Senior Consultant & Unit Head, Interventional Cardiology, BLK-Max Super Speciality Hospital, New Delhi
Part 2 of 8 in Diagnosis and Management of Acute Coronary Artery Disease
How a Heart Attack Develops: From Plaque to Complete Blockage
June 2, 2024
Understanding why a stable blockage suddenly turns into a heart attack starts with how coronary artery disease actually develops.
From fatty streaks to a ruptured plaque
The heart is the first organ to receive blood from its own pumping, supplied by the left main artery (which branches into the LAD and LCX) and the right coronary artery. Over time, arteries develop fatty streaks lined by a fibrous cap, caused by a combination of high cholesterol, hypertension, diabetes, smoking and a sedentary lifestyle. When this narrowing is not yet fully blocking the artery, walking or exertion produces angina because blood supply cannot keep up with demand.
Stable angina versus an acute event
When the fibrous cap over a plaque ruptures, it exposes the sub-endothelium, which recruits platelets; these release ADP, activating further platelets that combine with fibrin to form a clot. This is the mechanism that turns chronic stable angina, where pain only occurs on exertion, into unstable angina or a full heart attack, where pain occurs at rest because the artery is now completely blocked.
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
Dr. Williams
How is a PCI (angioplasty) actually performed?
Dr. Vikas Thakran
Access is gained through either the radial artery in the wrist or the femoral artery in the groin. An angiography is first done through a catheter placed in that artery to locate the blockages, and a treatment plan is formed. A wire is then passed across the blockage, a balloon is used to open it, and a stent is placed. If there are multiple complex blockages that would need too many stents, coronary artery bypass surgery is recommended instead, decided by a heart-team approach. In an acute heart attack, PCI directly clears the thrombus, places a stent, and restores flow.
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Frequently Asked Questions
In terms of statistics, how many heart transplant cases have you handled?▼
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.
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 causes a coronary artery blockage?▼
Fatty streaks build up in the artery over time due to high cholesterol, hypertension, diabetes, smoking and a sedentary lifestyle, narrowing the vessel with a fibrous cap over the plaque.
What turns stable angina into a heart attack?▼
When the fibrous cap over a plaque ruptures, it triggers platelet activation and clot formation, completely blocking the artery and causing pain at rest instead of only on exertion.
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