Criteria of Culprit Artery in Inferior Wall STEMI

Identifying the culprit artery (RCA vs LCX) in inferior wall STEMI from surface ECG helps anticipate complications, guide cath strategy, and assess myocardial area at risk.

This post summarizes ECG-based criteria commonly used to differentiate RCA from LCX occlusion.

ST Elevation in Leads III and II

Key principle: Lead III reflects RCA territory more strongly than lead II

Findings favoring RCA occlusion

ST elevation in lead III > lead II

ST depression in aVL greater than lead I

These patterns indicate an injury vector directed inferiorly and rightward, consistent with RCA involvement.

---

Role of Lateral Precordial Leads (V5–V6)

---

V5 and V6 have limited value in differentiating RCA from LCX occlusion

Presence of ST elevation in V5–V6 suggests:

Larger myocardial area at risk

Possible extension beyond isolated inferior infarction

They should be interpreted as markers of infarct size rather than culprit artery.

---

ST-Segment Behavior in Lead I

---

Lead I provides useful lateral wall information.

Patterns and interpretation

ST depression in lead I → RCA occlusion

ST elevation in lead I → LCX occlusion

Isoelectric ST in lead I with STE II > III → LCX occlusion

LCX infarctions tend to generate a leftward injury vector, explaining ST elevation or neutrality in lead I.

---

STD in V3 / STE in Lead III Ratio

---

This ratio helps localize proximal vs distal RCA and differentiate from LCX.

Interpretation

< 0.5 → Proximal RCA occlusion

0.5 – 1.2 → Distal RCA occlusion

> 1.2 → LCX occlusion

Higher ratios indicate greater posterior or lateral involvement, favoring LCX.

---

Practical Summary

---

Findings favoring RCA

STE III > II

STD in aVL > I

STD in lead I

Low V3/III ratio (<1.2)

Findings favoring LCX

STE in lead I

Isoelectric lead I with STE II > III

High V3/III ratio (>1.2)

---

Clinical Takeaway

---

No single ECG criterion is absolute. Accuracy improves when multiple ECG features are integrated with:

Clinical presentation

Hemodynamic status

Echocardiographic findings

Surface ECG remains a powerful bedside tool for early culprit artery prediction—especially before angiography.

Comments

𝘼𝙣𝙩𝙞𝙘𝙤𝙖𝙜𝙪𝙡𝙖𝙩𝙞𝙤𝙣 𝘼𝙛𝙩𝙚𝙧 𝙎𝙩𝙧𝙤𝙠𝙚

𝘼𝙣𝙩𝙞𝙘𝙤𝙖𝙜𝙪𝙡𝙖𝙩𝙞𝙤𝙣 𝘼𝙛𝙩𝙚𝙧 𝙎𝙩𝙧𝙤𝙠𝙚 in Patient with AF and acute IS/TIA European Heart Association Guideline recommends: • 1 days after TIA • 3 days after mild stroke • 6 days after moderate stroke • 12 days after severe stroke Early anticoagulation can decrease a risk of recurrent stroke and embolic events but may increase a risk of secondary hemorrhagic transformation of brain infarcts. The 1-3-6-12-day rule is a known consensus with graded increase in delay of anticoagulation between 1 and 12 days after onset of ischemic stroke or transient ischemic attack(TIA), according to neurological severity based on European expert opinions. However, this rule might be somewhat later than currently used in a real-world practical setting.

Learn Echocardiography | Standard Protocol for Performing Comprehensive Echocardiogram | Explained with Images and Videos

If you are just starting to learn echocardiography, you will find that learning the full echo examination protocol will be immensely useful. The full protocol will provide a solid foundation for your career in echo. I personally found that once I could execute the standard protocol flawlessly, I was able to add and refine additional echo scanning skills while deepening my understanding of the purpose of each echo image. The echo protocol illustrated in this article is the same one we currently use for all our patients in the hospital and meets or exceeds the standards of American Society of Echocardiography (ASE) for an adult echocardiography examination. The protocol presented here is meant as a guideline and does not cover every aspect (such as off axis views) of an echo examination. Also other hospitals will probably have slight variations of this protocol depending on the lab's needs, which is normal. This article's main purpose is to provide a solid foundation for ...

2025 AHA/ACC Hypertension Guidelines Key points

2025 AHA/ACC Hypertension Guidelines Explained: A Clear Summary for Clinicians and Students Hypertension remains one of the most significant contributors to cardiovascular morbidity and mortality worldwide. With continual refinement of evidence and risk-based strategies, the 2025 AHA/ACC Hypertension Guidelines bring an updated, practical approach that clinicians can use in daily practice. To make learning easier, I’ve created a clean and modern infographic summarizing all major recommendations. You can download it below and use it for study, teaching, or clinical reference. Download Infographic (PNG): 2025 Hypertension Guideline Infographic This post breaks down the key points from the guidelines and complements the infographic for a complete understanding. --- BP Categories: Understanding the Updated Thresholds The guidelines maintain the well-established classification of blood pressure: Normal: <120 / <80 Elevated: 120–129 / <80 Stage 1 Hypertension: 130–139 and/or 8...

Dr. Usman's Cardiology Notes

Search This Blog