Scoring systems in cardiac surgery adult and congenital

1. Dr. Gaurav Gogoi (PDT) Cardiac
Anesthesia
Moderator-Dr .Sandeep Kar
(Asst.Professor)
Scoring systems in cardiac
surgery

2. Introduction
• Risk stratification/scoring models are widely used to predict outcomes after
cardiac surgery.
• These models enable surgeons to select the ideal treatment option for a
specific patient and to counsel patients accordingly
• At least 19 risk-stratification models exist for open-heart surgery.
• They allow for comparison of postoperative results and assist in assessment
of quality-improvement programs.
• The focus of risk models was originally on pre-operative prediction of
mortality.
• But now Risk modelling has been expanded to also allow for the calculation
of postoperative morbidity

4. Uses of scoring systems
1. Risk scores enable preoperative risk assessment of a patient, thereby explaining operative risk to patients and families.
2. They also enable analysis of cost–benefit ratio for a particular operation, thus appropriating resources available with a hospital.
3. Determination of very high-risk score for a particular patient may aid in changing the choice of therapy in such a situation.eg-
the use of transcatheter aortic valve implantation (TAVI) (in place of surgical aortic valve replacement) for an octogenarian
patient with severe calcific aortic stenosis.
4. Scoring systems also enable surgical triage. (which patient diagnosis to be operated at which centre).
5. Quality control—comparison of results of a particular operation between centres
6. The hospital audit can be helpful in establishing different surgical programmes at different centres (centres of excellence for a
particular procedure may be developed, eg, TAVI or minimally invasive cardiac surgery -MICS CABG and so on)

5. The objective of this presentation is to
provide a review of the most common
currently used risk-stratification models in
cardiac surgery

6. Currently used models
• Three of the most widely used models, applicable to multiple cardiac procedures in adults,
include
1. The European system for cardiac operative risk evaluation (euro score),
2. The Society of thoracic surgeons (STS) algorithms, and
3. The Parsonnet score
• In pediatric surgery
1. Risk Adjusted classification for Congenital Heart Surgery( RACHS)
2. Aristotle score(Basic and comprehensive)
3. Society of Thoracic Surgery–European Association for Cardio-Thoracic Surgery
Mortality Score(STS-EACTS)

7. The European System for Cardiac Operative Risk
Evaluation
• It has been studied widely and is believed by many to be the gold standard
• The European system for cardiac operative risk evaluation (Euro-SCORE) was
introduced in 1999.
• It was developed from a large European database including 19030 patients across 128
centres.
• The Euro-SCORE provided two methods for calculating predicted outcome: the
additive model and the logistic model.
• the Additive and logistic Euro-SCORE models are now out of date.
• A new model has been prepared from fresh data and is launched at the 2011 EACTS
meeting in Lisbon. The model is called Euro-SCORE II

8. The Logistical Euro-score Identified
The Following Areas Of Improvement.
Creatinine clearance (CC) is a better predictor than absolute serum
creatinine
Defining unstable angina using intravenous nitrates is out of date
Some continuous variables are treated as dichotomous (number of
previous heart operations, serum creatinine, pulmonary artery pressure).
The model is not sufficiently sensitive to the ‘weight’ of the
intervention.

9. low risk (EuroSCORE 0-2), moderate risk (EuroSCORE 3-5) and high risk (EuroSCORE >6)

10. Euro score II
risk factors
• Patient related factors
1. Age
2. Gender
3. Renal impairment
4. Extracardiac
arteriopathy
5. Poor mobility
6. Previous cardiac
surgery
7. Chronic lung disease
8. Active endocarditis
9. Critical pre-operative
state
10. Diabetes on insulin
• Cardiac related factors
1. NYHA
2. CCS class 4 angina
3. LV function
4. Recent MI
5. Pulmonary HTN
• Operation related factors
1. Urgency
2. Weight of
intervention
3. Surgery on
thoracic aorta.

