ST Depressions in Inferior Leads and V4-6: Not a Sign of RV Strain
No, ST depressions in inferior leads (II, III, aVF) and in V4-6 are not signs of right ventricular strain. In fact, this pattern suggests the opposite clinical scenario—either posterior (inferolateral) wall ischemia or multivessel coronary disease involving the left anterior descending artery system.
What ST Depressions in These Leads Actually Indicate
Inferior Lead ST Depression
- ST depression in the inferior leads typically represents reciprocal changes from anterior or lateral wall ischemia, not RV involvement 1
- When proximal left anterior descending (LAD) artery occlusion occurs, ST elevation appears in V1-V4, I, and aVL, with reciprocal ST depression in leads II, III, and aVF 1
- This reciprocal pattern indicates extensive anterior wall ischemia, not right ventricular pathology 1
V4-6 ST Depression
- Maximal precordial ST depression in leads V4-V6 during inferior wall myocardial infarction indicates severe coronary artery disease involving the LAD or its diagonal branch (71% had >50% stenosis, 57% had >70% stenosis) 2
- This pattern is associated with increased in-hospital mortality due to multivessel disease, not RV strain 2
- ST depression in V1-V3 may represent posterior wall involvement, but when maximal depression occurs in V4-V6, it specifically suggests LAD system disease 2
Actual ECG Signs of Right Ventricular Infarction/Strain
The Gold Standard
- ST elevation ≥0.5 mm (≥1 mm in men <30 years) in right-sided leads V3R and V4R is the primary ECG criterion for RV infarction 1, 3
- These right-sided leads should be recorded immediately in all patients with inferior MI, as ST elevation in these leads is transient and resolves within 10 hours in 50% of patients 3, 4
Standard 12-Lead Findings
- ST elevation in lead V1 (≥0.5 mm) has 84% specificity for RV infarction but only 35% sensitivity overall 5
- The sensitivity improves to 69% when there is no concomitant ST depression in V2, but drops to 35% when V2 depression is present 5
- A discordant pattern of ST elevation in V1 with ST depression in V2 is a specific sign for RV infarction 6
Ratio-Based Approach
- When ST depression in lead V2 is ≤50% of the magnitude of ST elevation in lead aVF, this suggests RV ischemia with 79% sensitivity and 91% specificity 7
- This ratio helps distinguish proximal right coronary artery (RCA) occlusion (involving RV branch) from distal RCA or left circumflex occlusion 7
Critical Clinical Pitfalls
Common Misinterpretation
- ST depression in lead I is NOT reliable for diagnosing RV infarction—it occurred in 86% of patients with RV infarction but also in 80% without RV infarction (p=0.56) 5
- The standard 12-lead ECG alone has inadequate diagnostic characteristics to definitively diagnose or exclude RV infarction 5
What You Should Do Instead
- When inferior MI is present on ECG, immediately record right-sided leads V3R and V4R before assuming the pattern represents RV involvement 1, 3
- ECG machines should be programmed to prompt recording of right-sided leads when ST elevation >1 mm is detected in leads II, III, and aVF 3
- Consider posterior leads (V7-V9) when ST depression appears in V1-V3 with inferior MI to confirm posterior wall involvement 1, 3
The Bottom Line on Your Specific Pattern
The combination of ST depression in inferior leads AND V4-6 suggests either:
- Proximal LAD occlusion causing extensive anterior wall ischemia with reciprocal inferior changes 1
- Multivessel disease with LAD involvement during an inferior MI 2
This pattern does not indicate RV strain and should prompt evaluation for extensive left ventricular ischemia, not right ventricular pathology.