| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
|
Interact CardioVasc Thorac Surg 2009;8:40-44. doi:10.1510/icvts.2007.173922 © 2009 European Association of Cardio-Thoracic Surgery
Changing risk of patients undergoing coronary artery bypass surgery
a Division of Cardio-thoracic and Vascular Surgery, Department of Surgery, Oulu University Hospital, P.O. Box 21, 90029 Oulu, Finland Received 20 December 2007; received in revised form 2 May 2008; accepted 6 May 2008
*Corresponding author. Tel.: +358 8 315 2813/+358 40 7333973; fax: +358 8 315 2577.
The aim of the present study was to evaluate the changing risk of patients undergoing coronary artery bypass grafting (CABG). Residents of Oulu who underwent coronary angiography and/or revascularization from 1993 to 2006 formed the basis of this community-wide study. One thousand three hundred and forty-nine consecutive patients who underwent CABG have been included in the analysis on changing operative risk and results after CABG. A significant increase in the operative risk occurred in patients who underwent CABG (mean logistic EuroSCORE in 1278 patients: 1993–1997: 3.7%; 1998–2002: 4.6%; 2003–2006: 5.4%; P<0.0001). Thirty-day mortality decreased during the last period (1993–1997: 2.5%; 1998–2002: 3.0%; 2003–2006: 1.6%; P=0.49). The area under the ROC curve of logistic EuroSCORE (1993–1997: 0.86; 1998–2002: 0.78; 2003–2006: 0.99) for prediction of 30-day postoperative mortality markedly improved during the last study period. Despite the increased operative risk, off-pump coronary surgery was associated with lower immediate postoperative mortality rates. Contrary to on-pump surgery, immediate postoperative death occurred after off-pump surgery only in patients with additive EuroSCORE  6. The results of this study suggest that improved perioperative care as well as changes in operative strategy are positively faced with the increased burden of comorbidities and operative risk of patients currently undergoing CABG.
Key Words: Coronary artery bypass surgery; Risk; Percutaneous coronary intervention.
Recently diagnostics and treatment options of coronary artery disease have evolved rapidly [1, 2]. During the past few years the shift towards percutaneous coronary interventions (PCIs) has had a marked influence on the treatment pathway and on patient selection. This has been challenging for cardiac surgeons who nowadays are facing a change in surgical volume [2] with a perceived increased operative risk [3, 4]. However, so far such changes in operative risk have not been estimated likely because of mixed referral pathways. In Finland cardiac surgery is centralised making easier the evaluation of the changing pattern of treatment of coronary artery disease. The aim of the present study was to evaluate the operative risk for the patients having undergone coronary artery bypass grafting (CABG) and its impact on the immediate and late outcome.
In order to exclude any bias in the referral pattern, we have included only those patients who were living in the city of Oulu during the study period. Thus, this study includes a consecutive series of 1349 patients who were residents of the city of Oulu and who were referred for isolated CABG to the Division of Cardio-thoracic and Vascular Surgery of the Oulu University Hospital, Oulu, Finland, from January 1993 to December 2006. Preoperative characteristics of the patients are reported in Table 1.
