Low-powered lasers were first used in the early 1980s to produce transventr
icular channels as an adjunct to coronary artery bypass graft surgery (CABG
). Early results were encouraging, but because of the combined procedure, c
ould not be attributed directly to use of the laser . High-powered laser
s were introduced into clinical practice in 1990 . These lasers are powe
rful enough to create a transmyocardial channel with minimal thermal damage
to surrounding tissues . Clinical studies, using transmyocardial laser
revascularization (TMR) as the sole operative therapy for patients with sev
ere and diffuse coronary artery disease (CAD) who have Class III or IV angi
na, and are on medical therapy, have been conducted since 1993. Based on th
e results of these studies, the FDA granted approval for the use of TMR as
a sole therapy. Clinical studies are currently underway to assess the resul
ts of combined TMR and CABG . Results of four controlled randomized stud
ies have been published [5-8]. The data from two of these studies formed th
e basis for FDA approval of two different types of laser systems. The resul
ts of these studies have not provided any additional insights into the mech
anism of action of TMR, which remains the Achilles' heel of this procedure.
In this review, background information about the TMR procedure will be dis
cussed along with an analysis of the recently published randomized studies.
(C) 2001 Lippincott Williams & Wilkins, Inc.