From controlled trials to clinical practice

Transmyocardial revascularization (TMR): current status and future directions

Purpose

Cardiac surgeons are increasingly faced with a more complex patient who has developed a pattern of diffuse coronary artery disease (CAD), which is refractory to medical, percutaneous, and surgical interventions. This paper will review the clinical science surrounding transmyocardial revascularization (TMR) with an emphasis on the results from randomized controlled trials.

Methods

Randomized controlled trials which evaluated TMR used as sole therapy and when combined with coronary artery bypass grafting were reviewed. Pertinent basic science papers exploring TMR's possible mechanism of action along with future directions, including the synergism between TMR and cell-based therapies were reviewed.

Results

Two laser-based systems have been approved by the United States Food and Drug Administration (FDA) to deliver laser therapy to targeted areas of the left ventricle (LV) that cannot be revascularized using conventional methods: the holmium:yttrium-aluminum-garnet (Ho:YAG) laser system (CryoLife, Inc., Kennesaw, GA) and the carbon dioxide (CO₂) Heart Laser System (Novadaq Technologies Inc., (Mississauga, Canada). TMR can be performed either as a stand-alone procedure (sole therapy) or in conjunction with coronary artery bypass graft (CABG) surgery in patients who would be incompletely revascularized by CABG alone. Societal practice guidelines have been established and are supportive of using TMR in the difficult population of patients with diffuse CAD.

Conclusions

Patients with diffuse CAD have increased operative and long-term cardiac risks predicted by incomplete revascularization. The documented operative and long-term benefits associated with sole therapy and adjunctive TMR in randomized trials supports TMR's increased use in this difficult patient population.

Alternative therapy for medically refractory angina: enhanced external counterpulsation and transmyocardial laser revascularization

Medically refractory angina pectoris (RAP) is defined by presence of severe angina with objective evidence of ischemia and failure to relieve symptoms with coronary revascularization. Medication and invasive revascularization are the most common approaches for treating coronary artery disease (CAD). Although symptoms are eliminated or alleviated by these invasive approaches, the disease and its causes are present after treatment. New treatment approaches are needed to prevent the disease from progressing and symptoms from recurring. External enhanced counterpulsation therapy provides a treatment modality in the management of CAD and can complement invasive revascularization procedures. Data support that it should be considered a first-line treatment of RAP.

Transmyocardial laser revascularization versus medical therapy for refractory angina

BACKGROUND

This is an update of a review previously published in 2009. Chronic angina and advanced forms of coronary disease are increasingly more frequent. In spite of the improvement in the efficacy of available revascularization treatments, a subgroup of patients continue suffering from refractory angina. Transmyocardial laser revascularization (TMLR) has been proposed to improve the clinical situation of these patients.

OBJECTIVES

To assess the effects (both benefits and harms) of TMLR versus optimal medical treatment in people with refractory angina who are not candidates for percutaneous coronary angioplasty or coronary artery bypass graft, in alleviating angina severity, reducing mortality and improving ejection fraction.

SEARCH METHODS

We searched the following resources up to June 2014: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, the metaRegister of Controlled Trials database, ClinicalTrials.gov, and the WHO International Clinical Trials Registry. We applied no languages restrictions. We also checked reference lists of relevant papers.

SELECTION CRITERIA

We selected studies if they fulfilled the following criteria: randomized controlled trials (RCTs) of TMLR, by thoracotomy, in patients with Canadian Cardiovascular Society or New York Heart Association angina grade III-IV who were excluded from other revascularization procedures.

DATA COLLECTION AND ANALYSIS

Three authors independently extracted data for each trial about the population and interventions compared and assessed the risk of bias of the studies, evaluating randomisation sequence generation, allocation concealment, blinding (of participants, personnel and outcome assessors), incomplete outcome data, selective outcome reporting, and other potential sources of bias.

