Objective: Outcome studies using databases collecting only hospital discharge data underestimate morbidity and mortality because of failure to capture postdischarge events. The proportion of postdischarge major adverse events is well characterized in patients undergoing carotid endarterectomy (CEA) but has yet to be characterized after carotid artery stenting (CAS).Methods: We retrospectively reviewed all patients undergoing CAS from 2011 to 2017 using the American College of Surgeons National Surgical Quality Improvement Program procedure targeted database to evaluate rates of 30-day major adverse events, stratified by in-hospital and postdischarge occurrences. The primary outcome was 30-day stroke/death. Multivariable analysis using purposeful selection was used to identify independent factors associated with in-hospital, postdischarge, and 30-day stroke/death events.Results: Of the 899 patients undergoing CAS, reporting of in-hospital outcomes alone would yield a stroke/death rate of 2.7%, substantially underestimating the 30-day stroke/death rate of 4.0%. In fact, 35% of stroke/deaths, 27% of strokes, 73% of deaths, 35% of cardiac events, and 35% of stroke/death/cardiac events occurred after discharge. More postdischarge stroke/death events occurred after treatment of symptomatic compared with asymptomatic patients (47% vs 27%; P < .001). During this same study period, the 30-day stroke/death rate after CEA was 2.6%, with similar proportions of postdischarge strokes (28% vs 27%; P = .51) compared with CAS but lower proportions of postdischarge deaths (55% vs 73%; P < .001). After CAS, patients experiencing postdischarge stroke/death events had a shorter postoperative length of stay compared with patients with in-hospital stroke/death (1 [1-2] vs 5 [3-10] days; P < .001). Chronic obstructive pulmonary disease was independently associated with postdischarge stroke/death (odds ratio [OR], 4.4; 95% confidence interval [CI], 1.2-16; P = .02) after CAS. Nonwhite ethnicity was independently associated with overall 30-day stroke/death (OR, 3.4; 95% CI, 1.4-7.9; P < .01), whereas statin use was associated with not having stroke/death within 30 days (OR, 0.5; 95% CI, 0.2-1.0; P = .049).Conclusions: More than one-quarter of perioperative strokes occur following discharge after both CAS and CEA. A higher proportion of postdischarge deaths occur after CAS in symptomatic patients, which may reflect treatment of a population of higher risk patients. Further investigation is needed to elucidate the cause of postdischarge stroke to develop methods to reduce these complications.