When it comes to cardiac surgery, prediction of operative risk is of vital importance to patients, surgeons and medical teams. Tools such as theEuroSCORE, the STS Score and the Ambler Score enable us to accurately estimate the risk of post-operative mortality and morbidity.

EuroSCORE (European System for Cardiac Operative Risk Evaluation), developed by theEuropean Association of Cardio-Thoracic Surgery, is particularly well known. It is used to predict operative mortality within 30 days of cardiac surgery, by analyzing various clinical aspects of the patient as well as the characteristics of the surgery.

These calculators are not limited to statistical analysis. They are major clinical tools, helping to better inform patients and guide surgical decisions for optimal management.

Understanding risk calculators in cardiac surgery

Importance of risk calculators

Risk calculators in cardiac surgery play an essential role in medical decision-making. These tools estimate operative mortality and morbidity, helping surgeons and patients to assess the benefit-risk ratio of surgical interventions. They reduce the subjective element in surgical risk assessment, and provide an objective basis for discussing treatment options and potential risks with patients.

In addition, these calculators are indispensable for improving quality of care in cardiac surgery and ensure greater transparency in results. By offering standardized data, they make it easier to compare performance between different surgery centers, and clearly identify areas requiring improvement. This can range from optimizing interventional practices to adjusting post-operative follow-up protocols.

What's more, these tools help optimize available resources and enable more effective planning of post-procedure care, anticipating any complications that may arise.

Overview of scores

Currently, several risk calculators are used in cardiac surgery, each with its own characteristics and advantages. The choice of a score often depends on the nature of the surgical procedure envisaged, as well as the patient's specific profile.

For example, EuroSCORE, developed by the European Association of Cardio-Thoracic Surgery, is one of the most widely used risk stratification systems. It stands out for its ease of use and its ability to reliably estimate 30-day mortality after cardiac surgery. There are two main versions of this score: the additive version and the logistic version, while the more recent EuroSCORE II offers greater precision thanks to methodological adjustments.

On the other hand, the Society of Thoracic Surgeons ( STS ) score, based on a rich American database, takes into account a far greater number of variables than EuroSCORE. It is particularly well suited to a range of complex surgical procedures, such as coronary bypass surgery and valve replacement. What's more, it enables us to estimate not only operative mortality, but also the morbidity associated with these procedures.

For patients with valvular heart disease, the Ambler score is particularly relevant. Based on data from the Society of Cardiothoracic Surgeons of Great Britain and Ireland, it provides an accurate estimate of in-hospital mortality in patients undergoing valve surgery.

Although each of these scores presents specific approaches, they all share a common goal: to provide a robust and reliable assessment of operative risk. This enables better-informed medical decisions to be made and care to be better organized for patients requiring cardiac intervention.

The EuroSCORE

History and development of EuroSCORE

EuroSCORE, or European System for Cardiac Operative Risk Evaluation, was initiated by Samer Nashef and François Roques in the 1990s. This ambitious project was based on the collection of data from around 20,000 patients in 128 hospitals in eight European countries.

This collection focused on 97 risk factors, making it possible to draw up a precise risk profile for each patient and estimate postoperative mortality. Published in 1999, the first EuroSCORE model was immediately adopted worldwide, becoming the reference system for risk prediction in cardiac surgery. However, advances in surgical techniques and postoperative care have highlighted the need for an update. In response, EuroSCORE II was announced in 2011 and published in 2012, offering significantly improved calibration and accuracy.

How EuroSCORE is calculated

The EuroSCORE calculation is based on 17 parameters relating to the patient, cardiac conditions and the nature of the planned procedure. These parameters include :

• Patient-related factors: age, gender, chronic lung disease, etc.
• Cardiac factors: unstable angina, reduced ventricular ejection fraction, etc.
• Factors related to the operation: urgency of the procedure, type of surgery planned, etc.

The information gathered is then integrated into a model based on logistic regression to predict postoperative mortality. The initial model was based on an additive approach, whereas more recent versions, including the logistic model and EuroSCORE II, allow a more refined assessment thanks to the integration of precise numerical values for certain variables such as pulmonary artery pressure and ejection fraction.

