Transmyocardial laser revascularization: Experimental and clinical results

BACKGROUND: Transmyocardial laser revascularization (TMR) is an emerging therapy for the treatment of coronary artery disease not amenable to percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass surgery (CABG). OBJECTIVE: To summarize the experimental and clinical experience to date with TMR. Specifically, the history of the technique, preclinical and clinical data, patient selection and perioperative management, as well as future applications of TMR are discussed. DATA SOURCES: All English language articles pertaining to TMR published through March 1999. MEDLINE was searched with the key words 'myocardial revascularization', 'lasers' and 'laser surgery', as well as the text terms 'transmyocardial laser revascularization', 'TMR' and 'TMLR'. Reference lists of articles obtained from MEDLINE were studied for additional references not discovered in computer searches. Pertinent abstracts published within the past two years were reviewed as well. STUDY SELECTION: Studies that produced original experimental or clinical data were selected. DATA SYNTHESIS: Experimental studies demonstrate that TMR channels become occluded in the early postoperative period. However, experimental data indicate that laser injury appears to promote neovascularization with secondary improvements in perfusion in treated regions. Human clinical studies confirm the efficacy of the procedure, with significant improvements in anginal class up to at least one year postoperatively, although documented improvements in myocardial perfusion have been less consistent. Perioperative morbidity and mortality appear to be increased in patients with unstable angina or reduced left ventricular function. CONCLUSIONS: With careful patient selection and peri- operative management, TMR is a safe and effective therapy for severe angina pectoris secondary to end-stage coronary artery disease. Additional studies are required to define the role of TMR in combination with PTCA, CABG and angiogenic growth factors, as well as the safety and efficacy of catheter-based TMR.