Version July 2025
INTRODUCTION —
Evaluation of patients who may be candidates for surgical or transcatheter valve procedures includes assessment of the procedural risk associated with the proposed procedure(s).
Comprehensive assessment of risk associated with valvular surgery and transcatheter procedures will be reviewed here [1-6]. Other considerations in preoperative assessment of potential cardiac surgery candidates are discussed separately. (See "Overview of preoperative evaluation and management for cardiac surgery in adults" and "Revascularization in patients with stable coronary artery disease: Coronary artery bypass graft surgery versus percutaneous coronary intervention" and "Coronary artery bypass surgery: Perioperative medical management" and "Early noncardiac complications of coronary artery bypass graft surgery" and "Early cardiac complications of coronary artery bypass graft surgery".)
GENERAL CONSIDERATIONS
Role of evaluation — For patients with valve disease who have indications for valve intervention, accurate estimation of procedural risk and benefit by a multidisciplinary heart valve team is essential for counseling of patients and their caregivers, selection of a management approach, and planning perioperative care [7,8]. As an example, comparison of treatment options for aortic stenosis, including aortic valve surgery and transcatheter aortic valve implantation, requires accurate estimation of expected outcomes. In addition, knowledge of specific components of the risk score may suggest ways to reduce risk in an individual patient; for example, performing percutaneous coronary intervention before planned valve surgery, stabilizing the patient with advanced therapies to allow elective (rather than emergency) valve surgery, or optimizing heart failure therapy and hemodynamics prior to intervention.
Types of risk — A variety of factors affect the risk of mortality and morbidity associated with surgical or transcatheter interventions for valvular heart disease. These factors can be categorized as patient-related, procedure-related, operator-related, and medical center-related variables [7,8].
Patient- and procedure-related factors — An integrated approach to patient- and procedure-related risk factors combines an estimate of risk based on a risk model with consideration of additional risk factors not included in these models. (See 'Approach to risk assessment' below.)
Operator- and institutional-related factors — A key approach to optimize operator-related and medical center-related variables is appropriate referral to valve centers. An expert consensus statement from several professional societies recommended evaluation and treatment at a primary or comprehensive valve center to improve patient outcomes, with the choice of center based on the patient's risk and planned procedure [9]. When considering risk estimates from models (see 'Commonly used risk models' below), the heart team should also consider its own local data, experience, and expertise for cardiac surgery and any alternative interventions (eg, transcatheter valve therapy). (See 'Integrated approach' below.)
APPROACH TO RISK ASSESSMENT
Comprehensive assessment — A comprehensive multidisciplinary heart valve team approach to risk assessment for valve intervention includes the following elements [7,8]:
●Integration of risk factors – The patient's risk score (eg, Society of Thoracic Surgeons [STS] or EuroSCORE II) is integrated with additional risk factors that impact procedural outcomes. Of note, the patient's age impacts the risk score, as well as the likelihood of the patient requiring subsequent procedures. (See 'Integrated approach' below and 'Planning for subsequent procedures' below.)
●Risk adjustment for adjunctive procedures – Some patients undergoing valve procedures may undergo concomitant procedures which impact risk. (See 'Adjunctive procedures' below.)
●Consideration of potential subsequent procedures – It is important to identify patients who may require a subsequent valve procedure, since this may alter the approach to an initial valve procedure. (See 'Planning for subsequent procedures' below.)
●Management of advanced heart failure – Management for patients with valve disease and advanced heart failure includes heart failure consultation to consider potential need for short- or long-term mechanical circulatory support and heart transplantation. (See "Emergency care of adults with mechanical circulatory support devices" and "Treatment of advanced heart failure with a durable mechanical circulatory support device" and "Heart transplantation in adults: Indications and contraindications".)
Integrated approach — We assess procedural risk in patients with valve disease who may be candidates for intervention (surgical or transcatheter) using an integrated approach in which the patient's risk score (eg, STS or EuroSCORE II) is considered together with other factors that impact procedural mortality and morbidity, as recommended by the 2020 American College of Cardiology/American Heart Association (ACC/AHA) and the 2021 European Society of Cardiology guidelines [7,8].
