What is the role of the Global Registry of Acute Coronary Events (GRACE) score in assessing risk and guiding management in patients with ST-Elevation Myocardial Infarction (STEMI)?

Use of GRACE Score in STEMI

The GRACE risk score is a validated and useful tool for predicting in-hospital and 6-month mortality in STEMI patients, with excellent discriminative ability (C-statistic 0.83), and should be calculated at hospital admission to guide treatment intensity and identify patients who will benefit most from aggressive therapy including early revascularization. 1

Risk Prediction Performance in STEMI

The GRACE model demonstrates superior predictive accuracy compared to subjective physician assessment across all acute coronary syndrome presentations, including STEMI. 2 The score was developed from 11,389 patients and validated in subsequent GRACE and GUSTO IIb cohorts, consistently showing strong discrimination for mortality prediction. 1

Specific validation studies in STEMI populations confirm the score's reliability:

• In Japanese STEMI patients undergoing primary PCI, GRACE 1.0 achieved an area under the ROC curve of 0.95 for in-hospital mortality and 0.92 for 360-day mortality. 3
• In Thai STEMI patients, the score successfully stratified risk with observed in-hospital mortality of 23.3% in high-risk patients (≥155 points), 3.4% in intermediate-risk (126-154 points), and 0% in low-risk patients (≤125 points). 4
• Long-term follow-up data demonstrate that GRACE predicts not only early outcomes but also 5-year mortality, with hazard ratios of 2.14 for intermediate-risk and 6.36 for high-risk patients compared to low-risk strata. 5

Eight Variables That Comprise the Score

Calculate the GRACE score using these specific parameters at hospital admission: 1

• Age (odds ratio 1.7 per 10 years)
• Killip class (OR 2.0 per class) - assess for signs of heart failure on presentation
• Systolic blood pressure (OR 1.4 per 20 mm Hg decrease) - lower pressure indicates worse prognosis
• Heart rate (OR 1.3 per 30-beat per min increase) - tachycardia signals hemodynamic compromise
• ST-segment deviation (OR 2.4) - present in STEMI by definition but degree matters
• Cardiac arrest during presentation (OR 4.3) - strongest single predictor
• Serum creatinine level (OR 1.2 per 1-mg per dL increase) - renal dysfunction independently predicts mortality
• Positive initial cardiac biomarkers (OR 1.6) - troponin or CK-MB elevation

Clinical Application Algorithm

At hospital admission for STEMI patients: 1, 2

1. Calculate the GRACE score immediately using the 8 variables above
2. Apply the sum to the reference nomogram to determine predicted mortality from hospital discharge to 6 months
3. Stratify patients into risk categories:
   • Low risk: ≤125 points
   • Intermediate risk: 126-154 points
   • High risk: ≥155 points (or >140 per some guidelines) 2, 4

For high-risk patients (GRACE >140-155): 2, 6

• Pursue aggressive therapy with early invasive strategy
• Implement intensive antiplatelet therapy
• Ensure close monitoring during hospitalization
• Prioritize early transfer to PCI-capable facilities if initially presenting to non-PCI centers
• In post-fibrinolysis patients at non-PCI centers, use GRACE to identify those requiring urgent transfer rather than delayed intervention, as intermediate-to-high GRACE scores after successful fibrinolysis show significantly worse outcomes with delayed PCI (hazard ratio 2.97 for composite cardiovascular events at 6 months) 6

Critical Considerations for STEMI Specifically

The GRACE score applies across the entire ACS spectrum, but STEMI patients have unique considerations: 1, 5

• While STEMI carries the highest early mortality risk, long-term cumulative mortality rates at 5 years are similar across STEMI (19%), NSTEMI (22%), and unstable angina (17%). 5
• Two-thirds (68%) of STEMI deaths occur after initial hospital discharge, emphasizing the importance of risk stratification for post-discharge management. 5
• In-hospital mortality in STEMI patients with stage 4-5 chronic kidney disease approaches 30%, highlighting the critical importance of the creatinine component in the GRACE calculation. 1

Practical Implementation

The GRACE clinical application tool can be downloaded to handheld devices for bedside use and is available at www.outcomes-umassmed.org/grace. 1 This facilitates rapid calculation without manual computation, reducing errors and improving workflow efficiency.

Risk assessment should be repeated throughout hospitalization and at discharge, as dynamic changes in clinical status, biomarker evolution, and ECG findings provide additional prognostic information at key decision points. 1

Comparison to Alternative Risk Scores

While TIMI risk scores exist specifically for STEMI (predicting 30-day mortality), comparative analyses demonstrate that GRACE, TIMI, and PURSUIT all show good predictive accuracy for death and MI at 1 year. 1 However, GRACE demonstrates superior discriminative ability with its C-statistic of 0.83 compared to other models. 1, 2

The HEART score is designed specifically for emergency department evaluation of undifferentiated chest pain before ACS confirmation and is not the appropriate tool once STEMI is diagnosed. 2