Not all HEART scores are created equal: identifying "low-risk" patients at higher risk.

Objective: We sought to identify sub-groups of "low-risk" HEART score patients (history, ECG, age, risk factors, and troponin) at elevated risk of acute myocardial infarction or death within 30 days.

Methods: We performed a secondary analysis of prospective emergency department (ED) encounters for suspected acute coronary syndrome in a large health system with low-risk HEART scores (0-5 points). Logistic regression using the 5 components of the HEART score analyzed the increase risk attributable to points from each of the 5 score components.

Results: Of 30,971 encounters among 28,992 unique patients, 135 (0.44%, 95% confidence interval [CI] = 0.37-0.51) experienced acute myocardial infarction or death. Risk increased for each component of the HEART score from 0 to 1 to 2 points (history, 0.4% to 0.5% to 0.6%; ECG, 0.3% to 0.7% to 0.7%; age, 0.2% to 0.3% to 0.7%; risk factors, 0.1% to 0.4% to 0.8%), except troponin, which had the highest risk with 1 point (troponin, 0.4% to 2.7% to 0.9%). Odds ratios from our regression, which adjusts for other components, showed a similar pattern (from 1 vs 0 and 2 vs 0 points, respectively: history, 1.0 and 1.8; ECG, 2.2 and 3.5; age, 1.2 and 2.1; risk factors, 2.4 and 4.2; and troponin, 6.0 and 3.6).

Conclusion: Among "low-risk" suspected acute coronary syndrome encounters, increasing points within each of the 5 categories demonstrated small increases in risk of death or acute myocardial infarction, with the troponin and ECG components representing the largest risk increases.