CARDIAC RISK SCORING USING THE DERIVED ELECTROCARDIOGRAM AND CARDIAC ELECTRICAL BIOMARKER

Background: HEART and TIMI risk scores that include 12-lead electrocardiogram (ECG) changes and troponin I (cTnI) have been used to stratify patients presenting with chest pain that may indicate the presence of an acute coronary syndrome (ACS). It has been shown that the 12-lead electrocardiogram (ECG) can be derived (dECG) from 3 measured leads displayed on a cardiac monitor with high correlation. A new cardiac electrical biomarker (CEB®) that has shown correlation with cTnI can be constructed in real-time from the dECG with reportedly high diagnostic accuracy for detection of acute myocardial ischemic injury (AMII). The objective of this study is to compare the HEARTand TIMI cardiac risk scores to associated modified risk scores that include substitution of dECG for ECG and CEB® for cTnI.

Methods: This is a cross-sectional study of 133 consecutive patients presenting to an emergency facility with complaints of chest pain. The prevalence of AMII was 12.8% including 6 STEMI and 11 Non-STEMI. All patients had a 12-lead mECG and cTnI on presentation. The dECG and CEB® were constructed continuously from leads {I, II, V2} directly from a cardiac monitor/ECG device (VectraplexECG System, VectraCor Inc, Totowa, NJ). Each risk score was calculated and compared to a modified score that utilized the dECG observed changes instead of ECG changes, and used the CEB® instead of cTnI. Pearson and Spearman correlations were used to compare the dECG vs. ECG and the respective risk scores.

Results: The 12-lead mECG and dECG showed high Pearson correlation (r = 0.947). The CEB® showed high diagnostic accuracy for AMII with sensitivity 88.9%, specificity 95.1%, negative predictive value 98.0%, and positive predictive value 76.2%. HEART and TIMI risk scores vs. their associated modified scores showed high Spearman correlations of 0.928 and 0.966 respectively.

Conclusions: The modified HEART and TIMI cardiac risk scores based on substitution of the dECG for ECG and CEB® for cTn are comparable to the customary risk scores. The modified risk scores are easy to calculate and are available immediately allowing a shorter time to decision for possible admission. These modified risk scores may be applicable by hospitalists in facilities such as emergency departments, observation units, and during chest pain rapid response evaluations to immediately assess risk in real-time, at the point of care, continuously from a cardiac monitoring/ECG device.