Karen J. Buth

Frail Patients Are at Increased Risk for Mortality and Prolonged Institutional Care After Cardiac Surgery

Background— Frailty is an emerging concept in medicine yet to be explored as a risk factor in cardiac surgery. Where elderly patients are increasingly referred for cardiac surgery, the prevalence of a frail group among these is also on the rise. We assessed frailty as a risk factor for adverse outcomes after cardiac surgery. Methods and Results— Functional measures of frailty and clinical data were collected prospectively for all cardiac surgery patients at a single center. Frailty was defined as any impairment in activities of daily living (Katz index), ambulation, or a documented history of dementia. Of 3826 patients, 157 (4.1%) were frail. Frail patients were older, were more likely to be female, and had risk factors for adverse surgical outcomes. By logistic regression, frailty was an independent predictor of in-hospital mortality (odds ratio 1.8, 95% CI 1.1 to 3.0), as well as institutional discharge (odds ratio 6.3, 95% CI 4.2 to 9.4). Frailty was an independent predictor of reduced midterm survival (hazard ratio 1.5, 95% CI 1.1 to 2.2). Conclusions— Frailty is a risk for postoperative complications and an independent predictor of in-hospital mortality, institutional discharge, and reduced midterm survival. Frailty screening improves risk assessment in cardiac surgery patients and may identify a subgroup of patients who may benefit from innovative processes of care.

Coronary Bypass Surgery Performed off Pump Does Not Result in Lower In-Hospital Morbidity Than Coronary Artery Bypass Grafting Performed on Pump

Background—There is increasing evidence that cardiopulmonary bypass (CPB) may be responsible for the morbidity associated with coronary artery bypass grafting (CABG) surgery. Recent developments in cardiac stabilization devices have made CABG without CPB feasible. However, there is conflicting evidence to date from published trials comparing outcomes between CABG performed with and without CPB, with some trials indicating an advantage to the avoidance of CPB and others showing little benefit. Methods and Results—In a single-center randomized trial, 300 patients requiring CABG surgery at a single institution were prospectively randomized to have the procedure performed with CPB (n=150) or on the beating heart (n=150). Exclusion criteria for the trial included emergency procedure, concomitant major cardiac procedures, ejection fraction <30%, and reoperation. In-hospital outcomes were analyzed on an intention-to-treat basis. A mean of 3.0±0.9 grafts were performed in the CPB group compared with 2.8±0.9 grafts in the beating-heart group (P =0.06). There were no significant differences between the CPB group and the beating-heart group in mortality (0.7% versus 1.3%; P =1.0), transfusion (8.7% versus 9.3%), perioperative myocardial infarction (0.7% versus 2.7%; P =0.37), permanent stroke (0% versus 1.3%; P =0.50), new atrial fibrillation (32% versus 25%; P =0.20), and deep sternal wound infection (0.7% versus 0%; P =1.0). The mean time to extubation was 4 hours, the mean stay in the intensive care unit was 22 hours, and the median length of hospitalization was 5 days in both groups (P =NS). Conclusions—In contrast to published trials, we were unable to demonstrate any advantage with CABG performed without CPB in terms of patient morbidity. Excellent results can be obtained with either surgical approach.

Is body size the cause for poor outcomes of coronary artery bypass operations in women

