Calculating the STS Score for Cardiac Surgery Risk Assessment

Overview of the STS Score

The American College of Cardiology recommends using the STS score as a validated risk prediction tool to calculate the predicted risk of mortality and morbidity for patients undergoing cardiac surgical procedures, with a strength of evidence based on annual calibration to ensure predicted rates equal observed rates 1
The STS score serves as a benchmark for cardiac surgery reporting and is widely used for preoperative risk assessment, patient selection, and shared decision-making, as supported by the American College of Cardiology 2, 3

The American College of Cardiology defines low risk as an STS-PROM <3%, intermediate risk as STS-PROM between 3% and 8%, and high risk as STS-PROM ≥8%, with a strength of evidence based on clinical trials 4
The American College of Cardiology also defines extreme risk as STS-PROM ≥15%, which may indicate futility of certain procedures like TAVR, with a strength of evidence based on clinical trials 2, 3

The STS score helps determine surgical risk and guides decision-making for various cardiac procedures, including heart team discussions to choose between surgical and transcatheter approaches for aortic valve replacement, with a strength of evidence based on clinical trials 1, 2, 3
An STS-PROM score >15% may indicate futility of TAVR, as these patients showed no appreciable benefit in all-cause mortality compared to medical therapy in clinical trials, with a strength of evidence based on clinical trials 3
The score is also used to calculate risk for specific procedures, with median operative mortality rates varying by procedure type, such as 2.2% for isolated AVR and 9% for AVR plus mitral valve replacement, with a strength of evidence based on clinical data 1

The American Heart Association recommends visiting the official STS calculator website and entering all required patient data accurately to obtain risk estimates for mortality and major morbidities 1, 5
The calculator results should be used as part of a shared decision-making process with patients, considering the results in the context of a heart team discussion for complex cases, with a strength of evidence based on clinical trials 1, 3

The American College of Cardiology recommends using the STS-PROM score as the primary surgical risk stratification tool for determining candidacy for TAVR versus SAVR in aortic stenosis patients, with scores >15% indicating potential futility of intervention 6
The STS-PROM score guides Heart Team discussions about procedural approach, with higher scores favoring transcatheter over surgical approaches 6
The score has limitations, including underestimation of risk in certain populations, and should not be used as the sole decision-making tool 6

The American College of Cardiology notes that conditions such as end-stage renal disease, advanced oxygen-dependent lung disease, slow ambulation, poor LV systolic function, severe pulmonary hypertension, advanced dementia, and severe cachexia or frailty are not adequately reflected in the STS score 6
The American College of Cardiology recommends that all STS-PROM assessments be reviewed by a Heart Valve Team comprising cardiac surgeons, interventional cardiologists, imaging specialists, anesthesiologists, and geriatric specialists before final treatment decisions 6

The STS Adult Cardiac Surgery Risk Calculator requires comprehensive entry of patient-specific variables, including demographic factors, cardiac factors such as left ventricular ejection fraction and presence of heart failure, and procedure-specific factors 7