Patrick D. Kilgo

Off-Pump Coronary Artery Bypass Disproportionately Benefits High-Risk Patients

BACKGROUND It is not known which patient subgroups may benefit most from off-pump coronary artery bypass grafting (OPCAB) rather than coronary artery bypass grafting on cardiopulmonary bypass (CPB). METHODS The Society of Thoracic Surgeons database was queried for all isolated, primary coronary artery bypass graft cases between January 1, 1997, and December 31, 2007, at a US academic center. The Society of Thoracic Surgeons Predicted Risk of Mortality (PROM) was calculated by a formula based on 30 preoperative risk factors. It was used in three ways to compare 30-day operative mortality between patients treated with OPCAB versus CPB. First, patients were divided into quartiles based on their PROM, and mortality rates were compared between OPCAB and CPB patients within each PROM quartile. Second, a logistic regression model tested for an interaction between surgery type and PROM; a significant interaction would indicate that the relative mortality risk of OPCAB versus CPB varied with different PROM levels. Finally, locally smoothed kernel regression curves were used to visually estimate a threshold PROM point at which mortality rates diverge for the surgery types. RESULTS There were 14,766 consecutive patients, 7,083 OPCAB (48.0%) and 7,683 CPB (52.0%). There was no difference in operative mortality between OPCAB and CPB for patients in the lower two risk quartiles. In the higher risk quartiles there was a mortality benefit for OPCAB (odds ratio, 0.62 and 0.45 for OPCAB in the third and fourth risk quartiles). Logistic regression analysis confirmed a significant interaction between surgery type and PROM (p = 0.005) meaning that OPCAB is especially beneficial to patients with higher PROM. This benefit is most significant for patients with PROM values above 2.5% to 3%, where mortality curves sharply diverge. CONCLUSIONS Off-pump coronary artery bypass grafting is associated with lower operative mortality than coronary artery bypass grafting on CPB for higher risk patients. This mortality benefit increases with increasing PROM.

New-Onset Atrial Fibrillation Predicts Long-Term Mortality After Coronary Artery Bypass Graft

OBJECTIVES We sought to investigate the association between new-onset atrial fibrillation after coronary artery bypass graft (CABG) (post-operative atrial fibrillation [POAF]) and long-term mortality in patients with no history of atrial fibrillation. BACKGROUND POAF predicts longer hospital stay and greater post-operative mortality. METHODS A total of 16,169 consecutive patients with no history of AF who underwent isolated CABG at our institution between January 1, 1996, and December 31, 2007, were included in the study. All-cause mortality data were obtained from Social Security Administration death records. A multivariable Cox proportional hazards regression model was constructed to determine the independent impact of new-onset POAF on long-term survival after adjusting for several covariates. The covariates included age, sex, race, pre-operative risk factors (ejection fraction, New York Heart Association functional class, history of myocardial infarction, index myocardial infarction, stroke, chronic obstructive pulmonary disease, peripheral arterial disease, smoking, diabetes, renal failure, hypertension, dyslipidemia, creatinine level, dialysis, redo surgery, elective versus emergent CABG, any valvular disorder) and post-operative adverse events (stroke, myocardial infarction, acute respiratory distress syndrome, and renal failure), and discharge cardiac medications known to affect survival in patients with coronary disease. RESULTS New-onset AF occurred in 2,985 (18.5%) patients undergoing CABG. POAF independently predicted long-term mortality (hazard ratio: 1.21; 95% confidence interval: 1.12 to 1.32) during a mean follow-up of 6 years (range 0 to 12.5 years). This association remained true after excluding from the analysis those patients who died in-hospital after surgery (hazard ratio: 1.21; 95% confidence interval: 1.11 to 1.32). Patients with POAF discharged on warfarin experienced reduced mortality during follow-up. CONCLUSIONS In this large cohort of patients, POAF predicted long-term mortality. Warfarin anticoagulation may improve survival in POAF.

American Association for the Surgery of Trauma Organ Injury Scale I: spleen, liver, and kidney, validation based on the National Trauma Data Bank.

