What is the preferred risk stratification score between TIMI (Thrombolysis In Myocardial Infarction) and GRACE (Global Registry of Acute Coronary Events) in patients with acute coronary syndromes?

GRACE vs TIMI Risk Scoring in Acute Coronary Syndrome Risk Stratification

The GRACE score is the preferred risk stratification tool over the TIMI score for patients with acute coronary syndromes due to its superior predictive ability for both short-term and long-term mortality. 1

Comparison of Scoring Systems

GRACE Score

• Recommended by the American College of Cardiology 1

• Includes 8 clinical variables:

  • Age
  • Killip class
  • Systolic blood pressure
  • Heart rate
  • ST-segment deviation
  • Cardiac arrest on admission
  • Serum creatinine
  • Cardiac biomarker elevation

• Risk categorization:

  Risk Category	GRACE Score	In-hospital Mortality
  Low	≤108	<1%
  Intermediate	109-140	1-3%
  High	>140	>3%

• Excellent discrimination with C-statistic of 0.83-0.91 for predicting in-hospital mortality 1

• Maintains predictive value up to 4-5 years after the initial ACS event 1

TIMI Score

• Includes 7 variables (each worth 1 point):

  • Age ≥65 years
  • ≥3 risk factors for coronary artery disease
  • Previous coronary artery stenosis ≥50%
  • ST segment deviation
  • ≥2 angina events in previous 24 hours
  • Aspirin use in previous 7 days
  • Elevated cardiac biomarkers

• Risk prediction:

  Score	Risk
  0-1	4.7%
  2	8.3%
  3	13.2%
  4	19.9%
  5	26.2%
  6-7	40.9%

Evidence Supporting GRACE Over TIMI

Superior Discrimination

• The GRACE score demonstrates significantly better discrimination compared to the TIMI score:

  • C-statistic of 0.91 vs 0.69 for in-hospital events 2
  • C-statistic of 0.79 vs 0.69 for 1-year mortality 3

• GRACE score maintains excellent performance (C > 0.80) across all ACS subtypes (STEMI, NSTEMI, and unstable angina) 4

Clinical Utility

• The GRACE score has potential prognostic superiority as it:

  • Treats variables in a semi-quantitative form
  • Incorporates renal function in its calculation 2
  • Provides mortality estimates at hospital discharge, 6 months, 1 year, and 3 years 1

• High GRACE scores (>140) identify patients who derive significant benefit from early invasive management 1

Implementation Considerations

• The GRACE score can be calculated using web applications or mobile devices (available at www.outcomes-umassmed.org/grace) 1

• A GRACE score of 126 has been identified as an optimal cut-off for predicting severe coronary artery disease (SYNTAX score ≥33) with 53.5% sensitivity and 66% specificity 5

• Despite excellent predictive ability, there is insufficient evidence that routine use of risk scores in hospitalized patients with ACS translates into reduced cardiovascular events 1

Clinical Pitfalls and Caveats

• Neither GRACE nor TIMI should be used as diagnostic tools, but rather for risk stratification in patients with suspected or confirmed ACS 1

• The 6-month mortality GRACE score may perform less well in patients undergoing percutaneous coronary intervention (PCI) compared to those who do not (C = 0.73 vs 0.76) 4

• Special consideration should be given to patients with renal insufficiency, who have higher risks of bleeding, heart failure, and arrhythmias 1

• While the RISK-PCI score has shown promising results for predicting 30-day events and target vessel revascularization in some studies 6, the GRACE score remains the recommended standard by major cardiology societies 1