Clinical Significance Of ST Segment Depression In AVR Lead To Predict Culprit Artery In Inferior Wall STEMI

Background:The electrocardiogram, a non-invasive test and easy to perform, remains the principalmethod for identifying patients with coronary heart disease. The coronary angiography isconsidered a gold standard in the management of patients with coronary artery disease. Theinfero-lateral and inferior wall of left ventricle are supplied by the right coronary artery (RCA)and the left circumflex (LCX).RCA irrigates most of the right ventricle.Consequently, inferior wall myocardium infarction (MI),corresponding to ST segmentelevation in2or3of the inferiors leads (II,III and aVF); which accounts for40-50%of all acuteMI, can be caused by the occlusion of either the RCA or LCX.ECG remains the primary diagnosis tool used to evaluate the patients suffer from chest painand suspected from acute MI. Multiple ECG criteria have been studied to make presumptivepredictor culprit artery in inferior-STEMI.In many studies the ECG markers have shown varyingsensitivity, specificity and predictive value according to used criteria, sample size, delay fromECG recording and angiography and patient settings. ECG lead aVR is frequently ignored, butsome investigators have suggested that this lead can provide ECG information that is useful forthe characterization of inferior AMI, which is more often caused by the right coronary artery(RCA) occlusion than by the left coronary circumflex artery (LCX) occlusion. ST depression inaVR lead has been suggested, many times, as a predictor of LCX involvement.Objective and Methods:The main objective of this study is to make the differential diagnosis in12leads ECGbetween LCX and RCA as presumptive predictor of a culprit artery in patients with acuteinferior ST elevation myocardium infarction (I-STEMI) according to ST change in aVR lead.Evaluate, therefore, the sensitivity, specificity, positive predictive value and negative predictivein these coronary arteries (LCX, RCA).Are included in this study all patients with the followingparameters: Patients with chest pain lasting more than30minutes before hospital admission,Elevation of Creatine kinase MB (CK-MB) greater than twice the upper limit,ECG showed ST elevation more than0.1mv in at least2of the3inferior leads (II, III, aVF) and ST segmentchange in aVR lead, coronary angiography during hospitalization with total occlusion or criticalstenosis more than70%in single vessel either LCX or RCA.Are exclude in our study all patients with: previous history of acute myocardium infarction,coronary artery bypass surgery or percutaneous coronary intervention prior to the currenthospitalization, evidence of recent left bundle branch block in ECG.,significant stenosis in bothLCX and RCA so that a single infarct-related artery could not defined.Results:Our study was focused only in the117patients met the inclusion criteria with the followingdistribution:84men and33women and aged between30to76years, mean58±11. Afterreviewing coronary angiography we found36LCX and81RCA in this study samplecorresponding respectively to30.7%and69.3%.Among the117patients included in our studypopulation37patients (31.62%) were found to have ST segment depression in lead aVR of atleast1mm,and of those,significantly more patients had culprit LCX infarctions compared tothose without ST depression in this lead aVR.The sensitivity and specificity of ST depression in lead aVR to predict LCX as the culpritartery were67%and84%respectively.The positive predictive value and negative predictive value to predict LCX as the culpritartery were65%and85%respectively.In the opposite side, the80patients, with ST segment elevation or ST isoelectric or STdepression less than1mm in lead aVR, called without ST segment depression in lead aVR weresignificantly to predict RCA as culprit artery68(85%) compared to12(15%).The sensitivity and specificity for the patients without ST depression in lead AVR to predictRCA as culprit artery were84%and67%respectively.The positive predictive value and negative predictive value for the patients without STdepression in lead AVR to predict RCA as the culprit artery were85%and67%respectively.Baseline clinical characteristics (hypertension, dyslipidemia, diabetes mellitus, smoking, killip1,TIMI0, left ventricle ejection fraction...) were otherwise significantly similar between thepatients with and without ST depression in lead aVR.Conclusion:Many years ago, in multiple studies, many algorithms were published to guide clinicians inthe management of inferior wall myocardial infarction especially in the presumption ofpredictive culprit artery. In our study, we confirmed, once again, that ST segment depression or without depressionin lead aVR study in the setting of inferior-STEMI are associated with a good sensitivity,specificity and predictive value in predicting either RCA or LCX, respectively, as culprit artery.The use of ST segment in aVR lead remains a simple method with good result for predictingculprit artery..