| Coronary Artery Disease (CAD) is a major health problem throughout the world and acute myocardial infarction (AMI) is one of the most common presentations of CAD. AMI is a major cause of mortality and morbidity worldwide.Background:Although coronary angiography remains the gold standard for identification of Infarct related artery, the conventional12lead ECG is still an absolute tool to diagnose AMI. The changes whether anterior, lateral or inferior wall infarctions, are all reflected on the electrocardiogram as ST segment and Q wave changes.Despite the development of diagnostic strategies, the ECG plays a central role in the diagnostic pathway for AMI. The ECG is non invasive, cheap, simple yet valuable method and the first test we all can perform on patients attending the emergency department with chest pain or any other symptoms guiding us towards a heart disease.Moreover, in the acute phase of STEMI, the ECG can provide useful information about the extent of area at risk, the degree of myocardial damages, reperfusion injury and infarct size.Despite current guideline-based ECG criteria, challenges remain in decision making and optimizing activation of the catheterization laboratory for primary PCI.The ECG remains the most important diagnostic tool in the evolving of STEMI, in influencing therapeutic strategies and in its management.Early prediction of occlusion site, mainly left anterior descending coronary artery (LAD) occlusion is essential because the more proximal the occlusion the less favourable the prognosis. Objectives:The aim of this study was to simplify&strengthen the accuracy of previously published ECG criteria for the identification of coronary artery occlusion in acute anterior wall myocardial infarction and create a new simplified and easy to use algorithm that can be used in daily practice by emergency physicians.The early and accurate identification of the infarct-related artery on the ECG can help predict the amount of myocardium at risk and guide decision regarding the urgency of revascularization.Methods:One hundred and twenty five patients with a first acute anterior wall Myocardial infarction (AWMI) were included in the present study. The ECG showing the most pronounced ST-segment deviation before initiation of reperfusion therapy was evaluated and correlated with the exact LAD occlusion site as determined by coronary angiography. The ECG criteria used to evaluate the chosen patients were those used in the previous articles to evaluate the site of LAD in AWMI. To obtain these ECG criteria, a literature review was conducted to identify previously published criteria to detect site of LAD occlusion, in AWMI. Then we used the criteria with the best diagnostic accuracy from the published articles on the patients in the present study. The findings were then confirmed with coronary angiography findings.We reviewed13articles14-26and two cardiology textbooks27,28published in the past years, from which we chose the24best ECG criteria according to their respective authors.Using spss software16.0, we compared patient and control group. The control group consisted of50confirmed non-AMI individuals. The ECG criteria with the best sensitivity&specificity being statistically significant&with a good AUC were used to create the new ECG algorithm.Results:Out of the24previously published ECG-criteria we used in the present study, only10ECG criteria with ST-deviations in different leads and presence of abnormal Q wave in V4-6, showed the best results. These ECG criteria were all statistically significant with p-value<0.05. They all had good diagnostic performance, sensitivity and specificity and they we included in the new algorithm.The new and easy to use ECG algorithm includes2steps:first, the location of the occlusion in relation to S1&D1, and second, to locate the occlusion in relation to S1and D1separately.Below is the new easy to use ECG algorithm: As seen in the algorithm, it starts by differentiating if the patient has an occlusion proximal or distal to both S1&D1. To attain this, we check whether there is a presence or an absence of ST-segment depression in inferior leads.In the present study when we used the criteria ST-segment depression (STD) in inferior leads (L â…¡,â…¢, AVF), it presented with a good diagnostic performance AUC=0.593, statistically significant that is p-value<0.05, sensitivity of58.7%(95%CI:49.60%to69.10%) and specificity of60%(95%CI:45.18%to73.59%) for LAD occlusion proximal to both first septal and diagonal artery. This concludes that according to the algorithm, STD in inferior leads means patient has an occlusion proximal to S1&D1.Once it has been confirmed that the occlusion is proximal to S1&D1according to the algorithm we can proceed to differentiate if it is proximal to S1or D1seperately.Subsequent analysis of the equation Sum of ST-deviation in aVR+STdevV1-V6>0, allows us to predict occlusion proximal to first septal artery (S1) with a Sensitivity of93.33%(95%CI:81.71%to98.53%), specificity of80%(95%CI:66.28%to89.95%), AUC of0.867&p-value<0.05. The criteria of ST-elevation (STE) in aVR on its own showed a Sensitivity of55.56%(95%CI:40.00%to70.35%), a Specificity of100%(95%CI:92.82%to100.00%), AUC of0.778&p-value<0.05, to predict occlusion proximal to S1. STE in V1>2mm predicted LAD occlusion proximal to S1with a Sensitivity of62.22%(95%CI:46.54%to76.22%) and a Specificity of86%(95%CI:73.25%to94.16%), AUC of0.741&p-value<0.05.For LAD occlusion proximal to D1, the ECG criteria of STD in lead â…¢ showed a Sensitivity of61.9%(95%CI:45.64%to76.42%), a Specificity of60%(95%CI:45.18%to73.59%), AUC of0.610&p-value<0.05. The ECG criteria of STE AVL was also considered, as it had a sensitivity of47.62%(95%CI:32.01%to63.58%), a very good specificity of90%(95%CI:78.17%to96.63%), a good AUC value of0.688and was statistically significant. Absence of STD in II, III, AVF presents a sensitivity of90.91%(95%CI:75.64%to97.98%), specificity of60%(95%CI:45.18%to73.59%), AUC of0.755&p-value <0.05, for LAD Occlusion distal to S1&D1. Which concludes that according to the algorithm absence of STD in inferior leads shows that the patient has an occlusion distal to S1&D1.For occlusion distal to S1it was associated with an abnormal Q-wave in leads V4-6with a Sensitivity of50%(95%CI:26.06%to73.94%), Specificity of80%(95%CI:66.28%to89.95%), AUC of0.650&p-value<0.05.For occlusion distal to D1STE or isoelectric ST-segment in â…¢, AVF showed a Sensitivity of46.67%(95%CI:21.34%to73.35%), a rather good Specificity of90%(95%CI:78.17%to96.63%), AUC of0.683&p-value<0.05. STD in lead AVL also predicted occlusion distal to D1with a Sensitivity of66.67%(95%CI:38.41%to88.05%), specificity of74%(95%CI:59.65%to85.36%), AUC of0.703&p-value<0.05.Conclusion:This new and simplified easy to use ECG algorithm based on ST-segment deviations and presence or absence of Q waves, in different leads allowed us to predict the location of occlusion in LAD with good accuracy. Cases with proximal LAD occlusion present the most markers of poor prognosis. We recommend the use of this algorithm in everyday clinical practice. |
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