BACKGROUND This study attempts to validate the American Association for the Surgery of Trauma (AAST) Organ Injury Scale (OIS) for spleen, liver, and kidney injuries using the National Trauma Data Bank (NTDB). STUDY DESIGN All NTDB entries with Abbreviated Injury Scale codes for spleen, liver, and kidney were classified by OIS grade. Injuries were stratified either as an isolated intraabdominal organ injury or in combination with other abdominal injuries. Isolated abdominal solid organ injuries were additionally stratified by presence of severe head injury and survival past 24 hours. The patients in each grading category were analyzed for mortality, operative rate, hospital length of stay, ICU length of stay, and charges incurred. RESULTS There were 54,148 NTDB entries (2.7%) with Abbreviated Injury Scale-coded injuries to the spleen, liver, or kidney. In 35,897, this was an isolated abdominal solid organ injury. For patients in which the solid organ in question was not the sole abdominal injury, a statistically significant increase (p < or = 0.05) in mortality, organ-specific operative rate, and hospital charges was associated with increasing OIS grade; the exception was grade VI hepatic injuries. Hospital and ICU lengths of stay did not show substantial increase with increasing OIS grade. When isolated organ injuries were examined, there were statistically significant increases (p < or = 0.05) in all outcomes variables corresponding with increasing OIS grade. Severe head injury appears to influence mortality, but none of the other outcomes variables. Patients with other intraabdominal injuries had comparable quantitative outcomes results with the isolated abdominal organ injury groups for all OIS grades. CONCLUSIONS This study validates and quantifies outcomes reflective of increasing injury severity associated with increasing OIS grades for specific solid organ injuries alone, and in combination with other abdominal injuries.

Elevated preoperative hemoglobin A1c level is predictive of adverse events after coronary artery bypass surgery

OBJECTIVE Diabetes mellitus has been associated with an increased risk of adverse outcomes after coronary artery bypass grafting. Hemoglobin A1c is a reliable measure of long-term glucose control. It is unknown whether adequacy of diabetic control, measured by hemoglobin A1c, is a predictor of adverse outcomes after coronary artery bypass grafting. METHODS Of 3555 consecutive patients who underwent primary, elective coronary artery bypass grafting at a single academic center from April 1, 2002, to June 30, 2006, 3089 (86.9%) had preoperative hemoglobin A1c levels obtained and entered prospectively into a computerized database. All patients were treated with a perioperative intravenous insulin protocol. A multivariable logistic regression model was used to determine whether hemoglobin A1c, as a continuous variable, was associated with in-hospital mortality, renal failure, cerebrovascular accident, myocardial infarction, and deep sternal wound infection after coronary artery bypass grafting. Receiver operating characteristic curve analysis identified the hemoglobin A1c value that maximally discriminated outcome dichotomies. RESULTS In-hospital mortality for all patients was 1.0% (31/3089). An elevated hemoglobin A1c level predicted in-hospital mortality after coronary artery bypass grafting (odds ratio 1.40 per unit increase, P = .019). Receiver operating characteristic curve analysis revealed that hemoglobin A1c greater than 8.6% was associated with a 4-fold increase in mortality. For each unit increase in hemoglobin A1c, there was a significantly increased risk of myocardial infarction and deep sternal wound infection. By using receiver operating characteristic value thresholds, renal failure (threshold 6.7, odds ratio 2.1), cerebrovascular accident (threshold 7.6, odds ratio 2.24), and deep sternal wound infection (threshold 7.8, odds ratio 5.29) occurred more commonly in patients with elevated hemoglobin A1c. CONCLUSION Elevated hemoglobin A1c level was strongly associated with adverse events after coronary artery bypass grafting. Preoperative hemoglobin A1c testing may allow for more accurate risk stratification in patients undergoing coronary artery bypass grafting.

Off-pump coronary bypass provides reduced mortality and morbidity and equivalent 10-year survival.

