LETTER TO THE EDITOR
From controlled trials to clinical practice: monitoring transmyocardial revascularization use and outcomes
Keith B. Allen, MD
Indiana Heart Institute, 10590 North Meridian Street, Indianapolis, IN 46260, USA
Robert D. Dowling, MD and
Wayne Richenbacher, MD
kallen2340{at}aol.com
Considering the significant clinical experience with transmyocardial revascularization (TMR) in both the controlled trial and "real-world" setting, we felt compelled to comment on the recent retrospective registry report by Peterson et al. (1) culled from the Society of Thoracic Surgeons national cardiac database. Regarding sole-therapy TMR, the investigators confirm findings observed in five prospective randomized trials comparing TMR to medical therapy in "no option" class III/IV angina patients: like most new technologies, there is a learning curve, and surgical risk is increased in sicker patients (2–6). Their commentary, similarly, is not new. Allen et al. (2) reported reduced operative mortality rate from 5% overall to 2% in the last 100 randomized patients, attributable to surgical technique refinement and patient selection; Frazier et al. (3) reported unstable angina as a significant predictor of operative mortality. Others with clinical experience in treating unstable patients (2,7,8) confirm that such patients without conventional options represent a higher risk group for TMR.
Although not the intent of their retrospective study, Peterson et al. (1) fail to summarize adequately the clinical benefits of sole-therapy TMR. In prospective randomized trials at one year, TMR provided superior angina relief, decreased rehospitalizations, and improved exercise times compared to patients managed medically. A recent five-year follow-up of randomized patients demonstrated significantly increased Kaplan-Meier survival rates and sustained, significantly superior angina relief in patients randomized to TMR compared to medical therapy (9).
As reported by the investigators (1), TMR is increasingly being utilized adjunctively with coronary artery bypass grafting (CABG) in patients with diffuse coronary artery disease (CAD) who would be incompletely revascularized by CABG alone. In a prospective, randomized trial involving 263 such patients, CABG/TMR provided operative and one-year mortality benefits with a trend toward superior angina relief compared to CABG alone (10). The retrospective report by Peterson et al. (1) compares patients in the STS database who received CABG/TMR with a concocted control group consisting of CABG-only patients with triple-vessel disease who received <3 grafts. The appropriateness of this comparison is questionable, because it assumes that incomplete revascularization in the control group occurred in an area of ischemic viable myocardium supplied by a diffusely diseased, ungraftable coronary artery and that all participating centers accurately and consistently defined three-vessel disease. It is not possible to verify this by simply querying the STS database. It is important also to note that surgeons are increasingly operating on patients with diffuse-CAD, which has been shown to be a powerful independent predictor of operative mortality (11,12). Unfortunately, the presence of diffuse-CAD is not factored into the STS database or other national databases. Thus, such case-matched comparisons against CABG/TMR-treated patients with diffuse-CAD can be unreliable because control database sources fail to account for diffuse-CAD and therefore underestimate predicted operative mortality in this select patient group.
We applaud the investigators in supporting continued physician training and education regarding the judicious application of sole-therapy TMR or adjunctively in patients who would be incompletely revascularized by CABG alone. Long-term follow-up of the latter group will further define the role of TMR in the treatment of an increasingly complex cardiac surgical patient.
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References
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1. Peterson ED, Kaul P, Kaczmarek RG, et al. From controlled trials to clinical practice: monitoring transmyocardial revascularization use and outcomes. J Am Coll Cardiol. 2003;42:1611–1616[Abstract/Free Full Text]
2. Allen KB, Dowling RD, Fudge TL, et al. Comparison of transmyocardial revascularization with medical therapy in patients with refractory angina. N Engl J Med. 1999;341:1029–1036[Abstract/Free Full Text]
3. Frazier OH, March RJ, Horvath KA. Transmyocardial revascularization with a carbon dioxide laser in patients with end-stage coronary disease. N Engl J Med. 1999;341:1021–1028[Abstract/Free Full Text]
4. Burkhoff D, Schmidt S, Schulman SP, et al. Transmyocardial revascularization compared with continued medical therapy for treatment of refractory angina pectoris. Lancet. 1999;354:885–890[CrossRef][Medline]
5. Schofield PM, Sharples LD, Caine N, et al. Transmyocardial laser revascularization in patients with refractory angina: a randomized controlled trial. Lancet. 1999;353:519–524[CrossRef][Medline]
6. Aaberge L, Nordstrand K, Dragsund M, et al. Transmyocardial revascularization with CO2 laser in patients with refractory angina pectoris. J Am Coll Cardiol. 2000;35:1170–1177[Abstract/Free Full Text]
7. Hattler B, Griffith B, Zenati M, et al. Transmyocardial laser revascularization in the patient with unmanageable unstable angina. Ann Thorac Surg. 1999;68:1203–1209[Abstract/Free Full Text]
8. Dowling RD, Petracek MR, Selinger SL, Allen KB. Transmyocardial revascularization in patients with refractory, unstable angina. Circulation. 1998;98(Suppl II):73–76[Abstract/Free Full Text]
9. Allen KB, Dowling R, Angell W, Gangahar D, et al. Transmyocardial revascularization versus medical therapy: five-year follow-up of a prospective, randomized, multicenter clinical trial. Circulation. 2003;108(Suppl IV):326–327
10. Allen KB, Dowling RD, DelRossi A, et al. Transmyocardial laser revascularization combined with coronary artery bypass grafting: a multicenter, blinded, prospective, randomized, controlled trial. J Thorac Cardiovasc Surg. 2000;119:540–549[Abstract/Free Full Text]
11. Graham MM, Chambers RJ, Davies RF. Angiographic quantification of diffuse coronary artery disease: reliability and prognostic value for bypass operations. J Thorac Cardiovasc Surg. 1999;118:618–627[Abstract/Free Full Text]
12. Osswald B, Blackstone E, Tochtermann U, et al. Does the completeness of revascularization affect early survival after coronary artery bypass grafting in elderly patients? Eur J Cardiothorac Surg. 2001;20:120–126[Abstract/Free Full Text]
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