11. The following modifications were done
• In the patient-related variables, insulin-dependent diabetes was added.
• Neurological dysfunction was changed into reduced mobility due to neurological or to musculoskeletal
dysfunction.
• Renal insufficiency defined in the initial Euro-SCORE as a serum creatinine of 200 μmol/l preoperatively was
replaced by creatinine clearance.
• In the cardiac-related variables, unstable angina, defined as rest angina requiring intravenous nitrates until arrival
in the anaesthetic room, was replaced by NYHA class II, III, IV and angina CCS class 4.
• The variables left ventricular dysfunction and pulmonary hypertension were divided into new categories.
• the operation-related variables, emergency surgery, defined as carried out on referral before the beginning of the
next working day, in the initial Euro-SCORE has been redefined in three different risk groups namely urgent,
emergency and salvage
• Other than isolated CABG’ is divided into several risk categories
• postinfarct septal rupture as mentioned in the initial Euro-SCORE is not identified in the Euro-SCORE II

12. Definitions of the risk factors
• Age –in completed years
• Renal impairment- estimated based on Cockcroft-gault formula
• On dialysis-regardless of creatinine clearance
• Moderately deranged renal function (50-85ml/min)
• Severely deranged renal function (<50ml/min) off dialysis.
• Extra-cardiac arteriopathy-one or more of the following
• Claudication
• Carotid occlusion or >50% stenosis
• Amputation for arterial disease
• Previous or planned intervention on the abdominal aorta, limb arteries or carotids.

13. Explanations of the risk factors
• Poor mobility-severe impairment of mobility secondary to musculoskeletal or neurological
dysfunction
• Chronic lung disease-long term use of bronchodilators or steroids for lung disease
• Active endocarditis- patient still on antibiotic treatment for endocarditis at time of surgery.
• Critical pre-operative state-ventricular tachycardia or ventricular fibrillation or aborted
sudden death, preoperative cardiac massage, preoperative ventilation before anaesthetic
room, preoperative inotropes or IABP, preoperative acute renal failure (anuria or oliguria
<10ml/hr)

14. Explanations of the risk factors
• Recent MI myocardial infarction within 90 days
• Pulmonary hypertension
• Moderate-PA systolic pressure(31-55mmHg)
• Severe-PA systolic (>55mmHg)

15. Explanations of the risk factors
• Urgency
• Elective-routine admission for operation
• Urgent-patients who have not been electively admitted for operation but who require intervention or surgery
on the current admission for medical reasons. These patients cannot be sent home without a definitive
procedure.
• Emergency-operation before the beginning of the next working day after decision to operate.
• Salvage-patients requiring cardiopulmonary resuscitation (external cardiac massage) en route to the operating
theatre or prior to induction of anaesthesia. This does not include cardiopulmonary resuscitation following
induction of anaesthesia

16. Explanations of the risk factors
• LV function or LVEF –
• good (LVEF 51% or more);
• moderate (LVEF 31–50%);
• poor (LVEF 21–30%);
• very poor (LVEF 20% or less).
• Weight of the procedure-this measures the extent or size of the intervention. The baseline is isolated
CABG
• Isolated non-CABG major procedure (e.g. single valve procedure, replacement of ascending aorta, correction of
septal defect, etc.)

17. Explanations of the risk factors
• Two major procedures (e.g. CABG+AVR), or CABG+ mitral valve repair (MVR),
or AVR+ replacement of ascending aorta, or CABG+ maze procedure, or
AVR+MVR, etc.)
• Three major procedures or more (e.g. AVR+MVR+CABG, or MVR+ CABG+
tricuspid annuloplasty, etc.), or aortic root replacement when it includes AVR or
repair+ coronary reimplantation + root and ascending replacement)

18. To calculate EURO-ScoreII

20. Limitations of euro score
• The original additive ES model generally underestimates morality in high-risk and overestimates it in
low-risk patients.
• Also it was designed primarily using data largely from CABG patients.
• In 2003, logistical ES scoring system was introduced with use of full logistic equation to improve
operative mortality prediction.
• However, the performance of both models declined progressively over a period of time.
• This could be due to an increase in operating on older individuals (>70 years), presence of more co-
morbidities than originally included in the risk score, and advances in the practice of cardiac surgery,
which leads to the introduction of ESII in 2012.

21. Limitations of euro score
• In a study by Chalmers et al. in 2012 in UK data from a single center with more than 5000 patients showed that
ESII is a better model for combined valve and CABG, best for isolated mitral surgery, and it exhibits poor
prediction in isolated CABG compared with aES or lES model.
• Their analysis also raised concerns in application of ESII in isolated aortic valve replacement and aortic surgeries.
• Even though age is considered as one of the predictors for mortality in certain high-risk surgery, all the existing
Euro-SCORE models did not include aortic calcification and diffuse coronary disease, important in determining
mortality especially above 70 years.
• In a study by Deepak Borde et in 2013 al EuroSCORE II over estimated mortality in high-risk category (additive
euro score risk-score > 5) of patients in Indian patients.

