between november 1980 and november 1985 , 54 patients ages greater than or equal to 70 years underwent percutaneous transluminal coronary angioplasty for unstable angina , defined as recent-onset ( less than 1 month ) angina , new onset of rest angina ( greater than or equal to 2 episodes ) or accelerating class iii or iv angina .
C0002965
unstable angina
C0002962
angina