Report from the workforce on evidence-based surgery
The Society of Thoracic Surgeons practice guideline series: transmyocardial laser revascularization

https://doi.org/10.1016/j.athoracsur.2004.01.007Get rights and content

Abstract

Background

Patients with chronic severe angina refractory to medical therapy who cannot be completely revascularized with either percutaneous catheter intervention or coronary artery bypass graft surgery present clinical challenges. Transmyocardial laser revascularization, either as sole therapy or as an adjunct to coronary artery bypass graft surgery, may be appropriate for some of these patients. Although transmyocardial revascularization has consistently been demonstrated as an efficacious means of relieving angina, the mechanism of its effects are still debated, and criteria for the selection of patients for this novel therapy have not been adequately defined.

Methods

We reviewed the available evidence to allow us to make recommendations for the appropriate therapeutic applications of transmyocardial revascularization following the format of the American Heart Association and the American College of Cardiology guidelines for diagnostic and therapeutic procedures. Our recommendations were classified as class I, IIA, IIB, or III. For each recommendation we defined the level of supporting evidence as A, B, or C.

Results

We identified class I indications for transmyocardial revascularization as sole therapy and class IIA indications for transmyocardial revascularization as an adjunct to coronary artery bypass graft surgery with levels of evidence A and B, respectively.

Conclusions

Transmyocardial laser revascularization may be an acceptable form of therapy for selected patients: as sole therapy for a subset of patients with refractory angina and as an adjunct to coronary artery bypass graft surgery for a subset of patients with angina who cannot be completely revascularized surgically.

Section snippets

Process

We reviewed articles obtained through a search of the MedLine database (1966 to present) and the National Center for Biotechnology Information (NCBI) PubMed database using keywords including “TMR,” “laser,” “revascularization,” “transmyocardial,” “TMLR” (transmyocardial laser revascularization), “PMR” (percutaneous myocardial revascularization), and “DMR” (direct myocardial revascularization) as well as subject headings to which these terms were mapped and logical combinations of these sets.

Background

The nature of the connections between the lumina of the ventricles and the coronary arteries has been debated at least since the description by Vieussens in 1706 of “fleshy vessels” thought to represent direct communications between left ventricular myocardium and the left cardiac chambers [1]. These communications are not to be confused with the channels described by Thebesius in 1708 [2]. This debate was reignited by Wearn and colleagues [3] with their classic description of myocardial

Lasers used for transmyocardial revascularization

Since the pioneering efforts of Mirhoseini and associates 15, 16, a variety of laser wavelengths have been investigated for the creation of transmyocardial channels. In contrast to the CO2 laser used by Mirhoseini and coworkers [16], the 800- to 1,000-W PLC laser (PLC Systems, Franklin, MA) was specifically designed with sufficient pulse energy to allow for creation of transmyocardial channels in the left ventricle in approximately 40 ms—fast enough to successfully create transmural channels in

Current hypotheses for transmyocardial revascularization mechanism of action

Clinical studies of TMR using a CO2 laser or holmium:YAG laser have consistently demonstrated a reduction in angina symptoms and, in several cases, an improvement in exercise tolerance and quality of life 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51. In general, however, these studies are not placebo-controlled, and the degree of angina improvement has varied significantly. The two leading proposed mechanisms of TMR effect include laser-induced angiogenesis with

Outcomes studies: symptoms, function, and survival

Numerous nonrandomized clinical studies using either the holmium:YAG laser or the CO2 laser consistently demonstrated a significant improvement in angina class using the Canadian Cardiovascular Society (CCS) scoring system. Many of these studies also demonstrated an increase in exercise capacity after TMR 33, 34, 36, 37, 38, 39, 40, 41, 42, 48, 49, 50.

Mortality

The largest retrospective study of TMR available is derived from the STS NCD [61]. In an analysis of results obtained from the STS NCD for procedures performed between January 1998 and December 2001, 661 patients underwent TMR alone (holmium:YAG and CO2 laser combined) with a perioperative mortality of 6.4%. As discussed above, for 2,475 patients who underwent TMR with concomitant CABG, the mortality was 4.2%. In the prospective randomized trials of CO2 laser TMR, proce-dural mortality ranged

Unstable angina

In the randomized trial by Frazier and associates [47], more than 70% of the patients who crossed over to TMR from the medical treatment arm had unstable angina, and these patients had the highest perioperative mortality rate (9%). In the study by Hughes and colleagues [65], the presence of unstable angina was also a significant predictor of postoperative morbidity and mortality. Similarly, in a multicenter study by Hattler and coworkers [68], perioperative mortality was 16% in patients with

Class I

  • 1.

    Patients with an ejection fraction greater than 0.30 and CCS class III or IV angina that is refractory to maximal medical therapy. These patients should have reversible ischemia of the left ventricular free wall and coronary artery disease corresponding to the regions of myocardial ischemia. In all regions of the myocardium, the coronary disease must not be amenable to CABG or percutaneous transluminal angioplasty either as a result of (1) severe diffuse disease, (2) lack of suitable targets

Class IIA

  • 1.

    Patients with angina (class I –IV) in whom CABG is the standard of care who also have at least one accessible and viable ischemic region with demonstrable coronary artery disease that cannot be bypassed either because of (1) severe diffuse disease, (2) lack of suitable targets for complete revascularization, or (3) lack of suitable conduits for complete revascularization (level of evidence: B).

Class IIB

  • 1.

    Patients without angina in whom CABG is the standard of care who also have at least one accessible and

Future applications of transmyocardial revascularization

Additional clinical applications have been suggested for TMR including the treatment of graft vasculopathy after cardiac transplantation [72], although no benefit has been demonstrated. There have also been new approaches proposed for the delivery of TMR. There have been several reports of the performance of TMR using thoracoscopy. These early reports suggest that the technique can be performed safely and adequately using this approach [73]. In contrast, the early results of randomized trials

Conclusions

Transmyocardial revascularization offers consistent amelioration of severe angina in patients having no conventional therapeutic alternative. Surgeons should recognize that the procedure is intended only for the purpose of reducing angina symptoms. There is no statistically conclusive evidence for increased longevity or enhanced myocardial function. Careful patient screening is particularly important because of the unacceptably high operative mortality in patients with acute ischemic syndromes

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    Copyright © 2004 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.