Thoracic Surgeons National Cardiac Surgery Research Articles

Safety and efficacy of off-pump coronary artery bypass grafting

Background. We evaluated the application of the off-pump coronary artery bypass (OPCAB) procedure relative to safety and efficiency as measured by operative mortality postoperative complications and longitudinal outcome.Methods. Three hundred and fifty OPCAB patients were compared to 3,171 on-pump or conventional coronary artery bypass (CCAB) patients between January 1, 1997 and December 31, 1998. The groups were divided into three preoperative predicted risk categories: low-risk (0 to 2.59%), medium-risk (2.6 to 9.9%), and high-risk (≥10%). Society of Thoracic Surgeons National Cardiac Surgery Database definitions and predicted risk group models were utilized to compare all preoperative, intraoperative, and postoperative variables using univariate analysis.Results. Overall comparison of the immediate outcome of CCAB and OPCAB shows little statistical significance in the variables analyzed. The operative mortality was 3.4% in both groups. When the immediate outcome was compared between groups (CCAB vs OPCAB), as well as individual risk groups (low, medium, and high), similar patterns of operative variables and postoperative complications were observed. The operative mortality in the low-risk group was 1.1% for CCAB and 1.4% for OPCAB; 7% for CCAB and 6% for OPCAB in the medium-risk group; and in the high-risk group 28.5% for CCAB compared to 7.7% for OPCAB group (p = 0.008). Short-term follow-up shows a trend of increased recurring angina and reinterventional procedures in the OPCAB patients.Conclusions. Safety for OPCAB is assessed through retrospective data review. Longitudinal follow-up for survival, reintervention, and quality of postoperative document efficacy and patency rates, compared to on-pump procedures, is mandatory. This study documented the immediate safety of the OPCAB procedure. Preliminary findings at 1-year follow-up is an important finding in this study, but it is not conclusive at this time. Long-term longitudinal follow-up is required to assess the future effectiveness of OPCAB.

Impact of gender on coronary bypass operative mortality

Background. In spite of many reports investigating the influence of gender on coronary artery operations, it is still uncertain whether gender is an independent risk factor for operative mortality. A major problem of previous reports has centered around the fact that men and women constitute quite different populations, thereby making direct comparisons difficult. Methods. The Society of Thoracic Surgeons National Cardiac Surgery Database was used to retrospectively examine 344,913 patients undergoing coronary artery bypass graft operations from 1994 through the most recent data harvest. The operative mortality of male and female patients was compared for a variety of single risk factors and combinations of risk factors. A logistic risk model was used to account for all important patient parameters so that individuals could be stratified into comparable categories allowing for direct comparisons of risk-matched male and female patients. Results. The univariate analysis showed that the 97,153 women carried a significantly higher mortality for each of the risk factors examined. The multivariate analysis and the risk model stratification showed that women had significantly higher mortality as compared to equally matched men in the low- and medium-risk part of the spectrum, but in high-risk patients, there was no difference between male and female mortality. Conclusions. Gender is an independent predictor of operative mortality except for patients in very high-risk categories.

Establishing and Using a Local/Regional Cardiac Surgery Database

In 1993, the Minnesota Society of Thoracic Surgeons and the Minnesota Cardiac Surgery Database were organized in response to a third-party payer demand for data about practice protocols and patient outcomes. It has matured to an active organization of 46 cardiothoracic surgeons, 14 institutions, and more than 7,000 patients who have undergone coronary artery bypass grafting. Data are validated for completeness and accuracy through a statewide auditing process. They are coded by hospital, analyzed using the standard Society of Thoracic Surgeons National Cardiac Surgery Database format and definitions, and reviewed quarterly in a continuous quality improvement process. Through data review and exchange site visits, variations in practice protocols and outcomes have been identified. For example, our statewide data review and continuous quality improvement process identified prolonged ventilation (more than 24 hours) as one variation. Multidisciplinary teams were defined, and statewide exchange site visits led by cardiovascular surgeons were implemented. An example of the improvement in the accuracy and completeness of the data used to study procedure outcomes is represented by the improved reporting of ejection fraction values that has resulted from this process. Using the standardized Society of Thoracic Surgeons National Cardiac Surgery Database and the Minnesota Society of Thoracic Surgeons organizational structure to establish a high-quality database will allow for statewide peer review, exchange of practice guidelines, and promotion of standardization, which eventually can improve outcomes and reduce costs. This organization or model can be replicated at any local, state, or regional level. Thoracic surgeons faced with similar challenges for public disclosure of surgical results can learn much from the successful development of the Minnesota Cardiac Surgery Database.

