Clinical Significance Of ST Segment Depression In Lead Ⅰ And ST Segment Elevation In Lead V1 To Identify Proximal Right Coronary Artery As Culprit Vessel In Patient With Inferior Wall Myocardial Infarction

Objective:Originated from a country where accessibility to more invasive procedure like coronary angiography for assessing and managing patient with Acute Myocardial Infarction(AMI)is still not yet widespread,the ability to identify the culprit vessel and the area of stenosis in a patient with AMI based only with ECG is crucial.The main purpose of this study is to assess,the clinical significance of the ST segment depression in lead Ⅰ and ST segment elevation in lead V1 to predict proximal right coronary artery(pRCA)lesion as compared to the more invasive procedure like coronary angiography in patients with STEMI.Background:The heart is a muscular organ located in the mediastinum,whose primordial function is to push forward(propel)blood throughout the body.The heart itself is supplied by the coronary arteries which major branches are Right Coronary Artery(RCA),Left Anterior Descending Artery(LAD)& Left Circumflex Artery(LCX).Constant oxygen supply by those arteries is primordial for myocardial cells function.Therefore,any form of obstruction or stenosis of these vessels may lead to myocardial ischemia and or myocardial infarction.The inferior wall of the heart is supplied by the RCA in approximatively 80% of people,via the posterior descending artery(PDA).However,in about 6-10% of the population,the LCX will supply the PDA.The involvement of the inferior and posterior part of the heart is seen in inferior wall myocardial infarction(IWMI).The electrocardiogram(ECG)is the primary diagnostic stool used to evaluate and guide therapy of patient suspected of AMI,12 lead ECG shows ST elevation in leads Ⅱ,Ⅲ and a VF.Right sided ECG leads can be used to examine the right ventricle.Cardiac biomarkers have also a great clinical importance in the diagnosis of acute myocardial infarction.Elevated cardiac biomarker in association with a positive clinical history of previous angina symptoms,a high risk score,ECG &echocardiography findings can help the clinician to make decision about performing an emergency angiography.Myocardial necrosis biomarkers use clinically are:creatine kinase myocardial band(CK-MB);myoglobin and cardiac troponin(c Tn).Non-invasive procedures like CT Heart Scan or Calcium Score can help in the evaluation of the risk of developing a myocardial infarction.Coronary angiography is known as the cornerstone in evaluation of coronary artery disease.Approximately 40-50% of all myocardial infarction concerned the inferior wall.Stenosis of the proximal right coronary artery pRCA often involve the right ventricle(RV)and it is usually associated with a worse outcome.Consequently,for adequate management of such patients,localization of the culprit vessel is primordial.Due to low availability of human resources for cardiovascular care in some region(developing country),interventional cardiology is not readily available,enhancing the importance to focused on reassessment of the ECG as a technique to obtain the location of the culprit vessel.Method:A retrospective hospital based study was performed from January 2017 to December 2017 by taking the clinical record of the 150 patients diagnosed with Acute Inferior Wall MI,admitted and underwent PCI in the department of Cardiovascular Medicine,First Hospital of Jilin University.We selected 150 patients(106 males and 44 females)that met our inclusion criteria defines as chest pain more than equal 30 minutes before hospital presentation,increased troponin Ⅰ levels,ST elevation in ECG leads Ⅱ,Ⅲ,a VF,coronary angiography showing total occlusion or severe obstruction in a single vessel that is RCA,or LCX.Exclusion criteria incorporates patients with a complete bundle branch block on ECG or ventricular pacing,previous history of myocardial infarction,previous PCI or CABG performed prior the current admission.The patients were divided into two groups,the proximal group and the middle,distal & LCX group(MDL).70 cases in the proximal group(46.7%);80 cases in the MDL group(53.3%).The age,gender,risk factors history(hypertension,diabetes mellitus,hyperlipidemia,smoking),troponin I,EF,ECG criteria(ST segment elevation in lead V1;ST segment depression in lead I)of the two group were collected and compared.Ethical approval from institutional Ethics committee(IEC)is obtained before the study.Results:We evaluated 150 patients with a diagnosis of inferior wall myocardial infarction.After assessing past medical,clinical,laboratory and investigation records.All 150 patients were included for further analysis.There were 106(70.7%)male patients and 44(29.3%)female patients.In term of risk factors,we found that the major risk factor was smoking in 93(62%)patients,68(45.3%)patients had hypertension,36(24%)patients had hyperlipidemia and 31(20.7%)patients had diabetes.The mean age of patient with proximal RCA stenosis in coronary angiogram was 60.16 years while the mean age of patients with middle,distal or LCX stenosis in coronary angiogram was 57.46 years.Proximal RCA occlusion was found in 49(70%)male patient and 21(30%)female patients.Middle,distal or LCX stenosis was found in 57(71.2%)male patients and 23(28.8%)female patients.The mean value of troponin Ⅰ in patient with proximal RCA obstruction was 56.45(10.45-110.75)and in patient with middle,distal or LCX stenosis was36.75(9.53-93.42).concerning Ejection Fraction EF,the mean value in proximal group was 56(50.75-58.25)and in the MDL group,the mean value was 56(52.0-58.75).Among the assessed patients,there was no statistical significant difference in the age(P=0.98),gender(P=0.867),hypertension(P=0.220),diabetes(P=0.306),hyperlipidemia(P=0.939),smoking(P=0.059),EF(P=0.635),Troponin I(P=0.628)in terms of proximal,middle or distal RCA or LCX stenosis.However,results suggested that ST depression in lead I,ST segment elevation in lead V1 and both combined ECG criteria were an influencing factor(P<0.05).It was observed that ST segment depression in lead I,ST segment elevation in lead V1 and both combined ECG criteria were more common in patient with proximal RCA stenosis.Therefore,the diagnostic performance was evaluated by analyzing accuracy,sensitivity,specificity,positive predictive value and the negative predictive value.Despite high specificity,the low sensitivity made these criterions questionable.Conclusion:In conclusion,ST-segment depression in lead Ⅰ and ST-segment elevation in lead V1 can help to predict pRCA occlusion in patients with inferior wall MI.However,the low sensitivity of these criteria made it not eligible for screening purpose.Coronary angiogram remains the gold standard in localization of the culprit vessel and the area of stenosis.Smoking and hypertension were the major risk factor of developing IWMI.