Key considerations — An integrated approach includes consideration of the following clinical characteristics that impact the risk-benefit analysis of valve intervention, as recommended by the ACC/AHA guideline [7]:
●Predicted risk of procedural mortality – The STS risk estimate is commonly used to predict procedural mortality [7] (see 'STS' below). The EUROSCORE II risk calculator is an alternative option for estimating procedural mortality (see 'EuroSCORE II' below). Use of a risk model to predict procedural mortality is appropriate only if institutional outcomes are within one standard deviation of the model's average observed/expected mortality ratio for the specific procedure.
●Frailty – This is stratified into no, mild, or severe frailty by the Katz Activities of Daily Living (ADL) score or other frailty scoring systems [7,8,10]. An approach with seven indices includes six metrics from the Katz ADL scoring system (independence in feeding, bathing, dressing, transferring, toileting, and urinary continence) plus independence in ambulation (no walking aid or assistance required, or completion of a 5 m walk in <6 s) [7,8].
●Major organ system compromise not to be improved postoperatively – Major organ system compromise that will not be improved after valve intervention include cardiac dysfunction (severe left ventricular systolic or diastolic dysfunction or right ventricular dysfunction, fixed pulmonary hypertension), kidney dysfunction (chronic kidney disease, stage 3 or worse), pulmonary dysfunction (forced expiratory volume in 1 s [FEV1] <50 percent or carbon monoxide lung diffusion capacity <50 percent of predicted), central nervous system dysfunction (dementia, Alzheimer disease, Parkinson disease, cerebrovascular accident with persistent physical limitation), gastrointestinal dysfunction (Crohn disease, ulcerative colitis, nutritional impairment, or serum albumin <3), cancer (active malignancy), and liver dysfunction (any history of cirrhosis, variceal bleeding, or elevated international normalized ratio in the absence of vitamin K antagonist therapy).
●Procedure-specific impediments – A number of procedure-specific risk factors (technical/anatomic and comorbidities) are not incorporated into commonly used risk models and should be considered in considering options for valve intervention. [7,8].
•Technical/anatomic risk factors
-For surgical aortic valve or surgical mitral valve repair or replacement – Relevant technical or anatomic risk factors for surgical aortic valve replacement (SAVR) include prior mediastinal radiation and ascending aortic calcification (porcelain aorta may pose a prohibitive risk) [7], as well as presence of a tracheostomy, chest malformation, and arterial coronary bypass graft adherent to the chest wall. (See "Choice of intervention for severe calcific aortic stenosis", section on 'Contraindications to SAVR'.)
-For transcatheter aortic valve implantation – Relevant technical or anatomic risk factors for transcatheter aortic valve implantation (TAVI) include aorto-iliac occlusive disease (precluding a transfemoral approach), protuberant aortic atherosclerosis, severe mitral or tricuspid regurgitation, a short distance from the valve plane to coronary ostia, basal septal hypertrophy, bicuspid or unicuspid valve, and extensive left ventricular outflow tract calcification [7]. (See "Choice of intervention for severe calcific aortic stenosis", section on 'Contraindications to TAVI'.)
-For mitral transcatheter edge-to-edge repair – Relevant technical or anatomic risk factors include multivalve disease, valve morphology (thickening, perforations, clefts, calcification, and stenosis), and prior mitral valve surgery [7].
•Comorbidities – Comorbidities associated with high procedural risk with surgical or transcatheter aortic or mitral intervention include severe chronic obstructive pulmonary disease or home oxygen therapy, pulmonary hypertension, hepatic dysfunction, and frailty [7]. Severe right ventricular dysfunction is an additional procedure-specific comorbidity for patients undergoing surgical or transcatheter aortic valve intervention.
●Futility – Valve intervention is generally considered futile for patients with very high risk of surgical mortality (STS score >15 percent) and/or limited prognosis (life expectancy <1 year) or if the patient's quality of life is unlikely to improve with the procedure (eg, patient is a poor candidate for rehabilitation) [7].
Surgical risk categories — The ACC/AHA integrated approach identifies risk categories based upon combinations of the above clinical characteristics [7]:
•Low surgical risk
-For SAVR – Low risk is identified if all of the following four criteria are present: STS-predicted risk of death <3 percent, no frailty indices, no other major organ system compromise that would not be improved after intervention, and no procedure-specific impediments.
