TCT 2008
Excimer Laser in Coronary and
Vascular Thrombotic Lesions:
Experience and Evidence
On Topaz, MD
Revascularization of Thrombus-Laden Lesions in AMI –
The Burden on the Interventionalist
On Topaz, MD
Throughout revascularization of coronary arteries and saphenous vein grafts in acute myocardial infarction (AMI) and acute coronary syndromes, the
burden of a thrombus can be "felt" by interventionalists. You know that ominous "feeling" when angiography demonstrates a large size thrombus — a
notorious marker of procedural complications. And, extensive literature clearly supports your concern,1-5 because visible thrombus
posses imminent risk of flow impairment, distal embolization, "no reflow" phenomenon with
microcircular obstruction and infarct expansion. If treated inadequately, thrombus turns into an active, "angry" component
causing further flow cessation and at times accounting for development of cardiogenic shock and even death. Can interventionalists discern the
presence, quantify the size of a thrombus and proceed accordingly with a dedicated treatment strategy? The answer is controversial. Traditionally, it
has been shown that angiography has a low sensitivity for detection of intracoronary thrombus, and it is likely that the true incidence of thrombus is
underestimated.67 However, with recent improved imaging in the cath lab and heightened awareness to visible thrombus and its deleterious effects on
outcome, interventionalists seem to have developed a more accurate appraisal of thrombus. When the accuracy of visual assessment of thrombus
was validated by independent core lab QCA analysis, it has been convincingly demonstrated that interventionalists can precisely identify and
differentiate between each level of TIMI thrombus grade and treat accordingly.8
The best method for the percutaneous undertaking of a large size thrombus in AMI is yet unknown and management strategies vary considerably.
Limited treatment with only heparin is still in use due to severe underestimation of the thrombus hazard. In contrast, attempts at complete thrombus
burden removal with mechanical devices appear to gain momentum. Unfortunately, many in the field still attempt to handle visible large size thrombus
with balloon only, perhaps due to a lingering influence of early days ("When I face a large coronary thrombus I just beat it to death with the balloon,"
was frequendy heard from one of the field's founders). Some continue to treat angiographic thrombus with the quite ineffective glycoprotein Ilb/IIIa
receptor antagonists,9'10 while others manage visible thrombus with unsubstantiated use of filter protection.11 Many then naively deploy a stent for
thrombus displacement hoping that it will somehow end up squeezing the thrombus and associated debris selectively onto die vessel's wall.