Senior Consultant & Unit Head, Interventional Cardiology, BLK-Max Super Speciality Hospital, New Delhi
Part 3 of 8 in Diagnosis and Management of Acute Coronary Artery Disease
STEMI, NSTEMI and Unstable Angina: Reading the ECG
June 2, 2024
The ECG is the first and most important test in a suspected heart attack, since it immediately splits patients into two very differently managed groups.
STEMI, NSTEMI and unstable angina
If the ECG shows ST elevation, the artery is considered 100% blocked and the patient is treated immediately, without waiting for further investigation; treatment within the first two hours is critical. If the ECG does not show ST elevation, cardiac markers (blood tests) are checked: positive markers mean NSTEMI (non-ST-elevation myocardial infarction), while negative markers mean unstable angina.
Localising the artery from the ECG
ECG changes also indicate which artery is affected: the LAD supplies the anterior wall, the LCX the posterior/lateral wall, and the right coronary artery the inferior wall. Anterior wall involvement shows ST elevation in leads V1-V6; inferior wall involvement in leads II, III and aVF; lateral wall involvement in leads I and aVL. Posterior wall involvement is trickier, often showing ST depression in V1-V6 rather than classical elevation, since dedicated posterior leads placed on the patient's back are needed to see the elevation directly. Deep T-wave inversions in the anterior leads (Wellens' syndrome) indicate a patient at high risk of a large anterior wall heart attack within the next two weeks, despite looking clinically stable.
This article is based on a Jivo Masterclass session conducted by Dr. Vikas Thakran, Senior Consultant & Unit Head, Interventional Cardiology, BLK-Max Super Speciality Hospital, New Delhi. The article has been summarised with the assistance of an AI tool from the original masterclass recording. Watch the full Masterclass recording
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This guide is based on a live Jivo Masterclass: Dr. Vikas Thakran taught doctors across Africa on June 2, 2024.
FROM THE LIVE Q&A
General Dimma
In terms of statistics, how many heart transplant cases have you handled?
Dr. Vikas Thakran
The need for heart transplantation has dropped drastically because of the medical and interventional therapies now available. Donor availability and financing also remain real constraints. In practice, the centre performs about two to three transplants a year, though the facility is available for extreme cases when a donor is available.
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Frequently Asked Questions
At what stage do we administer nitrates in managing ACS, what is the best source, and what are the nutritional considerations in ACS management?▼
Sublingual nitrate (sorbitrate) is the treatment of choice since it acts quickly and is widely available, except in patients with inferior wall STEMI, where nitrates should be used cautiously. If sublingual nitrate doesn't relieve pain, intravenous nitroglycerin can be given alongside opioids for severe pain. On nutrition, the acute-phase approach is largely about hydration status: patients presenting late with severe breathlessness should be given a low-salt diet and IV fluids should be limited to avoid overhydration. For long-term management after an ACS event, high-fat and deep-fried foods should be avoided to keep cholesterol levels down.
What are the main causes of acute coronary syndrome?▼
Smoking in young patients, diabetes, hypertension, a family history of cardiac disease, a sedentary lifestyle, and lack of sleep are the major risk factors. Pollution and extremes of temperature can also precipitate an event.
What is the role of cardiac defibrillation?▼
During an acute coronary event, external defibrillation is used for life-threatening ventricular tachycardia or ventricular fibrillation, whether at presentation, during the procedure, or post-operatively. On longer-term follow-up, patients with poor heart function (a low ejection fraction) may need an ICD, a device similar to a pacemaker, implanted to protect against these arrhythmias.
What are the expected complications of an angioplasty procedure?▼
Angioplasty is roughly 95 to 98% safe. The complications that can occur are access-site bleeding from the hand or groin, and rarer complications related to the coronary arteries themselves, such as stent thrombosis (a blocked stent) or, in difficult vessels, a perforation.
What motivates this line of work?▼
A heart attack patient left untreated has a 30 to 50% chance of dying; treated promptly with a procedure or thrombolysis, that risk falls to around 5%. Saving the largest number of lives in the smallest amount of time, across the globe, is the reason and the motivation.
What is the difference between STEMI, NSTEMI and unstable angina?▼
STEMI shows ST elevation on ECG and means a 100% blocked artery needing immediate treatment. Without ST elevation, positive cardiac markers mean NSTEMI, and negative markers mean unstable angina.
What is Wellens' syndrome?▼
Deep T-wave inversions in the anterior ECG leads that indicate a patient, though clinically stable, is at high risk of a large anterior wall heart attack within the next two weeks.
In This Series: Diagnosis and Management of Acute Coronary Artery Disease
- 1.Acute Coronary Syndrome
- 2.How a Heart Attack Develops: From Plaque to Complete Blockage
- 3.STEMI, NSTEMI and Unstable Angina: Reading the ECG
- 4.Managing a Heart Attack: STEMI vs NSTEMI Protocols
- 5.How PCI (Angioplasty) Is Performed, and When Bypass Is Better
- 6.Angioplasty: Complication Rates and Why Fast Treatment Matters
- 7.Heart Attack Risk Factors, Nitrate Therapy and Nutrition
- 8.Hospital Facilities and Evacuating Critical Patients Internationally