· Serial changes of ECG in STEMI
1. First ECG change in STEMI is tall T wave with ST elevation with upward concavity within first few minutes of STEMI.
2. Followed by T wave inversion with ST coving, convexity upwards with one day to one week of STEMI
3. Q waves appear after this and persist usually life long
· Significance of wave changes in STEMI
1. T wave changes in larger area and more leads denotes ischemia
2. ST changes in lesser number leads suggest myocardial injury
3. Q wave over infracted zone suggest necrosis
· ST elevation in leads and infarcted area
1. Lead II,III and AVF inferior wall MI
2. Anterior infarct lead V1 to V4
3. Lead 1 , aVL and V1 to V6 extensive anterior wall MI
4. Anterolateral infarct lead V1 to V6
5. RV infarct lead ST elevation in lead V3R and V4R
· False positive pattern (pseudo infarct pattern)
1. Hypertrophic Cardiomyopathy HCM
2. Early repolarization syndrome (ERPS)
3. Cardiomyopathy
4. Brugada syndrome
5. Pericarditis
· LBBB and MI
1. ST elevations with tall T waves are seen in right precordial leads and T wave inversions are seen as part of uncomplicated LBBB. This can cause confusion while diagnosing STEMI so following criteria are set, to diagnose MI with LBBB
2. ST segment elevation of 1mm with concordant T waves in lateral precordial leads in presence of LBBB suggest IHD (sensitivity 73% and Specificity 92%)
3. ST segment depression and /or deep T wave inversion in lead V1 to V3 suggest ischemia (sensitivity 25% and 96% specificity)
4. More than >0.5mV ST segment elevation in leads with QS and rS (discordant elevation) suggest ischemia (31% sensitivity and specificity 92%)
5. QR complexes in lead 1 aVL V5 and V6 suggest infarction
6. Chronic infarction suggested by notching of ascending limb wide S wave in mid precordial leads (Cabrera sign)
7. Chronic infarction is suggested by notching ascending limb of wide R wave in lead I aVL,V5,V6 (Chapman sign)
· Vessel localization in anterior wall MI
1. ST elevation in V2 to V6 suggest LAD occlusion proximal to first diagonal branch
2. ST elevation in lead I and aVL and V2 occlusion of first diagonal
3. ST elevation in lead I and aVL with V2 ST depression suggest, occlusion of LCX
4. ST depression in aVL with anterior wall MI suggest LAD occlusion distal first Diagonal branch
5. In anterior wall MI, ST elevation in inferior leads suggest occlusion of wrap around LAD distal first diagonal branch
6. ST elevation in aVR suggest occlusion of LAD proximal to first septal
7. RBBB suggest occlusion of LAD proximal to first septal
· Vessel localization in inferior wall MI
1. ST segment elevation in lead III more than lead II suggest RCA occlusion sensitivity 99% specificity 100%. When this is associated with ST elevation in lead V1 suggest occlusion of proximal acute marginal branch
2. ST segment elevation lead II more than lead III suggest LCx occlusion, sensitivity 93% and specificity 100%.
3. ST elevation in V5, V6 and lead 1 and aVL also suggest LCx occlusion
4. Abnormal R wave in lead V1 suggest LCx occlusion
· RV infarction and vessel localization
1. RV4 lead ST elevation more than 1mm, proximal RCA occlusion
2. RV4 lead No ST elevation and T wave upright distal RCA occlusion
3. RV4 lead ST depression more than 1 mm with T wave inversion suggest LCx occlusion
· Heart block and MI
Inferior wall MI | Anterior wall MI | |
Incidence | More common | Less common |
Level | Suprahisian | Infrahisian |
Escape rate | 40-60/min | 30-40/min |
QRS complex | Narrow | Wide |
Responds | Atropine | Isoprenaline |
Mortality | 10-15% | 65-75% |
