Novel Use of a Guide Extension Mother-and-Child Catheter for Adjunctive Thrombectomy During Percutaneous Coronary Intervention for Acute Coronary Syndromes

Abstract: Background. The use of adjunctive thrombectomy during primary percutaneous coronary intervention (PCI) has steadily increased with recent trials demonstrating an improved clinical and mortality benefit for manual aspiration thrombectomy. The use of an in-dwelling guide extension mother-and-child catheter allows direct aspiration of thrombus from the vessel with its larger extraction area. Methods. Between December 2011 and September 2013, a total of 17 patients who presented with acute coronary syndromes (ACS) in whom a guide extension catheter was utilized specifically for manual thrombus aspiration were identified and studied. Results. The guide extension catheter was utilized specifically for thrombus aspiration in 18 vessels involving 17 patients presenting with ACS where severe thrombus burden was noted. The cases involved 4 saphenous vein grafts and 14 native coronary arteries, with 4 cases involving vessels with late stent thrombosis. Successful outcomes with thrombus aspiration and TIMI-3 flow were achieved in 17/18 vessels treated, with no adverse outcomes of vessel trauma or strokes noted. Conclusions. Adjunctive manual aspiration thrombectomy utilizing a guide extension mother-and-child catheter affords a novel method of thrombus aspiration, offering a larger extraction area within the conventional 6 Fr system, with demonstrated efficacy for vessel lesions with a large thrombus burden.

J INVASIVE CARDIOL 2014;26(6):249-254

Key words: thrombus, adjunctive manual aspiration thrombectomy

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The use of adjunctive thrombectomy during primary percutaneous coronary intervention (PCI) has steadily increased, largely from increased utilization of manual aspiration thrombectomy.¹ Distal embolization with subsequent microvascular dysfunction during primary PCI is associated with worse outcomes, including larger infarct sizes and reduced survival.^2-4 Reduction of thrombus burden during primary PCI by manual thrombectomy has in some recent trials demonstrated an improved 30-day and 1-year survival compared with conventional PCI.^5-7

Manual thrombectomy involves an in-dwelling coronary aspiration catheter with vacuum aspiration performed with syringes. Devices such as the Export (Medtronic, Inc), the Diver CE (Invatec), Pronto (Vascular Solutions), Fetch catheter (Medrad), and PriorityOne AC (Terumo Interventional Systems) are a partial list of the numerous manual thrombectomy devices currently available on the market (Table 1). The success of manual aspiration is limited by multiple factors including catheter tip extraction area, vacuum generation, deliverability, and working length, as well as vessel and thrombus characteristics. The large majority of primary PCIs are performed utilizing 6 Fr guide systems. The average tip extraction area of these devices ranges from 0.80-1.24 mm² on a 6 Fr system. We hypothesized that the use of a larger tip extraction area afforded by a guide extension mother-and-child catheter would serve a greater aspiration potential with improved outcomes during primary PCI. The 6 Fr GuideLiner V2 catheter (Vascular Solutions) provides a tip extraction area of 1.58 mm², with a working length of 150 cm in combination with the 6 Fr guide utilized.

Methods

The 6 Fr GuideLiner V2 catheter (outer tip diameter, 1.7018 mm) was first tested under water utilizing a 6 Fr Launcher (inner diameter, 1.80 mm) guide catheter (Medtronic, Inc) to ensure a fairly acceptable seal between the proximal end of the extraction catheter (lying within the guide) and the distal extraction tip, with minimal air leak demonstrated. A maximum of 20 cm of the total 25 cm thrombectomy catheter length was allowed out of the distal guide tip during extraction. Extraction with a 30 cc vacuum syringe on a stopcock release mechanism ensured excellent aspiration potential of fine particulate sand, utilizing the device with the distal guide tip and catheter tip placed under water in this manner. The extraction was compared with a 6 Fr Pronto V4 thrombectomy catheter similarly positioned and was noted to be comparable or better in performance in terms of both extraction time and quantity. No visually apparent aspiration of particulate matter was noted in the syringe when the GuideLiner exit point from the guide was positioned to extract particulate sand, with the distal GuideLiner end occluded. The continuous aspiration revealed no apparent remnant particulate matter within the guide after completion of aspiration. 

