compulsive thrombus management in stemi interventions

Compulsive ThrombusManagement in STEMIInterventions
Sameer Mehta, MD, MBAa,b,e,*,Jennifer C. Kostela, MS, MDc,d, Estefania Oliveros, MDe,Ana Isabel Flores, MDe, Camilo Pena, MDe,Salomon Cohen, MDf, Rebecca Rowen, BSd,Kevin Treto, BSg
KEYWORDS

� STEMI � Acute myocardial infarction � D2B time � Pharmacoinvasive � Thrombus management

KEY POINTS

� The Mehta strategy is a selective strategy for thrombus management in STEMI interventions basedon the thrombus grade, with direct stenting recommended for low-grade thrombus, thromboaspi-ration for moderate thrombus, and rheolytic thrombectomy for high-grade thrombus (dependingon suitable anatomy).

� Thrombus grade must be determined before thrombectomy by crossing the entire lesion witha guide wire for optimal grading.

� To reach this point of optimal thrombectomy, we advocate making successive passes until the lastpass makes no further progress in debulking.

� Thromboaspiration is the default strategy for thrombusmanagement, because aspiration thrombec-tomy devices are user-friendly, relatively inexpensive, and take no more than a balloon catheter toprepare and deploy.

INTRODUCTION of thrombus is especially challenging. Not only is

Thrombus is central to the pathophysiology of ST-elevated myocardial infarction (STEMI); its identifi-cation and compulsive management constituteabsolute essentials in optimal door-to-balloon(D2B) STEMI interventions. Even in elective percu-taneous coronary interventions (PCI), management

Disclosure: Sameer Mehta is Chief Medical Officer, Asiaauthors report no conflict of interest regarding the conta Miller School of Medicine, University of Miami, 1400 NoMedical Center, 3663 South Miami Avenue, FL 33133, U56-45 Main Street, Flushing, NY 11355, USA; d Ross UnivBrunswick, NJ 08902, USA; e Lumen Foundation, 55 PinNeurocirugia, Instituto Mexicano del Seguro Social, AveniHuixquilucan Edo de Mexico, 52779, Mexico; g Ross UniveWinter Springs, FL 32708, USA* Corresponding author. 185 Shore Drive South, Miami,E-mail address: [email protected]

Intervent Cardiol Clin 1 (2012) 485–505http://dx.doi.org/10.1016/j.iccl.2012.06.0062211-7458/12/$ – see front matter � 2012 Published by E

thrombus associated with increased abrupt vesselclosure, lower procedural success, and increasedmajor in-hospital complications, including deathand myocardial infarction (MI) but it is also associ-ated with increased incidence of emergencybypass surgery.1–4 Several mechanical adjunctive

Pacific, for the Medicines Company. The rest of theent herein.rthwest 12th Avenue, Miami, FL 33136, USA; b MercySA; c Internal Medicine, New York Hospital Queens,ersity School of Medicine, 630 US Highway 1, Northta Road, Miami, FL 33133, USA; f Departamento deda Club de Golf #3 Torre A Dep. 1501, Lomas Country,rsity School of Medicine, 786 Seneca Meadows Road,

FL 33133.

lsevier Inc. interventional.th

eclinics.com

mailto:[email protected]

http://dx.doi.org/10.1016/j.iccl.2012.06.006

http://interventional.theclinics.com

Mehta et al486

devices and pharmacologic options have showndiverse benefits in managing thrombus.5,6

In our structured approach to D2B STEMI inter-ventions that are particularly challenged by theconstraints of a clicking clock, identification of theculprit lesion and compulsive management ofthrombus remain the critical determinant of proce-dural success. Our compulsive methodology forthrombus management in STEMI interventionshas been developed from our extensive work withthe SINCERE (Single Individual Community Experi-ence Registry) database, which has included 1034short D2B interventions. The Mehta strategy forselective thrombus management has recentlybeen published inClinics of America7 andwe antic-ipate that the simplicity of our quantitatively basedstrategymakes it anattractivemanagementoption.

Table 1TIMI thrombus grade

0 No cineangiographic characteristics ofthrombus present

1 Possible thrombus present. Angiographyshows characteristics such as reducedcontrast density, haziness, irregularlesion contour, or a smooth convexmeniscus at the site of total occlusionsuggestive but not diagnostic ofthrombus

2 Thrombus present, small size: definitethrombus with greatest dimensions lessthan or equal to half vessel diameter

3 Thrombus present, moderate size: definitethrombus but with greatest lineardimension greater than half but lessthan 2 vessel diameters

4 Thrombus present, large size: as in grade3 but with the largest dimension greaterthan or equal to 2 vessel diameters

5 Total occlusion

Data fromTheTIMI-IIIA Investigators. Early effects of tissue-type plasminogen activator added to conventional therapyon the culprit coronary lesion in patients presenting withischemic cardiac pain at rest. Circulation 1993;87:38–52;and van’t Hof AW, Liem A, Suryapranata H, et al. Angio-graphic assessment of myocardial reperfusion in patientstreated with primary angioplasty for acute myocardialinfarction: myocardial blush grade. Zwolle MyocardialInfarction Study Group. Circulation 1998;97:2302–6.

