Comparative Study of the Aristotle Comprehensive Complexity and the Risk Adjustment in Congenital Heart Surgery Scores

Comparison of risk stratification scoring system as a predictor of mortality and morbidity in congenital heart disease patients requiring surgery

Backgrounds

Risk stratification systems have been important in reducing morbidity and mortality among congenital heart disease (CHD) patients requiring cardiac surgery. Multiple risk stratification scoring systems have been developed, including Aristotle Basic Complexity Score (ABC), Aristotle Comprehensive Complexity Score (ACC), Society of Thoracic Surgeons and European Association for Cardiothoracic Surgery (STS-EACTS), and Risk Adjustment in Congenital Heart Surgery (RACHS-1). This study aims to access the superior risk stratification scoring system model in predicting mortality and morbidity.

Methods

The authors used Embase, PubMed, Scopus, and ProQuest as the primary databases for searching and included studies from hand searching. The area under the receiver operating characteristic curve was compared.

Results

A total of 11 articles were included in this review. The AUC of ABC for predicting mortality ranges from 0.59 to 0.71, and morbidity ranges from 0.673 to 0.743. The AUC of ACC score for predicting mortality ranges from 0.704 to 0.87, and a study revealed the AUC of morbidity is 0.730. The AUC of RACHS-1 for predicting mortality ranges from 0.68 to 0.782. The AUC of STS-EACTS for predicting mortality ranges from 0.739 to 0.8 and 0.732 for predicting morbidity.

Conclusion

ABC, ACC, RACHS-1, and STS-EACTS have acceptable to excellent discriminatory ability in predicting mortality and morbidity among CHD patients requiring cardiac surgery.

Predicting the risk of infant mortality for newborns operated for congenital heart defects: A population-based cohort (EPICARD) study of two post-operative predictive scores

BACKGROUND

Whereas no global severity score exists for congenital heart defects (CHD), risk (Risk Adjusted Cardiac Heart Surgery-1: RACHS-1) and/or complexity (Aristotle Basic Complexity: ABC) scores have been developed for those who undergo surgery. Population-based studies for assessing the predictive ability of these scores are lacking.

OBJECTIVE

To assess the predictive ability of RACHS-1 and ABC scores for the risk of infant mortality using population-based cohort (EPICARD) data for newborns with structural CHD.

METHODS

The study population comprised 443 newborns who underwent curative surgery. We assessed the predictive ability of each score alone and in conjunction with an a priori selected set of predictors of infant mortality. Statistical analysis included logistic regression models for which we computed model calibration, discrimination (ROC), and a rarely used but clinically meaningful measure of variance explained (Tjur's coefficient of discrimination).

RESULTS

The risk of mortality increased with increasing RACHS-1 and the ABC scores and models based on both scores had adequate calibration. Model discrimination was higher for the RACHS-1-based model (ROC 0.68, 95% CI, 0.58-0.79) than the ABC-based one (ROC 0.59, 95% CI, 0.49-0.69), P = 0.03. Neither score had the good predictive ability when this was assessed using Tjur's coefficient.

CONCLUSIONS

Even if the RACHS-1 score had better predictive ability, both scores had low predictive ability using a variance-explained measure. Because of this limitation and the fact that neither score can be used for newborns with CHD who do not undergo surgery, it is important to develop new predictive models that comprise all newborns with structural CHD.

Risk stratification models for congenital heart surgery in children: Comparative single-center study

OBJECTIVE

Three scores have been proposed to stratify the risk of mortality for each cardiac surgical procedure: The RACHS-1, the Aristotle Basic Complexity (ABC), and the STS-EACTS complexity scoring model. The aim was to compare the ability to predict mortality and morbidity of the three scores applied to a specific population.

DESIGN

Retrospective, descriptive study.

SETTING

Pediatric and neonatal intensive care units in a referral hospital.

PATIENTS

Children under 18 years admitted to the intensive care unit after surgery.

INTERVENTIONS

None.

OUTCOME MEASURES

Demographic, clinical, and surgical data were assessed. Morbidity was considered as prolonged length of stay (LOS > 75 percentile), high respiratory (>72 hours of mechanical ventilation), and high hemodynamic support (inotropic support >20).