22. The Society of Thoracic Surgeons Algorithms
• The Society of Thoracic Surgeons National Cardiac Database(STS NCD) was created in 1989.
• The primary aim for the development of the STS model was the support of national quality-
improvement programs.
• Data were collected prospectively from more than 950 participating centers in the United States.
• The predictive performance of the STS algorithms is in general comparable with other systems and
remains the most widely used model in the United States.
• STS risk models for cardiac procedures have been developed since 1999 and have undergone periodic
revisions

23. • STS began building risk model starting with isolated CABG mortality.
• Risk models now also include risk of death for isolated valve or valve concomitant with CABG
operations as well as several morbidity risk models.
• The last models, the “2008 Models,” were developed using data collected during 2002 to 2006. The
STS 2008 models are embedded in the version 2.61 data collection tools.
• The most up-to-date STS risk calculator (as of February 2018) is available online.
• It comprise 27 models, including nine end points for each of three cardiac procedure groups.

24. • Procedures
• Isolated CABG
• Isolated valve procedure (aortic valve replacement; mitral valve replacement or repair).
• Isolated valve procedure plus CABG
• Operative mortality was found to be greatest with the following risk factors
1. Salvage status
2. Renal failure
3. Emergency status
4. Multiple reoperations
5. NYHA class 4

25. • 9 additional end points apart from operative mortality were developed for each
model
1. Operative mortality(defined in all STS databases as all deaths, regardless of cause, occurring during the
hospitalization in which the operation was performed even if after 30 days (includes patients transferred
to other acute care facilities), and all deaths, regardless of cause, occurring after discharge from the
hospital but before the end of the 30th postoperative day
2. Permanent stroke-an acute episode of focal or global neurologic dysfunction caused by brain, spinal cord,
or retinal vascular injury as a result of hemorrhage or infarction in which the neurologic dysfunction lasts
for more than 24 hours;
3. Renal failure-a new requirement for dialysis or meeting the RIFLE (Risk, Injury, Failure, Loss of kidney
function, and End-stage kidney disease) criteria based on creatinine levels or glomerular filtration rate
4. Deep sternal wound infection(DSWI)-occurring during the index hospitalization or within 30 days of
operation;

26. 5. reoperation for bleeding, tamponade, or any cardiac reason
6. Prolonged ventilation time (>24 hours)
7. Operative death or major morbidity (of the five types above)
8. Short postoperative length of stay (<6 days and discharged alive)
9. Prolonged postoperative length of stay (>14 days)

27. • There are three ways to obtain a STS risk score.
1. From the STS-approved software
2. By using the online STS calculator for 1 patient at a time
3. By applying the published regression coefficients for 1 or more patients at a
time.
• The calibration of risk factors is based on observed/expected O/E ratio.
The expected mortality (E) is calibrated to obtain the national E/O ratio.

28. To calculate STS score

29. After selecting case
type, scroll down
and enter patient
values for risk
variables

30. • When all of the patient variables are
entered hit ‘CALCULATE’ for the
patient’s risk scores
• Eg.

31. SUMMARY
• The STS risk score, which is primarily used in the united states, has been found to be highly effective for determining the risk of
mortality in both the short and the long term.
• The STS risk score is calculated through the STS website and is continually adjusted over time to improve accuracy. The STS
Risk Calculator estimates a patient’s risk of mortality and other morbidities, such as long length of stay and renal failure
• However, it can be used only in the following specific surgical cases: isolated coronary artery bypass graft surgery (CABG),
isolated aortic valve replacement (AVR), isolated mitral valve replacement, isolated mitral valve repair, CABG with AVR, and
CABG with mitral valve replacement or mitral valve repair.
• Because of this limitation, the sts risk scoring system cannot be used to study other types of cardiac surgery that are not yet
included, such as the maze procedure for surgical ablation of atrial fibrillation and double valve replacement.

