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Safety and Feasibility of X-Sizer-Facilitated Rescue Percutaneous Coronary Intervention: A Preliminary Experience
January 2005
Although primary percutaneous coronary intervention (PCI) has been proven to be superior to thrombolytic therapy for the treatment of acute ST-elevation myocardial infarction (STEMI),1–3 the latter approach is still widely practiced due to reasons such as unavailability of experienced operators or long transport time to a dedicated angioplasty center. Failed reperfusion of the occluded coronary artery after thrombolysis occurs in up to 30% of the patients and is associated with high mortality.4 Failed thrombolysis manifests as unsolved chest pain, persistent ST-segment elevation in electrocardiogram (ECG), hemodynamic compromise or a combination of all. Performing PCI in patients after failed thrombolytic therapy, known as rescue PCI, is an available salvage therapy. Limited information, however, is available on the outcomes of patients after rescue PCI.5–7 In particular, there has been concern that rescue PCI is associated with a higher incidence of adverse events, especially in failed rescue procedures.
The X-Sizer (EndiCOR Medical Inc.) is a novel thrombectomy device that can effectively remove intracoronary thrombi.8 A recent study suggests that pre-treatment with X-Sizer thrombectomy before PCI in acute coronary syndrome can improve final epicardial flow and accelerate ST-segment recovery.9 To date, no data exist regarding the use of X-Sizer thrombectomy in rescue PCI. In this retrospective study, we sought to evaluate the safety and feasibility of X-Sizer facilitated rescue PCI (failed thrombolysis) and to compare the patient outcomes with those who underwent X-Sizer facilitated primary PCI (without thrombolysis).
METHODS
This is a retrospective study of the 30-day and six-month clinical outcomes in a tertiary university hospital. All patients who underwent X-Sizer facilitated primary or rescue PCI for STEMI during the period from November 2000 to February 2003 formed the study cohort. Diagnosis of STEMI was based on chest pain suggestive of coronary ischemia for more than 30 minutes and an ECG showing ST-segment elevation > 1mm in two contiguous leads or new onset left bundle branch block, with or without cardiac enzyme elevation. All patients underwent PCI within 12 hours after onset of chest pain. For patients who received thrombolytic therapy, diagnosis of failed thrombolysis was based on one or more of the following parameters at 90 minutes after administration of thrombolytic therapy: 1) unresolved chest pain; 2) persistent ST-segment elevation; or 3) hemodynamic compromise. Submission for PCI was based on the decision of the attending physicians. As per hospital protocol, patients found to have significant left main coronary stenosis by angiography were sent for emergency bypass surgery.
The PCI procedures were carried out in a standard fashion in the cardiac catheterization laboratory. Informed consent was obtained from all patients. They received a combined aspirin and ticlopidine/clopidogrel loading dose prior to the procedure. Weight-adjusted (100 U/kg) heparin with target activated clotting time (ACT) of > 300 seconds was administered before balloon inflation or stent deployment. When administration of a platelet glycoprotein IIb/IIIa inhibitor was anticipated, a reduced dose (70 U/kg) of heparin was administered with target ACT between 200 and 250 seconds. Details of the procedural strategy, including direct stenting versus balloon predilatation, use of an intra-aortic balloon pump (IABP) or other adjunctive devices, were left to the discretion of the individual operator.
The X-Sizer thrombectomy system consists of a dual-lumen catheter shaft connected to a handheld control module. The details have been described previously. 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 concurrently removed by vacuum through the outer lumen.
Patients who underwent an uneventful PCI were discharged home the day following the procedure. After stent implantation, dual antiplatelet therapy with aspirin indefinitely and clopidogrel 75 mg daily for 4 weeks was precribed. The patients’ in-hospital records, catheterization reports and discharge summaries were reviewed retrospectively in order to obtain information on patients’ demographics, presenting clinical history, procedural detail and in-hospital outcomes. Angiographic films were reviewed when relevant information was missing or inadequate. Hypercholesterolemia was defined as total cholesterol > 220 mg/dl. Hypertension was defined as systolic blood pressure > 140 mmHg and/or diastolic blood pressure > 90 mmHg. Diabetes mellitus was defined as fasting blood sugar > 140 mg/dl. Left ventricular ejection fraction was assessed by two-dimensional transthoracic echocardiography. Cardiogenic shock was defined as systolic blood pressure 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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