BACKGROUND This study compared in-hospital major adverse cardiac events (MACE) and long-term survival after off-pump (OPCAB) vs on-pump (CPB) coronary artery bypass grafting (CABG). METHODS Reviewed were 12,812 consecutive isolated CABG patients from 1997 to 2006. A propensity score (PS), including 40 preoperative risk factors, balanced characteristics between OPCAB and CPB groups. Multiple logistic regression models tested whether gender or surgery type, or their interaction, were associated with in-hospital mortality and MACE. A proportional hazards regression model and Kaplan-Meier curves related long-term survival with gender, surgery type, and their interaction, adjusted for PS and age. RESULTS OPCAB was associated with a significant reduction in operative mortality (adjusted odds ratio [AOR], 0.68; p = 0.045), stroke (AOR, 0.48; p < 0.001), and MACE (AOR, 0.66; p = 0.018). Female gender was associated with higher rates of death (AOR, 1.93), stroke (AOR, 1.82), myocardial infarction (AOR, 2.19), and MACE (AOR, 1.97; each p < 0.001). Women disproportionately benefited from OPCAB in operative mortality (p = 0.04). Odds of death for women on CPB were higher than for women treated with OPCAB (AOR, 2.07, p = 0.005). Odds of death for men on CPB were not significantly higher than for men treated with OPCAB (AOR, 1.16, p = 0.51). Male gender was associated with longer-term survival (p = .011), but surgery type (OPCAB vs CPB) was not (p = 0.23). CONCLUSIONS OPCAB provides significant early mortality and morbidity advantages, especially for women. During the 10-year follow-up, OPCAB and CPB result in similar survival, regardless of gender.

Bilateral Internal Thoracic Artery Grafting Is Associated With Significantly Improved Long-Term Survival, Even Among Diabetic Patients

BACKGROUND This study examines if bilateral internal thoracic artery (BITA) grafting provides improved outcomes compared with single internal thoracic artery (SITA) grafting, in the modern era, in which diabetes mellitus and obesity are more prevalent. METHODS The Society of Thoracic Surgeons database at a single large academic center was reviewed for all consecutive isolated coronary artery bypass grafting patients with two or more distal anastomoses from January 1, 2002, through December 31, 2010. Propensity-adjusted logistic and Cox regression models were used to estimate the effect of BITA on short-term outcomes and long-term survival for diabetic and nondiabetic patients. RESULTS A total of 3,527 coronary artery bypass grafting operations (812 BITA, 2,715 SITA) were performed. Fewer BITA than SITA patients had diabetes (28.6% vs 44.7% p<0.001). There was no significant difference in 30-day rates of death, stroke, or myocardial infarction between nondiabetic patients who had BITA vs SITA, or between diabetic patients who had BITA vs SITA. BITA grafting conferred a 35% reduction (95% confidence interval, 12% to 52%, p=0.006) in the long-term hazard of death equally for nondiabetic and diabetic patients (p=0.93). Deep sternal wound infection was more common among diabetic than among nondiabetic patients (1.5% vs 0.7%), but was similar within nondiabetic (1.0% vs 0.6%) and diabetic patients (1.7% vs 1.5%) who had BITA vs SITA. Overall, BITA and SITA patients had similar rates of deep sternal wound infection (1.2% vs 1.0%). CONCLUSIONS BITA grafting confers a long-term survival advantage and should be performed whenever suitable coronary anatomy exists and patient risk factors allow an acceptable risk of deep sternal wound infection.

Injury-associated hypothermia: an analysis of the 2004 National Trauma Data Bank.

