What are the risks of having a balloon angioplasty?

Angio risk: While there is a laundry list of possible complications like kidney injury from the "dye", bleeding from the puncture afterwards, injury to the vessel from the balloon...The vast majority of angioplasties, when conducted by an experienced doctor, go without a hitch. Your doctor should review complications with you as part of your consent process.

Tears, Bleeding, Etc: Angioplasty is only a brief hydraulic expansion of a blood vessel, using pressures~50 to 250 times above usual sbp. The expansion injures & can tear the vessel into leaking, promotes clots (showers downstream & sometimes closes the vessel), sometimes death & further complicates underlying artery ds. With careful operators, obvious complications are infrequent & I have done many with good results.