Evaluation of 7,000 Patients With Two Different Routes of Cardioplegia

Background. This study examined the efficacy and safety of retrograde cardioplegia in comparison with an antegrade/retrograde approach.Methods. Between January 1, 1991, and December 31, 1995, 7,032 coronary artery bypass procedures, alone or in combination with valve replacement/repair, were performed using either retrograde cardioplegia (R) or an antegrade/retrograde (AR) approach. There were 4,224 patients in the R group and 2,808 in the AR group. These included elective, urgent, emergent/salvage, first operative, and redo cases.Results. All preoperative, intraoperative, and postoperative variables listed in The Society of Thoracic Surgeons National Cardiac Surgery Database were used to compare the two groups using univariate analysis. The pump time was longer in the AR group, with fewer grafts per patient. The R group had higher predicted risk (3.2% versus 3.0%; p = 0.04), more postoperative atrial fibrillation (34% versus 31%; p = 0.006), and longer postoperative length of stay (8.8 versus 8.0 days; p < 0.001). Using The Society of Thoracic Surgeons National Cardiac Surgery Database predicted risk group model, a subgroup of 221 coronary artery bypass grafting patients in the retrograde (s-R) and 132 coronary artery bypass grafting patients in the antegrade/retrograde (s-AR) group fell into a greater incidence of predicted mortality group (≥10%). The s-R subgroup had more patients in New York Heart Association functional class IV. Univariate analysis revealed higher postoperative atrial fibrillation (51% versus 41%; p = 0.05) and longer postoperative length of stay (12.8 versus 10.8 days; p = 0.03) in the s-R subgroup versus the s-AR subgroup.Conclusions. The results appear to favor neither approach. Preoperatively, both retrograde groups (R and s-R) had higher preoperative predicted risk, but operative mortality or complications were not significantly increased when compared with the AR and s-AR groups. Retrograde cardioplegia alone was shown to be effective in the R and s-R groups, but atrial fibrillation developed in more patients, which could have contributed to longer length of stay in these groups. Antegrade/retrograde cardioplegia offers good immediate outcome but the delivery method can be cumbersome and confusing during the adjustments of flow clamps for antegrade/retrograde delivery and may contribute to prolonged pump times. From this retrospective, nonrandomized review, it appears that retrograde cardioplegia alone provides as good myocardial protection and safety as an antegrade/retrograde approach in either the low-risk or high-risk patient.(Ann Thorac Surg 1997;63:1619–24)

The Society of Thoracic Surgeons National Cardiac Surgery Database: Current Risk Assessment

Background. The Society of Thoracic Surgeons National Cardiac Surgery Database has recently completed gathering patient data from 1990 through 1994. Using information from more than 300,000 patients undergoing isolated coronary artery bypass grafting in this period, new risk models of operative mortality were developed. Methods. Logistic regression analysis was used to develop a risk model for each calendar year. A standard “training set/test set” approach was used for each model. Results. Five validation techniques were used to evaluate the reliability of the risk models. All models were found to predict operative mortality with good accuracy in this population. Conclusions. The new risk models for isolated coronary artery bypass operations serve as reliable predictors of operative mortality for the most recent harvest of patient data from The Society of Thoracic Surgeons National Cardiac Surgery Database.

Patient characteristics, safety, and benefits of same-day admission for coronary artery bypass grafting

