Thrombus Aspiration Without Additional Ballooning or Stenting to Treat Selected Patients (See Full Title Below)

Thrombus Aspiration Without Additional Ballooning or Stenting to Treat Selected Patients with ST-Elevation Myocardial Infarction

ABSTRACT: Background. The use of thrombus aspiration during percutaneous coronary intervention (PCI) is recommended in patients with ST-elevation myocardial infarction (STEMI) undergoing mechanical revascularization. When thrombus aspiration is adopted, the standard technique includes, after mechanical thrombus extraction, angioplasty and/or stent implantation to eliminate residual stenosis. To date, no data are available concerning the use of thrombectomy alone without additional ballooning or stenting. Methods and Results. We report the angiographic and clinical outcome of a series of selected STEMI patients undergoing mechanical reperfusion by thrombus aspiration without additional ballooning or stenting. Four patients out of 316 consecutive STEMI patients were managed by thrombus aspiration alone (1.3%). All patients had angiographic documentation of an occlusive large intracoronary thrombus in the infarct-related artery before intervention and complete restoration of coronary flow in the absence of critical coronary stenosis after thrombus aspiration. Three of these patients had a clinical contraindication to dual antiplatelet therapy, thus suggesting that to avoid stent implantation would be advisable. Angiographic reevaluation was performed before discharge in 3 patients confirming persistent patency of the infarct-related artery (in 1 case the residual stenosis was judged to require intravascular ultrasound evaluation and subsequent elective PCI with stent implantation). The thirty-day clinical course was uneventful in all patients. Conclusions. In selected patients with STEMI undergoing mechanical reperfusion, thrombus aspiration without additional ballooning or stenting may be successfully performed. Further studies are needed to assess the clinical relevance of this novel approach. J INVASIVE CARDIOL 2010;22:489–492 —————————————————————————————————————— The culprit lesion in ST-elevation myocardial infarction (STEMI) is composed of intracoronary thrombus and underlying atherosclerotic plaque. Since distal embolization of thrombotic material from the culprit lesion to the coronary microcirculation is a recognized cause of no-reflow,^1–3 the use of thrombectomy during percutaneous coronary intervention (PCI) is recommended in patients with STEMI undergoing mechanical revascularization.^4,5 Despite the overall angiographic^6,7 and clinical8 benefit observed in patients treated by thrombectomy, the response to thrombus aspiration is widely variable across different patients.⁹ When thrombus aspiration is adopted, the standard technique includes, after mechanical thrombus extraction, angioplasty and/or stent implantation to eliminate residual stenosis. However, when the atherosclerotic plaque is minimal and/or established contraindications to antiplatelet therapy are present, additional ballooning and stenting are probably not useful or advisable, and thus thrombectomy alone may be considered. As the feasibility of mechanical reperfusion based on thrombectomy alone has not been reported, we present and discuss a first case series of STEMI patients successfully managed with manual thrombus aspiration alone.

