Clinical Implication Of ST Segment Depression In Ⅱ,Ⅲ,aVF In Patient With Anterior Wall Myocardial Infarction

Objective:The aim of this study is to determine ECG parameters,assess the role of ST segment depression in the leads Ⅱ,Ⅲ,aVF to locate the culprit artery accurately as compared to Coronary Angiography and other parameters like Troponin I,and Ejection Fraction in anterior wall myocardial infarction Background:Heart is a pulsatile beating organ which is majorly supplied by three coronary arteries namely Right Coronary artery,Left Anterior Descending artery & Left Circumflex artery.Anterior wall of heart is chiefly supplied by Left Anterior Descending artery & AWMI occurs due to the blockade of this artery.The characteristic involvement of the anterior part of the heart and the ventricular septum is seen in AWMI.12 lead ECG shows ST elevation in leads V1-V6,I and aVL,elevation and depression significantly seen in chest lead V3 and in lead III respectively.Secondary prevention which includes early diagnosis and treatment is important to reduce mortality and morbidity from myocardial infarction as the risk of death from an AWMI is greatest in the early period i.e.within 24 to 48 hours.CK-MB is a better marker for MI and post MI blood levels increase 4 to 6 hours and return within normal between 24 to 48 hours.Following MI,Troponin –T increases within 3-5 hrs and blood level remains high till 21 days.Non-invasive CT scan of the heart known as Heart Scan,or Calcium Score will calculate risk of developing CAD by quantifying calcification in the coronary arteries.Coronary Angiogram remains the gold standard diagnostic and therapeutic investigation for Myocardial Infarction.Recurrence rate following AWMI is high in patients who survive after event & 10 % mortality is seen within 1year of occurrence of MI.Maximum mortality seen in the first 3 to 4 months and underlying cause for mortality is advanced atherosclerotic coronary artery disease(CAD).Methods:A retrospective hospital based study was done from January 2018 to December 2018 by taking the clinical records of the 151 patients having Anterior wall MI,admitted and underwent coronary angiography in the Department of Cardiovascular Medicine,First Hospital of Jilin University.Only 151 patients(male 112 and female 39)met our inclusion criteria of chest pain more than or equal to 30 minutes before hospital admission,elevated Troponin I levels,ST depression in 2 or more leads,Coronary angiography showing total occlusion or critical stenosis >70 % in single vessel i.e in LADWhereas exclusion criteria includes patients with ST elevation in ECG leads Ⅱ,Ⅲ,aVF,previous history of anterior wall MI,previous coronary bypass artery grafting or percutaneous coronary interventions prior to current hospital admission and significant stenosis in both LAD and RCA or triple vessel disease so that a single infarct related artery could not be defined.Ethical Approval from Institutional Ethics Committee(IEC)is obtained prior to the study.Results:We assessed 151 patients with a diagnosis of anterior wall myocardial infarction.After evaluating all the demographical,clinical,past medical,and investigation(Troponin I,EF,ECG,coronary angiography)records,all 151 patients were included for further analysis.There were 112(74.17%)male patients and 39(25.82%)female patients.The major risk factor was hypertension in 67(44.37%)patients,diabetes mellitus in 25(16.55%)patients.Among the included patients,106(70.19%)patients were smokers.Furthermore,the mean age of patients who had proximal stenosis in coronary angiogram was 61.47 years where as mean age of patients who had middle & distal stenosis in coronary angiogram was 59.76 years.Proximal stenosis was found in 11(52.4%)male patient and 10(47.6%)in female patients.Middle and distal stenosis was found in 101(77.7%)male patients and 29(22.3%)female patients.The mean value of troponin I in patient with proximal stenosis was 109.21±84.11 and in patient with middle and distal stenosis was 96.38±78.77.Additionally,mean EF in proximal stenosis was 53 with a range of 45-56 and for middle as well as distal stenosis was 51 with a range of 44-56.Among the assessed patient there was no statistically significant difference in the age(P=0.511),troponin I(P=0.494),EF(P=0.972),lead II-depression(P=0.390),lead III-depression(P=0.390),and lead aVF(P=0.390)in terms of proximal and middle or distal stenosis.However,the result suggested that gender was the influencing factor(P< 0.05).It was observed that the male patient had anterior wall MI than that of the female patients.(= P=0.014).Conclusion:In conclusion,ST-segment depression is not evident in 12 lead ECG in every patient with anterior wall MI.Coronary Angiogram is the gold standard investigation for diagnosing area of stenosis in spite of having normal ECG’s.Hence,patients who are clinically presenting with symptoms of MI and having normal ECG findings have to be further evaluated to rule out AWMI and to decrease morbidity and mortality.Regarding the risk factors hypertension,and diabetes mellitus patient was found to have greater chances of having AWMI.The AWMI was found higher in smoking population than the non-smokers.