ECGs: Ischemia and Infarction

AFAMS Resident Orientation26 March 2012

Outline

Terminology

• Injury– Acute MI– ST elevation in 2 contiguous leads– Reciprocal ST depression

• Ischemia– ST depression, T wave inversion

• Infarct– Q waves

EKG Stages of MI

• Hyperacute T waves (A)• ST elevation (B)• Q waves – usually

within 6-12h (C) • T wave inversions (D)• ST-T wave resolution– Q waves persist

European Heart Journal 2007; 28, 2985-2991

EKG Stages of MI

• Hyperacute T waves

Sinus tachycardia, Inferior MI – recent, Nonspecific ST-T wave changes

NSR, Biatrial Enlargement, Old inferior MI

Localization of MI

• Anteroseptal– ST elevation in V1-V3

• Anterior– ST elevation in V2-V4

• Lateral– ST elevation in I, AVL, V5-6

• Inferior– ST elevation in II,III,AVF

47 year old male with chest pain

NSR with anteroseptal myocardial infarction

65 year old male with chest tightness

NSR with acute anterior myocardial infarction

62 year old female with shortness of breath and chest discomfort

Sinus Tachycardia with Lateral Myocardial Infarction

45yo wm with 2 hours of SSCP that started during exertion

NSR with PVC, LAD, Acute anterolateral MI

Middle age white male awoke from sleep with chest pain

Sinus tachycardia, Acute Inferior MI

Right Sided ECG

• Who?– Any patient with inferior

ST elevation MI

• Why?– Investigate infarct

involvement of RV

• How?– Reverse Precordial Leads

• Where to Look?– ST elevation in V4R

Right Sided EKG

Not all ST changes are ischemia

• While ischemia and infarction are the most concerning causes of ST changes, other causes exist

• Use the clinical history to help you• Recognize patterns

20 year old asymptomatic male

Sinus bradycardia, Early repolarization -> Normal variant

NSR, PACs, LVH – voltage criteria, repolarization abnormality HCM

59yo female presents to the ER with CP

NSR, Acute pericarditis (Diffuse ST elevation and PR depression), and Pericardial effusion (electrical alternans)

26 year old male with syncope

NSR, RBBB, Long QT-> Brugada Syndrome

Differential Diagnosis of ST elevation

• STEMI• LV aneurysm• Left Ventricular

Hypertrophy• Pericarditis / Myocarditis• Early Repolarization

– Normal variant

• Hyperkalemia• Brugada Syndrome• ARVD

Examples of ST Elevations

NEJM 2003: 349:2128-35

Conclusions

• ST changes often represent ischemia, injury or infarction

• Many other possible diagnoses• Use clinical information to narrow down the

list• When you are unsure, call a cardiologist