As endovascular therapies gain increased acceptance for the treatment of vascular disease, postintervention surveillance becomes more critical. The underlying rationale for routine, systematic follow-up is multifactorial. The primary reason is to improve the results of treatment by detecting failures or recurrences early enough in their course that their correction is as minimally involved as possible. It has been well demonstrated, for example, that correction of a threatened saphenous vein bypass improves its patency when compared to simple observation.1–3 This finding is thought to be applicable to endovascular therapies as well: Treatment of a recurrent stenosis with a second endovascular procedure, perhaps with supplemental stenting, is more likely to be initially technically successful and durable than an attempt to recannulate an occlusion that results from ignoring the recurrence. Furthermore, treatment of an occlusion may require thrombolysis, which has its own inherent risks. The advantages of close postintervention surveillance become even more obvious when dealing with an artery feeding an end-organ (e.g., the renal artery), in which case progression to occlusion may cause irretrievable organ injury.