What Is the STS Score?
The STS Predicted Risk of Mortality (STS-PROM) is a statistical model developed by the Society of Thoracic Surgeons that estimates your risk of death within 30 days of cardiac surgery. It is calculated using dozens of clinical variables specific to your case — your age, gender, medical history, heart function, kidney function, and the specific procedure being performed.
Why Your STS Score Matters
Your STS score is not just a number — it is the foundation of informed surgical decision-making:
- It quantifies risk. Instead of hearing "moderate risk," you'll know if your risk is 1.2% or 4.8% — a meaningful difference.
- It enables comparison. Your surgeon's actual outcomes can be compared against the STS-predicted outcomes. This is how the STS star rating system works.
- It guides treatment decisions. ACC/AHA guidelines use STS scores as explicit thresholds for recommending surgical vs. catheter-based approaches. For example, a low STS score (<4%) for aortic valve replacement generally favors surgery, while a high score (>8%) may favor TAVR.
How to Read Your Score
| STS-PROM Range | Risk Category | Clinical Implication |
|---|---|---|
| < 3% | Low Risk | Standard surgical approach generally appropriate |
| 3-8% | Intermediate Risk | Both surgical and interventional options should be discussed |
| > 8% | High Risk | Careful assessment of alternatives; Heart Team discussion essential |
What the STS Score Doesn't Capture
While the STS-PROM is the gold standard for cardiac surgery risk prediction, it has limitations:
- Frailty — The STS model does not directly measure frailty, which significantly impacts surgical outcomes in elderly patients.
- Porcelain aorta — Severe aortic calcification that may preclude certain surgical approaches is not captured.
- Surgeon volume — Your risk is partly a function of who operates, not just your clinical variables. The STS score doesn't account for this.
- Institutional factors — ICU quality, perfusion team experience, and post-operative care protocols all affect outcomes beyond what the model predicts.
Why WhiteGloveMD Uses Three Risk Models
Because no single model captures every dimension of risk, WhiteGloveMD calculates your risk using three validated models simultaneously: STS-PROM, EuroSCORE II, and the AATS Risk Calculator. When these models agree, confidence is high. When they diverge, it reveals specific risk factors that warrant closer attention.
Calculate your STS score now using our free cardiac surgery risk calculator.