Understanding Non-ST Elevation Myocardial Infarction (NSTEMI) on ECG

Introduction

Non-ST Elevation Myocardial Infarction (NSTEMI) is a type of heart attack that occurs when there is partial blockage of a coronary artery, leading to reduced blood flow to the heart muscle. Unlike ST-Elevation Myocardial Infarction (STEMI), NSTEMI does not show an ST-segment elevation on the electrocardiogram (ECG), making its diagnosis more dependent on clinical symptoms and cardiac biomarkers.

ECG Findings in NSTEMI

While NSTEMI does not present with ST-segment elevation, there are other important ECG changes that can indicate myocardial ischemia:

• ST-segment depression (horizontal or downsloping)
• T-wave inversions (especially in leads related to the affected cardiac territory)
• Transient ST-segment changes
• Normal ECG (in some cases, highlighting the importance of cardiac biomarkers)

Diagnosis and Management

A diagnosis of NSTEMI is based on a combination of:

1. ECG changes (as mentioned above)
2. Clinical symptoms (chest pain, shortness of breath, diaphoresis, etc.)
3. Elevated cardiac biomarkers (troponins are particularly important)

Immediate Management:

• Antiplatelet therapy (Aspirin and P2Y12 inhibitors like clopidogrel)
• Anticoagulation (Heparin or enoxaparin)
• Beta-blockers (to reduce heart workload if not contraindicated)
• Statins (to stabilize atherosclerotic plaques)
• Coronary angiography and revascularization (depending on risk assessment using GRACE score)

Importance of Early Medical Attention

NSTEMI carries a risk of progression to a full-thickness myocardial infarction (STEMI) or significant cardiac complications. Early recognition and intervention are crucial to improve outcomes.

Conclusion

Recognizing NSTEMI on ECG requires careful attention to ST-segment depressions and T-wave changes, combined with clinical assessment and laboratory testing. Prompt medical evaluation and management are key to reducing the risk of complications like heart failure or sudden cardiac arrest.

Source recommendations

1. American College of Cardiology/American Heart Association (ACC/AHA) Guidelines for the Management of Non-ST Elevation Acute Coronary Syndromes

1. https://www.ahajournals.org/doi/10.1161/cir.0000000000000134
2. https://www.acc.org/Latest-in-Cardiology/Articles/2021/05/20/13/01/2020-ESC-NSTE-ACS-Guidelines
3. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001309
4. https://pubmed.ncbi.nlm.nih.gov/25260718/
5. https://www.sciencedirect.com/science/article/pii/S073510972106157X

2. European Society of Cardiology (ESC) Guidelines for the Management of Acute Coronary Syndromes in Patients Presenting Without Persistent ST-segment Elevation

1. https://pubmed.ncbi.nlm.nih.gov/26320110/
2. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Acute-Coronary-Syndromes-ACS-Guidelines
3. https://pubmed.ncbi.nlm.nih.gov/32860058/
4. https://academic.oup.com/eurheartj/article/42/14/1289/5898842
5. https://pubmed.ncbi.nlm.nih.gov/21873419/