Understanding Coronary Blockage: Why Percentage Isn't Everything

The question "Doctor, how much % blockage is there?" is one of the most common but misleading questions today.

The condition of the plaque is more important than just the percentage of blockage.

What we call "blockage" is not just a simple vessel closure. It involves inflammation, fat, and a tendency for clot formation.

1) Blockage means narrowing of the coronary artery, but cholesterol alone is not the cause.

Plaque is a mixture of fat, cholesterol, calcium, and inflammation.

2) Risk cannot be determined by percentage alone.

An angiography might show 40% blockage, but if the plaque is soft, the risk of rupture is higher. Soft plaque rupture can cause sudden clot formation leading to full blockage.

3) Why do some people live for years with 70–80% blockage?

Because their plaques are stable with a thick fibrous cap and calcium, reducing rupture risk. Blood flow is somewhat reduced but the risk of sudden attack is lower.

4) How can an attack happen even with 30–40% blockage?

Because the attack is not due to the percentage of blockage but due to plaque rupture causing sudden clot formation. The clot can block the artery from 30% to 100% within seconds.

5) Understanding types of blockage helps in decision making: - Soft plaque: more dangerous - Calcified plaque: less dangerous but more narrowing - Thrombus: sudden clot, emergency - Total occlusion: 100% block, urgent stent or bypass needed

6) Angiography shows only what is visible: percentage and length of blockage. It does not show plaque nature, softness, clot presence, or calcium.

7) Therefore, IVUS (Intravascular Ultrasound) and OCT are very important. They provide microscopic details of plaque. Is it soft or hard? Is there rupture risk? Is there clot? This makes the decision scientifically clear.

8) When to do angioplasty? A simple, safety-first answer: - Severe symptoms - Positive stress test - Weak blood flow - High-risk soft plaque on IVUS/OCT - Thrombus or unstable plaque In these cases, stenting can save lives.

9) If calcium is present, stenting is not easy. Calcium deposits do not open easily with a balloon. Advanced techniques like rotablation or Shockwave IVL are needed.

10) Heart attacks are increasing among young people due to increased plaque rupture tendency.

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Dr Ravindra L. Kulkarni, MD, DNB, FSCAI (Cardiology) Just For Hearts