Riding the wave: a quantitative report of electrocardiogram utilization for myocardial infarction confirmation

Abstract

The purpose of this study was to generate a quantitative profile of electrocardiograms (ECG) for confirming surgical success of permanent coronary artery ligation. An ECG was recorded at baseline, and 0-, 1-, and 5-min after ligation and analyzed using iWorkx LabScribe software. Cohort 1 (C57Bl6/J n=8/sex) was enrolled to determine ECG characteristics that were confirmed in Cohort 2 (C57Bl6/J n=6/sex; CD8-/- n=6 males/4 females). Of the 16 mice in Cohort 1, 12 (6/sex) had an infarct ≥35% and 4 mice (2/sex) had <35% based on 2,3,5-triphenyltetrazolium chloride staining. After ligation, the QRS complex and R-S amplitude were significantly different compared to baseline. No differences were observed in the R-S amplitude between mice with infarcts ≥35% versus <35% at any time point whereas, the QRS complex was significant 1-min after ligation. Receiver operating characteristic (ROC) curve linked changes in the QRS complex but not the R-S amplitude at 1- and 5-min with surgical success. Data was normalized to baseline values to calculate fold-change. ROC analysis of the normalized QRS data indicated strong sensitivity and specificity for infarcts ≥35%; normalized R-S amplitude remained non-significant. Using a cut-off generated by ROC analysis of Cohort 1 (˃80% sensitivity; ˃90% specificity), the non-normalized QRS complex of Cohort 2 had an 86% success rate (2 false-positives; 1 false-negative). The normalized data had a 77% success rate (2 false-positives; 3 false-negatives). Sex nor genotype were associated with false-predictions (p=0.18). Our data indicate the area under the QRS complex 1-min after ligation can improve reproducibility in MI surgeries.