How to Interpret the GRACE Score in Acute Coronary Syndrome
The GRACE score predicts mortality risk in patients with acute coronary syndrome (ACS) and should be used to determine the timing and intensity of treatment, with a score >140 indicating high risk requiring coronary angiography within 24 hours. 1, 2
What the GRACE Score Predicts
The GRACE risk model predicts in-hospital mortality and the composite of death or myocardial infarction across all forms of ACS including STEMI, NSTEMI, and unstable angina, with excellent discrimination (C statistic = 0.83). 1
The score also accurately predicts long-term outcomes including 6-month, 1-year, 2-year, 3-year, and 4-year mortality with C indices consistently >0.80, making it useful beyond just the acute hospitalization. 3
The 8 Variables Used in Calculation
Calculate the GRACE score using these variables with their associated odds ratios for mortality: 1
- Age (OR 1.7 per 10 years)
- Killip class (OR 2.0 per class) - reflects heart failure severity
- Systolic blood pressure (OR 1.4 per 20 mm Hg decrease)
- ST-segment deviation on ECG (OR 2.4)
- Cardiac arrest during presentation (OR 4.3)
- Serum creatinine level (OR 1.2 per 1-mg per dL increase)
- Positive initial cardiac biomarkers (OR 1.6)
- Heart rate (OR 1.3 per 30-beat per min increase)
Non-linear relationships exist for age, systolic blood pressure, pulse, and creatinine, meaning the risk does not increase proportionally—the updated GRACE 2.0 score accounts for these non-linear associations and has improved discrimination compared to the original linear model. 4
How to Apply the Score to Clinical Decisions
Risk Stratification Thresholds
GRACE score >140 defines high-risk patients who require coronary angiography within 24 hours of hospital admission. 1, 2
GRACE score ≤140 indicates lower-risk patients who can be managed with delayed angiography beyond 24 hours or a selective invasive approach. 2
Evidence Supporting the 140 Threshold
The TIMACS trial demonstrated that early intervention (median 14 hours) in patients with GRACE >140 reduced the primary ischemic endpoint from 21.0% to 13.9% (HR 0.65,95% CI 0.48-0.89, P=0.006), while patients with GRACE ≤140 showed no benefit from early intervention. 2
The VERDICT trial confirmed this interaction, showing benefit with early invasive strategy only in GRACE >140 patients (HR 0.81,95% CI 0.67-1.00 vs HR 1.21,95% CI 0.92-1.60 for GRACE ≤140; P for interaction=0.02). 2
Timing Definitions
Immediate angiography (<2 hours) is reserved for very high-risk features regardless of GRACE score: hemodynamic instability, cardiogenic shock, refractory chest pain, life-threatening arrhythmias, mechanical complications, or acute heart failure. 1, 2
**Early angiography (<24 hours)** is indicated for GRACE >140 or presence of elevated troponin with dynamic ST changes. 1, 2
Delayed angiography (>24 hours) is appropriate for GRACE ≤140 without high-risk features. 2
Practical Application Tools
The GRACE clinical application tool can be downloaded to a handheld device for bedside use and is available at www.outcomes-umassmed.org/grace. 1
Apply the sum of scores to a reference nomogram to determine the corresponding all-cause mortality risk from hospital discharge to 6 months. 1
Additional Predictive Value Beyond Mortality
The GRACE score predicts heart failure admission following ACS, with patients in the highest quintile having nearly 10-fold higher risk (HR 9.87,95% CI 5.93-16.43) and a C-statistic of 0.74 for 1-year CHF admission. 5
Early invasive strategy in GRACE >140 patients significantly reduces refractory ischemia (3.3% vs 1.0%, P<0.001) and recurrent MI beyond just mortality reduction. 2
Critical Caveats
Use the GRACE risk score for in-hospital death when applying the >140 threshold for timing decisions, as this is what the TIMACS and VERDICT trials validated—there are several different GRACE risk scores predicting different outcomes at different time points. 1, 2
The score performs well across all ACS subtypes (STEMI, NSTEMI, unstable angina) and maintains excellent discrimination regardless of whether patients undergo coronary angiography or revascularization. 6
Calibration may require adjustment in specific healthcare settings despite excellent discrimination—the predicted probability of mortality may differ from observed mortality even though the score accurately ranks patients by risk. 6
Renal impairment is a key component of the GRACE score and independently predicts both short-term and long-term mortality, with mild-to-moderate dysfunction conferring moderately increased risk and severe dysfunction conferring severely increased risk. 1