-For surgical mitral valve repair for primary mitral regurgitation – Low risk is identified if all of the following four criteria are present: STS-predicted risk of death <1 percent, no frailty, no other major organ system compromise that would not be improved after intervention, and no procedure-specific impediments.
•High surgical risk – Surgical risk is deemed high if one or more of the following criteria is present (and no prohibitive risk factors are present): STS-predicted risk of death >8 percent, ≤1 frailty index, compromise of one or two major organ systems that would not be improved after intervention, or a possible procedure-specific impediment.
•Prohibitive surgical risk – Surgical risk is deemed prohibitive if one or more of the following criteria is present: STS-predicted risk of death or major morbidity >50 percent at one year, two or more frailty indices, compromise of three or more organ systems, or a severe procedure-specific impediment.
Adjunctive procedures — Patients undergoing valve surgery commonly have indications for concomitant procedures, which may or may not impact procedural risk as well as longer term outcomes. Thus, the choice of valve procedure type (eg, surgical versus transcatheter) may be influenced by presence of concurrent indications for adjunctive surgical or transcatheter procedures.
Examples of adjunctive surgical procedures include coronary artery bypass graft surgery with arterial grafts, surgical ablation of atrial fibrillation (Maze procedure), and tricuspid valve repair for tricuspid regurgitation (as an adjunct to mitral valve surgery).
Limitations and complications of the Maze procedure (including risk of requiring a pacemaker) are discussed separately. (See "Atrial fibrillation: Surgical ablation", section on 'Limitations and complications'.)
As discussed separately, tricuspid valve repair as an adjunct to mitral valve surgery may not increase the risk of mitral valve surgery. (See "Tricuspid regurgitation: Management and prognosis", section on 'At the time of left-sided valve surgery'.)
Planning for subsequent procedures — An additional consideration in treating patients with longer anticipated life expectancy (eg, younger patients with lower cardiovascular risk) is the potential need for future interventions (eg, valve in transcatheter heart valve or valve in surgical bioprosthetic valve), which should inform selection of the initial intervention. These issues are particularly important for patients with size or anatomy variations (eg, lower coronary arteries, small sinuses, small aortic annuli, smaller prostheses).
RISK MODELS
Commonly used risk models — Validated cardiac surgery risk stratification models estimate procedural risk based upon patient-related and procedure-related variables. Risk scores provide a starting point for estimating the surgical mortality and morbidity of valve surgery in an individual patient. The most commonly used cardiac surgery risk models are the Society of Thoracic Surgeons (STS) and EuroSCORE II models discussed below. (See 'STS' below and 'EuroSCORE II' below.)
Risk models are helpful but have a number of limitations, as discussed below. (See 'Limitations of risk models' below.)
Risk stratification models for hospital mortality following cardiac surgery (coronary artery bypass graft surgery, valve surgery, or both) include the following calculators. The updated STS and EuroSCORE II risk models provide risk stratification based upon large contemporary databases with adjustment for multiple clinical variables. These risk scores are used to estimate operative risk in patients in settings similar to those represented by their respective databases.
STS — The STS risk model is the most widely used algorithm and it is continuously updated. As of 2023, the STS Adult Cardiac Surgery Database contained over 9 million procedures [11]. In 2022 there were 1010 sites (nearly all North American) with 3651 individual surgeons who performed 278,202 procedures. The model provides estimates of risk of mortality as well as several nonfatal complications such as stroke, kidney failure, and prolonged ventilation. A calculator is available online (www.sts.org/resources/acsd-operative-risk-calculator).
The key elements in the STS operative risk calculator are type of surgery, urgency, age, sex, body size, cardiac risk factors, heart failure, ventricular function, coronary disease, arrhythmias, and other concurrent conditions including chronic lung disease and cerebrovascular disease.
EuroSCORE II — The first EuroSCORE model was developed based upon data from 1995 to stratify risk of in-hospital mortality [12]. This model has been replaced by the 2011 EuroSCORE II model, which was developed based on data from 22,381 patients in 43 countries undergoing cardiac surgery during May to July 2010 [13]. Overall mortality was 3.9 percent, which is lower than would have been predicted by old risk models (additive predicted 5.8 percent and logistic predicted 7.6 percent). A calculator for the EuroSCORE II is available online (euroscore.org). EuroSCORE 3 is in development.