RESULTS

One thousand and thirty-seven patients were included, in which 205 were newborns (18%). The category 2 was the most frequent in the three scores: In RACHS-1, ABC, 44.9%, and STS-EACTS, 40.8%. Newborns presented significant higher categories. Children required cardiopulmonary bypass in more occasions (P < .001) but the times of bypass and aortic cross-clamp were significantly higher in newborns (P < .001 and P = .016). Thirty-two patients died (2.8%). A quarter of patients had a prolonged LOS, 17%, a high respiratory support, and 7.1%, a high hemodynamic support. RACHS-1 (AUC 0.760) and STS-EACTS (AUC 0.763) were more powerful for predicting mortality and STS-EACTS for predicting prolonged LOS (AUC 0.733) and the need for high respiratory support (AUC 0.742).

CONCLUSIONS

STS-EACTS seems to stratify better risk of mortality, prolonged LOS, and need for respiratory support after surgery.

Early Outcomes of Hypoplastic Left Heart Syndrome Infants: Meta-Analysis of Studies Comparing the Hybrid and Norwood Procedures

The hybrid strategy is an alternative to the traditional Norwood procedure for initial palliation of infants with hypoplastic left heart syndrome (HLHS) who are deemed to be at high surgical risk. Numerous single-center studies have compared the two procedures, showing similar early outcomes, although the cohort sizes are likely insufficiently powered to detect significant differences. The current meta-analysis aims to explore the early morbidity and mortality associated with the hybrid compared to the Norwood procedure. MEDLINE, Cochrane Libraries, and Embase were systematically searched, and 14 studies were included for statistical synthesis, comprising 263 hybrid and 426 Norwood patients. Early mortality was significantly higher in the hybrid patients (relative risk [RR] = 1.54, P < .05, 95% confidence interval [CI]: 1.02-2.34), whereas interstage mortality was comparable between the two groups (RR = 0.88, P > .05, 95% CI: 0.46-1.70). Six-month (RR = 0.89, P < .05, 95% CI: 0.80-1.00) and one-year (RR = 0.88, P < .05, 95% CI: 0.78-1.00) transplant-free survival was also inferior among the hybrid patients. Furthermore, the hybrid patients required more reinterventions following initial surgical palliation (RR = 1.48, P < .05, 95% CI: 1.09-2.01), although the two groups had comparable length of hospital and intensive care unit stay postoperatively. In conclusion, our results suggest that the hybrid procedure is associated with worse early survival compared to the traditional Norwood when used for initial palliation of infants with HLHS. However, due to the hybrid being used preferentially for high-risk patients, definitive conclusions regarding the efficacy of the procedure cannot be drawn.

Intravenous morphine versus intravenous paracetamol after cardiac surgery in neonates and infants: a study protocol for a randomized controlled trial

BACKGROUND

Morphine is worldwide the analgesic of first choice after cardiac surgery in children. Morphine has unwanted hemodynamic and respiratory side effects. Therefore, post-cardiac surgery patients may potentially benefit from a non-opioid drug for pain relief. A previous study has shown that intravenous (IV) paracetamol is effective and opioid-sparing in children after major non-cardiac surgery. The aim of the study is to test the hypothesis that intermittent IV paracetamol administration in children after cardiac surgery will result in a reduction of at least 30% of the cumulative morphine requirement.

METHODS

This is a prospective, multi-center, randomized controlled trial at four level-3 pediatric intensive care units (ICUs) in the Netherlands and Belgium. Children who are 0-36 months old will be randomly assigned to receive either intermittent IV paracetamol or continuous IV morphine up to 48 h post-operatively. Morphine will be available as rescue medication for both groups. Validated pain and sedation assessment tools will be used to monitor patients. The sample size (n = 208, 104 per arm) was calculated in order to detect a 30% reduction in morphine dose; two-sided significance level was 5% and power was 95%.

DISCUSSION

This study will focus on the reduction, or replacement, of morphine by IV paracetamol in children (0-36 months old) after cardiac surgery. The results of this study will form the basis of a new pain management algorithm and will be implemented at the participating ICUs, resulting in an evidence-based guideline on post-operative pain after cardiac surgery in infants who are 0-36 months old.