Between December 2011 and September 2013, patients who presented with acute coronary syndromes (ACS) at a single university hospital during which the GuideLiner catheter was utilized specifically for direct manual thrombus extraction in vessels deemed to have a very large thrombus burden undergoing PCI were identified. This is an observational study of this series of patients with retrospective analysis of patient data. No comparators with alternate methods of thrombectomy were performed except in individual cases. A single reader as part of the observational series performed review of films retrospectively. The PCI methods utilized for thrombectomy were as follows. A 6 Fr guide catheter was utilized in all cases. The vessels were wired utilizing a suitable guidewire after anticoagulation with either heparin or bivalirudin at the operator’s discretion. No glycoprotein IIb/IIa inhibitors were used in this series of patients evaluated. All patients received a thienopyridine drug load either prior to or at the time of intervention. The GuideLiner catheter was introduced directly to the thrombus-laden lesion. The working length of the catheter allows 25 cm of usable length with radiopaque markers demarcating these crucial boundaries, although the extraction length was limited to 20 cm. A locked 30 cc vacuum aspiration syringe attached to the manifold assembly by a three-way stopcock afforded aspiration once the catheter was delivered to the thrombotic lesion. During aspiration, the distal tip of the GuideLiner was gradually advanced from the proximal edge of the thrombotic lesion, positioning it in gradual increments further distally. Care was taken to avoid any back and forth movement during actual thrombus aspiration in order to avoid clot dislodgment and distal embolization. The guide was aspirated prior to further contrast injection or device delivery with the guide extension catheter left within the coronary vessel. Lesions were then direct stented post aspiration with the avoidance of balloon dilation before or after stenting.

All angiographic data were reviewed and clinical data were obtained from retrospective chart review. Troponin I testing was performed post procedurally every 6 hours for the first 48 hours of admission. Electrocardiogram (ECG) was performed daily until discharge or if symptoms of ischemia or instability occurred in hospital.

Results

Between December 2011 and May 2013, a total of 17 patients presenting with ACS (12 ST-elevation myocardial infarction [STEMI] and 5 non-ST elevation myocardial infarction [NSTEMI]) involving 18 culprit vessels were treated specifically for manual thrombus aspiration utilizing the guide extension catheter, wherein severe thrombus burden was identified (Table 2). This included 9 right coronary artery (RCA) interventions (Figure 1), 4 saphenous vein graft (SVG) interventions (Figure 2), 2 left anterior descending (LAD) artery interventions, 2 left circumflex (LCX) coronary artery interventions, and 1 ramus intermedius (RI) artery intervention. Four culprit native vessel lesions were the result of late thrombosis within previously placed stents. A 6 Fr Launcher guide catheter was utilized in all cases of manual aspiration with the GuideLiner V2 catheter as the mother-and-child aspiration system. Drug-eluting stents were deployed in all but 1 case post aspiration, using the direct stenting technique.

Successful outcomes as judged by symptom resolution, improvement in ST-segments, and obtaining brisk Thrombolysis in Myocardial Infarction (TIMI)-3 flow occurred in 17/18 vessels treated. Myocardial blush grade (MBG) of 2 or greater was achieved in 94.4% of patients undergoing PCI with manual aspiration (Table 3). A single case of an acutely occluded SVG that was thrombus laden proximal to distal had an unsuccessful outcome. Initial aspiration with the Pronto catheter in 3 cases and the Export catheter in 1 case was unsuccessful (Figure 3B). Subsequent use of the guide extension catheter provided a successful outcome with thrombus aspiration (Figures 3C and 3D). In 1 case involving the LCX artery, delivery of the GuideLiner to the lesion was unsuccessful and aspiration was performed proximal to the lesion with direct stenting of the lesion with a successful outcome noted both clinically and by angiography. 

No cases of adverse clinical outcome related to guide extension catheter utilization were noted and no mortalities occurred at hospital discharge. No vessel trauma related to the guide extension catheter requiring additional stenting occurred. No subsequent strokes occurred at procedure termination or in hospital. 

Discussion

During PCI, the avoidance of distal embolization and microvascular injury is paramount to an optimal outcome. The occurrence of distal embolization is especially concerning during PCI for ACS with the presence of thrombus within vessel lesions. Vessels with limited or no branches lend themselves to the development of large thrombi with the occurrence of a flow-limiting occlusive lesion. The thrombus usually extends proximally and distally to the nearest outflow branch or vessel. This is especially true in an SVG and in the body of the RCA. In-stent thrombosis is also characterized by severe thrombus burden, likely due to the presence of exposed metal stent struts. Further injury and possible infarct expansion associated with distal embolization occur to the jeopardized myocardium with device introduction, manipulation, and during performance of PCI to lesions with large thrombus burden.

