Transmyocardial revascularization and autologous stem cells

Among the wide range of options that are available or under development for the treatment of coronary artery disease, one that has not drawn a great deal of attention is transmyocardial revascularization (TMR).  In TMR, a laser is use to drill multiple (15-40) millimeter sized channels through the myocardium in order to increase blood flow for patients with angina who may not be good candidates for bypass grafting. 

Two systems have been approved by the FDA for use in the U.S., an Ho:YAG laser system by Cardiogenesis and a CO2 laser system by PLC Medical Systems.

The principal reason that TMR has not drawn much attention, coincident with the small number of FDA approvals, is the lack of good data demonstrating the direct benefit of TMR in relief of angina.  Indeed, some cardiologists suggest that any benefit of TMR in in relief of angina is either due to denervation of the tissue or a placebo effect (Allen et al; Anesthesiology Clin 2008;26:501–519).  However, five-year follow-up data (which take some of the steam out of placebo benefits), suggest that the channeling does indeed increase vascularization and associated benefit in both angina and perfusion.

A paper was presented at the 2009 European Society of Cardiology Congress on the use of PLC Medical Systems’ CO2 TMR laser in conjunction with autologous stem cells.  As described in The Medical News:

This study is designed to examine the safety and feasibility of transplanting stem cells during TMR used in combination with coronary bypass grafting in patients with end-stage heart failure. According to the initial results of the study, this procedure was effective in improving cardiac function, as assessed by echocardiography and magnetic resonance imaging prior to therapy and post surgery, as well as three, six and twelve months afterwards. In addition, the treatment thus far has proven feasible and safe; no intra- or post-operative major adverse cardiac events occurred in the patients enrolled in the study.

The great majority of treatments for ischemic heart disease are alternatively addressed by coronary artery bypass grafting (CABG) or the use of angioplasty, typically with stenting (most often with drug-eluting stents).  TMR represents a unique technology that may, alone or even in combination with CABG or with, as described above, the use of autologous stem cells, provide clinical benefit for a subset of patients whose ischemic heart disease contraindicates CABG or angioplasty/stent alone.

The MedMarket Diligence report #C245 addresses the "Worldwide Market for Drug-Eluting, Bare Metal and Other Coronary Stents, 2008-2017."


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