The EuroSCORE II calculator divides the key elements into patient-related factors (age, sex, chronic lung disease, extracardiac arteriopathy, poor mobility, previous cardiac surgery, active endocarditis, critical status, and kidney impairment), cardiac-related factors (ventricular function, angina, and heart failure symptom class) and operation-related factors (urgency and type of surgery).
Models for specific procedures — Risk models developed for specific valve disorders and procedures may provide more accurate risk prediction than more general risk models.
●TAVR In-hospital Mortality Risk App – The Society of Thoracic Surgeons/American College of Cardiology (STS/ACC) TAVR In-Hospital Mortality Risk App estimates the risk of in-hospital mortality for patients undergoing transcatheter aortic valve implantation (TAVI, also known as transcatheter aortic valve replacement [TAVR]) for severe aortic stenosis [1]. The calculator enables comparison of individual patient risk with the national average based on data from the STS/ACC Transcatheter Valve Therapy (TVT) Registry. The United States national average for in-hospital mortality in the STS/ACC TVT registry as of May 2015 was 4 percent.
●For primary mitral regurgitation – A novel risk score for surgical risk in patients undergoing mitral valve repair for primary mitral regurgitation has been proposed [14]. Risk models were developed based on data on 53,462 consecutive patients in the STS Adult Cardiac Surgery Database. Overall 30-day operative mortality was 1.16 percent, the risk of mortality plus morbidity was 8.88 percent, and the rate of conversion to replacement was 6.36 percent. Risk of operative death was <1 percent in patients under age 65 years. The proposed model was highly discriminative (area under the curve [AUC] 0.80) and had excellent calibration for operative death.
●For tricuspid regurgitation – Surgery for isolated tricuspid regurgitation is associated with high risk (eg, 10 percent in-hospital mortality [15]). A TRI-SCORE has been proposed to estimate surgical risk for isolated tricuspid regurgitation [15]. Comparison with other risk models is discussed below. (See 'Comparison of models' below.)
The TRI-SCORE includes eight parameters with a maximum score of 12 points:
•Each of the following factors contribute 2 points: signs of right-sided heart failure, daily dose of furosemide ≥125 mg, glomerular filtration rate <30 mL/min, and elevated bilirubin.
•Each of the following factors contribute 1 point: age ≥70 years, New York Heart Association functional class III to IV, left ventricular ejection fraction <60 percent, and moderate or severe right ventricular dysfunction.
Limitations of risk models — Risk stratification models are subject to limitations that may reduce their prognostic value.
●Models lag clinical practice – The data on which risk models are based lag behind evolving clinical practice, technologies, and outcomes. STS and EuroSCORE models have been updated infrequently in processes extending over years. The models estimate risk for only specified procedures (eg, the 2018 STS risk model does not include estimates for concomitant aortic and mitral valve surgery [16]). These include dependence upon incomplete or uncertain clinical variables. The models may not be generalizable to patient populations different from the ones in which they were formulated, and they require revision over time as surgical and perioperative care evolve and as the recognition and impact of clinical variables change.
In addition, risk models for cardiac surgery do not necessarily indicate the risk of newer transcatheter procedures, such as TAVI, that increasingly are effective alternates to conventional surgery [17]. Guidelines recommend evaluation of patients by a specialized heart valve clinic when valve intervention is needed so that risks and benefits of a surgical versus transcatheter procedure can be discussed by a multidisciplinary team [18,19].
●Additional risk factors – Risk stratification models do not include several variables that may be clinically important. These additional risk factors are considered in the integrated approach described above (see 'Integrated approach' above), while other risk factors may require separate consideration.