Severe injury and shock are frequently associated with abnormalities in patient body temperature. Substantial increases in mortality have been associated with profound hypothermia, especially below 35°C. The purpose of this study was to further characterize the impact of hypothermia in a large dataset of trauma patients. This study was a retrospective analysis of the 2004 version of the National Trauma Data Bank (NTDB), which contains approximately 1.1 million patients from over 400 trauma centers. Admission temperature was analyzed with respect to mortality, injury severity score (ISS), base deficit (BD), Glasgow Coma Score (GCS), and hospital outcomes. The NTDB contained 701,491 patients with temperatures recorded upon trauma center admission. Of these, 11,026 patients had admission temperatures <35°C, and 802 had temperatures <32°C. Comparison of core temperature versus mortality revealed that as temperature decreased, the mortality rate increased, reaching approximately 39% at 32°C, and remained constant at lower temperatures. Surprisingly, 477 patients (59.5%) survived with temperatures <32°C. Similarly, BD increased as hypothermia worsened until body temperature reached 31°C, below which there was little further increase. Patients with admission temperatures less than 35°C had significantly greater mortality (25.5% vs. 3.0%, P < 0.001) and BD (7.8 vs. 3.7, P < 0.001) when compared with patients with temperatures ≥35°C. In survivors, average ventilator days and intensive care unit (ICU) days were 14.4 and 12.8, respectively, for patients with temperatures <35°C as opposed to more normothermic patients who demonstrated an average of 9.5 ventilator days and 9.1 ICU days (P < 0.001). When grouped by individual ISS, BD level, and GCS motor score, mortality was significantly greater when admission temperature was below 35°C (ISS mean difference = 11.4%, BD mean difference = 22.8%, and GCS motor mean difference = 9.85%). Logistic regression revealed that hypothermia remains an independent determinant of mortality after correction for confounding variables (odds ratio = 1.54, 95% confidence interval 1.40-1.71). Admission hypothermia is associated with greater mortality, increased injury severity, more profound acidosis, and prolonged ICU/ventilator courses. However, although mortality at <32°C is high, patients with temperatures this low do survive. As temperatures drop below 32°C, mortality rates remain constant, which may indicate a threshold below which physiologic mechanisms are unable to correct body temperature regardless of injury severity. Although shock severity is highly indicative of outcome, hypothermia independently contributes to the substantial mortality associated with severe injury.

Long-Term Outcomes After Isolated Aortic Valve Replacement in Octogenarians: A Modern Perspective

BACKGROUND With the recent advent of percutaneous valve therapy, an increased need for the evaluation of outcomes after open aortic valve replacement (AVR) in elderly patients is warranted. This study compares the short- and long-term survival outcomes of octogenarians after AVR with younger age groups in the modern surgical era. METHODS A retrospective review was performed on patients who underwent isolated, primary AVR from 1996 to 2006 at the Emory Healthcare Hospitals. Five-hundred fifteen patients were divided into three age groups: 60 to 69 (n = 206), 70 to 79 (n = 221), and 80 to 89 years of age (n = 88). Outcomes were compared among the age groups using logistic regression and analysis of variance techniques. Long-term survival between age groups was compared using the Cox proportional hazards model. Kaplan-Meier plots were used to determine survival rates. RESULTS The groups were similar with respect to in-hospital mortality (p = 0.66) and hospital length of stay (p = 0.08). Preoperative predictors of in-hospital mortality included stroke (odds ratio [OR] 5.36), chronic lung disease (OR 4.51), and renal failure (OR 1.39). As expected, age significantly impacted long-term survival (hazard ratio [HR] 1.06). Other predictors of long-term survival included stroke (HR 2.15), current smoker (HR 2.03), diabetes (HR 1.53), and renal failure (HR 1.4). The Kaplan-Meier estimate of median survival for octogenarians was 7.4 years. CONCLUSIONS In the modern era, octogenarians have acceptable short- and long-term results after open AVR. Comparisons of less invasive techniques for AVR should rely on outcomes based in the modern era and decisions regarding surgical intervention in patients requiring AVR should not be based on age alone.