Oulu is one of the main towns of Finland with a population which increased from 103,539 in 1993 to 128,962 inhabitants in 2006. The list of patients who underwent coronary angiography, PCI and isolated CABG was retrieved from our Institutional databases. Patients not officially residing in Oulu were excluded from the analysis. This was done in order to better assess the changing face of coronary artery disease and its treatment in a well determined area. Furthermore, this allowed us to estimate the cardiovascular events having occurred after CABG. Our Institution is a tertiary referral university hospital for cardiac surgery and serves 49.5% of Finland's surface where approximately 723,000 inhabitants reside. Interventional cardiology was centralized to our Institution up to February 2006, after which interventional cardiology was started also in another three central hospitals in this area. Data were collected retrospectively from records including files of all departments of this hospital. Risk factors have been defined according to the EuroSCORE criteria [5]. The risk of postoperative stroke was estimated by the Northern New England Cardiovascular Disease Study Group stroke risk scoring method [6]. Dates and causes of death have been retrieved from a National Registry (Tilastokeskus). Statistical analysis was performed using SPSS statistical software (SPSS v. 14.0.1, SPSS Inc., Chicago, IL, USA). Continuous variables are reported as the mean±standard deviation. The Pearson's 2 test, Fisher exact test, the Mann–Whitney test and the Kruskal–Wallis test were used for univariate analysis. Receiver operating characteristics (ROC) curve was used to estimate the predictive value of continuous variables. Survival rates were estimated by the Kaplan–Meier method. Logistic regression and Cox-regression with the help of backward selection were used for multivariate analysis. A P-value of <0.05 was considered statistically significant.
Fig. 1 summarizes the changing prevalence of coronary angiographies which occurred at our Institution as well as the changing prevalence of CABG and PCI. Of note is the rapid increase in the amount of PCIs performed (Fig. 1). Meantime, also the methods of coronary surgical revascularization have changed with the introduction of the off-pump technique. The latter method is currently performed in more than 65% of our patients.
In order to better depict the changes which have occurred over this time among patients who underwent CABG, we have divided them in to three different temporal groups, the latest being marked by the increasing use of OPCAB. In the overall, consecutive series of 1349 patients, the 30-day postoperative mortality rates for the periods 1993–1997, 1998–2002 and 2003–2006 were 2.6%, 2.8% and 1.6%, respectively (P=0.50). The final analysis was limited to 1278 patients in whom it was possible to retrieve complete data to calculate EuroSCORE. Both additive (P<0.0001) and logistic EuroSCORE (P<0.0001) significantly increased along the three study periods (Fig. 2). However, no significant changes in the main immediate postoperative outcome measures were observed (Fig. 2). The only significant difference was in the decrease of prolonged tracheal intubation (P=0.034). Thirty-day postoperative mortality rate decreased during the last study period, but this did not reach statistical significance (P=0.49).
ROC curve analysis showed that logistic EuroSCORE (AUC: 0.84, 95% CI 0.77–0.91, P<0.0001) was predictive of 30-day postoperative death. Interestingly, the area under the curve of ROC of logistic EuroSCORE (1993–1997: 0.86; 1998–2002: 0.78; 2003–2006: 0.99) for prediction of 30-day postoperative mortality markedly improved during the last study period. Indeed, logistic EuroSCORE (mean values: 11.9±13.4, 18.5±20.8 and 46.8±19.4, respectively, P=0.022) of patients who died during the immediate postoperative period differed along with the study periods. By assuming that the introduction and the increasing use of OPCAB could have been one of the factors involved in the improved immediate outcome despite an increase in operative risk during this time, this has been further investigated by excluding from the analysis patients who had undergone previous cardiac surgery and/or who underwent emergency surgery. This is because an emergency operation and previous cardiac surgery more frequently pose the surgeon with the need to choose CCAB because of profound hemodynamic derangements or technical difficulties related to a scarred operative field in certain patients. Fig. 3 depicts the significant increase of additive (P<0.0001) as well as logistic EuroSCORE (P<0.0001) which also occurred during the study periods among these patients. Thirty-day operative mortality was again lower in the last study period, but the difference was not statistically significant. No significant differences were noted in the other outcome end-points, but tracheal extubation >24 h (P=0.013).
Logistic EuroSCORE (mean: 4.2±5.1% vs. 3.6±5.2%, P=0.24) tended to be higher in patients who underwent OPCAB as compared to CCAB. Also, when emergency and redo operations were excluded, logistic EuroSCORE (mean: 4.7±6.7% vs. 4.3±6.8%, P=0.085) tended to be higher in patients who underwent OPCAB as compared to CCAB. Fig. 4 shows the increased mortality risk along with higher additive EuroSCORE quartiles.