PATHOPHYSIOLOGY OF THROMBUS

Atherosclerosis is thechronic inflammatoryprocessthat is fundamental to intimal plaque developmentin human vasculature, including the coronaryvessels. Several risk factors, including advancedage, male sex, genetics, hyperlipidemia, hyperten-sion, tobacco use, and diabetes mellitus, predis-pose to endothelial injury. Atherogenesis, orplaque formation, involves a dynamic interplay ofendothelial injury and inflammatory element recruit-ment (eg, lipoproteins, macrophages, platelets,smooth muscle cells, collagen) and deposition.8

In addition to locally produced mediators, prod-ucts of blood coagulation and thrombosis likelycontribute to atheroma evolution and complication.This involvement justifies theuse of the termathero-thrombosis to convey the inextricable linksbetweenatherosclerosis and thrombosis.8 Plaque is sub-jected toavarietyof intrinsicandextrinsic stressors,which lead toanacuteplaquechange.9 The rupture,fissuring, erosion, or ulceration of plaque initiatesthe thrombosis cascade in one of 2 pathways.8

The first pathway involves exposed collagen of thevessel wall. The exposed collagen of disruptedendothelium interacts with platelet glycoproteins.Specifically, platelet glycoprotein VI binds with thecollagen of the exposed vessel, whereas plateletglycoprotein Ib-V-IX interacts with the collagen-bound von Willebrand factor. This process notonly secures theadherenceofplatelets to thevesselwall but also initiates platelet activation and granulerelease, independent of thrombin.10 This pathwayleads to the formation of the white thrombi consist-ing of varying amounts of cellular debris, fibrin, andplatelets anda limited number of erythrocytes. Suc-ceeding the white thrombi, the second pathwayleads to formation of a red thrombi, anerythrocyte-rich and thrombin-rich complex.11

A membrane protein–tissue factor mediates thesecond pathway. Among its functions, tissue factorinitiates the extrinsic coagulation cascade. It bindsto the activated factor VII, which then activatesfactor IX, leading to the cascade that generatesthrombin. The thrombin then cleaves protease-activated receptor 4 on the platelet surface. Thiscleavage in turn activates platelets, causing therelease of adenosine diphosphate, serotonin, andthromboxaneA2, all ofwhichare agonists in theacti-vation of other platelets.10 Depending on the initialsize of plaque, both pathways can occlude thelumen of the coronary vessel, leading to anMI.12–16 The timing and intrinsic ability of the secondpathway to stabilize, enlarge, and increase thedensity of the primary white thrombi11 contributeto the complexity of management of thrombus,especially in the setting of D2B time constraints.

THROMBUS BURDEN

Clinical experience recommends against the useof balloon angioplasty in thrombus burden (TB),because they cause distal embolization andmyocardial necrosis, TB has been shown to

Management in STEMI Interventions 487

adversely affect clinical outcomes in both cere-brovascular accidents and acute coronarysyndromes.17–20 Barreto and colleagues under-took a retrospective review of patients with strokeand correlated the clinical outcomes to the angio-graphic TB, using the same classification schemeoutlined in Table 1. Compared with the patients

Table 2Trials of thrombus aspiration

Study Thrombectomy Device Pr

Aspiration Thrombectomy

Ciszewski et al,23 2011 Rescue/Diver CE (1

TOTAL24 2010 Export On

INFUSE AMI25 2011 Atrium ClearWay On

TASTE26 2010 Export On

EXPIRA27,28 2009 Export (1

Liistro et al,29 2009 Export (1

Lipiecki et al,30 2009 Export (5

TAPAS31 2008 Export (1

EXPORT32 Export (1

VAMPIRE33 2008 TVAC (1

Chao et al,34 2008 Export (1

PIHRATE35 2008 Diver CE (5

Andersen et al,36 2007 Rescue (1

Kaltoft et al,37 2006 Rescue (-)

DEAR-MI38 2006 Pronto (1

De Luca et al,39 2006 Diver CE (1

REMEDIA40 2005 Diver CE (1

Mechanical Thrombectomy

SMART-PCI41 2011 AngioJet On

JETSTENT42 2010 AngioJet (1

AIMI43 2006 AngioJet (1

X-AMINE ST44 2005 X-Sizer (–)

