Safety and Feasibility of X-Sizer-Facilitated Rescue Percutaneous Coronary Intervention: A Preliminary Experience

Author(s): 

Chi Hang Lee, Huay Cheem Tan, Swee Guan Teo, Antono Sutandar, Yean Teng Lim

Discussion
The main findings of the present study were that X-Sizer thrombectomy can be performed safely in the setting of rescue PCI. There were no device-related complications. The 30-day and 6-month outcomes of the patients who underwent X-Sizer-facilitated rescue PCI (failed thrombolysis) were similar to those who underwent X-Sizer-facilitated primary PCI (without thrombolysis).
Failure to restore coronary reperfusion remains a major limitation of thrombolytic therapy for treatment of STEMI. Several parameters have been used to assess the adequacy of reperfusion after thrombolytic therapy. These include presence or absence of chest pain, resolution of ST-segment elevation in ECG, development of shock, and/or the presence or absence of reperfusion arrhythmia. Once failed reperfusion is recognized, an alternative management strategy becomes necessary to improve patient outcomes.
Repeat thrombolysis is associated with doubtful benefit and increased risk of hemorrhagic complications. Rescue PCI with balloon angioplasty, with or without stent implantation, is an established therapeutic option. A decade ago, a study of rescue angioplasty versus conservative treatment in patients with failed thrombolysis had shown a reduced incidence of death or severe heart failure at 30 days in the angioplasty group.5 Recent studies have suggested that stent implantation in rescue angioplasty is feasible, safe and associated with better angiographic results and possibly improved outcomes.10,11
Thrombus formation over a ruptured or ulcerated atherosclerotic plaque leading to coronary occlusion is the underlying pathophysiology of STEMI. Rapid and complete restoration of coronary perfusion has been recognized as an important determinant of clinical outcome. In this regard, it is conceivable that patients who already have documented resistance to thrombolytic therapy are likely to have a high thrombus burden in the culprit coronary artery.
Although simple coronary interventions with balloon angioplasty and stent implantation can restore coronary epicardial perfusion in a high proportion of patients, impairment of microvascular function may occur due to dislodgment of thrombus, leading to distal embolization. Therefore, any device that can effectively remove thrombus and reduce the overall thrombus burden is desirable in the setting of rescue PCI. Rheolytic thrombectomy using Angiojet has been shown to be safe as an adjunct treatment in myocardial infarction and effective in reducing intracoronary thrombus.12,13 However, this device was not available in our institution during the study period.
The X-Sizer thrombectomy system consists of a dual-lumen catheter shaft connected to a handheld control module. The X-Sizer catheter was inserted over a 0.014-inch guidewire and was gently advanced to the culprit lesion. The inner lumen contains a helical cutter rotated at 2.100 rpm. Activation of the system leads to fragmentation of the thrombus, which is consecutively removed by vacuum through the outer lumen.
In patients with acute coronary syndrome, pre-treatment with X-Sizer thrombectomy before conventional PCI has been shown to be associated with better post-procedural epicardial flow (assessed by TIMI frame count) and microvascular perfusion (assessed by ST-segment resolution) compared with conventional PCI.9 This suggests that X-Sizer thrombectomy is an effective thrombus-removing device and potentially beneficial in rescue PCI for failed thrombolysis. To our knowledge, this is the first report showing the safety and feasibility of X-Sizer-facilitated rescue PCI.
As this was not a randomized study, data on patients who underwent rescue PCI without adjunctive X-Sizer thrombectomy were not available. Although the present study lacks a true control group, insight can be obtained by comparing the outcome of patients who underwent rescue PCI without X-Sizer thrombectomy in other reported series14 with those from the present series. Both the procedural success rate (85% versus 100%) and long-term mortality (9% versus 13.3%) were found to be comparable.
Bleeding is an important concern in rescue PCI, as the patients have received prior full-dose thrombolytic therapy. Therefore, the relative risk-benefit of platelet glycoprotein IIb/IIIa inhibitors in this setting remains unclear.15 It has been suggested that treatment with abciximab during rescue angioplasty positively affects clinical outcome at 6-month follow-up without increasing peri-procedural bleeding.16 Intravenous abciximab was administered in three patients in our series. There were no incidences of major bleeding. Prospective studies on the safety and efficacy of platelet glycoprotein IIb/IIIa inhibitors in rescue PCI are warranted.
A non-significant trend towards a longer fluoroscopy time, higher peak creatine kinase level and lower left ventricular ejection fraction were found in the rescue PCI when compared with the primary PCI group. These are in accordance to the belief that patients with failed thrombolysis are associated with higher thrombus burden, larger infarcted area and more complex coronary anatomy. Despite these disparities, no significant differences in 30 days and 6-month outcomes were detected.
Limitations. This study presents several limitations due to its limited sample size and its non-randomized nature. None of the patients in the rescue PCI group was in cardiogenic shock. This paradox was probably due to the fact that patients who were regarded as too ill and unstable were not submitted for rescue PCI. Thus, this may be a biased sample. Myocardial blush score was not systemically evaluated. Serial echocardiography was not performed and relative change in left ventricular function over the follow-up period was unknown. Therefore, the main purpose of this study is to demonstrate the safety and feasibility but not the absolute effectiveness of X-Sizer facilitated rescue PCI. Finally, a cost-benefit analysis was not performed.

Conclusion
Our study suggests that X-Sizer-facilitated rescue PCI is safe, feasible and associated with a high technical success rate. Thirty-day and 6-month outcomes of the patients who underwent X-Sizer facilitated rescue PCI were similar to those who underwent X-Sizer-facilitated primary PCI.


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