Various methods of reducing distal embolization developed to date have centered on either reduction in thrombus burden with thrombus extraction or in protection against distal embolization utilizing proximal and distal embolic protection devices. The use of distal protection devices has failed to date to show a benefit in primary PCI.^8-10

Thrombus reduction devices include the previously named vacuum-assisted manual aspiration devices and mechanical aspiration devices such as the Angiojet Rheolytic Thrombectomy device (Possis Medical, Inc) and the X-Sizer device (ev3, Inc). Manual aspiration devices have seen larger growth and utilization during primary PCI than mechanical devices. Recent analysis of data from the Cath PCI registry of primary PCI indicates that between 2009 and 2010, aspiration thrombectomy was utilized in 18.9% of primary interventions, with manual aspiration accounting for 18.3% of all primary PCIs, and with rheolytic thrombectomy used in 0.6%. The use of manual aspiration thrombectomy appeared to steadily increase over the time period studied.¹

The Angiojet in Acute Myocardial Infarction (AiMI) randomized multicenter trial utilizing the Angiojet rheolytic thrombectomy device in primary PCI studied 481 patients with acute MI and found a paradoxically larger infarct size and higher mortality occurring with thrombectomy compared with conventional PCI.¹¹ The findings of the AiMI trial run contrary to other randomized trials utilizing the Angiojet device. In the JETSTENT (Angiojet Rheolytic Thrombectomy Before Direct Infarct Artery With Direct Stenting Alone in Patients With Acute Myocardial Infarction) trial, a total of 501 acute myocardial infarction patients with angiographic evidence of thrombus benefited from rheolytic thrombectomy with a higher early ST-segment resolution (85.8% vs 78.8%; P=.04) and freedom from major adverse cardiac events (MACE) at 1 year (85.2% vs 75.0%; P<.01). This appeared primarily driven by lower death and target vessel revascularization in the thrombectomy arm.¹² The VeGAS-2 (Vein Graft Angiojet Study) comparing rheolytic thrombectomy with intracoronary urokinase for coronary and vein graft thrombus demonstrated a higher procedural success rate with rheolytic thrombectomy, but no significant difference in immediate MACE rates. One-year follow-up did show a significantly reduced MACE rate in those receiving rheolytic thrombectomy.¹³ Limiting factors of this device included a learning curve in set-up and use, time constraints involved during primary PCI, and possible paradoxical device-induced distal embolization.

Manual aspiration thrombectomy has found favor for its rapidity of utilization, ease of set-up, lower cost, and the lack of need for associated bulky extraction machinery. The TAPAS trial utilizing the 6 Fr Export catheter in a total of 1071 patients demonstrated a better MBG, improved ST-segment resolution, lower persistent ST-deviation, as well as a trend to lower 30-day mortality in the thrombectomy arm versus conventional PCI. A lower 1-year cardiac mortality at 3.6% in the thrombectomy group compared with 6.7% in the conventional PCI group was also noted. Interestingly, the majority of the patients in both groups were treated with direct stenting.⁵ 

The Randomized evaluation of the effect of Mechanical reduction of DIstal embolization by thrombus aspiration in primary and rescue Angioplasty (REMEDIA) trial evaluated 100 patients with STEMI utilizing the Diver CE device and demonstrated improved MBG and better ST-segment resolution without a significant difference in clinical outcomes.¹⁴

In the DEARMI (Dethrombosis to Enhance Acute Reperfusion in Myocardial Infarction) study, the Pronto extraction catheter was studied in 148 AMI patients randomized to manual aspiration routinely prior to PCI, compared to no routine aspiration. Improved rates of ST-segment resolution (68% vs 50%; P<.05), better MBG scores, less no-reflow, and less CPK release were noted, without a significant benefit in clinical outcomes being demonstrated.¹⁵

A meta-analysis of 9 randomized trials with a total of 2417 patients with STEMI, comparing adjunctive manual thrombectomy with routine PCI, again demonstrated significantly improved postprocedural TIMI-3 flow (87.1% vs 81.2%; P<.001), postprocedural MBG 3 scores (52.1% vs 31.7%; P<.001), and less distal embolization (7.9% vs 19.5%; P<.001), but with improved 30-day mortality (1.7% vs 3.1%; P=.04).¹⁶ In the recent multicenter, prospective, randomized open-label Thrombus Aspiration in ST-Elevation Myocardial Infarction in Scandinavia (TASTE) trial, comparing routine thrombus aspiration and PCI with PCI only in 7224 patients with STEMI failed to demonstrate a benefit in the broad primary endpoint of all-cause mortality at 30 days.¹⁷ Trends toward reduction in recurrent hospitalization and stent thrombosis with routine aspiration did not reach statistical significance. This calls into question the routine use of thrombectomy as opposed to a more selective approach in ACS.

