From the Guidelines
Lateral ischemia on an EKG is a critical finding that requires immediate medical attention, as it may indicate significant coronary artery disease, particularly involving the left circumflex artery, and is associated with a higher risk of death and cardiac ischemic events 1. The implications of lateral ischemia on an electrocardiogram (ECG) are significant, as it can indicate inadequate blood flow to the lateral wall of the left ventricle, typically seen as ST-segment depression or T-wave inversions in leads I, aVL, V5, and V6. This finding requires prompt medical attention, as it may indicate significant coronary artery disease, particularly involving the left circumflex artery. Some key points to consider when evaluating lateral ischemia on an EKG include:
- The ECG is an integral part of the diagnostic work-up of patients with suspected myocardial infarction (MI) and should be acquired and interpreted promptly 1
- Dynamic changes in the ECG waveforms during acute myocardial ischemic episodes often require acquisition of multiple ECGs, particularly if the ECG at initial presentation is non-diagnostic
- The magnitude of the ECG abnormality provides important prognostic information, with patients having at least 3 ECG leads showing ST-segment depression and maximal ST depression of greater than or equal to 0.2 mV being at higher risk for acute non–Q-wave MI 1
- Serial ECG tracings or continuous ST-segment monitoring can increase the ability to diagnose unstable angina (UA) and MI, and identification of new injury on serial 12-lead ECG is the principal eligibility criterion for emergency reperfusion therapy
- The patient should undergo cardiac biomarker testing and be considered for cardiac catheterization depending on clinical presentation and risk factors
- Initial management includes administering aspirin, supplemental oxygen, and nitroglycerin for chest pain, as well as antiplatelet therapy with P2Y12 inhibitors, anticoagulation with heparin, and pain control. Lateral ischemia occurs when myocardial oxygen demand exceeds supply, often due to atherosclerotic plaque in coronary arteries restricting blood flow to the lateral myocardium, which is primarily supplied by the left circumflex artery.
From the Research
Implications of Lateral Ischemia on an Electrocardiogram (ECG)
- Lateral ischemia can manifest on an ECG as subtle features suggestive of ischemia, which may facilitate more rapid triage of patients with acute coronary occlusion 2.
- The modified Sgarbossa criteria can be used to identify acute myocardial infarction in left bundle branch block or ventricular pacing, while the 3- and 4-variable formula can differentiate normal ST elevation from subtle ECG signs of left anterior descending coronary artery occlusion 2.
- Lateral ischemia can also be associated with ST-elevation myocardial infarction (STEMI) and right bundle branch block (RBBB), which is an ominous sign of critical coronary occlusion and requires prompt intervention 3.
- The use of lead aVL in the recognition of inferior myocardial infarction can also be helpful in identifying lateral ischemia 2.
- Prehospital ECG assessment can contribute to identifying the presence of myocardial ischemia in chest pain patients, including those with lateral ischemia 4.
- Implementing a "chest pain pathway" using smartphone messaging applications can improve ischemia time in STEMI patients, including those with lateral ischemia 5.
- Electrocardiographic manifestations of acute inferior wall myocardial infarction, which can be associated with lateral ischemia, include specific patterns on the 12-lead EKG, right-sided chest leads, and posterior chest leads 6.