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Risk factors for thromboembolic occlusions and efficacy of aspiration thrombectomy

A recent study from researchers at Shanghai Jiao Tong University has evaluated the predictive factors behind thromboembolic occlusions occurring during endovascular revascularization (EVR) and the success rate of percutaneous aspiration thrombectomy. A total of 260 patients underwent EVR. EVR was done using intraluminal and/or subintimal recanalization with 4000U heparin given prior to angioplasty. Uncovered self-expandable stents were placed in patients with flow-limiting dissections or residual stenosis. Of the 260 patients, 237 patients had restoration of flow without thromboembolic occlusion. 23 patients had EVR with subsequent thromboembolic occlusion. In patients with thromboembolic occlusion, a 5F or 6F guiding catheter was introduced and passed though the thromboembolic segment. A 20- or 50-mL syringe was connected to the guiding catheter after removal of the guide wire. After confirming adequate clot removal, 250,000–500,000 U urokinase was diluted in 50 mL saline solution and gradually infused into the treated artery to dissolve any remaining clots in all cases, even though no clots were present angiographically. Technical success was defined as <30% residual stenosis. Investigators report a technical success rate of 95.7% in the aspiration thrombectomy group. Interestingly, there were no significant differences in the clinical outcomes of the two groups including ABI, maximum walking distance, ulcer healing, restenosis/occlusion, and limb salvage rates. Further, there were few factors that could be cited as significant risk factors for thromboembolic occlusion during EVR including stenosis >90% and intraluminal angioplasty. The authors concluded that aspiration thrombectomy is an effective therapy for acute thromboembolic occlusion and may be considered primary treatment when this event occurs during infrainguinal arterial EVR.

Commentary:

This manuscript is interesting and noteworthy for the simple methods used to both perform revascularization and to treat a thromboembolic complication. While this study is limited due to the small sample size of thromboembolic occlusions (n=23), the small number of variables strengthen the results. All patients were treated initially with either PTA or self-expanding stent. If there was an occlusion, it was treated with aspiration thrombectomy using a 5F or 6F catheter and a syringe. The low thromboembolic occlusion rate (6.6%) and high likelihood of success after aspiration thrombectomy argue against the added cost and complexity of a distal embolic protection device. However, more research is needed to determine the risk in interventions with limited runoff vessels and more complex revascularization techniques.

Figure 3. Arterial thrombosis in the left SFA in a 78-year-old man with severe claudication for 3 weeks. (a,b) Long-segment occlusion is detected in the left SFA on contrast-enhanced MR angiography and DSA (arrows, aand b), and severe arterial thrombosis after stent placement is observed in the SFA (arrows, c). PAT was performed and arterial thrombotic material was aspirated out (d). (e) Final angiogram shows good SFA patency.