Antoniucci et al,45 2004 AngioJet (1

Napodano et al,46 2003 X-Sizer (1

Beran et al,47 2002 X-Sizer (1

Abbreviations: (1), improved endpoint; (5), neutral effect on eThrombectomy in Patients Undergoing Primary Angioplasty foDethrombosis to Enhance Acute Reperfusion in Myocardial InInfarct-Related Artery During Primary Percutaneous Coronaryized Study of the Export Aspiration Catheter; IS, infarct size; JEBefore Direct Infarct Artery Stenting with Direct Stenting Alomajor adverse cardiac and cerebral events; MBG, myocardHungarian Randomized Thrombectomy Trial; REMEDIA, Randof Distal Embolization by Thrombus Aspiration in Primary anAspiration with Rheolytic Thrombectomy in Patients Undergotion; TAPAS, Thrombus Aspiration During Percutaneous CoroTASTE, Thrombus Aspiration in ST-ElevationMyocardial Infarcttion flow grade; TOTAL, Trial of Routine Aspiration ThrombectPCI Alone in Patients With ST-Segment Elevation Myocardial Inration Thrombus Removal; X-AMINE ST, X-Sizer in AMI for NeThrombus Vacuum Aspiration Catheter.

with thrombus grades 0 to 3, patients withthrombus grade 4 required longer treatment timesand experienced increased mechanical clotdisruption, poor outcomes, and mortality.21 Usingthe same classification scheme, Sianos andcolleagues reported in their landmark work theimportance of TB in clinical outcomes in acute

imary and Clinical End Points

) Myocardial salvage, (5) In-hospital mortality

going

going

going

) MBG >2, (1) STR, (1) IS, (1) 2-y CD, (1) 2-y MACE

) STR, (5) 6-mo MACE

) IS

) MBG 0-1, (1) STR, (1) 1-y mortality, (1) 1-y CD

) MBG 3, (1) STR, (5) 30-d MACCE

trend) SR/NR, (1) 8-month MACE

) TIMI flow, (1) MBG

) STSR, (5) 6-mo mortality

) Left ventricular function

Myocardial salvage, (5) 30-d MACE

) MBG 3, (1) STR, (5) 30-d MACE

) TIMI flow, (1) MBG 3, (1) 30-d MACE

) STR, (1) MBG �2

going

) STR, (5) IS, (1) 1-y MACE

) IS, (–) TIMI flow, (–) MBG, (–) STR, (–) 30-d MACE

IS, (–) TIMI flow, (–) 30-d MACE

) STR, (–) 30-d MACE

) MBG 3, (5) 30-d MACE

) STR, (5) 30-d MACE

ndpoint; (–), worsened endpoint; AIMI, AngioJet Rheolyticr Acute Myocardial Infarction; CD, cardiac death; DEAR-MI,farction; EXPIRA, Thrombectomy with Export Catheter inIntervention; EXPORT, Prospective, Multicentre, Random-TSTENT, Comparison of AngioJet Rheolytic Thrombectomyne in Patients with Acute Myocardial Infarction; MACCE,ial blush grade; NR, no-reflow; PIHRATE, Polish-Italian-omized Evaluation of the Effect of Mechanical Reductiond Rescue Angioplasty; SMART-PCI, Comparison of Manualing Primary PCI; SR, slow-reflow; STSR, ST-segment resolu-nary Intervention in Acute Myocardial Infarction Study;ion in Scandinavia; TIMI, thrombolysis in myocardial infarc-omy with Percutaneous Coronary Intervention (PCI) Versusfarction Undergoing Primary PCI; VAMPIRE, Vacuum Aspi-gligible Embolization and Optimal ST Resolution; TVAC,

Table 3Strategy based on thrombus grade for management of the STEMI lesion: Mehta classification

Grade Thrombus Definition Angiographic ExamplesMehta

Classification

Technical Tips of Use

Aspiration catheter AngioJet

0 No cineangiographiccharacteristics of thrombuspresent

Direct stent �predilatation

Most effective with freshdot; organizedthrombus is moreresistant to debulking

Have different profiles,different pushability,tractability, andaspiration rates

All are 6-Fr compatible; itis useful to stock and befamiliar with the use ofat least one

Flush catheter lumen wellbefore use because itfacilitates bettertracking over the wire

Avoid kinking thecatheter: advanceslowly over the initial,softer portion of thecatheter

Monitor distal tip of theguide wire as theaspiration catheter isadvanced; it is notuncommon for theguide wire to advanceduring this maneuver

Advance the aspirationcatheter through thelength of occlusivedisease

Can be used from theradial route. AlthoughLAD (left anteriordescending) and someLCX (left circumflex)may not need a TPM(temporarypacemaker), we placeTPMs in all AngioJetprocedures