For example, a severely calcified ascending aorta (also known as porcelain aorta, a risk factor for patients undergoing cardiac surgery) and severe mitral annular calcification (a risk factor in patients undergoing mitral surgery (see "Management and prognosis of mitral annular calcification", section on 'Mitral valve surgery')) are each associated with high operative morbidity and mortality but are not included in standard risk models [20-24]. Other clinically important variables that are not included in risk models are difficult to measure, such as frailty, exercise capacity, and nutritional status, as well as other hemodynamic factors such as pulmonary pressures and right ventricular dysfunction. These additional factors are especially important when considering the choice between a surgical or transcatheter valve procedure. Some of these factors may be the determining factor in this decision for specific patients. (See "Choice of intervention for severe calcific aortic stenosis".)
●Operator- and institution-specific effects – As noted above, risk models are appropriate only in settings in which risk-adjusted institution-specific outcomes are similar to those predicted by risk models. (See 'Operator- and institutional-related factors' above.)
●Lack of availability for some procedures – Risk calculators are not available for certain procedures that are more commonly considered in younger patients (eg, Ross and David procedures). (See "Bicuspid aortic valve: Intervention for valve disease or aortopathy in adults", section on 'Types of intervention' and "Bicuspid aortic valve: Intervention for valve disease or aortopathy in adults", section on 'Ross procedure'.)
Comparison of models — The limited available data comparing risk models are illustrated by the following examples:
●For cardiac surgery – A meta-analysis of 22 observational studies of patients undergoing cardiac surgery (coronary artery bypass graft surgery and/or valve surgery) compared the predictive value for in-hospital or one-month mortality of the STS score, EuroSCORE II, and Age, Creatinine, Ejection Fraction (ACEF) score [25]. The STS score (summary AUC 0.76, 95% CI 0.73-0.79) and EuroSCORE II (summary AUC 0.77, 95% CI 0.75-0.79) performed similarly and outperformed the ACEF score (summary AUC 0.72, 95% CI 0.68-0.76).
●For tricuspid valve surgery – In a retrospective study of 252 consecutive patients with tricuspid regurgitation undergoing tricuspid valve surgery, the discriminatory capacity of the TRI-SCORE for in-hospital mortality was high (C-statistic 0.87, 95% CI 0.81-0.92), which was higher than for the EuroSCORE-II (0.67, 95% CI 0.58-0.79) [26].
SOCIETY GUIDELINE LINKS —
Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cardiac valve disease".)
SUMMARY AND RECOMMENDATIONS
●General considerations – For patients with valve disease who have indications for valve intervention, multidisciplinary heart valve team assessment for accurate procedural risk-benefit analysis is essential for counseling of patients and their caregivers, selection of a management approach, and planning perioperative care. Patient-related, procedure-related, operator-related, and medical center-related variables affect the risk of mortality and morbidity associated with surgical or transcatheter valve interventions. (See 'General considerations' above.)
●Comprehensive assessment – Comprehensive risk assessment for valve intervention includes the following elements (see 'Comprehensive assessment' above):
•Integration of risk factors (Society of Thoracic Surgeons [STS] or EuroSCORE II risk score, plus additional risk factors including frailty, major organ system compromise not to be improved postoperatively, and procedure-specific impediments). (See 'Integrated approach' above.)
•Assessment for futility. (See 'Key considerations' above.)
•Risk adjustment for adjunctive procedures. (See 'Adjunctive procedures' above.)
•Consideration of potential subsequent procedures. (See 'Planning for subsequent procedures' above.)
•Heart failure consultation for patients with advanced heart failure. (See 'Key considerations' above.)
●Risk models
•Role of risk models – Validated cardiac surgery risk stratification models estimate procedural risk based upon patient-related and procedure-related variables. Risk scores provide a starting point for estimating the mortality and morbidity associated with valve surgery for a patient. The most commonly used cardiac surgery risk models are the STS (www.sts.org/resources/acsd-operative-risk-calculator) and EuroSCORE II (euroscore.org) models. (See 'STS' above and 'EuroSCORE II' above.)
•Limitations – Risk stratification models are subject to limitations that may reduce their prognostic value. Models are available for a limited set of procedures and are based upon prior data that may not reflect evolving clinical practice and outcomes. Risk models are appropriate only in settings in which institution-specific outcomes are similar to those predicted by risk models. Since risk models do not include a number of clinically important risk factors, a comprehensive approach to risk assessment involves integration of risk model scores with additional risk factors as well as with other procedural planning. (See 'Limitations of risk models' above.)
