Novel Thrombectomy System for Below-the-Knee and Visceral Arterial Interventions: PRISM Retrospective Interim Results

Abstract

Purpose Existing endovascular options in the treatment of peripheral and visceral arterial thromboembolism face the challenges of incomplete revascularization and significant bleeding risk (among other complications). The Penumbra/Indigo Systems (Alameda, California) are designed to address these challenges by providing a novel approach to mechanical thrombo-embolectomy in the periphery using a trackable, relatively small diameter aspiration system that has a proven track record in the treatment of ischemic stroke. The PRISM trial is the first multicenter study designed to obtain initial safety and effectiveness data as well as to define optimal technique for the use of these systems in patients with confirmed peripheral or visceral artery occlusions. This abstract outlines the current status of the trial and discusses its preliminary findings. Material and Methods To date, 38 patients have been enrolled in this retrospective, single-arm, multicenter trial (total planned enrollment = 100). Mechanical thrombo-embolectomy using the Penumbra/Indigo Systems was performed in cases of failed thrombolysis, acute ischemia without adequate time for thrombolysis, or in patients with emboli as a complication of an endovascular intervention. The primary site of occlusion was located in the popliteal (17/38 patients, 44.7%), peroneal (5/38, 13.2%), superficial femoral (4/38, 10.5%), posterior tibial (4/38, 10.5%), profunda femoris (2/38, 5.3%), superior mesenteric (2/38, 5.3%), anterior tibial (2/38, 5.3%), renal (1/38, 2.6%), or brachial (1/38, 2.6%) arteries. Baseline characteristics were obtained and an angiographic assessment of vessel patency was recorded using the Thrombolysis in Myocardial Infarction (TIMI) score classifications both before and after use of the device in order to assess technical effectiveness. A review of procedural complications and adverse events was conducted to monitor safety. Results Mean patient age was 71.6 (standard deviation [SD] 14.8) years and 44.4% (16/38) were female. Procedural information presented in the following analyses was available for 24 patients and final revascularization data was available for 22 patients at the time of this abstract (data collection ongoing). A baseline angiographic TIMI score of 0 or 1 was reported for all 24 patients. Prior to intervention with the Penumbra/Indigo Systems, 41.7% of patients had no prior treatment, 45.8% received thrombolytic therapy alone, 4.2% received mechanical intervention alone, and 8.3% received both. The mean time from symptom onset to procedure was 5.3 days (SD 7.4). Following mechanical thrombo-embolectomy, 86.4% of patients were successfully revascularized to TIMI 3 and 13.6% to TIMI 2 flow. Four adverse events were reported, 1 of which was classified as serious (cardiac arrest, not related to use of the study device). Three cases were noted in which distal branch occlusion occurred secondary to emboli during the procedure. None of these 3 events were clinically significant. Conclusions Early experience with the Penumbra/Indigo Systems shows promising results with safe and effective mechanical thrombo-embolectomy in the peripheral arterial vasculature. Its successful use across a broad range of clinical applications including acute ischemia, removal of emboli that occurred during other endovascular procedures, and after failed thrombolysis is encouraging. Optimal technique will be discussed.