Omar M. Lattouf

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.

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.

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 Techniques Disproportionately Benefit Women and Narrow the Gender Disparity in Outcomes After Coronary Artery Bypass Surgery

Background— Women experience greater morbidity and mortality than men after conventional coronary artery bypass grafting (CABG) on cardiopulmonary bypass (CPB). The objective of this study was to determine whether off-pump CABG (OPCAB) alters this gender-based disparity. Methods and Results— Retrospective review of risk factors and clinical outcomes for 11 413 consecutive patients having isolated CABG between January 1, 1997, and May 31, 2005, at a US academic center. Interventions were OPCAB or CABG/CPB, performed at the discretion of 14 faculty surgeons. Main outcome measures included in-hospital death, stroke, myocardial infarction or combined major adverse cardiac events (MACE=death or stroke or myocardial infarction). Odds ratios of adverse events, adjusted for 31 risk factors, were compared between women and men who had OPCAB versus CABG/CPB. Covariates included Propensity Score, Society of Thoracic Surgeons’ Predicted Risk, surgeon and body habitus. Female patients (n=3248) and those treated with OPCAB (n=4492) were older, had more comorbidities and higher predicted risk than male patients (n=8165) and those treated with conventional CABG/CPB (n=6921), respectively. Women treated with CABG/CPB had a risk-adjusted odds ratio of 1.60 for death (P=0.01), 1.71 for stroke (P=0.007), 2.26 for myocardial infarction (P=0.008) and 1.71 for MACE (P<0.001) compared with men who had CABG/CPB. In contrast, women treated with OPCAB had outcomes statistically similar to men who had either OPCAB or CABG/CPB. Among women, OPCAB was associated with a significant reduction in death (OR 0.39, P=0.001), stroke (OR 0.43, P=0.002) and MACE (OR 0.43, P<0.001). Conclusions— OPCAB is associated with fewer major adverse cardiac events and benefits women disproportionately, thereby narrowing the gender disparity in clinical outcomes after CABG.

Impact of preoperative renal dysfunction on long-term survival for patients undergoing aortic valve replacement.

BACKGROUND The impact of the degrees of renal dysfunction (RD) after aortic valve replacement (AVR) has not been well described. The purpose of this study was to compare patients undergoing AVR with a range of renal function from normal to dialysis-dependence. METHODS A retrospective review of 2,408 patients undergoing AVR with or without coronary artery bypass graft surgery (CABG) from January 1996 to March 2009 was performed. Glomerular filtration rate (GFR) was estimated for patients using the Modification of Diet in Renal Disease formula. Multivariable logistic and Cox regression methods were used to determine the independent association of GFR with outcomes. Adjusted odds ratios were calculated for in-hospital outcomes, and Kaplan-Meier curves were created to estimate long-term survival. RESULTS In all, 1,512 patients (62.8%) had isolated AVR, and 896 (37.2%) underwent AVR plus CABG. Preoperative RD was common among all patients: 1,148 of 2,408 (47.7%) with mild RD (GFR 60 to 90 mL·min(-1)·1.73 m(-2)), 644 of 2,408 (26.7%) moderate RD (GFR 30 to 59 mL·min(-1)·1.73 m(-2)), 59 of 2,408 (2.5%) severe RD (GFR 15 to 30 mL·min(-1)·1.73 m(-2)), and 114 (4.7%) with kidney failure (GFR<15) or requiring dialysis. In-hospital mortality generally rose with RD, from 2.9% for patients with no RD to 15.8% for patients with severe RD, and 17.3% for patients requiring dialysis. Patients with severe RD or preoperative dialysis were associated with significantly poorer outcomes. Adjusted long-term survival is progressively worse across levels of RD, as was postoperative length of stay (p<0.001). CONCLUSIONS Preoperative RD is common among the AVR population and is associated with diminished long-term survival. The association between RD and worse outcomes after AVR surgery has significant clinical implications.

The impact of body mass index on morbidity and short- and long-term mortality in cardiac valvular surgery

OBJECTIVE Limited data exist on patients with cardiac cachexia or morbid obesity presenting for valvular heart surgery. The objective of this study was to investigate the relationship between body mass index and morbidity and mortality after valvular surgery. METHODS A retrospective review of 4247 patients undergoing valvular surgery from 1996 to 2008 at Emory University Healthcare Hospitals was performed. Patients were divided into 3 groups: body mass index 24 or less (group 1, n = 1527), body mass index 25 to 35 (group 2, n = 2284), and body mass index 36 or more (group 3, n = 436). Data were analyzed using multivariable regression analysis, adjusted for 10 preoperative covariates. A smooth kernel regression curve was generated using body mass index and in-hospital mortality as variables. Long-term survival comparisons were made using adjusted Cox proportional hazards regression models and Kaplan-Meier product-limit estimates. Kaplan-Meier curves were generated that provide survival estimates for long-term mortality using the Social Security Death Index. RESULTS Patients in group 3 were significantly younger (group 1, 61.7 ± 16.1 years; group 2, 61.9 ± 13.6; group 3, 57.5 ± 13.0; P < .001) and more likely to be female (group 1, 778/1527 [51.0%]; group 2, 912/2284 [39.9%]; group 3, 240/436 [55.0%]; P < .001). Mean ejection fractions were similar among groups (P = .51). Patients in group 2 had significantly shorter postoperative length of stay (group 1, 9.6 ± 10.3 days; group 2, 8.7 ± 8.2 days; group 3, 10.8 ± 11.0 days; P < .001). In-hospital mortality for the entire cohort was 5.8% (245/4247), and by group was 111 of 1527 (7.3%) in group 1, 110 of 2284 (4.8%) in group 2, and 24 of 436 (5.5%) in group 3 (P = .006). Actual survival at 1, 3, 5, and 10 years was significantly lower in group 1 (P < .001). A lower body mass index was a significant independent predictor for both in-hospital and long-term mortality. CONCLUSIONS Patients with body mass index 24 or less are at significantly increased risk of in-hospital and long-term mortality after cardiac valvular surgery. This high-risk patient population warrants careful risk stratification and options for less-invasive valve therapies.