Often, multiple passes arerequired. Try to pauseafter every 2–3 passesto enablehemodynamics to berestored, to optimizeguide wire and guidingcatheter support, andto evaluate the results

Often, just the firstpassage restoresadequate flow

Resistant and stubbornthrombus requiresmore distaladvancement that mustbe performed morecarefully

Avoid advancing in severetortuosity and in vessels<2 mm

Because the AngioJet isused for large TB andhigh thrombus grade,consider abciximab asadjunctive therapy

1 Possible thrombus present.Angiography showsreduced contrast density,haziness, irregular lesioncontour, or a smoothconvex meniscus at the siteof total occlusion,suggestive but notdiagnostic of thrombus

2 Thrombus present, small size:definite thrombus withgreatest dimensions lessthan or equal to half vesseldiameter

Aspirationthrombectomy

3 Thrombus present, moderatesize; definite thrombus butwith greatest lineardimension greater thanhalf but less than 2 vesseldiameters

4 Thrombus present, large size;as in grade 3, but with thelargest dimension �2vessel diameters

AngioJet5 Total occlusion

Mehta

etal

488


coronary syndromes.22 Compared with small TB(grades 0–3), these investigators found that largeintracoronary TB (grade 4) was an independentpredictor of mortality and major adverse cardio-vascular event (MACE). Evidently, clinical outcomeis dependent on TB.

Thrombus removal before STEMI interventionhas proved superior to standard PCI alone asshown by randomized controlled trials and retro-spectives studies as outlined in Table 2.

Table 4Thrombectomy devices

Device Unique Character

Aspiration Thrombectomy

Diver CE Available in 2 versthrombus remolumenwithout safter symptom

Ultraflexible shaf

Export Optimal kink resisvariable braidin

The distal end is fThe proximal endpushability

Pronto Embedded longitresistance

Patented Silva dis

QuickCat 6F aspiration cathkinks easily, andof catheter

Mechanical Thrombectomy

AngioJet Rheolytic thrombthe distal cathecollect the thro

Only thrombectomand synthetic g

X-Sizer Uses a helix cutteThe Archimedes squickly drawing

Despite the positive clinical outcome of theTAPAS (Thrombus Aspiration During Percuta-neous Coronary Intervention in Acute MyocardialInfarction Study) trial,48 we strongly believe thatthis study is constrained by having a singlestrategy for all-comers without volumetric adjust-ments for TB. Although philosophically we remainin complete agreement with the intent to aspiratethrombus, as is clearly demonstrable in the TAPAStrial, we believe that this sole aspiration strategy

istics

ions: aspiration lumen with side holes (for freshval, 2–6 h after symptom onset) and aspirationideholes (fororganized thrombus removal, 6–24honset)t from increased trackability

tance and deliverability as a result of full wallg technology:lexible with high-density variable braidinghas low-density variable braiding for support and

udinal wire enhances deliverability and kink

tal tip provides vessel protection

eter with a low-profile moderate suction ability,could perform better with more tensile strength

ectomy system that uses high-velocity saline jets atter tip. The jets create a negative pressure tombusy device indicated for native coronary arteries

rafts

r at the distal tip of the cathetercrew is designed to grab thrombus on contact,it in, shearing, and removing it

Mehta et al490

does not suffice for all thrombus grades and itparticularly fails to effectively treat dense, orga-nized thrombus that is commonly seen in delayedpresentations. Dense, organized thrombus in late-presenting anterior MI (AMI) is the commonestpresentation in developing countries that lacksophisticated ambulance systems and STEMIsystems of care. In such situations, it is infrequentto find the easy-to-treat, white thrombus with aspi-ration thrombectomy, as was shown in the TAPAStrial. Dense, organized thrombus, which is presentoften in these infarct-related vessels, is simply toocomplex to manage with simple, presently avail-able, aspiration catheters. Based on our work,we strongly consider that such lesions are bettermanaged by mechanical devices, such as theAngioJet (Possis Medical, Minneapolis, MN),provided the anatomy is favorable (avoid severetortuosity and vessels <2.5 mm). Although thereis little evidence of benefit for such use, we alsobelieve that the excimer laser coronary

