What are the HEART (History, ECG, Age, Risk factors, Troponin) score and TIMI (Thrombolysis In Myocardial Infarction) score and how can they be easily remembered for risk stratification in patients with chest pain or acute coronary syndromes?

Understanding HEART and TIMI Scores for Risk Stratification in Chest Pain

The HEART score is superior to the TIMI score for risk stratification of patients with chest pain in the emergency department, with better discrimination and predictive value for 30-day major adverse cardiac events. 1

HEART Score Explained

The HEART score was specifically designed for evaluation of patients with chest pain in the emergency department without a diagnosis of acute coronary syndrome 2. It consists of 5 components that can be easily remembered using the acronym "HEART":

Components (0-2 points each, total 0-10):

• History (clinical presentation)

  • 0 points: Slightly suspicious
  • 1 point: Moderately suspicious
  • 2 points: Highly suspicious

• ECG findings

  • 0 points: Normal
  • 1 point: Nonspecific abnormalities
  • 2 points: Significant ST-segment depression

• Age

  • 0 points: <45 years
  • 1 point: 45-65 years
  • 2 points: >65 years

• Risk factors (hypertension, diabetes, smoking, hypercholesterolemia, family history)

  • 0 points: No risk factors
  • 1 point: 1-2 risk factors
  • 2 points: ≥3 risk factors

• Troponin

  • 0 points: ≤ normal limit
  • 1 point: 1-3× normal limit
  • 2 points: >3× normal limit

Risk Stratification:

• Low risk: 0-3 points (2% risk of 30-day MACE)
• Moderate risk: 4-6 points (28% risk of 30-day MACE)
• High risk: 7-10 points (63% risk of 30-day MACE) 1

TIMI Score Explained

The TIMI (Thrombolysis In Myocardial Infarction) risk score was originally developed for patients with confirmed unstable angina/non-ST elevation MI 2.

Components (1 point each, total 0-7):

• Age ≥65 years
• ≥3 CAD risk factors (family history, hypertension, hypercholesterolemia, diabetes, smoking)
• Known CAD (stenosis ≥50%)
• Aspirin use in last 7 days
• Severe angina (≥2 episodes in 24 hours)
• ECG ST-segment deviation ≥0.5 mm
• Cardiac marker elevation

Risk Stratification:

• Low risk: 0-1 points (5-8% risk of adverse events)
• Intermediate risk: 2-4 points (13-20% risk of adverse events)
• High risk: 5-7 points (26% or higher risk of adverse events) 2

Comparison and Clinical Application

1. Diagnostic Accuracy:

   • HEART score has superior discrimination with c-statistic of 0.78 compared to TIMI's 0.65 1
   • For ruling out 30-day MACE:
     • HEART ≤3: Sensitivity 99%, NPV 98%
     • TIMI=0: Sensitivity 97%, NPV 91% 1

2. Risk Stratification Capability:

   • A HEART score of 0-3 identifies patients with <1% risk of 30-day adverse events 3
   • The combination of HEART=0 and TIMI=0 identifies patients with essentially zero risk (0-0.8%) 3

3. Clinical Decision Making:

   • Low-risk HEART score (0-3): Consider early discharge with outpatient follow-up
   • Moderate-risk HEART score (4-6): Consider observation and further testing
   • High-risk HEART score (7-10): Consider admission and early invasive strategy 2

Easy Ways to Remember

For HEART Score:

• Use the acronym "HEART" itself: History, ECG, Age, Risk factors, Troponin
• Remember "210" pattern: Each component scores 0-1-2 points
• Think "3-6-7": <3 is low risk, 4-6 is moderate risk, ≥7 is high risk

For TIMI Score:

• Use the acronym "ACCASES":
  • Age ≥65
  • ≥3 CAD risk factors
  • Known CAD (stenosis ≥50%)
  • Aspirin use in last 7 days
  • Severe angina (≥2 episodes in 24 hours)
  • ECG ST-segment deviation
  • Serum cardiac marker elevation
• Remember "1-3-5": 0-1 is low risk, 2-4 is intermediate risk, ≥5 is high risk

Clinical Pitfalls and Caveats

1. HEART Score Subjectivity: The history component is subjective and requires clinical judgment 2. When in doubt, consider upgrading the score to err on the side of caution.

2. TIMI Score Limitations: TIMI was designed for confirmed ACS patients, not undifferentiated chest pain. It underestimates risk associated with ECG changes or cardiac troponin elevation 4.

3. Risk Score Integration: Neither score should be used in isolation. Always consider them as part of a comprehensive evaluation that includes clinical judgment and serial assessments 2.

4. Special Populations: Both scores may perform differently in elderly patients or those with comorbidities like renal failure. Consider these factors when interpreting scores.

5. Troponin Assay Sensitivity: The performance of both scores may vary depending on the sensitivity of the troponin assay used. High-sensitivity troponin assays may change the interpretation of these scores 2.

In summary, while both scores are valuable, the HEART score has emerged as the preferred tool for emergency department chest pain evaluation due to its superior performance and specific design for this clinical scenario.