TRIAL REGISTRATION

Dutch Trial Registry ( www.trialregister.nl ): NTR5448 on September 1, 2015. Institutional review board approval (MEC2015-646), current protocol version: July 3, 2017.

Analysis of congenital heart surgery results: A comparison of four risk scoring systems

Background

This study aims to evaluate the surgical results of our clinic according to presumption systems of Risk Adjustment in Congenital Heart Surgery, Aristotle Basic Complexity score, Aristotle Comprehensive Complexity score, and Society of Thoracic Surgeons and European Association for Cardiothoracic Surgery mortality categories and to compare the efficiency of these systems in predicting morbidity and mortality.

Methods

In the study, classification and the risk scoring were performed with the four different systems for 1,950 patients (1,038 males, 912 females; mean age 5.5 months; range, 1 day to 18 years) who were administered congenital heart surgery between 1 October 2012 and 31 December 2016. The hospital mortality and morbidity were calculated for each category from the four models. The discriminatory ability of the models was determined by calculating the area under the receiver operating characteristic curve and the receiver operating characteristic curves of the four models were compared.

Results

Median weight of the patients was 7.2 kg (range, 1.8-80 kg). Among the patients, 53% were males and 47.5% were younger than one year of age. Of totally 1,950 operations, mortality was observed in 149 (7.6%) and morbidity was observed in 541 (27.7%). Areas under the receiver operating characteristic curve for mortality were 0.803, 0.795, 0.729, and 0.712 for the Society of Thoracic Surgeons and European Association for Cardiothoracic Surgery mortality categories, Aristotle Comprehensive Complexity, Risk Adjustment in Congenital Heart Surgery, and Aristotle Basic Complexity scores, respectively. Areas under the receiver operating characteristic curve for morbidity were 0.732, 0.731, 0.730, and 0.685 for the Society of Thoracic Surgeons and European Association for Cardiothoracic Surgery mortality categories, Risk Adjustment in Congenital Heart Surgery, Aristotle Comprehensive Complexity, and Aristotle Basic Complexity scores, respectively.

Conclusion

Society of Thoracic Surgeons and European Association for Cardiothoracic Surgery mortality categories, Risk Adjustment in Congenital Heart Surgery, Aristotle Basic Complexity, and Aristotle Comprehensive Complexity score systems were effective in predicting the morbidities and mortalities of patients who underwent congenital heart surgery and evaluating the performance of the surgical centers. Society of Thoracic Surgeons and European Association for Cardiothoracic Surgery mortality categories were on the forefront due to high feasibility and performance. Aristotle Basic Complexity score system had the lowest performance. Combinations of systems will provide the most benefit during evaluation of results.

Cardiac surgery in adults with high-surgical complexity CHD: results of a network collaborative programme

BACKGROUND

Adults with CHD often exhibit complex cardiac abnormalities, whose management requires specific clinical and surgical expertise. To enable easier access of these patients to highly specialised care, we implemented a collaborative programme that incorporates medical and surgical specialists belonging to both paediatric and adult cardiovascular institutions.

OBJECTIVES

The objective of this study was to review the experience gained and to analyse the surgical outcome of major cardiac surgery.

METHODS

We retrospectively reviewed all consecutive patients admitted for major cardiac surgery using our network between January, 2010 and December, 2013. Analysis of surgical outcome was performed in patients selected for major cardiac surgery with cardiopulmonary bypass. Early and late outcomes were evaluated.

RESULTS

Out of a total of 433 inward patients, 86 were selected for surgery. The median age was 25.5 years, -64 patients (74.4%) had previously undergone heart surgery, and -55 patients (64%) had been subjected to at least one sternotomy. Abnormalities of the left ventricular and right ventricular outflow tract were the most frequent (37.2% and 30.2%, respectively), and despite high-surgical complexity only one death occurred (in-hospital mortality 1.1%). On a median follow-up time of 4 years no deaths and no heart-failure events have occurred; one patient underwent further cardiac surgery programmed at the time of discharge.