Table 5Step-by-step technique for STEMI interventions

Step Technique

1 Obtain a clean, 6F arterial access

2 Cineangiography with 6F diagnostic catheterof the noninfarct-related vessel

3 6F guiding catheter for culprit vesselcannulation

4 Hydrophilic 0.36-mm (0.014-in) guide wire

5 Accurately assessing thrombus grade andusing a selective thrombectomy strategy

6 Abciximab for large TB

7 Stenting

8 Liberal intracoronary nitroprusside

9 Left ventriculography

10 Sheath removal

Prefer rheolytic mechanical thrombectomy

A For thrombus grade 4 and 5

B In large vessels with voluminous thrombus

C Saphenous vein graft (SVG) STEMI interventio

D For treating dense, organized thrombus, in p

E Failure to treat thrombotic lesions with aspir

angioplasty (ELCA) may prove effective in ablatingsuch dense, thrombotic lesions. The speed oflaser angioplasty (single pass with appropriatelysized catheter) makes the use of ELCA particularlyattractive for such applications.Concerning clinical support for our selective

thrombus management strategy, the drawbackof using a single-aspiration thrombectomy strat-egy has been partially corrected in the JETSTENT(AngioJet Thrombectomy and Stenting for Treat-ment of Acute Myocardial Infarction) trial, whichuses angiography to grade the TB beforethrombus aspiration and subsequent PCI interven-tion.45 Yet, despite using a selective strategy forthrombus intervention, the overall results of thetrial provide little advance. For almost the samereasons of lacking a selective strategy, we havesome reluctance about the design for the new in-tracoronary abciximab infusion and aspirationthrombectomy in patients undergoing percuta-neous coronary intervention for anterior ST

Comments

Routinely from the right femoral route (radialroute for failed attempt with both groins,and for selected pharmacoinvasive, transferpatients)

Two orthogonal views for left coronary arteryand a single left anterior oblique projectionfor the right coronary artery

Obtaining set-up shots that precisely definethe occluded segment

Particularly useful for crossing thromboticlesions

Direct stenting for low-grade thrombus,thromboaspiration for moderate thrombus,and mechanical thrombectomy for large TB

Preferably via intracoronary use

Drug-eluting stent for left anteriordescending, diabetic, long lesions, andsmall vessels

After confirming satisfactory stent result andremoving the guide wire

In right anterior oblique projection

With closure device

ns

articular, in patients who present late

ation thrombectomy


segment elevation myocardial infarction (INFUSEAMI) trial.25 This disparity notwithstanding, weemphatically agree with the strategy in the INFUSEAMI trial about the use of bivalirudin as a founda-tion anticoagulant for STEMI interventions.

Because TB or grade can be quickly assessedangiographically, a thrombus-grade approach ispractical. This is the major advantage of the Mehtaclassification (Table 3), because it providesa selective strategy for thrombus management,based on the thrombus grade. This methodologycontradicts the notion that thrombus can bemanaged by a single modality, as proposed bythe TAPAS trial, which used thromboaspirationas an effective strategy, irrespective of thethrombus grade.48 In this article, and in the articleon illustrated cases by Mehta and colleagues else-where in this issue, we present numerous cases

Fig. 1. Primary PCI for STEMI with low TB. Lesions with loneed for more complex catheters or procedures. The follwith an acute anterior wall STEMI. The initial angiogramlesion with a low grade 0 to 1 TB (A). The lesion was direa D2B time of 56 minutes, and final angiography showing

that support our rationale for a selective,thrombus-grade–based strategy. Specifically, wecite numerous procedures in which dense, orga-nized thrombus could not be effectively managedby thromboaspiration, instead requiring a changeto mechanical thrombectomy. Table 4 outlinesavailable thrombectomy devices (within the UnitedStates). In Table 5, we have identified 5 distinctsituations in which the use of mechanical throm-bectomy seems mandatory. Some of the mostmemorable successes in the SINCERE databaseused these tenets. The situation with organized,dense thrombus in late-presenting patients withSTEMI is the most noteworthy of these cases.These can be difficult cases, and their manage-ment (from crossing the impenetrable lesions todebulking them) requires considerable skills, andoften, mechanical thrombectomy. The technical

w-grade thrombus can be treated safely without theowing angiograms are from a patient who presentedshowed a critical mid-left anterior descending culpritct stented with a 3.5-mm drug-eluting stent (B) withTIMI 3 flow (C).

Mehta et al492

tips and teaching highlights for performing thesespecific cases are described in detail in thecomments after the illustrated cases, and wehope that they show our clinically based strategyto guide STEMI interventions.

MEHTA STRATEGY FOR THROMBUSMANAGEMENT

The TIMI (thrombolysis in myocardial infarction)flow grade classifies the thrombus based on angi-ography (see Table 1) and is the basis for theMehta strategy for thrombus management (seeTable 3). The pioneering work by Sianos andcolleagues22 led to this classification, which hasnow been routinely practiced in more than 1034short D2B STEMI interventions in the SINCEREdatabase.49 Table 4 presents a formulation of thestepwise technique of performing the entire STEMIprocedure using this standardized algorithm.Optimal angiographic visualization of thrombus

is the first step; however, thrombus is labile andits grading for the purpose of further managementis better performed after crossing the thrombotic

Fig. 2. Direct stenting for low-grade thrombus. (A) Grade 1metal stent). (C) After stenting.

