IMPORTANCE Same-day discharge (SDD) after elective percutaneous coronary intervention (PCI) is associated with lower costs and preferred by patients. However, to our knowledge, contemporary patterns of SDD after elective PCI with respect to the incidence, hospital variation, trends, costs, and safety outcomes in the United States are unknown. OBJECTIVE To examine (1) the incidence and trends in SDD; (2) hospital variation in SDD;(3) the association between SDD and readmissions for bleeding, acute kidney injury (AKI), acute myocardial infarction (AMI), or mortality at 30, 90, and 365 days after PCI; and (4) hospital costs of SDD and its drivers. DESIGN, SETTING, AND PARTICIPANTS This observational cross-sectional cohort study included 672 470 patients enrolled in the nationally representative Premier Healthcare Database who underwent elective PCI from 493 hospitals between January 2006 and December 2015 with 1-year follow-up.EXPOSURES Same-day discharge, defined by identical dates of admission, PCI procedure, and discharge. MAIN OUTCOMES AND MEASURES Death, bleeding requiring a blood transfusion, AKI and AMI at 30, 90, or 365 days after PCI, and costs from hospitals' perspective, inflated to 2016. RESULTS Among 672 470 elective PCIs, 221 997 patients (33.0%) were women, 30 711 (4.6%) were Hispanic, 51 961 (7.7%) were African American, and 491 823 (73.1%) were white. The adjusted rate of SDD was 3.5% (95% CI, 3.0%-4.0%), which increased from 0.4% in 2006 to 6.3% in 2015. We observed substantial hospital variation for SDD from 0% to 83% (median incidence rate ratio, 3.82; 95% CI, 3.48-4.23), implying an average (median) 382% likelihood of SDD at one vs another hospital. Among SDD (vs non-SDD) patients, there was no higher risk of death, bleeding, AKI, or AMI at 30, 90, or 365 days. Same-day discharge was associated with a large cost savings of $5128 per procedure (95% CI, $5006-$5248), driven by reduced supply and room and boarding costs. A shift from existing SDD practices to match top-decile SDD hospitals could annually save $129 million in this sample and $577 million if adopted throughout the United States. However, residual confounding may be present, limiting the precision of the cost estimates.CONCLUSIONS AND RELEVANCE Over 2006 to 2015, SDD after elective PCI was infrequent, with substantial hospital variation. Given the safety and large savings of more than $5000 per PCI associated with SDD, greater and more consistent use of SDD could markedly increase the overall value of PCI care.