We studied the safety and feasibility of selective laser thrombolysis (LT) of coronary artery thrombi in 18 patients with acute myocardial infarction (AMI). A pulsed dye laser emitted 1.0ms duration pulses (3Hz at 480nm, a wavelength highly absorbed by thrombus and minimally absorbed by vessel wall constituents. Laser energy was delivered via flowing, fluid core light guides using radiographic contrast (Angiovist) as the optical core fluid with 0.3 or 0.5ml/s flow rates. Patient inclusion criteria were AMI with ST elevation in > 2 EKG leads, ongoing ischemia, contra-indications or failure of fibrinolytic drugs and coronary thrombi by angiography. 240-600 laser pulses between 60-75mJ per pulse were delivered. LT removed thrombi in 17/18 patients and mean TIMI grade coronary flow increased from 0.7 to 2.4. All patients then underwent adjunctive balloon angioplasty or atherectomy for residual underlying fixed stenosis. Mean coronary artery stenosis decreased from 99% pretreatment to 80% after laser to 24% after adjunctive therapy. Procedural success (residual stenosis < 50% and > TIMI grade 2 flow) was achieved in 17/18 patients (94%). No perforations were observed. There were no acute vessel closures, recurrent infarctions or deaths during hospitalization. We conclude that selective laser thrombolysis may be feasible and safe method of removing coronary artery thrombi in acute myocardial infarction.

Gregory, KW, Block, PD, Knopf WD, Buckley LA, Cates, CU, Laser thrombolysis in acute myocardial infarction. Lasers in Surgery and Medicine (Suppl.) 5:13, 1993.