32. Parsonnet score
• In 1989, Parsonnet proposed a preoperative
score for adult cardiac surgery (’’initial
Parsonnet’s score’’).
• This score is simple, additive and grades the
severity of illness of patients into five groups.
• Two risk factors of the “initial Parsonnet’s
score” are however imprecise and their
weights are arbitrarily chosen by the surgeon
(catastrophic states, other rare circumstances

33. Parsonett V et al. Circulation (1989);79(1);1.3-1.12.

34. • This original score was later
modified(Bernstein and Parsonnet)
including thirty new risk factors .
• These 30 new risk factors take the place of
the 2 imprecise risk factors of the initial
score, and this new score is referred to as
the “modified Parsonnet’s score”.
• The authors developed a logistic regression
model which 47 potential risk factors were
considered

35. • In a study by Mirsad et al in 2007 the initial and modified Parsonnet’s scores are predictive
for operative mortality of the cardiac surgery in adults.
• However, these scores remain imperfect as
• many risk factors are non-significant
• the initial Parsonnet’s score has only a moderate predictive value
• use of modified Parsonnet’s score is too complex and many of its risk factors are subjective or not well
defined. Establishment of a new score seems to be necessary. Ideally it has to be as predictive as the
modified Parsonnet’s score and as objective and simple to use as the initial Parsonnet’s score.
Kacila M, K Tiwari K, Granov N, Omerbasić E, Straus S. Assessment of the Initial and Modified Parsonnet score in mortality prediction of the patients operated in the
Sarajevo Heart center. Bosn J Basic Med Sci. 2010;10(2):165-168. doi:10.17305/bjbms.2010.

36. Comparison.
• Still, even today, different scores give differing prediction of morbidity and
mortalities.
• The parameter used to gauge their accurate predicting ability-C-index is variable for
same patient population .
• Good predictive ability is when C-index is above 0.7 and is strong for values above
0.8.
Hote M. Cardiac surgery risk scoring systems: In quest for the best. Heart Asia. 2018;10(1):e011017. Published 2018 Apr 4. doi:10.1136/heartasia-2018-011017

37. Contd.
• In this study The STS and Euro-SCORE II scoring systems
yielded mortality rates that were both close to the actual rates
observed at their institution, whereas Euro-SCORE I resulted
in greater overestimation of mortality rates.
• The discriminatory ability of Euro-SCORE II was slightly
higher than that of the STS score for isolated CABG and for
mitral valve surgery
• Conversely, the STS score had greater discriminatory ability for
aortic valve surgery and for CABG with concomitant valve
surgery.
• The STS risk score has been found to be superior to the Euro-
SCORE not only in this study, but also in another study finding
it to be superior to both the Euro-SCORE I and the Euro-
SCORE II in trans-catheter valve implantations
A single center study from January 2001 to 2015

38. Indian population • This was a prospective study conducted at Max Heart
and Vascular Institute, New Delhi, from June 2012 to
June 2013.
• One thousand and ninety-eight consecutive adult
patients undergoing off-pump or on-pump CABG,
valve surgery, surgeries for mechanical complications
of myocardial infarction (MI), and surgeries on the
thoracic aorta with the exclusion of congenital
cardiac surgery were considered.
• The present study suggests that the Euro-SCORE-II
model in its present form is not validated for use in
the Indian population.

39. Pediatric
score
systems
• Children with congenital heart
defects who undergoes corrective
surgeries have varied outcomes.
• Risk prediction scoring
systems allow comparison of
outcome of therapy for children
undergoing surgery for congenital
heart diseases.

40. RACHS-1 (Risk Adjustment in Congenital Heart Surgery)
scoring system.
• Special attention in the literature is given to the study by Jenkins et al. in 1995, which propose an easily applicable risk score, called Risk
Adjustment for Congenital Heart Surgery 1 (RACHS-1)
• This system started in 1997 and completed in 2001-2002.
• The aim was to be able to foresee the short-term mortality of congenital heart surgery in patients under age 18.
• However morbidity was not aimed at evaluating.
• RACHS-1 was based on the categorization of several surgical procedures - palliative or corrective - which had similar in-hospital
mortality.
• Therein, the diseases were assigned to one of six risk categories, according to the expected mortality rate predicted by each disease.
• In this scoring system no division regarding surgical technique was made.
• If any additional procedure was undertaken, procedure with high risk category was considered