Methods and Results

At our Institution, from December 2007 to December 2009, 4 patients with STEMI (out of 316 primary or rescue PCI patients, 1.3%), underwent urgent coronary PCI performed using thrombus aspiration alone. Thrombus aspiration was performed in all cases with the Diver CE catheter (Invatec, Roncadelle, Italy) according to a previously described technique⁹ as a primary approach after guidewire crossing of the lesion. The clinical characteristics of the 4 patients are reported in Table 1. All patients had ongoing chest pain and persistent ST elevation in greater than or equal to 2 contiguous leads at the time of PCI. Table 2 shows the location of the culprit lesion, thrombolysis in myocardial infarction (TIMI) flow (graded according to TIMI group),¹⁰ thrombus score,¹¹ myocardial blush grade (MBG)¹² before and after thrombus aspiration and PCI for each patient. In all patients pre-PCI TIMI flow grade in the infarct-related arteries was 0, and the culprit lesion consisted of a large angiographically evident intraluminal thrombus (thrombus score 4 or 5), and wire crossing of the lesion was not associated with significant flow improvement. After thrombus aspiration, the infarct-related artery in all patients showed a dramatic angiographic improvement (flow normalization and angiographic thrombus disappearance with no angiographically evident distal embolization) in the absence of an angiographically critical residual stenosis (Table 2), such that we decided not to perform additional dilatations and/or stent implantation. Patients were treated with antiplatelet therapy as showed in Table 1 and were transferred to the CCU where ST-segment resolution > 70% was documented in all cases. Mean troponin T peak was 4.38 ng/ml (range 0.75–13.99 ng/ml) and the mean time to troponin T peak was 12 hours. Left ventricular ejection fraction, evaluated echocardiographically after the procedure, was greater than or equal to 55% in all the patients. Coronary angiography was repeated in 3 patients after 2–8 days, and in all of them, normal antegrade flow and persistence of a good angiographic result were evident (Table 2). In 1 case the residual stenosis was judged to require further intravascular ultrasound evaluation, which showed significant reduction of the luminal area (minimal lumen area 2), thus elective PCI with stent implantation was successfully performed (Table 2). The 30-day clinical course was uneventful in all the patients.

Discussion

In the present report, we describe the angiographic and clinical outcome of a small series of selected STEMI patients treated by thrombus aspiration without additional ballooning or stenting. Mechanical removal of thrombotic material from the infarct-related artery by adjunctive thrombectomy is an emerging strategy to treat STEMI patients,¹³ which may be associated with better reperfusion rates^6,7 and clinical outcomes.⁸ According to the standard technique, thrombectomy is used as a first step and is followed by stenting (with or without balloon predilatation) in order to treat the culprit atherosclerotic plaque underlying the occlusive thrombus. However, culprit-lesion coronary plaques at the site of an acute obstruction causing acute myocardial infarction are often not critical.¹⁴ As a consequence, theoretically, a subgroup of STEMI patients may not require, further intervention on the infarct-related artery in cases of successful thrombus removal. Before thrombus aspiration was an established technique, we reported the successful management with aggressive antithrombotic therapy for selected STEMI patients (referred for emergent intervention) characterized by re-established coronary flow, large thrombus and low atherosclerotic burden.¹⁵ Similarly, Isaaz and colleagues reported their promising experience using a “minimally invasive approach” (in which urgent PCI during STEMI is stopped as soon as coronary flow is reestablished and further intervention is performed only in the case of significant residual stenosis at early follow up) showing that a remarkable subgroup of patients may not require aggressive ballooning and/or stenting.¹⁶ In such cases, thrombectomy may offer an additional option to successfully manage highly thrombotic lesions with a minimal underlying atherosclerotic component. Indeed, when using thrombus aspiration devices, thrombus removal is greater when the thrombus burden is larger,¹⁷ and complete removal of angiographically evident thrombus may sometimes occur. This latter situation (complete removal of coronary thrombus in a patient with non-significant atherosclerotic plaque), although unpredictable and infrequent, may offer the possibility of avoiding further intervention in selected patients. Although the safety of avoiding ballooning and stenting after thrombectomy has still to be evaluated, the present report suggests that this strategy can be considered, especially in clinical situations where there may be poor compliance with antiplatelet therapy.

Conclusion

In selected patients with STEMI undergoing mechanical reperfusion, thrombus aspiration without additional ballooning or stenting may be successfully performed. Further studies are needed to assess the clinical relevance of this novel approach.

References

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—————————————————————————————————— From the Institute of Cardiology, Catholic University of the Sacred Heart, Rome, Italy. The authors report no conflicts of interest regarding the content herein. Manuscript submitted June 10, 2010, provisional acceptance given June 23, 2010, final version accepted July 1, 2010. Address for correspondence: Francesco Burzotta, MD, PhD, Via Prati Fiscali 158, 00141 Rome, Italy. E-mail: f.burzotta@rm.unicatt.it