Diagnostic flowchart to estimate the morphology of left descending artery lesions by initial electrocardiogram in ST‐elevation myocardial infarction

Abstract Background ST‐segment deviations in an initial 12‐lead electrocardiogram provide anatomical information in ST‐elevation myocardial infarction (STEMI). A diagnostic flowchart was formulated to estimate the anatomical characteristics of a culprit left anterior descending artery (LAD). Methods The present study analyzed 252 STEMI patients whose culprit lesions were confirmed to be LAD as an observational study. LAD morphology, wrapped (n = 26) or not (n = 226), and the positional relationship to first diagonal branch (n = 162 in proximal, n = 90 in distal lesions) were assessed. Their ST‐segment deviations and such anatomical characteristics were examined. Results Reciprocal ST depression in nonwrapped LAD was frequent in patients without diagonal branch flow (49.3%–18.8% in II, p < .01; 66.4%–36.3% in III, p < .01; 63.7%–30.0% in aVF, p < .01). ST elevation in inferior leads was the characteristics of wrapped LAD but was not the case in patients without diagonal flow (50%–0% in II, 60%–0% in III, and 60%–0% in aVF). ST elevation in lateral leads to the diagonal branch in nonwrapped LAD is more frequent for proximal than distal lesions (36.3% vs. 15.0% in I, p < .01; 50.7% vs. 16.3% in aVL, p < .01), but this was not observed for wrapped LAD (18.8% vs. 20.0% in I, p = .72; 31.3% vs. 10.0% in aVL, p = .21). Positive and negative predictive values for the diagnostic accuracy of suggested diagnostic flow based on the above results were 0.794 and 0.478, respectively. Conclusions Our suggested diagnostic flowchart provides enough diagnostic accuracy to estimate culprit morphology.


| Study design and population
To design a diagnostic flowchart to estimate the morphology and locationofculpritLADlesionsbyinitialECGinSTEMI,therelationship between the distribution of ST-segment deviations and LAD morphology or major branches was analyzed. The present study was designedasanobservationalstudythatsurveyed1,019consecutive STEMIpatients,fromJanuary2006toApril2018,atTokaiUniversity School of Medicine who met the diagnostic criterion of the fourth universal definition of myocardial infarction (Thygesen et al.,  The present study was approved by the Institutional Review BoardforClinicalResearch,TokaiUniversity.

| Statistical analysis
Numerical factors with a skewed distribution are shown as medi-

| RE SULTS
The present study assessed the relationship between the distribution of ST-segment deviation, and the morphology and location of culpritLADlesionsbyinitialECGinSTEMI.Thisledtothedesignof a diagnostic flowchart to estimate the morphology and location of culpritLADlesions.

| Relationship between ST-segment deviation and first septal branch flow
The study population was assessed in terms of whether the culprit lesion was located at a site proximal or distal to the first septal branch. The

| Wrapped LAD and first diagonal branch flow
The study population was divided into those with a wrapped or nonwrappedLAD;moreover,theywereassessedonwhetherthe culprit lesion was located at a site proximal or distal to the first diagonalbranch. Table3showsthenumberofpatientswithST

| D ISCUSS I ON
The present study assessed the relationship between the distribu-tionofST-segmentdeviations,andthemorphologyandlocationof

| Role of diagonal branch in reciprocal STsegment depression
Acute transmural ischemia provides incomplete depolarization and decreases the resting membrane potential. This leads to a potential

| Diagnostic flow to estimate anatomical features
The present study suggested that diagnostic flow could be used to estimate anatomical characteristics. The diagnostic accuracy was confirmed to be comparatively high in spite of the simple algorism.

| CON CLUS ION
AninitialECGinSTEMIisusefultoestimateculpritLADmorphology or the existence of major side branch flow.