EuroSCORE limits and accuracy

Although it is widely used and has helped improve cardiac surgery outcomes, EuroSCORE has its limitations. One obstacle lies in inter-observer reliability, since the encoding of risk factors may vary from one practitioner to another. Any variation in data interpretation can therefore introduce bias into the final calculation.

In addition, the initial model sometimes tended to overestimate mortality risk, particularly for certain procedures such as valve surgery. Fortunately, EuroSCORE II has corrected these excesses by improving both the model's calibration and discriminatory power.

These improvements underline the continuing importance of refining risk assessment models, to reflect ongoing advances in cardiac surgery and provide patients with the most rigorous and accurate estimate of operative risk possible.

The STS Score

Development and application of the STS Score

The Society of Thoracic Surgeons ( STS) Score is derived directly from the extensive database of the Society of Thoracic Surgeons, located in the USA. This score has been specifically designed to provide an accurate estimate of the risk of post-operative mortality and morbidity in cardiac surgery.

It is widely recognized and used in specialized thoracic surgery centers to assess the operative risk of patients undergoing various cardiac procedures, including coronary bypass, valve replacement and other complex surgical procedures.

The STS Score is also highly flexible. It features models adapted to each type of cardiac surgery, enabling even more precise risk assessment in line with the specificity of the procedure and the patient's needs. In this way, it promotes a personalized and refined surgical approach.

STS Score calculation and components

The calculation of the STS Score is based on a broad spectrum of variables, far more numerous than those taken into account by EuroSCORE. These includeage, gender, medical history such as coronary heart disease or heart failure, and factors such as ventricular function or pulmonary arterial pressure. These data, when combined in advanced statistical models, provide a detailed and reliable estimate of the probability of postoperative complications or death.

Unlike the EuroSCORE, which can be calculated additively or logistically, the STS Score requires the use of specific software or online calculators to be produced accurately. While this mathematically advanced approach guarantees remarkable accuracy, it may prove slightly less practical in contexts requiring rapid estimation at the patient's bedside.

Advantages and disadvantages of the STS Score compared with EuroSCORE

The main advantage of the STS Score lies in its ability to assess not only operative mortality, but also associated morbidity. This broader view of surgical risks guides surgeons towards more informed, better-adapted decisions.

What's more, it is often judged to be more accurate than EuroSCORE, particularly for patients in intermediate or high-risk categories. This is due to the inclusion of a greater number of variables, and the use of much more advanced statistical models.

Nevertheless, a number of limitations remain. The complexity of its calculation can be an obstacle, particularly in emergency situations where speed is essential. Furthermore, it may underestimate the risk for certain patients with extreme risk factors or requiring atypical interventions.

In conclusion, the STS Score is a particularly precise and flexible tool. However, it requires a certain technical skill and may have limitations in specific situations. Its use will depend on the clinical context and the particular requirements of the patient and the care team.

The Ambler Score

Origins and usefulness of the Ambler Score

The Ambler Score was designed specifically for patients with heart valve disease, based on a database developed by the Society of Cardiothoracic Surgeons of Great Britain and Ireland. The aim of this score is to estimate in-hospital mortality in patients requiring heart valve surgery. It is particularly useful for procedures involving valves such as the aortic or mitral valve, whether or not associated with coronary bypass surgery.

The main strength of the Ambler Score lies in its ability to provide a precise, targeted prediction of mortality risk in a specific population: that of patients undergoing valve surgery. This enables medical teams to plan management steps more effectively, and to clearly inform patients of the risks and benefits associated with their surgery.

Methodology for calculating the Ambler Score

The calculation of the Ambler Score is based on a national database which analyzed over 32,000 patients during its development and validation phase. This score includes a combination of clinical factors specific to patients requiring heart valve intervention. Thanks to this methodology, it is particularly relevant for accurately predicting in-hospital mortality in this specific context.

Unlike other assessment tools such as EuroSCORE or the STS Score, which are applicable to a wide variety of cardiac surgeries, the Ambler Score stands out for its specialism. This specificity makes it a robust and useful tool for surgeons and medical teams wishing to anticipate postoperative outcomes in valve surgery.

