Increasing numbers of patients are undergoing diagnostic catheterizati
on as outpatients; however, a small proportion of patients requires ho
spital admission following the procedure. Unplanned admissions after c
onsecutive outpatient cardiac catheterizations performed during 1 year
were prospectively reviewed to determine the incidence of and reasons
for admission. Among 847 patients undergoing outpatient cardiac cathe
terization, 130 patients (15%) required hospital admission after the p
rocedure. Admitted patients were divided into four groups: patients un
dergoing immediate percutaneous transluminal coronary angioplasty (PTC
A) (Group 1; 33%), patients with severe cardiac disease requiring urge
nt intervention (Group 2; 48%), patients suffering complications or he
modynamic instability (Group 3; 15%), and patients whose procedures we
re completed too late to allow same-day discharge (Group 4; 4%). Patie
nts over 65 were more likely to require admission and women were more
likely to be admitted with complications or hemodynamic instability. F
indings are compared with results of other outpatient series, and impl
ications regarding appropriate setting for outpatient catheterization
are discussed.