Although small body size and coronary artery diameter are recognized as major contributors to the increased risk of coronary artery bypass grafting in women, few studies have established the independent influence of body size and gender on outcome. We studied 7025 consecutive patients (5694 men, 1331 women) undergoing isolated coronary artery bypass grafting between 1990 and 1994. Women were older, had higher preoperative prevalences of urgent operation because of unstable angina, diabetes, peripheral vascular disease, hypertension, and single-vessel coronary artery disease (p < 0.0001), and a lower prevalence of left ventricular ejection fraction 40% or less (p < 0.0001). The prevalences of operative mortality (men, 1.8%; women, 3.5%), low-output syndrome (men, 6.6%; women, 14.8%), and myocardial infarction (men, 2.8%; women, 5.5%) were higher in women (p < 0.0001). Patients were divided into quartiles for body surface area, weight, height, and body mass index. For both men and women, there was no difference in operative mortality between the highest and lowest quartiles of body size. Women, however, had a higher prevalence of operative mortality than men in the lower quartiles of body surface area, height, and weight and in the higher quartiles of body mass index. Among men, the prevalence of low-output syndrome increased (p < 0.0001) with decreasing body surface area, weight, and body mass index, suggesting that body size did influence the prevalence of low-output syndrome. However, women had a higher prevalence of low-output syndrome than men in every category and quartile of body size (p < 0.0001). Multivariable analysis identified gender as a significant determinant of operative mortality (odds ratio 1.83, 95% confidence interval 1.27 to 2.64) and low-output syndrome (odds ratio 2.52, 95% confidence interval 2.05 to 3.11). When multivariable adjustments were made for body size and preoperative risk factors, gender remained a predictor of both operative mortality and low-output syndrome. Multivariable assessment of risk for men and women separately identified that urgent operation was a predictor of operative mortality (odds ratio 2.52, 95% confidence interval 1.32 to 5.61) and low-output syndrome (odds ratio 1.57, 95% confidence interval 1.14 to 2.17) in women but not men. In conclusion, the increased risk of coronary artery bypass grafting in women may be explained in part by dramatic differences in preoperative risk factors between men and women. In both men and women, small body size did not increase the risk of operative mortality, but may have contributed to the risk of low-output syndrome.(ABSTRACT TRUNCATED AT 400 WORDS)

Preoperative prediction of prolonged mechanical ventilation following coronary artery bypass grafting

OBJECTIVE Few studies have attempted to evaluate who would require prolonged mechanical ventilation following heart surgery. The objectives of this study were to identify predictors of prolonged ventilation in a large group of coronary artery bypass grafting (CABG) patients from a single institution. METHODS One thousand, eight hundred and twenty-nine consecutive patients undergoing CABG were reviewed retrospectively and evaluated for preoperative predictors of prolonged ventilation which included: age, gender, ejection fraction (EF), renal function, diabetes, angina status, New York Heart Association Class, number of diseased vessels, urgency of the procedure, re-operation, chronic lung disease (COPD) and intraoperative variables such as IABP, inotropes, stroke and myocardial infarction. Prolonged ventilation was defined as > or = 24 h. Stepwise logistic regression analysis was performed. RESULTS Patients were on average 65.4+/-10.6 years of age, 30% were diabetic, 80% had triple vessel disease and 93% were of functional class III/IV. The mean ejection fraction was 60+/-16 percent. Overall peri-operative mortality was 2.7%. There were 157 patients that required prolonged ventilation with a peri-operative mortality of 18.5% (P < 0.001). Preoperative independent predictors of prolonged ventilation were found to be: unstable angina (OR 5.6), EF < 50 (OR 2.3), COPD (OR 2.0), preop. renal failure (OR 1.9), female gender (OR 1.8) and age > 70 (OR 1.7). Based on these predictors, a model was created to estimate of the risk of prolonged ventilation in individual patients following CABG with results ranging from < or = 3% in patients without any risk factors to > or = 32% in patients with five or more independent risk factors. Certain intraoperative variables were strong predictors of prolonged ventilation and included: stroke (OR 12.3), re-operation for bleeding (OR 6.9) and perioperative MI (OR 5.8). CONCLUSION We were able to create a stable model where several preoperative and intra-operative variables were shown to be predictive of prolonged ventilation after CABG surgery. The ability to identify patients at increased risk for prolonged ventilation may allow the development of pre-emptive strategies and more effective resource allocation.

Is it safe to train residents to perform cardiac surgery

BACKGROUND The impact of surgical training on patient outcomes in cardiac surgery is unknown. METHODS All cases performed by residents from 1998 to 2001 were compared to staff surgeon cases using prospectively collected data. Operative mortality and a composite morbidity of: reoperation for bleeding perioperative myocardial infarction, infection, stroke, or ventilation more than 24 hours were compared using multivariate analysis. RESULTS Four residents performed 584 cases. The cases were as follows: coronary artery bypass grafting (CABG), 366 cases; aortic valve replacement (AVR) with or without CABG (AVR +/- CABG), 86 cases; mitral valve replacement, 31 cases; mitral valve repair, 25 cases; thoracic aneurysm/dissection, 22 cases; aortic root, 20 cases; transplantations, 14 cases; and adult congenital defect repairs, 20 cases. There were 2,638 CABGs and 363 AVR +/- CABG performed by the staff during the same period. Crude operative mortality in CABG patients was 2.5% (resident) and 2.9% (staff) (p = 0.62). In multivariate analysis, resident was not associated with operative mortality odds ratio (OR) of 0.59 (p = 0.19). Resident cases had a higher incidence of the composite morbidity outcome for CABG cases (19.4% vs 13.6% for staff; p = 0.003). However, in multivariate analysis, resident was not associated with increased morbidity (OR = 1.23, p = 0.16). The AVR +/- CABG crude mortality was 3.6% (resident) and 2.8% (staff) (p = 0.69). Because of the small number of cases (n = 447), operative mortality was combined with the composite morbidity outcome for the AVR +/- CABG model. In all, 16.7% of resident cases and 19.8% of staff cases had the composite outcome or died (p = 0.51). In multivariate analysis resident was not associated with this outcome (OR = 0.74, p = 0.35). CONCLUSIONS In this analysis of our experience with residency training, the operative morbidity and mortality in CABG and AVR patients was similar for residents and staff. Training residents to perform cardiac surgery appears to be safe.

