State of the Art: Trans‐ and Percutaneous Myocardial Revascularization

Traditional approaches to improve myocardial perfusion in patients with coronary artery disease previously have applied methods to restore blood flow through the existing coronary vessels. In contrast laser myocardial revascularization techniques rely on the creation of new myocardial channels to produce effects leading to improved perfusion and reduction in angina. Laser transmyocardial revascularization (TMR) is performed via open thoracotomy to access the epicardial surface, is relatively safe, and appears to have a beneficial effect on myocardial perfusion. Percutaneous myocardial revascularization (PMR), however, uses transmission of laser energy along a flexible, fiber‐optic catheter, thus permitting creation of laser channels from the endocardial surface of the left ventricle via a femoral artery approach. Tissue responses to lasers are dependent upon the energy used and its means of delivery, thermal, mechanical, or chemical effects of laser channel creation may all impact on the myocardium, although stimulation of angiogenic growth factors, with consequent neovascularization appears to be the principal underlying mechanism responsible for improvement in myocardial perfusion. Patients with severe, chronic angina refractory to drug therapies and in whom standard surgical or angioplasty revascularization approaches are not possible may be candidate for TMR or PMR techniques. Clinical studies of TMR have described reductions in angina class, hospital admissions, and the number of myocardial perfusion defects. PMR studies have reported improvements in angina class, increased exercise duration, and trends toward improvement in radionuclide perfusion defects. Randomized trials are underway and will provide more definitive insights into the future clinical role of laser myocardial revascularization techniques.