STEMI lesion with the guide wire. Balloon cathe-ters are not recommended because they causedistal embolization and myocardial necrosis. Werecommend their use for only 3 rare situations:(1) uncertainty as to whether the guide wire isin the true lumen, after it has crossed a thromboti-cally occluded segment; in this situation, a small2.0-mm balloon can be rapidly inflated; (2) fora patient with overwhelming ischemia andmassiveST segment elevation; the role of the balloon is toachieve some TIMI flow rapidly; however, even thismay result in thrombus migration and this strategymust be used with discretion; and (3) unavailablethrombectomy catheters or devices.Often, there is no change in thrombus grade, but

thrombus grade 5 most commonly is downsizedafter wire passage. If the extent of thrombus issmall (thrombus grade 0–1), direct angioplastyand stenting may be sufficient (Figs. 1–4).Moderate TB, grades 2 to 3, warrants pretreat-ment with an aspiration catheter. Several random-ized controlled trials have shown that aspirationcatheters result in superior myocardial blushgrade, ST-segment resolution, improved clinical

thrombus. (B) Direct stenting with 4.0-mm BMS (bare

Fig. 3. Direct stenting for low-grade thrombus. (A) Grade 1 thrombus. (B) Direct stenting with 4.0-mm BMS.(C) After stenting.


outcome, rates of TIMI 3 flow rates, and decreasedangiographic evidence of distal emboliza-tion.45,48,49 Figs. 5–8 show aspiration pretreat-ment in a STEMI with moderate TB.

GRADE 0 TO 1

With low thrombus grades, direct stenting is anacceptable strategy and we advocate it over theuse of predilatation, which carries its individualrisk of distal embolization. Clearly, we complementthis strategy, as with all STEMI interventions, withthe use of intracoronary vasodilators. Althoughvarious pharmacologic agents can be used forthis purpose (adenosine, verapamil, diltiazem,nicardipine, clevidipine), our preferred agent asan intracoronary vasodilator is nitroprusside. Ourtechnique of using intracoronary nitroprussidehas been highlighted in other articles elsewherein this issue.

GRADE 2 TO 3

Moderate TB management with aspiration cathe-ters can be augmented with some practical tech-niques. Passes with the aspiration cathetersshould be made until there is no angiographicevidence of thrombus; often just 2 passes aresufficient. It is important to advance the catheterthroughout the length of thrombus. Despite theirease of use and effectiveness, the aspiration cath-eters are not perfect monorail devices, and atten-tion should be paid to the tip of the guide wire asthese catheters are advanced. Reducing theimaging magnification and monitoring the distalend of the guide wire as the aspiration catheter isadvanced are practical techniques in preventingadverse results. Thrombus often clogs the aspira-tion holes of these catheters, halting aspiration.Before abandoning them as unsuccessful, it isimportant to remove the catheter, flush itprofusely, and reuse. In rare situations, the

Fig. 4. Direct stenting for low-grade thrombus. (A) Grade 1 thrombus. (B) Direct stenting with 4.0-mm BMS.(C) After stenting.

Mehta et al494

aspiration catheter drags the tail of a long threadthrombus which may get dislodged. In 1 clinicalcase documented in the SINCERE database,a thrombus was dragged from the obtuse marginalbranch and lodged at the bifurcation of the leftcircumflex; this was managed by suctioning withthe AngioJet. The newer, aspiration catheters areeasy to use and their use has now become thedefault strategy for managing thrombus for mostlesions, except for those with very large TB, inwhom mechanical thrombectomy is invaluable.

Grade 4 to 5

Larger TB (grades 4–5) presents more challenges.As shown in Figs. 9–12, aspiration may be insuf-ficient in patients with grade 4 to 5 thrombus. Insuch patients, thrombectomy may be justified.The AngioJet catheter is an effective device for

debulking such voluminous thrombi. Thrombusis aspirated and extracted after high-velocitywater jets create a vacuum in this catheter-based system.50 Compared with stenting alone,trials have found the AngioJet to be successfulin improving epicardial flow, frame count,myocardial blush grade, and infarct size.45,51

The VeGAS (Vein Graft AngioJet Study) 2 trialfound that the AngioJet catheter system wassuperior to intracoronary urokinase administra-tion in improving device and procedural success,with lower major adverse effects, bleeding, andvascular complications.52

Some practical techniques in using the AngioJetthrombectomy device improve clinical outcomes.The new Spiroflex AngioJet device is quick to setup; the speed of set-up is vital to maintain thegoals of achieving short D2B times. The new cath-eters, including the 4F thrombectomy catheter,