Delirium as a predictor of sepsis in post-coronary artery bypass grafting patients: a retrospective cohort study

IntroductionDelirium is the most common neurological complication following cardiac surgery. Much research has focused on potential causes of delirium; however, the sequelae of delirium have not been well investigated. The objective of this study was to investigate the relationship between delirium and sepsis post coronary artery bypass grafting (CABG) and to determine if delirium is a predictor of sepsis.MethodsPeri-operative data were collected prospectively on all patients. Subjects were identified as having agitated delirium if they experienced a short-term mental disturbance marked by confusion, illusions and cerebral excitement. Patient characteristics were compared between those who became delirious and those who did not. The primary outcome of interest was post-operative sepsis. The association of delirium with sepsis was assessed by logistic regression, adjusting for differences in age, acuity, and co-morbidities.ResultsAmong 14,301 patients, 981 became delirious and 227 developed sepsis post-operatively. Rates of delirium increased over the years of the study from 4.8 to 8.0% (P = 0.0003). A total of 70 patients of the 227 with sepsis, were delirious. In 30.8% of patients delirium preceded the development of overt sepsis by at least 48 hours. Multivariate analysis identified several factors associated with sepsis, (receiver operating characteristic (ROC) 79.3%): delirium (odds ratio (OR) 2.3, 95% confidence interval (CI) 1.6 to 3.4), emergent surgery (OR 3.3, CI 2.2 to 5.1), age (OR 1.2, CI 1.0 to 1.3), pre-operative length of stay (LOS) more than seven days (OR 1.6, CI 1.1 to 2.3), pre-operative renal insufficiency (OR 1.9, CI 1.2 to 2.9) and complex coronary disease (OR 3.1, CI 1.8 to 5.3).ConclusionsThese data demonstrate an association between delirium and post-operative sepsis in the CABG population. Delirium emerged as an independent predictor of sepsis, along with traditional risk factors including age, pre-operative renal failure and peripheral vascular disease. Given the advancing age and increasing rates of delirium in the CABG population, the prevention and management of delirium need to be addressed.

Outcomes in octogenarians undergoing coronary artery bypass grafting

Background: Although octogenarians are being referred for coronary artery bypass grafting (CABG) with increasing frequency, contemporary outcomes have not been well described. We examined data from 4 Canadian centres to determine outcomes of CABG in this age group. Methods: Data for the years 1996 to 2001 were examined in a comparison of octogenarians with patients less than 80 years of age. Logistic regression analysis was used to adjust for preoperative factors and to generate adjusted rates of mortality and postoperative stroke. Results: A total of 15 070 consecutive patients underwent isolated CABG during the study period. Overall, 725 (4.8%) were 80 years of age or older, the proportion increasing from 3.8% in 1996 to 6.2% in 2001 (p for linear trend = 0.03). The crude rate of death was higher among the octogenarians (9.2% v. 3.8%; p < 0.001), as was the rate of stroke (4.7% v. 1.6%, p < 0.001). The octogenarians had a significantly greater burden of comorbid conditions and more urgent presentation at surgery. After adjustment, the octogenarians remained at greater risk for in-hospital death (odds ratio [OR] 2.64, 95% confidence interval [CI] 1.95–3.57) and stroke (OR 3.25, 95% CI 2.15–4.93). Mortality declined over time for both age groups (p for linear trend < 0.001 for both groups), but the incidence of postoperative stroke did not change (p for linear trend = 0.61 [age < 80 years] and 0.08 [age ≥ 80 years]). Octogenarians who underwent elective surgery had crude and adjusted rates of death (OR 1.31, 95% CI 0.60–2.90) and stroke (OR 1.59, 95% CI 0.57–4.44) that were higher than but not significantly different from those for non-octogenarians who underwent elective surgery. Interpretation: In this study, rates of death and stroke were higher among octogenarians, although the adjusted differences in mortality over time were decreasing. The rate of adverse outcomes in association with elective surgery was similar for older and younger patients.

