How to deal with thrombus in ACS "Zap it" - Laser for Thrombus

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How to deal with thrombus in ACS "Zap it" -
Laser for Thrombus

• Suneel Talwar
• Dorset Heart Centre
• Royal Bournemouth Hospital

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Conflict of Interest

• Consultant/Advisory Board
• Spectranetics
• Clinical Research Grant Support
• Boston Scientific Corporation
• Cordis

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Excimer Laser
- Photoablation is the use of light to vaporize
and remove tissue

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Mechanism of Action
Three distinct mechanisms of action contribute to
Excimer Laser Photoablation
? Photochemical ? Photothermal ? Photomechanical
Breaking molecular bonds Producing thermal energy Creating kinetic energy
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Photochemical Mechanism Breaking Molecular Bonds
0 - 125 billionths of a second

• UV light pulse hits tissue for 125 billionths
  of a second
• 50 microns penetration
• Billions of molecular bonds fractured per pulse

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Photothermal Mechanism Producing thermal energy

• Absorption creates molecular vibration in tissue
• Vibration of molecules heats intracellular water
• Water vaporizes, rupturing cells
• Steam forms expanding vapor bubble

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Photomechanical Mechanism Creating kinetic energy
400 millionths of a second

• Expansion and collapse of vapor bubble breaks
  down tissue and clears by-products away from tip
• By-products of ablation are water, gas, and small
  particles (90lt10 microns size of red blood
  cell)

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The Excimer wavelength is very close to what is
used in eye surgery, indicative of its shallow
depth of penetration and hence safety
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Affinity for Photon Absorption
The Excimer wavelength is ideally suited for
absorption by the acute thrombus
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The Antiplatelet Effects of Laser Energy
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placebo
30mj
60mj
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Am J Cardiol 200493694-701
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The data obtained from the participating centres
was submitted to independent core laboratories
for quantitative coronary analysis and
statistical analysis.
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High risk patients included

• 30 of the patients had Diabetes
• 24 had previous CABG
• 23 had sustained a previous MI
• 28 had a contraindication to thrombolysis
• 13 presented to the cath lab with cardiogenic
  shock.
• The target vessel for revascularisation was an
  old saphenous vein graft in 21 of patients.

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The greater amount of thrombus the better the
result with the Laser
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High flow rates post laser
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The CARMEL Study-Complications
 
  Death 6(4)
  Laser Induced Perforation 0
  Laser Induced dissection 6(4)
  Acute closure 1(0.6)
  Laser induced no-flow 1(0.6)
  Stent induced no-flow 1(0.6)
  Groin bleeding complications 3 (2)
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Extended FAMILIFlow in Acute Myocardial
Infarction Patients after Laser Intervention -
Extended Pilot Study
Study Summary
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Extended FAMILI
Objective To benchmark microvascular coronary
blood flow in AMI patients after percutaneous
intervention that includes excimer laser coronary
atherectomy Study Design Prospective
non-randomized study in up to 20 sites, and up to
80 patients. Principal
Investigators Jeffrey Moses, MD Antonio
Columbo, MD
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EXTENDED FAMILI
RESULTS

• Laser Success Defined as TIMI 2-3 with gt 20
  reduction in DS post laser.
• Procedure Success Defined as TIMI 3 flow and lt
  50 DS on final angiogram without in-hospital
  MACE.
• - Laser Success 94
• - Procedure Success 96
• - 30 Day-MACE 3
• Low MACE correlated with the high Blush Scores

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EXTENDED FAMILI
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Thrombus Aspiration during Primary PCI TAPAS
study
Svilaas T et al. N Engl J Med 2008358557-567
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Extended FAMILI Conclusions

• Laser appears safe for thrombus ablation in Acute
  MI 30 Day MACE 3
• High Procedural Success Rate of 91
• Extended FAMILI appears equivalent in TIMI flow
  rates compared to other thrombectomy studies.
• Blush scores post-procedure appear to be
  significantly better than the other thrombectomy
  studies.
• .

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TAAMI Thrombus Ablation in Acute Myocardial
Infarction

• Randomised controlled study comparing a
  Laser-Stent strategy to a Balloon-Stent strategy
• N 200
• 5 sites in Poland

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TAAMI Thrombus Ablation in Acute Myocardial
Infarction

• Primary Endpoint
• Complete ST resolution and MBG 3 immediately post
  procedure
• Secondary Endpoint
• MACE 30 days
• MBG
• TIMI Flow rates post Laser
• TIMI frame count
• ST reolution at 60 minutes post procedure

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Our Approach in AMI

• Turn on the Laser prior to arrival of patient in
  the Lab to avoid delays
• Laser Catheter For most total occlusions start
  with a 0.9/1.4 catheter (both are 6F compatible)
• The laser will work over any 0.014 wire
• The vapor bubble works best in a saline medium
  (blood and contrast must be flushed prior to
  lasing)
• Activate the laser a few mm proximal to the
  start of the lesion
• to maximize the effect of the advancing vapor
  bubble
• and to avoid cavitation into the plaque
• Use higher energies and rates from the start
  (60/40)
• to create a larger vapor bubble
• and lead to better inhibition of platelet
  aggregation
• In order to get the effect of the advancing vapor
  bubble, the laser catheter must be advanced very
  slowly (rate of lt1mm per second)

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Conclusion

• The use of the excimer laser is feasible and safe
  in the setting of an AMI
• Laser treatment has been shown to result in
  significant thrombus removal, suggesting direct
  laser energy absorption and thrombus vaporisation
• The potential clinical benefits of the stunned
  platelet phenomenon await clinical confirmation
• A prospective randomised multicentre comparing
  this to convention angioplasty and stenting as
  well as thrombectomy is necessary to confirm the
  observations made so far