Comparing the Ambler score with other scores

The Ambler Score is a tool designed for specific indications, which differentiates it from other tools such as EuroSCORE or the STS Score. The latter are generalist scores, covering a wide range of cardiac surgery types. In contrast, the Ambler Score offers greater accuracy when used in the context of valve surgery, due to its dedicated design.

However, studies have shown that this score can sometimes overestimate risk, particularly in the highest risk quartiles. Despite this limitation, the Ambler Score retains good discriminatory power, being able to effectively differentiate low-risk from high-risk patients. In comparison, the EuroSCORE II and the STS Score are sometimes better calibrated, but this in no way detracts from the relevance of the Ambler Score for specific valvulopathies. It therefore remains a valuable tool for practitioners specializing in this type of procedure.

Comparison and selection of the appropriate score

Factors influencing the choice of score

The choice of the appropriate risk score for cardiac surgery is based on a detailed analysis of several essential criteria. First and foremost, the nature and complexity of the surgical procedure are central to this decision.

For example, the STS score is frequently preferred for complex or combined procedures, such as coronary bypass surgery combined with valve surgery, as it offers remarkable accuracy in the simultaneous assessment of operative mortality and morbidity risks.

In addition, individual patient characteristics play a key role. The Ambler score, designed specifically for people with heart valve disease, is particularly relevant because of its ability to provide a fine estimate of the risk of in-hospital mortality.

The accessibility and ease of use of scores cannot be overlooked. For example, the EuroSCORE, in its additive version, is often chosen for its simplicity and speed of calculation, making it ideal for emergency situations requiring rapid decision-making.

Practical application of scores in clinical decision-making

In the clinical context, risk scores are integrated into the decision-making process to accurately assess the benefit-risk ratio of surgical interventions. They enable surgeons and medical teams to provide patients with informed information on the potential risks and benefits of surgery.

For example, a patient with a high-risk EuroSCORE or STS score should be engaged in an in-depth discussion of possible therapeutic alternatives or preoperative preparation measures aimed at minimizing risk.

In addition, these scores help optimize the management of medical resources. For example, a patient identified as being at high risk may require intensive monitoring in post-operative care, including specific cardiac support measures.

Impact of scores on cardiac surgery outcomes

The integration of risk scores into surgical practice is having a positive impact on cardiac surgery outcomes. By reducing subjectivity in risk assessment, these tools enable more accurate stratification of patients and better-informed decisions.

This process can significantly reduce post-operative mortality and morbidity, particularly by reserving appropriate resources for higher-risk profiles. It also facilitates the comparison of results between different cardiac surgery centers, helping to identify best practices and improve standards of care.

Finally, these scores play a key role in the evaluation of innovative techniques and surgical protocols, paving the way for continuous improvement in cardiac surgery outcomes.

In short, their integration into clinical practice promotes a more methodical and precise approach to managing the risks associated with cardiac surgery.

Recent and future developments in risk calculators

Technological innovations and new calculation models

Cardiac surgery risk calculators are constantly evolving, thanks to technological advances and advances in data analysis. A major innovation recently introduced is the integration of artificial intelligence (AI) into predictive models. For example, the Oxford Risk Factors And Noninvasive imaging (ORFAN) cohort study has enabled the development of an AI-enhanced cardiac risk prediction algorithm. This combines thePerivascular Fat Attenuation Index (FAI) with coronary plaque measurements and clinical risk factors.

This model was found to be positively associated with cardiac mortality and coronary events, particularly in patients without significant coronary stenosis. In addition, traditional tools such asEuroSCORE and the STS score continue to be improved. EuroSCORE II, for example, has replaced previous models and is now based on 18 clinical characteristics for a more refined, personalized assessment of surgical risk.

At the same time, advanced technologies such as Positron Emission Tomography(PET) and Magnetic Resonance Imaging(MRI) are being integrated into the data collection process. These devices pave the way for a more detailed assessment of patients' cardiac status, enhancing the accuracy of models and their ability to predict post-operative outcomes.