41. • For the development of the score a nationally representative panel of pediatric cardiologists and cardiac surgeons
used clinical judgment to place surgical procedures into groups with similar risk for in-hospital death.
• the risk categories were then refined empirically using data from the Pediatric Cardiac Care Consortium and 3
statewide hospital discharge databases.
• To apply the RACHS-1 method, cardiac procedures are grouped into 1 of 6 predefined risk categories; category 1
has the lowest risk of in-hospital mortality and category 6 has the highest.
• Cases with a combination of cardiac surgical procedures (eg, repair of coarctation of the aorta together with
ventricular septal defect closure) are placed in the category of the single highest-risk procedure

44. The Aristotle score
• The study for this scoring system was started in 1999
• In above year, Lacour- Gayet and a committee of experts created a tool for stratification of complexity and called
it a score of Aristotle
• The first step was establishing the Basic Score, which adjusts only the complexity of the procedures and is based
on three factors: the potential for mortality, the potential for morbidity, and the anticipated technical difficulty.
• The second step was the development of the Comprehensive Score, which further adjusts the complexity
according to the specific patient characteristics.
• The Aristotle score allows precise scoring of the complexity for 145 congenital heart surgery procedures.
• Aristotle basic complexity score (ABC score) developed in 2004 categorized the operations according to scores
(range: 1.5–15) and levels 1–4.
• The Aristotle Comprehensive Complexity Score (ACC Score) is calculated on 25 points: it equals the Aristotle
Basic Complexity Score plus 5 points for Procedure-dependent Factors and 5 points for Procedure-independent
Factors
• The Aristotle score, electronically available, was introduced in the EACTS and STS databases.
• A validation process, designed to evaluate its predictive value, is being developed.

45. • The Basic Score is a procedure-adjusted complexity
and only applies to procedures.
• An international group including more than 50
prominent centers and 23 Nations was asked,
through a questionnaire, to score 145 procedures of
the short list of the International Nomenclature,
according to potential of mortality, potential of
morbidity and estimated technical difficulty
• For each procedure, the median value of mortality,
morbidity and technical difficulty obtained from the
50 centers was calculated.
• The sum of these three median values gives the final
basic score for each procedure
The scale ranged from 1.5 to 15

46. • The Comprehensive Aristotle Score introduces patient-adjusted complexity. It
includes two categories of complexity factors
• Procedure dependent factors adjust each patient's procedure to a specific complexity
• Anatomical factors.
• Associated procedures .
• Age- The impact of age varies in either direction depending on the procedure.
• Each factor is scored for contribution to mortality, morbidity, and difficulty
• Procedure independent factors- adjust for each patient's clinical status a specific complexity
• General factors
• Clinical factors
• Extra-cardiac factors
• Surgical factors
• Each factor is scored for contribution to mortality, morbidity, and difficulty.
• The comprehensive score adds 10 points and two levels of complexity to the basic
score scale, (15.1–20=level 5 and 20.1–25=level 6)

50. For Aristotle comprehensive scoring

51. Examples of procedure dependent factors

52. Example of Procedure independent complexity factors

54. STS-EACTS mortality score
• The newest of the three tools for stratification of complexity is the STS-EACTS
mortality score, published in 2008.
• It was developed primarily using objective data, with minimal use of subjective
probability.
• The mortality risk was estimated for 148 procedure types, using real data from 77,294
patients (33,360 patients from the EACTS and 43,934 patients from the STS)
between 2002 and 2007.
• Using Bayesian statistics that fits the data for small denominators, mortality rates
were calculated for each procedure.

55. • Each procedure received a score which ranged from 0.1 to 5.0, based on
the estimated mortality
• The procedures were then distributed by the growing risk and grouped
into 5 categories.
• The STS-EACTS mortality score represents an evolution of the previous
stratification models which were highly subjective.

57. Comparison
• In this study In the present cohort, STS-
EACTS model was found to be the best
predictor of both hospital mortality
followed by ABC which performed better
than the RACHS-1 model
• Although all 3 complexity scoring models
have been validated to predict the mortality
and outcome post cardiac surgery no clear
superiority of one over another exists
Shahzad Alam, Akunuri Shalini, Rajesh G. Hegde, Rufaida Mazahir, Akanksha Jain,
A comparative study of the risk stratification models for pediatric cardiac surgery, The Egyptian Journal of Critical Care Medicine, Volume 6, Issue 1, 2018, Pages 5-8,

58. Thank you