ObjectivesThis study aimed to examine the 30-day unplanned readmissions rate, predictors of readmission, causes of readmissions, and clinical impact of readmissions after percutaneous coronary intervention (PCI). BackgroundUnplanned rehospitalizations following PCI carry significant burden to both patients and the local health care economy and are increasingly considered as an indicator of quality of care. MethodsPatients undergoing PCI between 2013 and 2014 in the U.S. Nationwide Readmission Database were included. Incidence, predictors, causes, and cost of 30-day unplanned readmissions were determined. ResultsA total of 833,344 patients with PCI were included, of whom 77,982 (9.3%) had an unplanned readmission within 30 days. Length of stay for the index PCI was greater (4.7 vs. 3.9 days) and mean total hospital cost ($23,211 vs. $37,524) was higher for patients who were readmitted compared with those not readmitted. The factors strongly independently associated with readmissions were index hospitalization discharge against medical advice (odds ratio [OR]: 1.91; 95% confidence interval [CI]: 1.65 to 2.22), transfer to short-term hospital for inpatient care (OR: 1.62; 95% CI: 1.38 to 1.90), discharge to care home (OR: 1.57; 95% CI: 1.51 to 1.64), and chronic kidney disease (OR: 1.50; 95% CI: 1.44 to 1.55). Charlson Comorbidity Index score (OR: 1.28; 95% CI: 1.27 to 1.29) and number of comorbidities (OR: 1.18; 95% CI: 1.17 to 1.18) were independently associated with unplanned readmission. The majority of readmissions were due to noncardiac causes (56.1%). ConclusionsThirty-day readmissions after PCI are relatively common and relate to baseline comorbidities and place of discharge. More than one-half of the readmissions were due to noncardiac causes.