From the Guidelines
Right-sided cardiac involvement on a 12-lead ECG is most accurately indicated by ST-segment elevation in leads V1-V3, particularly when more prominent in V1 than in V6, and ST elevation in right-sided leads, especially V4R, as noted in studies 1.
Key ECG Changes
- Right axis deviation, typically greater than +90 degrees
- ST-segment elevation in leads V1-V3, particularly when more prominent in V1 than in V6
- Right bundle branch block pattern
- Tall R waves in right precordial leads (R/S ratio >1 in V1)
- Right atrial enlargement manifested as tall, peaked P waves in leads II, III, and aVF (P pulmonale)
- ST elevation in right-sided leads, especially V4R, in acute right ventricular infarction
Clinical Context
The presence of these ECG changes can indicate right ventricular involvement, particularly in the context of inferior wall infarction, as suggested by studies 1. The joint task force of the AHA and the American College of Cardiology recommends recording right-sided chest leads VR and V4R in all patients presenting with ECG evidence of acute inferior wall ischemia/infarction 1.
Diagnostic Considerations
Understanding these patterns is crucial for early identification of conditions like right ventricular infarction, pulmonary hypertension, pulmonary embolism, and congenital heart diseases affecting the right heart, as highlighted in the recommendations 1. The S1Q3T3 pattern may also indicate right ventricular strain, often seen in pulmonary embolism.
Recommendations
The most recent and highest quality study 1 supports the use of right-sided chest leads, especially V4R, for diagnosing right ventricular involvement in the setting of an inferior wall infarction.
From the Research
ECG Changes Indicating Right-Sided Involvement
The following ECG changes in a 12-lead ECG may indicate right-sided cardiac involvement:
- ST-segment elevation in leads V1 and V4R-V6R, with a discordant pattern of ST-segment elevation in lead V1 and ST-segment depression in lead V2, is a specific sign for right ventricular infarction (RVI) 2
- ST-segment elevation in lead V4R is a sensitive and specific indicator of RVI, with a sensitivity of 100% and a specificity of 68.2% 3
- A Q wave in lead V4R may also indicate RVI, but its specificity is low 3
- ST-segment elevation in leads V1 to V3 may be present in RVI, but its accuracy is too low to be considered a useful diagnostic criterion 4
- Isolated right ventricular myocardial infarction may present with ST-segment elevation in a single precordial lead, such as V1, and may be missed if not suspected 5
- ST elevations in leads V1 to V5 may be caused by right coronary artery occlusion and acute right ventricular infarction, with the highest ST-segment elevation typically in lead V1 or V2 6
Key ECG Leads for Right-Sided Involvement
The following ECG leads are important for diagnosing right-sided involvement:
- Lead V1: ST-segment elevation or depression may indicate RVI 2, 5, 6
- Lead V2: ST-segment depression may indicate RVI, especially in combination with ST-segment elevation in lead V1 2
- Lead V4R: ST-segment elevation is a sensitive and specific indicator of RVI 3
- Leads V1 to V3: ST-segment elevation may be present in RVI, but its accuracy is too low to be considered a useful diagnostic criterion 4
- Leads V1 to V5: ST elevations may be caused by right coronary artery occlusion and acute right ventricular infarction 6