Fig. 5. Primary PCI for STEMI with moderate TB. Lesions with moderate-grade thrombus are best treated withaspiration thrombectomy devices, before definitive treatment and stenting. The next angiogram showsa moderate thrombus (grade 3) in a patient with ST-elevation in leads D to V. The first angiogram showsa discerning mid-right coronary artery culprit lesion with a moderate-grade thrombus (A). The lesion was treatedthen with an aspiration catheter (B) followed by angioplasty and stenting with a 4.0-mm bare-metal stent witha D2B time of 61 minutes with great results (C).


track well. Thrombectomy should be performedthrough the length of thrombus; the most frequenterror with this device is inadequate passes and notablating through the complete length of the throm-botic segment. In addition to being a critical devicefor removing large and bulky thrombus, the Angio-Jet is invaluable in managing organized thrombusin late-presenting patients. The SINCERE data-base includes several successful AngioJetprocedures in which aspiration thrombectomycatheters were unsuccessful in aspirating suchdense, organized thrombus. Temporary pacing isrecommended for all AngioJet procedures. Thepacing wire can be removed after the procedure,even although pacing is rare.

We offer another valuable tip for using both theaspiration and mechanical catheters: when isthrombectomy deemed adequate? To reach this

point of optimal thrombectomy, we advocatemaking successive passes until the last passmakes no further progress in debulking. Some-times, this goal can be difficult to assess by angi-ography, but this broad strategy providesa philosophic approach to approaching thesethrombotic lesions with thrombectomy devices.

The Mehta strategy is offered as “a selectivestrategy for thrombusmanagement in STEMI inter-ventions based on the thrombus grade, with directstenting recommended for low-grade thrombus,thromboaspiration for moderate thrombus, andrheolytic thrombectomy for high-grade thrombus(depending on suitable anatomy). For unsuitableanatomy or unavailability of rheolytic thrombec-tomy, a strategy of de thrombosis with intracoro-nary abciximab via the ClearWay catheter is anacceptable approach.”

Fig. 7. Thromboaspiration for moderate thrombus. (A) Grade 1/2 thrombus. (B) Thromboaspiration performed byexport catheter. (C) After thrombectomy. (D) 3.5-mm BMS. (E) After stenting.

Fig. 6. Thromboaspiration for moderate thrombus. (A) Grade 2 thrombus. (B) Thromboaspiration performed byexport catheter. (C) After thrombectomy. (D) 3.5-mm BMS. (E) After stenting.

Mehta et al496

Fig. 8. Thromboaspiration for moderate thrombus. (A) Grade 2/3 thrombus. (B) Thromboaspiration performed byexport catheter. (C) After thrombectomy. (D) 3.5-mm drug-eluting stent. (E) After stenting.

497

LIMITATIONS OF THE MEHTA STRATEGY

1. Several catheterization laboratories are notequipped with mechanical thrombectomydevices (AngioJet [Possis Medical Inc, Minne-apolis, Minnesota], X-Sizer [eV3, White BearLake, Minnesota], and ThromCat [KenseyNash Corporation, Exton, Pennsylvania]), oroperators are not familiar with their use or findtheir use causes D2B delays. In these situa-tions, we believe that drug delivery of abcixi-mab via the ClearWay catheter (Atrium)provides a good alternative.

2. The same recommendation as number 1 existswith unfavorable anatomy for the AngioJet (ourpreferred mechanical thrombectomy device),although the newer 4F catheter has narrowedour relative contraindications for their use inSTEMI interventions (<2.5-mm vessel size andsevere tortuosity).

Fig. 9. Primary PCI for STEMI with large TB. Lesions with hbefore definitive treatment and stenting. The initial aacute inferior wall STEMI, showed a large amount of thrinitially used for rheolytic thrombectomy and after angioexcellent (C).

3. Although we recommend mechanical throm-bectomy for large thrombus grade, we havebeen surprised in numerous cases in whichthromboaspiration works well in large thrombusgrade. We have presented numerous examplesof these situations (Figs. 13–18); thrombusgrade is high (4–5), yet excellent debulking isobserved with the simple aspiration catheters.We suspect that this situation happens inpatients who present very early, with fresh,red, soft thrombus that is easily and completelyaspirated with these catheters. This observa-tion is contrary to our proposed hypothesis,yet this powerful observation is shared for itstremendous practical benefit. We haveobserved this finding most often in thromboticocclusions in which it made more sense toadvance a small aspiration catheter thana more bulky mechanical device. This is alsoa rare situation in which we use a low-profile

igh-grade thrombus may require some thrombectomyngiogram on this patient, who presented with anombus (grade 3–4) (A). An AngioJet catheter (B) wasplasty and stenting, the final angiographic result was

Fig. 10. Rheolytic thrombectomy for large thrombus. (A) Grade 5 thrombus. (B) Rheolytic thrombectomy per-formed with AngioJet. (C) After thrombectomy. (D) 4.0-mm BMS. (E) After stenting.

