ACCURACY OF 12 LEAD ECG FOR DIAGNOSIS OF POSTERIOR MYOCARDIAL INFARCTION

Objective: To determine the accuracy of 12 lead ECG for diagnosis of acute Posterior Myocardial Infarction (MI) after its confirmation by 15 leads ECG. Methodology: This study was conducted in Cardiology Department, Lady Reading Hospital Peshawar from January to July, 2012. Patients presenting to CCU with typical chest pain, pain epigastrium, sweating, nausea or vomiting and with admitting diagnosis of acute coronary syndrome (ACS) were included. The diagnostic criteria for posterior MI on 12 leads ECG was when R:S was more than 1:1 in V2 or there was tall R wave in V1 or V2 (more than S in the same leads) or more than 2mm ST segment depression in anterior lead. Posterior MI was confirmed on 15 leads ECG taking it as a standard when ST segment elevation of 1mm was present in C7,8,9. Results: Out of 176 randomly selected patients, 90(51.1%) were male and 86(48.9%) female; with mean age of 63 years. Out of these, 70 were in the age range of 51 to 60 years and 40 each in 41-50 and 61-70 years. Eighteen patients had changes of posterior MI on 12 leads ECG and amongst them 10 patients had true posterior MI on 15 leads ECG. We had 8 false positive cases on 12 leads ECG with no false negative cases after confirmation with 15 leads. Conclusion: The accuracy of 12 leads ECG for detection of posterior MI was 55% after confirmation with 15 leads and there was no age and gender difference in its accuracy.