CONCLUSIONS

Low mortality and morbidity rates can be obtained in high-surgical complexity adults with CHD populations when paediatric and adult cardiac specialists operate in the same multidisciplinary environment.

Collaborative Quality Improvement in the Congenital Heart Defects: Development of the ASSIST Consortium and a Preliminary Surgical Outcomes Report

OBJECTIVE

ASSIST is the first Brazilian initiative in building a collaborative quality improvement program in pediatric cardiology and congenital heart disease. The purposes of this manuscript are: (a) to describe the development of the ASSIST project, including the historical, philosophical, organizational, and infrastructural components that will facilitate collaborative quality improvement in congenital heart disease care; (b) to report past and ongoing challenges faced; and (c) to report the first preliminary data analysis.

METHODS

A total of 614 operations were prospectively included in a comprehensive online database between September 2014 and December 2015 in two participating centers. Risk Adjustment for Congenital Heart Surgery (RACHS) 1 and Aristotle Basic Complexity (ABC) scores were obtained. Descriptive statistics were provided, and the predictive values of the two scores for mortality were calculated by multivariate logistic regression models.

RESULTS

Many barriers and challenges were faced and overcome. Overall mortality was 13.4%. Independent predictors of in-hospital death were: RACHS-1 categories (3, 4, and 5/6), ABC level 4, and age group (≤ 30 days, and 30 days - 1 year).

CONCLUSION

The ASSIST project was successfully created over a solid base of collaborative work. The main challenges faced, and overcome, were lack of institutional support, funding, computational infrastructure, dedicated staff, and trust. RACHS-1 and ABC scores performed well in our case mix. Our preliminary outcome analysis shows opportunities for improvement.

Clinical Factors Associated with Dose of Loop Diuretics After Pediatric Cardiac Surgery: Post Hoc Analysis

A post hoc analysis of a randomized controlled trial comparing the clinical effects of furosemide and ethacrynic acid was conducted. Infants undergoing cardiac surgery with cardiopulmonary bypass were included in order to explore which clinical factors are associated with diuretic dose in infants with congenital heart disease. Overall, 67 patients with median (interquartile range) age of 48 (13-139) days were enrolled. Median diuretic dose was 0.34 (0.25-0.4) mg/kg/h at the end of postoperative day (POD) 0 and it significantly decreased (p = 0.04) over the following PODs; during this period, the ratio between urine output and diuretic dose increased significantly (p = 0.04). Age (r -0.26, p = 0.02), weight (r -0.28, p = 0.01), cross-clamp time (r 0.27, p = 0.03), administration of ethacrynic acid (OR 0.01, p = 0.03), and, at the end of POD0, creatinine levels (r 0.3, p = 0.009), renal near-infrared spectroscopy saturation (-0.44, p = 0.008), whole-blood neutrophil gelatinase-associated lipocalin levels (r 0.30, p = 0.01), pH (r -0.26, p = 0.02), urinary volume (r -0.2755, p = 0.03), and fluid balance (r 0.2577, p = 0.0266) showed a significant association with diuretic dose. At multivariable logistic regression cross-clamp time (OR 1.007, p = 0.04), use of ethacrynic acid (OR 0.2, p = 0.01) and blood pH at the end of POD0 (OR 0.0001, p = 0.03) was independently associated with diuretic dose. Early resistance to loop diuretics continuous infusion is evident in post-cardiac surgery infants: Higher doses are administered to patients with lower urinary output. Independently associated variables with diuretic dose in our population appeared to be cross-clamping time, the administration of ethacrynic acid, and blood pH.

Retuning mortality risk prediction in paediatric cardiac surgery: the additional role of early postoperative metabolic and respiratory profile

OBJECTIVES

The existing risk stratification scores for paediatric patients undergoing cardiac surgery include the Aristotle Basic Complexity (ABC) Score, the Risk Adjustment in Congenital Heart Surgery-1 (RACHS-1) Score and the Aristotle Comprehensive Complexity (ACC) Score. They are all based on the nature of the surgical operation (ABC and RACHS-1 Scores) with possible adjustment for a number of patient conditions (ACC Score). The present study investigates if the early postoperative parameters may be used to improve the preoperative mortality risk prediction.

