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

Suneel TalwarDorset Heart Centre

Royal Bournemouth Hospital

Conflict of Interest

• Consultant/Advisory Board– Spectranetics

• Clinical & Research Grant Support– Boston Scientific Corporation– Cordis

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

Excimer Laser

Photochemical

Photothermal

Photomechanical

Breaking molecular bonds

Producing thermal energy

Creating kinetic energy

Mechanism of Action

Three distinct mechanisms of action contribute to ExcimerLaser Photoablation

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

0 - 125 billionths of a second

Photochemical Mechanism: Breaking Molecular Bonds

Absorption creates molecular vibration in tissue

Vibration of molecules heats intracellular water

Water vaporizes, rupturing cells Steam forms expanding vapor bubble

Photothermal Mechanism: Producing thermal energy

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 (90%<10 microns = size of red blood cell)

400 millionths of a second

Photomechanical Mechanism: Creating kinetic energy

The Excimer wavelength is very close to what is used in eye

surgery, indicative of its shallow depth of penetration and hence safety

The Wavelength StoryThe Wavelength Story

Excimer (CVX-300Ø)

InfraredUltraviolet

UltravioletUltraviolet vs vs. Infrared. Infrared

Excimer (ophthalmology)

CO2

Ho:YAG

308nm193nm 2090nm

10600nm

Spectrophotometric Spectrophotometric Scan ofScan ofFresh ThrombusFresh Thrombus

0

10

20

30

40

50

60

70

0 400 500 600

Wavelenth (nm)

% A

bsor

ptio

n

Lee et al . Am J Card. 1983: 52; 876-877

Affinity for Photon AbsorptionAffinity for Photon Absorption

The Excimer wavelength is ideally suited for absorption by the acute thrombus

The Antiplatelet Effects of Laser Energy

placebo

60mj

30mj

The Laser inhibits platelet aggregationacting like a localized IIB IIIa Inhibitor

Am J Cardiol 2004;93:694-701

The data obtained from the participating centres was submitted to independent core laboratories for quantitative coronary analysis and statistical analysis.

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.

The greater amount of thrombus the betterthe result with the Laser

High flow rates post laser

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%)

Study SummaryStudy Summary

Extended FAMILIFlow in Acute Myocardial Infarction Patients after Laser Intervention - Extended Pilot Study

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

EXTENDED FAMILIRESULTS

Laser Success: Defined as TIMI 2-3 with > 20% reduction in %DS post laser.

Procedure Success: Defined as TIMI 3 flow and < 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

EXTENDED FAMILI

Extended FAMILIExtended FAMILI

n=79 n=100 n=101 n=240 n=240 n=252 n=249

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

Registry RCT-DeviceArm

RCT-Control PossisAngiojet

RCT-Control Guardwire Control

Ext FAMILI X-Amine AIMI EMERALD

Blush 0/1

Blush 2

Blush 3p<0.001

p<0.001

p=0.009

p<0.001

p<0.001

p<0.001

Blush Post-ProcedureBlush Post-Procedure

Svilaas T et al. N Engl J Med 2008;358:557-567

Thrombus Aspiration during Primary PCI: TAPAS study

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.

.

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

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

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 <1mm per second)

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