From the Guidelines
ECG changes indicating right-sided involvement include ST-segment elevation in the right precordial leads, particularly V4R, which is the most sensitive and specific finding for right ventricular infarction, as recommended by the AHA and ACC guidelines 1. When suspecting right-sided involvement, it's crucial to obtain right-sided ECG leads, especially V4R, as standard 12-lead ECGs may miss these changes. Other changes that may indicate right-sided involvement include:
- ST elevation in leads II, III, and aVF with ST elevation in lead III greater than lead II, suggesting inferior wall infarction with right ventricular involvement
- Complete or incomplete right bundle branch block
- Right axis deviation
- Tall R waves in right precordial leads
- Right atrial enlargement patterns (P pulmonale)
- The classic S1Q3T3 pattern, consisting of an S wave in lead I, Q wave in lead III, and inverted T wave in lead III, which may be seen in acute right heart strain, such as in pulmonary embolism These ECG changes reflect the altered electrical activity resulting from right ventricular myocardial injury, increased right ventricular pressure, or right ventricular volume overload. The joint task force of the AHA and the American College of Cardiology, in collaboration with the Canadian Cardiovascular Society, has recommended that right-sided chest leads VR and V4R be recorded in all patients presenting with ECG evidence of acute inferior wall ischemia/infarction 1. Additionally, the ACC/AHA guidelines suggest that in patients with inferior STEMI, right-sided ECG leads should be obtained to screen for ST elevation suggestive of right ventricular (RV) infarction 1.
From the Research
ECG Changes Indicating Right-Sided Involvement
The following ECG changes can indicate right-sided involvement:
- ST-segment elevation in leads V1 and V2, which can be caused by occlusion of a right coronary artery branch 2
- ST-segment elevation in right precordial leads, which is a more reliable indicator of right ventricular infarction 3
- Right bundle branch block and persistent ST segment elevation in leads V1 to V3, which can be associated with sudden cardiac death 4
- ST segment elevation in lead V4R, which can indicate a proximal right coronary artery occlusion 5
- ST segment elevation in leads V1 and V2, which can be present in patients with acute inferior wall myocardial infarction and right ventricular involvement 5
Specific Lead Involvement
The involvement of specific leads can provide clues about the location and extent of right-sided involvement:
- Leads V1 and V2: ST-segment elevation in these leads can indicate right ventricular infarction 2, 5
- Leads V4R: ST-segment elevation in this lead can indicate a proximal right coronary artery occlusion 5
- Right precordial leads: ST-segment elevation in these leads is a more reliable indicator of right ventricular infarction 3
Clinical Implications
The recognition of ECG changes indicating right-sided involvement is crucial for early diagnosis and treatment:
- Right ventricular infarction can result in right ventricular failure and cardiogenic shock 3
- Early recognition of right ventricular infarction can have important diagnostic and therapeutic implications 3
- The use of a 15-lead ECG can provide a more complete anatomic picture of acute coronary ischemic syndromes, including right-sided involvement 6