The move toward outpatient and same-day surgery has been phenomenal in the past several years. Efforts in this area have focused on limiting inpatient hospitalization, reducing ancillary services, and decreasing length of stay. Two hundred seventy-six DRG 107 patients who were operated on at our institutions in 1994 and registered in The Society of Thoracic Surgeons National Cardiac Surgery Database were reviewed. There were 185 patients randomly admitted to the hospital on the day of operation and 91 patients admitted 1.78 +/- 1.94 days before. These patients were analyzed according to The Society of Thoracic Surgeons National Cardiac Surgery Database predicted risk group and expected operative mortality modules. Univariate analysis of all risk variables listed in The Society of Thoracic Surgeons National Cardiac Surgery Database were used to identify the difference between 176 elective procedure patients in the same-day admission group and 67 elective procedure patients in the non-same-day admission group. The same-day admission group had lower expected operative mortality (1.3% versus 2.9%), fewer female patients (17% versus 29%), younger age (62 versus 67 years), and fewer patients in the higher predicted risk group. Univariate analysis showed only age and ejection fraction variables were significantly different between the two elective groups. Comorbidities predictive of elective non-same-day admission revealed that age and New York Heart Association class IV were significant predictors. The length of stay was shorter and the total charges were less in the same-day admission group. There was no increase in preoperative, intraoperative, or postoperative complications in the same-day admission patients. Same-day admission was safe and cost-effective and could be carried out as a routine admission for several selected groups of patients.

Definitions of terms of the society of thoracic surgeons national cardiac surgery database

Definitions of terms of the society of thoracic surgeons national cardiac surgery database

Coronary artery bypass grafting: The Society of Thoracic Surgeons National Database experience

The need for accurate risk assessment has become an indispensable element in the practice of cardiac surgery. The Society of Thoracic Surgeons National Cardiac Surgery Database allows subscribing institutions to perform sophisticated patient risk assessment using traditional statistical tools and a newly developed risk model of operative mortality. The database experience with isolated coronary artery bypass grafting has been studied most closely at this point and serves as the basis for this report. The approach to operative risk assessment is presented along with an analysis of important risk factors in the practice of coronary artery surgery from 1980 through 1990. The database contains records of 80,881 patients undergoing coronary artery bypass grafting in numerous institutions from 1980 through 1990. These records were used to conduct a detailed analysis of risk factors associated with coronary operations in this time interval and to present statistical methods used to formulate a risk equation that allows one to predict the probability of operative death. In the course of this decade, there were clearly defined trends showing a statistically significant increase in adverse patient risk factors. The risk model has proven to be a reliable tool for predicting the probability of operative death in an individual patient and may be valuable in both patient counseling and medical decision making. Large multiinstitutional databases of this type are key ingredients of modern operative risk assessment. A database containing a broad national experience of this type can represent an aggregate experience that may well approximate a universally accepted standard of care.

Impact of internal mammary artery conduits on operative mortality in coronary revascularization

The long-term advantages of internal mammary artery (IMA) conduits in cotonary artery bypass graft (CABG) procedures are widely recognized, but the immediate short-term impact of IMA grafts is not well defined. The purpose of this study was to investigate the influence of IMA conduits on CABG operative mortality (OM). A retrospective study of two groups of patients undergoing isolated CABG was performed. Patients having at least one IMA graft (group 1) were compared with those with only venous conduits (group 2). The patient population was taken from The Society of Thoracic Surgeons National Cardiac Surgery Database, which contains a broad multiinstitutional experience. A total of 38,578 registered patients undergoing isolated CABG from 1987 through 1991 were studied. Of these, 18,614 patients had at least one IMA conduit (group 1), whereas 19,964 had CABG using entirety venous conduits (group 2). The OM for group 1 was 2.0% ( 365 / 18,614 ), whereas the mortality was 4.5% ( 903 / 19,964 ) for group 2 ( p < 0.005). Patient sub-groups were examined to determine if the improved OM associated with IMA grafting was present in these patient subsets. The population was broken down according to age, sex, ejection fraction, extent of coronary disease, and operative priority. For each subset, univariate analysis showed that group 1 OM was significantly less ( p < 0.005) than the OM for group 2. Numerous combinations of these patient parameters were also analyzed. Group 1 patients had a significant ( p < 0.05) improvement in OM in each combination except for patients more than 70 years of age requiring reoperations. Multivariate analysis also demonstrated that the use of an IMA was independently associated with improved patient survival ( p < 0.0025). To consolidate the net effect of numerous patient risk factors, a Bayesian risk model was used to stratify patients into risk quartiles. For the lowest risk quartile (predicted OM <1.14%) there was no significant difference in group 1 versus group 2 patients. For every other risk category, there was a significant improvement in OM associated with IMA use ( p < 0.005). We conclude that in the vast majority of patient subsets, IMA conduits are associated with a statistically significant improvement in OM when compared with use of venous conduits alone.