Fig. 11. Rheolytic thrombectomy for large thrombus. (A) Large, bulky thrombus in mid-left anterior descendingartery. (B) Rheolytic thrombectomy performed with AngioJet. (C) After thrombectomy. (D) After stenting, finalresult.

Mehta et al498

Fig. 12. Rheolytic thrombectomy for large thrombus. (A) Grade 5 thrombus. (B) Rheolytic thrombectomy per-formed with AngioJet. (C) After thrombectomy. (D) 4.5-mm BMS. (E) After stenting.


balloon to verify that the guide wire is in the truelumen. Based on an increasing number ofsimilar cases, as shown in Figs. 13–18, wepostulate thromboaspiration as a defaultstrategy. The rationale for this strategy is

Fig. 13. Thromboaspiration as default strategy. (A) Gradexport catheter. (C) After thrombectomy. (D) 3.5-mm Xien

simple: the aspiration catheters are user-friendly, relatively inexpensive, and take nomore than a balloon catheter to prepare anddeploy. With this methodology, we gradethrombus nevertheless, then quickly make

e 5 thrombus. (B) Thromboaspiration performed byce drug-eluting stent. (E) After stenting.

Fig. 14. Thromboaspiration as default strategy. (A) Grade 5 thrombus. (B) Thromboaspiration performed byexport catheter. (C) After thrombectomy. (D) 4.0 BMS. (E) After stenting.


Mehta et al500



a pass with the aspiration catheter, and eitherpersist with more thromboaspiration oradvance to using mechanical thrombectomy.

4. Similarly, we have also experienced numerouscases, even with moderate TB, in which thedense, organized thrombus cannot be debulkedwith thromboaspiration. In these situations, the

Fig. 17. Thromboaspiration as default strategy. (A) Gradexport catheter. (C) After thrombectomy. (D) 4.0 BMS. (E)

default strategy gives way to using mechanicalthrombectomy, consistent with the Mehtaclassification.

5. Although several newer trials seem to validateour strategy with the appropriate presentlyavailable device, greater scientific validity isneeded. Founded on extensive experience,

e 5 thrombus. (B) Thromboaspiration performed byAfter stenting.

Fig. 18. Thromboaspiration as default strategy. (A) Grade 5 thrombus. (B) Thromboaspiration performed byexport catheter. (C) After thrombectomy. (D) 4.0 Xience V drug-eluting stent. (E) After stenting.

Mehta et al502

we feel confident in our strategy for effectivethrombus management for STEMI interven-tions; nevertheless, this strategy needsendorsement by clinical trials. A single indi-vidual experience, irrespective of its expertise,cannot substitute for data from large, random-ized, clinical trials or established guidelines.

6. We have also explored the possibilities of usinga time-to-presentation–based strategy forapplying a thrombectomy device. This idea isakin to use of prehospital lysis, as in the CAP-TIM (Comparison of Angioplasty and Prehospi-tal Thrombolysis in Acute Myocardial Infarction)trial, in which the cohorts of patients with veryearly AMI benefit from very early lysis.53 Thissituation probably results from effective lysisof a fresh clot. The same principles as very earlylysis may be extended to the use of a thrombec-tomy device during STEMI, with thromboaspi-ration working as effective therapy for earlypresenters (<3 hours) and mechanical throm-bectomy for late presenters (>3 hours). Ofcourse, calculating the time to presentation isnot without its challenges. We also recognizethe numerous variables that affect thrombuspresentation in STEMI and the heterogeneityof thrombus and of its oversimplification. Yet,this topic deserves further attention, because

interventional management of soft, red, earlythrombus is different than that of dense, orga-nized thrombus.

SUMMARY

The management of thrombus in STEMI interven-tions is of paramount importance. To accomplishthis complex task successfully, a systematicapproach is necessary. Because of the dynamicnature of thrombosis formation, an interventionalapproach must incorporate a thrombus gradingsystem, which also integrates mechanical adjunctdevices. The limitations of equivocal clinicalresults from multiple trials fail to endorse the truepotential of mechanical adjunct devices for STEMIintervention. The Mehta strategy skillfully tacklesboth problems. The algorithm has established (1)a thrombus-graded adjunct device approach tomanaging TB, which has already produced excel-lent clinical results (as shown in the SINCEREdatabase), and (2) a scientific platform for futurerandomized multicenter controlled studies of theMehta strategy. Even if perfection is obtained inthe catheterization laboratory, patient educationand legislation to streamline the STEMI proce-dures are still hurdles that must be overcome.


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