Risk Stratification in Acute Coronary Syndrome: GRACE and TIMI Scores
Primary Recommendation
Use the GRACE risk score as your primary risk stratification tool for all patients with ACS, as it demonstrates superior discriminative ability (C-statistic 0.82-0.84) compared to TIMI and should guide decisions regarding timing of invasive strategy, intensity of antiplatelet therapy, and monitoring requirements. 1, 2
Why GRACE Outperforms TIMI
Superior Predictive Accuracy
GRACE demonstrates consistently better discrimination across all ACS presentations with C-statistics of 0.82-0.84 for predicting mortality, significantly outperforming TIMI particularly in NSTE-ACS populations. 1, 3, 4
In direct head-to-head comparisons, GRACE achieved a C-statistic of 0.85 for in-hospital mortality in UA/NSTEMI patients versus only 0.54 for TIMI (p<0.01), representing a clinically meaningful difference. 4, 5
For STEMI patients specifically, both scores perform similarly well (GRACE C-statistic 0.82-0.84 vs TIMI 0.77-0.83), making either acceptable in this population. 3, 4
Comprehensive Risk Assessment
GRACE incorporates 8 variables including hemodynamic parameters (Killip class, systolic blood pressure, heart rate) and renal function (serum creatinine), which capture disease severity better than TIMI's 7 equally-weighted variables. 2, 6
The inclusion of heart failure indicators and hemodynamic instability markers in GRACE explains its superior performance—these are the key missing elements that limit TIMI's discriminative power in NSTE-ACS. 4
GRACE treats variables semi-quantitatively rather than as binary yes/no criteria, allowing for more nuanced risk assessment. 5
Clinical Application Framework
When to Calculate Each Score
Calculate GRACE score immediately at hospital admission for all confirmed ACS patients to predict in-hospital, 6-month, 1-year, and 3-year mortality or death/MI. 2
TIMI remains useful as a rapid bedside tool when computer access is unavailable, particularly in STEMI where it performs comparably to GRACE. 6, 4
For undifferentiated chest pain in the emergency department before ACS confirmation, consider the HEART score instead (C-statistic 0.753), which outperforms TIMI in this specific population. 2, 7
Risk Category Thresholds and Actions
GRACE Score Interpretation: 1, 2
Low risk (≤108): <1% in-hospital mortality
- Conservative management acceptable
- Stress testing before discharge reasonable
- Standard antiplatelet therapy
Intermediate risk (109-140): 1-3% in-hospital mortality
- Early invasive strategy within 24-72 hours
- Dual antiplatelet therapy with potent P2Y12 inhibitor
- Continuous telemetry monitoring
High risk (>140): >3% in-hospital mortality
- Immediate invasive strategy (coronary angiography within 2-24 hours)
- Intensive antiplatelet therapy including consideration of glycoprotein IIb/IIIa inhibitors
- ICU-level monitoring for hemodynamic instability
For Your Patient Population (Hypertension, Diabetes, Hyperlipidemia)
These traditional risk factors alone do not adequately stratify acute risk—you must incorporate acute presentation variables (hemodynamics, ECG changes, biomarkers) through GRACE scoring. 2, 6
Diabetes and renal dysfunction (common comorbidity) are captured in GRACE through creatinine measurement, making it particularly relevant for this population. 1, 5
The presence of ≥3 traditional risk factors only contributes 1 point to TIMI score, potentially underestimating risk in patients with multiple comorbidities but stable hemodynamics. 6
Practical Implementation
Calculation Methods
GRACE requires computer or smartphone calculator (available at www.outcomes.org/grace) due to its complexity, but this should not deter use given its superior accuracy. 1, 2
TIMI can be calculated manually at bedside in <1 minute using 7 binary variables, making it practical when technology is unavailable. 6
Both scores use readily available admission data—no specialized testing required beyond standard ACS workup (ECG, troponin, basic metabolic panel). 2, 6
Critical Pitfalls to Avoid
Do not rely on clinical gestalt alone—physician subjective assessment is inferior to GRACE scoring for predicting death or MI. 2
Do not use risk scores as diagnostic tools—they stratify risk only in suspected or confirmed ACS, not for excluding ACS in undifferentiated chest pain. 2
Do not calculate GRACE score only once—recalculate at discharge as clinical status changes, particularly after revascularization or if complications develop. 1
Serial troponin measurements are essential; a single negative troponin does not exclude ACS, and risk scores perform poorly when biomarkers haven't yet risen in very early presenters. 7
Evidence Quality Considerations
The 2025 ACC/AHA/ACEP/NAEMSP/SCAI guidelines explicitly reference both GRACE and TIMI as validated tools, with GRACE receiving stronger endorsement based on discriminative performance. 1
The 2011 ESC guidelines specifically state GRACE provides "the most accurate stratification of risk both on admission and at discharge due to its good discriminative power." 1
Meta-analysis of 82 studies including 248,177 patients confirms GRACE superiority with pooled C-statistics of 0.82-0.84 versus 0.54-0.77 for TIMI across different ACS presentations. 3
When TIMI Remains Appropriate
In STEMI populations, TIMI performs equivalently to GRACE (both C-statistics ~0.77-0.83), making the simpler TIMI score acceptable for rapid bedside assessment. 3, 4
When immediate computer access is unavailable and rapid risk stratification is needed, TIMI provides reasonable discrimination despite being inferior to GRACE. 6
For research or quality improvement initiatives requiring simple, reproducible scoring without technology dependence, TIMI offers practical advantages. 6