How does a doctor decide if one needs angioplasty?

Depends. On vessel involved and symptoms. Ask your doctor directly.
TheirBeliefs&Biases. Angioplasty, a hydraulic expansion of a blood vessel, is widely promoted as a way to reduce symptoms of reduced blood flow to an area. It brings higher pay & has the public illusion of high-tech. At the same time, it complicates disease & does not ↓incidence of heart attack, stroke, etc. Long term. Mds who do procedure recommend more commonly than those who don’t. It’s your body, focus on disease.