Delivery assist catheters for mechanical thrombectomy: a systematic review.

INTRODUCTION: Mechanical thrombectomy for acute ischemic stroke is often limited by the tortuous anatomy and the 'ledge effect' caused at the junction of a large-bore aspiration catheter and smaller inner devices. Novel delivery assist catheters with smooth tapered distal tips have been developed to facilitate the navigation of aspiration or microcatheters to the clot. METHODS: We performed a PRISMA-guided systematic review of these tapered delivery assist catheters, analyzing their design, regulatory status, and all available evidence on technical performance, clinical outcomes, and safety. A comprehensive literature search (through July 2025) was conducted for studies and reports on the above devices. RESULTS: A total of 18 reports met the inclusion criteria, covering 7 distinct assist catheters. All devices share a common design of a variably stiff, single-lumen catheter with an atraumatic tapered distal segment that minimizes the gap between the inner device and the outer aspiration catheter. Use of these catheters enabled successful trackability and clot engagement in >90% of cases across most series, often without a guidewire, and with low complication rates. CONCLUSIONS: Tapered delivery assist catheters represent an innovation in thrombectomy. Ongoing studies and broader adoption will further clarify their impact on procedural efficiency and patient outcomes.