METHODS

A retrospective study on 1392 consecutive patients aged ≤12 years old, undergoing cardiac surgery with cardiopulmonary bypass and without a residual right-to-left shunt was conducted. The ABC Score and metabolic and respiratory postoperative parameters at arrival in the intensive care unit were tested for association and discriminative power for operative mortality.

RESULTS

The ABC yielded a c-statistic of 0.746. Additional independent predictors of operative mortality were postoperative hypoxia [Formula: see text] and arterial blood lactates. In a multivariable model including the ABC Score, postoperative hypoxia and arterial blood lactates remained independently associated with operative mortality. A modified ABC Score was created, consisting of the ABC Score plus 1.5 points in case of postoperative hypoxia plus 1 point per each 1 mmol/l of arterial blood lactates. The new model was significantly (P = 0.043) more discriminative than the ABC Score, with a c-statistic of 0.803.

CONCLUSIONS

Early postoperative respiratory and metabolic parameters increased the accuracy and discrimination of the ABC Score. An external validation is needed to confirm our results.

Stratification of complexity in congenital heart surgery: comparative study of the Risk Adjustment for Congenital Heart Surgery (RACHS-1) method, Aristotle basic score and Society of Thoracic Surgeons-European Association for Cardio- Thoracic Surgery (STS-EACTS) mortality score

OBJECTIVE

To determine whether stratification of complexity models in congenital heart surgery (RACHS-1, Aristotle basic score and STS-EACTS mortality score) fit to our center and determine the best method of discriminating hospital mortality.

METHODS

Surgical procedures in congenital heart diseases in patients under 18 years of age were allocated to the categories proposed by the stratification of complexity methods currently available. The outcome hospital mortality was calculated for each category from the three models. Statistical analysis was performed to verify whether the categories presented different mortalities. The discriminatory ability of the models was determined by calculating the area under the ROC curve and a comparison between the curves of the three models was performed.

RESULTS

360 patients were allocated according to the three methods. There was a statistically significant difference between the mortality categories: RACHS-1 (1) - 1.3%, (2) - 11.4%, (3)-27.3%, (4) - 50 %, (P<0.001); Aristotle basic score (1) - 1.1%, (2) - 12.2%, (3) - 34%, (4) - 64.7%, (P<0.001); and STS-EACTS mortality score (1) - 5.5 %, (2) - 13.6%, (3) - 18.7%, (4) - 35.8%, (P<0.001). The three models had similar accuracy by calculating the area under the ROC curve: RACHS-1- 0.738; STS-EACTS-0.739; Aristotle- 0.766.

CONCLUSION

The three models of stratification of complexity currently available in the literature are useful with different mortalities between the proposed categories with similar discriminatory capacity for hospital mortality.

A cross-sectional retrospective analysis of the regionalization of complex surgery

Background

The Veterans Health Administration (VHA) system has assigned a surgical complexity level to each of its medical centers by specifying requirements to perform standard, intermediate or complex surgical procedures. No study to similarly describe the patterns of relative surgical complexity among a population of United States (U.S) civilian hospitals has been completed.

Methods

Design: single year, retrospective, cross-sectional.

Setting/Participants: the study used Florida Inpatient Discharge Data from short-term acute hospitals for calendar year 2009. Two hundred hospitals with 2,542,920 discharges were organized into four quartiles (Q 1, 2, 3, 4) based on the number of complex procedures per hospital. The VHA surgical complexity matrix was applied to assign relative complexity to each procedure. The Clinical Classification Software (CCS) system assigned complex procedures to clinically meaningful groups. For outcome comparisons, propensity score matching methods adjusted for the surgical procedure, age, gender, race, comorbidities, mechanical ventilator use and type of admission.

Main Outcome Measures: in-hospital mortality and length-of-stay (LOS).

