcome was maximum change in creatinine from baseline within 7 days after surgery. Secondary outcome was AKI (ie, >0.5 mg/dL or >or=25% increase in creatinine from baseline). RESULTS Creatinine increased in both groups (0.45 +/- 0.7 mg/dL in NAC vs 0.55 +/- 0.9 mg/dL in placebo, P = .53) and peaked on postoperative day 5. Acute kidney injury occurred in 41 patients (22 NAC vs 19 placebo, P = .44) by postoperative day 5, but persisted in only 14 (7 NAC vs 7 placebo, P = .94) by day 30. In multivariable analysis, perioperative NAC was unassociated with AKI (relative risk 1.2, 95% CI, 0.8-1.9, P = .34). Five patients (3 NAC vs 2 placebo, P = .68) underwent hemodialysis, and 5 (2 NAC vs 3 placebo, P = 1.0) died perioperatively. There was no difference in lengths of stay in the intensive care unit (4.9 +/- 7 days in NAC vs 6.5 +/- 9 days in placebo, P = .06) and the hospital (13.2 +/- 13 days in NAC vs 16.7 +/- 17 days in placebo, P = .12). CONCLUSION Prophylactic perioperative NAC administration does not prevent AKI after cardiac surgery.

Usefulness of Revascularization of Patients With Multivessel Coronary Artery Disease Before Elective Vascular Surgery for Abdominal Aortic and Peripheral Occlusive Disease

The Coronary Artery Revascularization Prophylaxis (CARP) study showed no survival benefit with preoperative coronary artery revascularization before elective vascular surgery. The generalizability of the trial results to all patients with multivessel coronary artery disease (CAD) has been questioned. The objective of this study was to determine the impact of prophylactic coronary revascularization on long-term survival in patients with multivessel CAD. Over a 4-year period, 1,048 patients underwent coronary angiography before vascular surgery during screening into the CARP trial. The cohort was composed of registry (n = 586) and randomized (n = 462) patients, and their survival was determined at 2.5 years after vascular surgery. High-risk coronary anatomy without previous bypass surgery included 2-vessel disease (n = 204 [19.5%]), 3-vessel disease (n = 130 [12.4%]), and left main coronary artery stenosis > or = 50% (n = 48 [4.6%]). By log-rank test, preoperative revascularization was associated with improved survival in patients with a left main coronary artery stenoses (0.84 vs 0.52, p <0.01) but not those with either 2-vessel (0.80 vs 0.79, p = 0.83) or 3-vessel (0.79 vs 0.71, p = 0.15) disease. In conclusion, unprotected left main coronary artery disease was present in 4.6% of patients who underwent coronary angiography before vascular surgery, and this was the only subset of patients showing a benefit with preoperative coronary artery revascularization.

Incidence and Predictors of Post-Cardiotomy Delirium

OBJECTIVE To determine the incidence and predictors of delirium after cardiac surgery. METHOD A prospective, observational study of postcardiotomy surgical patients was conducted during a 5 month period at the Minneapolis, MN, VAMC. RESULTS Of the 53 patients who completed the study, 12 patients (23%) met criteria for postoperative delirium and 18 patients (34%) met criteria for postoperative subsyndromal delirium. Significant predictors of postoperative delirium included a history of cerebrovascular disease (Charlson Index item, VA CICSP), high medical comorbidity (VA morbidity risk score, Charlson Index), increased preoperative creatinine level, and an increased preoperative pain rating. When delirium and subsyndromal delirium patients were combined, a history of cerebrovascular disease, left ventricular dysfunction, or diabetes predicted the development of delirious symptoms. CONCLUSIONS Incident delirium occurred in 23% of patients after cardiac surgery and incident delirium symptoms, in 57%. The strongest predictor of both incident delirium and delirium symptoms was a history of cerebrovascular disease.

Prospective, randomized trial of autotransfusion after routine cardiac operations

To study the effectiveness of autotransfusion of shed mediastinal blood in decreasing the need for homologous blood transfusion in the routine cardiac surgical patient, we prospectively randomized 35 consecutive patients into two groups. The experimental group (n = 18) received autotransfusion for 12 hours after completion of the operative procedure. The control group (n = 17) was treated with standard chest drainage and fluid replacement. Both groups received homologous blood transfusion when the hemoglobin level fell to less than 8.0 g/dL. Students t test, chi 2 analysis, and multivariate logistic regression analysis were used where appropriate. Packed red blood cells were required postoperatively in 6 of the 17 control and 6 of the 18 autotransfusion patients (p = not significant). Postoperative colloid fluid replacement (excluding autotransfusion fluid) in the autotransfusion group (333 +/- 78 mL; 95% confidence bounds, 168 to 498 mL) was less than in the control group (615 +/- 114 mL; 95% confidence bounds, 372 to 857 mL; p = 0.048). Total homologous blood product exposure tended to be higher in autotransfusion patients (83%) than in control patients (47%) (p = 0.057). Fibrin split products were elevated only in the serum of the autotransfusion patients (p < 0.002). No transfusion-related complications were apparent in either group. Although the sample size is small, autotransfusion of shed mediastinal blood does not appear to decrease the need for homologous blood transfusion in the routine cardiac surgical patient.

Comparison of Risk Scores to Estimate Perioperative Mortality in Aortic Valve Replacement Surgery

BACKGROUND Transaortic valve implantation has recently been introduced as an alternative to aortic valve replacement (AVR) for high-risk patients with aortic stenosis. However, accurate assessment of surgical risk is critical for appropriate patient selection. We compared the accuracy of The Society of Thoracic Surgeons (STS) risk score, the European System for Cardiac Risk Evaluation (EuroSCORE), and the Veterans Administration (VA) risk score in predicting perioperative mortality after AVR. METHODS We included 537 consecutive patients who underwent AVR for severe aortic stenosis at the Minneapolis VA Medical Center between 1997 and 2008. Observed and predicted perioperative (30-day) mortality rates were compared. Hosmer-Lemeshow goodness-of-fit test and receiver operating characteristic curves were performed to assess the performance of the scores. RESULTS Perioperative mortality rate was 5.9% (n=32). Predicted mortality rates for the EuroSCORE, STS score, and VA score were 15.6%, 3.6%, and 6.7%, respectively (p=0.001). The EuroSCORE overestimated mortality in all patients, most notably among those with ejection fraction less than 35% (49% predicted versus 9% observed). The EuroSCORE had poor calibration (goodness-of-fit test p<0.008), whereas the STS and the VA scores were well calibrated. However, all three scores displayed good discrimination characteristics per the areas under the receiver operating characteristic curves: STS score 0.73 (95% confidence interval: 0.69 to 0.77); VA score 0.66 (95% confidence interval: 0.62 to 0.70); and EuroSCORE 0.68 (95% confidence interval: 0.64 to 0.72; p>0.05). CONCLUSIONS The EuroSCORE substantially overestimates perioperative mortality risk in AVR, particularly in patients with low ejection fraction. These data have implications when deciding the appropriate intervention (transaortic valve implantation versus AVR) for high-risk aortic stenosis patients.