New Onset Postoperative Atrial Fibrillation is Associated with a Long-Term Risk for Stroke and Death Following Cardiac Surgery†

We sought to evaluate the long‐term impact of post‐cardiac surgery atrial fibrillation on the risk of stroke and survival.

Impact of Preoperative Angiotensin-Converting Enzyme Inhibitor Use on Clinical Outcomes After Cardiac Surgery

BACKGROUND Controversy exists about whether preoperative angiotensin-converting enzyme inhibitor (ACEi) therapy is associated with adverse outcomes after coronary artery bypass grafting (CABG). METHODS We analyzed the outcomes of consecutive patients who underwent isolated CABG between 1998 and 2007 at a single institution. We used multivariable models to examine the association between preoperative ACEi therapy and in-hospital and long-term outcomes. RESULTS Of the 5946 patients undergoing isolated CABG during the study period, 3,262 (54.9%) were treated with an ACEi preoperatively and 2,684 (45.1%) were not. Median follow-up was 3.8 years. Patients treated with an ACEi preoperatively were more likely to have diabetes, hypertension, an ejection fraction of less than 40%, and recent myocardial infarction (all p<0.0001). They were less likely to have pre-existing renal failure (p=0.004) or require an urgent or emergent CABG (p=0.03). Postoperative use of an inotrope (26% vs 20%, p<0.0001) or intra-aortic balloon pump (1.8% vs 1.1%, p=0.03) was more frequent in patients treated preoperatively with an ACEi; however, preoperative ACEi use was not an independent predictor of in-hospital mortality (odds ratio [OR], 1.1; p=0.76), prolonged length of stay in the intensive care unit (OR, 0.9; p=0.09), or new-onset renal failure (OR, 0.7; p=0.09). Furthermore, preoperative use of an ACEi had no independent association with long-term survival (p=0.54) or freedom from acute coronary syndrome (p=0.07). However, it was associated with an increased risk of readmission for heart failure over time (hazard ratio, 1.2; p=0.007). CONCLUSIONS We found no association between preoperative ACEi therapy and adverse in-hospital outcomes or long-term survival after CABG. Preoperative ACEi therapy appears to be safe in patients undergoing CABG.

Complete revascularization is compromised in off-pump coronary artery bypass grafting

OBJECTIVE Patients who undergo off-pump coronary artery bypass grafting (OPCAB) commonly receive fewer bypass grafts and are more often incompletely revascularized compared with those receiving conventional coronary artery bypass (CCAB) recipients. Because this can compromise survival, we sought to determine whether patients undergoing OPCAB are incompletely revascularized and whether this affects long-term survival and freedom from cardiac events. METHODS OPCAB cases (n = 411) performed from January 1, 1997 to June 30, 2003 were considered for inclusion and matching with 874 randomly selected, contemporary CCAB cases. After propensity matching, 308 OPCAB cases and 308 CCAB cases were included in the final analysis. We compared the number of bypass grafts and the completeness of revascularization by coronary territory. Survival and readmission for cardiac causes were monitored for up to 10 years postoperatively, with a median follow-up period of 5.9 years. RESULTS On average, the patients undergoing OPCAB received significantly fewer distal anastomoses than did those undergoing CCAB (mean ± standard deviation, 2.6 ± 0.9 vs 3.0 ± 1.0, P < .0001). The circumflex territory was the most likely territory to be ungrafted during OPCAB in patients with angiographically significant obstruction (P = .0006). The frequency of complete revascularization was significantly different between the 2 groups (OPCAB, 79.2% vs CCAB, 88.3%; P = .0.002). The OPCAB group had a significantly greater rate of total arterial grafting (OPCAB, 66.6% vs CCAB, 49.7%; P = .0001). No difference was seen in 8-year survival or freedom from cardiac cause hospital readmission between the 2 groups. CONCLUSIONS Despite receiving fewer distal anastomoses and the decreased frequency of complete revascularization, OPCAB and CCAB techniques produced comparable results.