Current manual aspiration devices are limited in their tip extraction area through a 6 Fr delivery guide to between 0.80-1.24 mm² (Table 1). The 6 Fr GuideLiner V2 mother-and-child guide extension catheter allows a larger tip extraction area of 1.58 mm². The extraction area increases to the inner diameter of the guide (extraction area of 2.55 mm² for a 6 Fr Launcher guiding catheter) after the initial 25 cm of GuideLiner catheter length. The 6 Fr GuideLiner V2 catheter is compatible with guide catheters with inner diameters ≥1.78 mm (≥0.070˝). The extraction potential and safety of the 6 Fr GuideLiner in guide catheters with inner diameters >1.8 mm is not tested and not assured by this approach. The all-polymer collar provides flexibility and is less traumatic to the vessel compared with standard guide tips. The catheter offers trackability, allowing distal positioning within the vessel for thrombus aspiration. The seal provided by the 6 Fr mother-and-child catheter within the guide allows effective aspiration through its rapid exchange length. The radiopaque marker within the usable length of the catheter allows maintenance of the proximal open end of the catheter within the guide at all times. Continuous aspiration directly from the guide, with the ability for direct arterial pressure measurement, helps prevent remnant clot fragments being present within the guide after completion of aspiration. Standard thrombectomy catheters require the operator to ensure no dislodged clot remains in the guide following catheter removal by adequate guide aspiration. The vacuum extraction force generated by the 6 Fr GuideLiner V2 catheter within a 6 Fr guide (with an inner diameter 1.78-1.80 mm) utilizing a 30 cc syringe locked in vacuum mode appears in vivo to provide greater aspiration potential compared with a 6 Fr Pronto V4 device and the 6 Fr Export catheter in this limited observational patient series. Once in position within the vessel, the GuideLiner catheter further allows ease of stent delivery in tortuous or difficult anatomy post aspiration.

Care was taken to prevent distal and proximal embolization periprocedurally that would be detrimental to a successful outcome. Continuous aspiration during withdrawal of the GuideLiner catheter is of utmost importance, as the ability to aspirate larger thrombus fragments does lend to a higher risk of significant embolic events with thrombus dislodgment. The stoppage of aspiration during continuous vacuum suction would imply the presence of thrombus fragment occluding at the distal tip or in the body of the catheter, and utmost care needs to be taken at this point to avoid thrombus dislodgment. Avoidance of additional balloon dilatation either before or after stenting was utilized to avoid shearing clot with resultant distal embolization. No cases of stroke occurred in this case series. A recent meta-analysis of randomized trials of thrombectomy in primary PCI did show a trend to a higher stroke rate, with no time to event occurrence reported.¹⁸

Study limitations. This is an observational case series with no comparison group to demonstrate the feasibility of utilization of the guide extension catheter for thrombus aspiration during PCI involving vessels with severe thrombus burden. Larger randomized trials would afford greater evidence of benefit for this novel approach and allow wider utilization. It would take a larger series of patients to demonstrate with confidence the safety of this approach, despite the lack of adverse events noted in this observational series.

The GuideLiner extraction is also potentially limited by reduced distal deliverability and a limited working length for distal vessel thrombus extraction.

Conclusion

The use of manual aspiration thrombectomy for primary PCI is steadily increasing in use with recent data to suggest improved outcomes. The GuideLiner guide extension mother-and child catheter affords a novel method of thrombus aspiration with a larger extraction area within a conventional 6 Fr system. This observational series of patients studied retrospectively demonstrates the feasibility for thrombus aspiration of this approach, especially in vessels with a large thrombus burden.

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From the Division of Cardiovascular Diseases, Department of Medicine, Stony Brook University Medical Center, Stony Brook, New York.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted July 8, 2013, provisional acceptance given August 27, 2013, final version accepted December 3, 2013.

Address for correspondence: Anil J. Mani, MBBS, Division of Cardiology, HSC-T-16-80, Stony Brook University Hospital, Stony Brook, NY 11794. Email: Anil.Mani@stonybrookmedicine.edu