3.1. Impact of previous percutaneous transluminal angioplasty on immediate and late outcome A slightly higher 30-day mortality was observed among patients who have previously undergone PCI (3.8% vs. 2.3%, P=0.24), coronary bypass surgery performed after PCI during the same in-hospital stay being significantly associated with immediate postoperative death (P=0.04). Indeed, four patients (out of six patients who died and had previously undergone PCI) had CABG immediately after PCI. A previous PCI did not affect negatively the overall survival (at 10 years, 72.8% vs. 71.1%, P=0.89), even when adjusted with EuroSCORE. This finding did not change along the study periods. In fact, during the last period, which was characterized by an increasing use of PCI, the need for CABG after PCI was not associated with worse 4-year overall survival (96.9% vs. 91.3%, respectively, P=0.49). At 10 years, the overall survival rate was 71.3%, freedom for redo-CABG and/or PCI was 95.5%, freedom from redo-CABG was 99.6% and freedom from PCI was 95.6%. Fig. 5 shows that 4-year overall survival among 30-day operative survivors was somewhat lower in patients operated on during the last study period. This difference was not statistically significant at univariate analysis as well as when adjusted for EuroSCOREs. Surgical technique did not have an influence on late outcome.
The present study documented in a community-wide perspective the dramatic changes that recently occurred in terms of the use of invasive coronary diagnostic as well as PCIs. Even if we did not have the possibility to retrieve EuroSCORE estimates in all patients, these results suggest that a significant change occurred also in terms of increased operative risk. This confirmed the perceived increased burden of perioperative treatments in patients undergoing CABG which occurred during the last years. Importantly, it seems that despite the increased prevalence of high-risk patients, the immediate postoperative outcome did not worsen, indeed, operative mortality has recently clearly decreased. This trend was confirmed also by the subanalysis of patients undergoing non-emergent, primary CABG. This study cannot provide clear evidence on those factors associated with such satisfactory results, but certainly changes in anesthesiological and intensive care methods as well as implemented nursing care might have significantly contributed to such an improved outcome. We also believe that the introduction of OPCAB, which is employed in all operations by a few of the cardiac surgeons of our Institution, had a major contribution in reducing the operative mortality despite the increasing operative risk. The aim of this study was not planned to demonstrate the superiority of OPCAB over CCAB, but it seems that the former was associated with a rather low operative mortality which, contrarily to CCAB, was limited to patients with clearly increased EuroSCOREs, i.e. additive EuroSCORE 6. However, it is worth noting that this scoring method performed exceptionally well during the last study period, thus indicating a marked reduction of the immediate postoperative mortality in low-risk patients. Herein we have also observed that the rate of postoperative stroke did not decrease despite the introduction of OPCAB. This finding can be explained by a certain increase of stroke risk (Table 1), but mostly by the fact that just recently we have recognized the neuroprotective efficacy of OPCAB only when adopted by an ‘off-pump surgeon’ who routinely performs epiaortic ultrasound scanning [7]. Furthermore, in order to reduce any potentially atrial fibrillation-related stroke [7], only recently we have adopted an anticoagulation policy in these patients. Previously we have shown the predictive value of EuroSCORE on the long-term outcome [8]. This study confirmed this finding and Fig. 5 suggests that the increased mortality risk is not ‘forgotten’ among operative survivors as during the last study period a certain, but not significant, decreased survival among these patients has been observed. Such tendency toward poorer late survival was not related to the revascularization technique, and it occurred despite our current aggressive secondary prevention of atherosclerosis. The analysis of late outcome of these patients has demonstrated that a previous PCI was not associated with poorer results. However, more conclusive data on this issue are needed, especially to evaluate the impact of a currently more aggressive PCI policy. In conclusion, the results of this study suggest that improved perioperative care as well as changes in operative strategy are positively faced with the increased burden of comorbidities and operative risk of patients currently undergoing CABG.
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
Top
Abstract
1. Introduction