Elevated Preoperative Hemoglobin A1c Level is Associated With Reduced Long-Term Survival After Coronary Artery Bypass Surgery

BACKGROUND The predictive role of hemoglobin A1c (HbA1c) on long-term outcomes after coronary artery bypass surgery has not been evaluated. METHODS Preoperative HbA1c levels were obtained in 3,201 patients undergoing primary, elective coronary artery bypass surgery at Emory Healthcare Hospitals from January 2002 to December 2006 and entered prospectively into a computerized database. Long-term survival status was determined by cross-referencing patient records with the Social Security Death Index. Log-rank (unadjusted) and Cox proportional hazards regression models (adjusted) were employed to determine whether HbA1c and diabetes mellitus were independent risk factors for reduced long-term survival, adjusted for 29 covariates. Hazard ratios for each unit increase in continuous HbA1c were calculated. RESULTS Patients with HbA1c of 7% or greater had lower unadjusted 5-year survival compared with patients with HbA1c less than 7% (p = 0.001). Similarly, patients with diabetes mellitus had lower unadjusted 5-year survival compared with patients without diabetes (p < 0.001). After multivariable adjustment, higher HbA1c (measured as a continuous variable) was associated with reduced long-term survival for each unit increase in HbA1c (hazard ratio 1.15, p < 0.001), but preoperative diagnosis of diabetes was not associated with reduced long-term survival after coronary artery bypass surgery (p = 0.41). Other multivariable predictors of reduced long-term survival included age, cerebrovascular disease, elevated serum creatinine, renal insufficiency, congestive heart failure, previous myocardial infarction, chronic lung disease, and peripheral vascular disease. CONCLUSIONS Poor preoperative glycemic control, as measured by an elevated HbA1c, is associated with reduced long-term survival after coronary artery bypass surgery. Optimizing glucose control in these patients may improve long-term survival.

Off-Pump and On-Pump Coronary Artery Bypass Grafting Are Associated With Similar Graft Patency, Myocardial Ischemia, and Freedom From Reintervention: Long-Term Follow-Up of a Randomized Trial

BACKGROUND The Surgical Management of Arterial Revascularization Therapies trial was conceived to rigorously compare completeness of revascularization, clinical outcomes and resource utilization in unselected patients referred for elective, primary coronary artery bypass grafting randomly assigned to undergo off-pump (OPCAB) or conventional on-pump coronary artery bypass grafting using cardiopulmonary bypass (CPB). The goal of this follow-up study was to compare long-term survival, graft patency, myocardial ischemia, and clinical outcomes among survivors who volunteered to return for clinical evaluation and imaging studies. METHODS Two hundred unselected patients with multivessel coronary artery disease were randomly assigned to OPCAB or CPB coronary artery bypass grafting between March 2000 and August 2001. All-cause mortality was determined by individual patient contact and referencing the Social Security Death Master File. Of 140 survivors, 87 volunteered to return after a minimum of 6.8 years (maximum, 8.4 years; mean, 7.5 years) for assessment of graft patency (computed tomographic angiography) and myocardial ischemia (cardiac positron emission tomography and 12-lead electrocardiogram). Age at follow-up ranged from 38 to 90 years (mean, 68 years). RESULTS There were 26 deaths from all causes among OPCAB patients and 31 among CPB patients as of March 30, 2009. Graft patency was similar between groups among 622 grafts assessed by angiography before hospital discharge (99% OPCAB versus 97.7% CPB; p=0.22, Fishers exact test), among 511 grafts assessed by angiography at 1 year (93.6% OPCAB versus 95.8% CPB; p=0.33), and among 190 grafts assessed by computed tomographic angiography at late follow-up (76% OPCAB versus 83.5% CPB; p=0.44). Twelve of 34 OPCAB (35.3%) and 16 of 39 CPB patients (41.0%) had any ischemia on positron emission tomography scanning (p=0.62). Four OPCAB patients (11.8%) and 9 CPB patients (23.1%) had an ischemic region in excess of 10% of myocardium (p=0.21). At late follow-up, recurrent angina had occurred in 11 of 43 (25.6%) OPCAB patients and 5 of 44 (11.4%) CPB patients (p=0.09). Percutaneous reintervention had been performed at the discretion of blinded local cardiologists in 1 of 43 (2.3%) OPCAB patients and 1 of 44 (2.3%) CPB patients (p=1.0). No patient in either group has undergone repeat CABG. CONCLUSIONS In this randomized trial, off-pump and on-pump coronary artery bypass grafting were associated with similar early and late graft patency, incidence of recurrent or residual myocardial ischemia, need for reintervention, and long-term survival.