Results

Only 5.2% of all inpatient discharges involve a complex procedure. The highest volume complex procedure hospitals (Q4) have 49.8% of all discharges but 70.1% of all complex procedures. In the 133,436 discharges with a primary complex procedure, 374 separate specific procedures are identified, only about one third of which are performed in the lowest volume complex procedure (Q1) hospitals. Complex operations of the digestive, respiratory, integumentary and musculoskeletal systems are the least concentrated and proportionately more likely to occur in the lower volume hospitals. Operations of the cardiovascular system and certain technology dependent miscellaneous diagnostic and therapeutic procedures are the most concentrated in high volume hospitals. Organ transplants are only done in Q4 hospitals. There were no significant differences in in-hospital mortality rates and the longest lengths of stay were found in higher volume hospitals.

Conclusions

Complex surgery in Florida is effectively regionalized so that small volume hospitals operating within the range of complex procedures appropriate to their capabilities provide no increased risk of post surgical mortality.

Analysis of preoperative condition and interstage mortality in Norwood and hybrid procedures for hypoplastic left heart syndrome using the Aristotle scoring system

OBJECTIVE

The 'hybrid procedure', consisting of surgical banding of the pulmonary arteries with intraoperative stenting of the arterial duct, was developed as primary palliation in hypoplastic left heart syndrome (HLHS), avoiding the risks of cardiopulmonary bypass. In many centres, it is reserved for low birth weight, premature or unstable neonates; however, its role in such high risk cases of HLHS has yet to be defined.

METHODS

The preoperative condition of all patients with HLHS who underwent either the hybrid or the Norwood procedure for HLHS between 2005-2011 was analysed retrospectively, using a modified comprehensive Aristotle score. We then compared operative, interstage and 1 year mortalities between the groups after Aristotle adjustment via Cox proportional hazards analyses.

RESULTS

Of 138 patients with HLHS, 27 had hybrid and 111 Norwood procedures. The hybrid group had significantly higher Aristotle scores (mean 4.1 vs 1.8; p<0.001); however, there was no significant difference in mortality at any stage. At 1 year, the overall unadjusted survival among Norwood and hybrid patients was 58.6% and 51.9%, respectively, yielding an Aristotle adjusted hazard ratio for mortality among hybrid patients of 1.09 (95% CI 0.56 to 2.11, p=0.80).

CONCLUSIONS

Applying a hybrid approach to high risk patients with HLHS produces a comparable early and interstage mortality risk to lower risk patients undergoing the Norwood procedure. Prospective studies are needed to establish whether the hybrid procedure is a viable alternative to the Norwood procedure in all HLHS patients in terms of both mortality and long term morbidity.

The RACHS-1 risk category can be a predictor of perioperative recovery in Asian pediatric cardiac surgery patients

PURPOSE

The Risk Adjustment for Congenital Heart Surgery (RACHS-1) classification was originally designed to facilitate the prediction of in-hospital mortality for pediatric cardiac surgery patients. However, there have been few reports on clinical outcomes predicted by the RACHS-1 category, especially in an Asian population. The aim of this study was to determine whether RACHS-1 classification can predict patient outcomes.

METHODS

A total of 580 pediatric cardiac surgery procedures performed from January 2005 to December 2009 were retrospectively classified into the six RACHS-1 categories. The association between RACHS-1 category and clinical outcomes, including length of catecholamine requirement, mechanical ventilation time, intensive care unit stay, and in-hospital mortality, were examined.

RESULTS

The frequencies of RACHS-1 categories in the study population were: category 1, 10.7 %; category 2, 36.7 %; category 3, 42.8 %; category 4, 6.6 %; category 5, 0.0 %; category 6, 3.3 %. There was a significant linear correlation between RACHS-1 category and in-hospital mortality (r = 0.96, p < 0.001). Kaplan-Meier analysis demonstrated that length of catecholamine infusion, mechanical ventilation time, and ICU stay were significantly different (p < 0.05) in the different RACHS-1 categories, except for those between category 4 and 6 (p = 0.09).

CONCLUSIONS

Based on the results of our analysis, we conclude that the RACHS-1 stratification system can predict in-hospital mortality and patient outcomes in patients undergoing pediatric cardiac surgery.