Integrating risk calculators into clinical practice

The widespread use of risk calculators in clinical practice has become the norm. Hospitals and specialized centers rely heavily on interactive online tools to quickly and accurately estimate surgical risks. These tools contribute to informed medical decisions, while providing more transparent and detailed information to patients on the potential risks and benefits associated with surgical procedures.

What's more, electronic medical record (EMR) management systems have also evolved to integrate these calculators. This integration ensures data fluidity, enabling continuous assessment and optimal monitoring throughout the course of care. It contributes to improving the quality and safety of interventions, reducing errors and optimizing available resources, particularly in critical care.

Finally, the ongoing training is essential to ensure optimum use of these tools by healthcare professionals. Conferences, workshops and online training programs are organized on a regular basis to keep medical teams up to date with the latest advances in this key field.

Conclusion

Risk calculators in cardiac surgery, such asEuroSCORE, the STS score and the Ambler score, play an important role in estimating operative mortality and morbidity. With these tools, patients can be effectively stratified to reduce the subjectivity of risk assessment and improve overall quality of care.

Each score has its strengths and weaknesses, and their choice always depends on the specific nature of the surgical procedure and the particularities of each patient.

However, these tools should not be used in isolation. It is essential to integrate them into daily clinical practice, and to complement them with expert clinical judgment. Ongoing technological advances and regular revisions of these models guarantee increasingly accurate prediction of postoperative outcomes.

To maximize the positive impact of these calculators, their systematic use is essential. It is equally important to continue optimizing them through analysis of data from clinical practice and advances in technological innovation. In this way, we will be able to make more informed medical decisions and significantly improve cardiac surgery outcomes for patients.

FAQ

What are the main risk calculators used in cardiac surgery, and what are their respective objectives?

The main risk calculators used in cardiac surgery are theEuroscore, the STS score and the Ambler score.

• Euroscore: Developed by the European Association of Cardio-Thoracic Surgery, it estimates 30-day operative mortality for all types of cardiac surgery. Additive and logistic versions are available.
• STS Score: Derived from the Society of Thoracic Surgeons database, it is based on a larger number of variables than the Euroscore. This score is used to estimate operative mortality and morbidity for different types of cardiac surgery.
• Ambler score: developed specifically for valvulopathy, based on a database provided by the Society of Cardiothoracic Surgeons of Great Britain and Ireland.

How does the EuroSCORE score calculation work, and what is the difference between the additive and logistic versions?

The EuroSCORE score assesses the risk of mortality following cardiac surgery, using a range of variables. Here are the main differences between the two versions:

• EuroSCORE Addendum: This model assigns a simple sum of points (17 risk factors) to assess risk. Although practical, it may underestimate risk in high-risk patients.
• EuroSCORE Logistique: This model uses a calculation based on logistic regression to combine risk factors. This provides a more accurate prediction, particularly for high-risk patients.

The logistic model is more rigorous, but requires more advanced calculation tools.

What are the main differences between the STS score and the EuroSCORE score in terms of the variables used and the types of cardiac surgery assessed?

The differences between these two scores lie mainly in the number of variables taken into account and the specificity of the types of surgery evaluated:

• STS Score: Developed by the Society of Thoracic Surgeons, it is based on over 50 demographic and operative variables. In addition, it offers specific models for various types of cardiac surgery, such as valve or coronary surgery.
• EuroSCORE II: Created by the European Association of Cardio-Thoracic Surgery, this score uses 18 variables. Although more general and simpler to calculate, it is applicable to all types of cardiac surgery, with no precise distinction between types of procedure.

Why was the Ambler score developed specifically for cardiac valve surgery, and how does it compare with other risk scores?

The Ambler score was designed specifically for cardiac valve surgery, based on a database collected by the Society of Cardiothoracic Surgeons of Great Britain and Ireland. Its aim is to estimate in-hospital mortality for these patients. Special features include:

• Greater specialization in valvulopathies, unlike the more general EuroSCORE.
• A risk ofoverestimation, particularly in high-risk patients, whereas EuroSCORE II is more precise and better calibrated in this area.

Compared with the STS score, the Ambler score remains simpler but uses a smaller number of variables, making it less exhaustive for other types of cardiac surgery.

‍