Amitabh Bachchan hospitalised in Mumbai: Why did the actor undergo angioplasty?

Actor Amitabh Bachchan underwent an angioplasty at the Kokilaben Hospital in Mumbai on Friday morning, after he was hospitalised early in the day. The 81-year-old also shared a cryptic social media post soon after, saying 'T 4950 - in gratitude forever.' The operation happened a year after he suffered an injury on the set of Kalki 2898 AD when a harness strained his back. He had to be on bed rest for a while. He also suffered from a torn muscle and strained rib cartilage and even had to decide against travelling to the San Diego Comic Con as doctors advised against it. He also underwent wrist surgery early this year. 

Why the angioplasty?
Big B was apparently attending events during which he experienced discomfort and difficulty to breath. As per reports, after a routine checkup, doctors recommended the operation. Angioplasty is a medical procedure to fix narrowed or blocked blood vessels, especially coronary arteries in the heart or arteries in other parts of the body. It's often done for patients experiencing symptoms related to reduced blood flow to a particular area of the body due to atherosclerosis, a condition where fatty deposits (plaque) build up in the arteries. Some of the common reasons to do the procedure are:
1) Coronary artery diseases, which occur when plaque buildup narrows the arteries that supply blood to the heart muscle. This can result in chest pain (angina) or shortness of breath.

2) Cardiac arrest or acute myocardial infarction, during which a coronary artery is completely blocked by a blood clot. Angioplasty is often performed quickly to restore blood flow to the affected part of the heart muscle. 
3) A chest pain that occurs even at rest or with minimal exertion - called unstable angina, can also call for angioplasty. This indicates a high risk of a heart attack.