The impact of gestational age on resource utilization after open heart surgery for congenital cardiac disease from birth to 1 year of age

The impact of gestational age on perioperative morbidity was examined using a novel construct, the resource utilization index (RUI). The medical records of subjects from birth to 1 year of age entered into a pediatric cardiothoracic surgery database from a major academic medical center between 2007 and 2011 were reviewed. The hypothesis tested was that infants born at 37-38 weeks (early-term infants) experience greater resource utilization after open heart surgery than those born at 39 completed weeks and that this association can be observed until 1 year of age. The results support the premise that resource utilization increases linearly with declining gestational age among infants at 0-12 months who undergo cardiac surgery. Five of the six variables comprising the RUI showed statistically significant linear associations with gestational age in the predicted direction. Multivariate linear regression analysis showed that gestational age was a significant predictor of an increased RUI composite. Further investigation is needed to test the concept and to expand on these findings.

Complexity stratification of the arterial switch operation: a second learning curve

The arterial switch operation has become a safe operation in many centres. The complexity of the procedure has evolved over the last two decades. Several anatomical features can hardly be considered complex today, namely, normal coronary anatomy, circumflex coming off the right coronary artery, eccentric ostium, and early take-off of an infundibular artery. In addition, as peri-operative mortality becomes very low, the outcomes need to be evaluated on the peri-operative morbidity, late reoperations, and late deaths. The arterial switch operation remains complex in around 20% of the cases, where one or several complexity factors are associated. The complexity of the coronary arteries is a major factor. According to a classification essentially based on the course of the coronary arteries, complex coronaries include: double-looping coronaries, anterior-looping coronaries, intramural coronaries, and single coronary ostium. The most challenging coronary pattern remains the association of a single ostium with intramural course. Other features are equally complex: severe malalignment of the commissures, aortic arch obstruction, multiple ventricular septal defect, Taussig-Bing with subaortic obstruction, double-outlet right ventricle non-committed ventricular septal defect, transposition of the great arteries-intact ventricular septum >3 weeks, transposition of the great arteries-ventricular septal defect with high lung resistances and weight <2.5 kg. Owing to the fact that the risks of arterial switch operation vary according to the experience of the centres, we defined the arterial switch operation complexity based on a subjective approach as proposed by the Aristotle comprehensive score. The recent introduction of a morbidity score will allow to stratify more accurately the outcomes when the peri-operative mortality is very low or nil. The complexity of the coronary patterns tends to be well controlled today. It remains that rare coronary failures and aortic root dilation will occur in the long term, requiring a close follow-up of the most complex patients. Successfully achieving complex arterial switch operation implies a second learning curve.

Morbidity of the arterial switch operation

BACKGROUND

The arterial switch operation (ASO) has become a safe, reproducible surgical procedure with low mortality in experienced centers. We examined morbidity, which remains significant, particularly for complex ASO.

METHODS

From 2003 to 2011, 101 consecutive patients underwent ASO, arbitrarily classified as "simple" (n=52) or "complex" (n=49). Morbidity was measured in selected complications and postoperative hospitalization. Three outcomes were analyzed: ventilation time, postextubation hospital length of stay, and a composite morbidity index, defined as ventilation time+postextubation hospital length of stay+occurrence of selected major complications. Complexity was measured with the comprehensive Aristotle score.

RESULTS

The operative mortality was zero. Twenty-five major complications occurred in 23 patients: 6 of 25 (12%) in simple ASO and 19 of 49 (39%) in complex ASO (p=0.002). The most frequent complication was unplanned reoperation (15 vs 6, p=0.03). No patients required permanent pacing. The complex group had a significantly higher morbidity index and longer ventilation time and postextubation hospital length of stay. In multivariate analysis, factors independently predicting higher morbidity were the comprehensive Aristotle score, arch repair, bypass time, and malaligned commissures. Myocardial infarction caused one sudden late death at 3 months. Late coronary failure was 2%. Overall survival was 99% at a mean follow-up of 49±27 months.

CONCLUSIONS

In this consecutive series without operative mortality, morbidity was significantly higher in complex ASO. The only anatomic incremental risk factors for morbidity were aortic arch repair and malaligned commissures, but not primary diagnosis, weight less than 2.5 kg, or coronary patterns.