MAIN RESULTS

From a total of 502 references, we retrieved 47 papers for more detailed evaluation. We selected 20 papers, reporting data from seven studies, which included 1137 participants, of which 559 were randomized to TMLR. Participants and professionals were not blinded, which suggests high risk of performance bias. Overall, 43.8% of participants in the treatment group decreased two angina classes, as compared with 14.8% in the control group: odds ratio (OR) 4.63, 95% confidence interval (CI) 3.43 to 6.25), and heterogeneity was present. Mortality by intention-to-treat analysis was similar in both groups at 30 days (4.0% in the TMLR group and 3.5% in the control group), and one year (12.2% in the TMLR group and 11.9% in the control group). However, the 30-day mortality as-treated was 6.8% in the TMLR group and 0.8% in the control group (pooled OR was 3.76, 95% CI 1.63 to 8.66), mainly due to a higher mortality in participants crossing from standard treatment to TMLR. The assessment of subjective outcomes, such as improvement in angina, was affected by a high risk of bias and this may explain the differences found. Other adverse events such as myocardial infarction, arrhythmias or heart failure, were not considered in this review, as they were not predefined outcomes in trials design and they show a high inconsistency across studies. No new trials on transmyocardial laser revascularization have been published in the last ten years and it is very unlikely that new research will be undertaken in this field.

AUTHORS' CONCLUSIONS

This review shows that risks associated with TMLR outweigh the potential clinical benefits. Subjective outcomes are subject to high risk of bias and no differences were found in survival, but a significant increase in postoperative mortality and other safety outcomes suggests that the procedure may pose unacceptable risks.

Holmium:YAG laser system for transmyocardial revascularization

Transmyocardial revascularization, using the US FDA-approved holmium: yttrium-aluminum-garnet (Ho:YAG) laser system, is a surgical option for patients with debilitating angina caused by diffuse coronary artery disease in areas of the heart not amenable to complete revascularization using conventional treatments. Increased utilization of this therapy is warranted, in parallel with continuing research into therapeutic or cell-based methods for enhancing the clinically relevant, positive outcomes. This article will review the clinical science surrounding Ho:YAG transmyocardial revascularization with an emphasis on the randomized controlled trials performed in these patient groups.

Long-term outcomes after transmyocardial revascularization

BACKGROUND

Two independent reports documented substantially higher operative mortality associated with transmyocardial revascularization (TMR) when used in isolation than that reported in the premarket clinical trials. To clarify the state of the art, this article assesses temporal trends in the use of TMR, short-term and long-term outcomes, and outcomes stratified by procedure type (TMR only and TMR + coronary artery bypass graft [CABG]) and by the 2 specific TMR devices.

METHODS

The study population included all patients undergoing TMR in isolation or in combination with CABG at 435 cardiothoracic hospitals in the United States participating in the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database (ACSD) from January 2000 through November 2006 (n = 15,386). Analysis of long-term outcomes was accomplished through linkage to Medicare claims data. Short-term and long-term (7 years) adverse outcomes were assessed and compared between the 2 TMR device types.

RESULTS

The use of TMR in conjunction with CABG surgery is increasing. This study showed modest differences in short-term morbidity and mortality between the 2 devices. In combination with CABG, after risk adjustment, patients treated with the holmium:YAG laser (experienced a higher rate of operative mortality (3.5% vs 2.5%; adjusted hazard ratio 1.39, 95% confidence level 1.03 to 1.87) but no difference in the composite short-term rate of major morbidity or mortality, compared with the Heart Laser CO2 transmyocardial revascularization system (PLC Medical Systems, Inc, Milford, MA). However, there were no clinically meaningful differences in long-term results.

CONCLUSIONS

Modest differences in short-term morbidity and mortality between the 2 devices suggest the usefulness of further research.

Leveraging observational registries to inform comparative effectiveness research

Comparative effectiveness research (CER) has gained increased prominence over the past few years, but significant confusion surrounds the scope and definition of what constitutes CER. In some circles, CER is heralded as a tool to improve care quality and patient outcomes while simultaneously reducing health care costs. However, others contend that CER will lead to poorly designed studies whose results will be misinterpreted to limit the development and approval of new therapies. Leading to this confusion is the fact that CER spans a wide spectrum of clinical research domains that includes randomized, controlled trials; observational data analyses; and cost-effectiveness analyses. Recent federal mandates have injected significant funds for observational CER priorities, earmarked incentives for technology investments, and recommended a centralized collection of certain medical information, setting the stage for CER and observational data to gain further prominence as the foundation of many new investigations. In this review article, we define CER and highlight opportunities, and potential pitfalls, of observational registries to expand evidence through CER.

Transmyocardial laser revascularization versus medical therapy for refractory angina

BACKGROUND

Chronic angina and advanced forms of coronary disease are increasingly more frequent. Although the improved efficacy of available revascularization treatments, a subgroup of patients present with refractory angina. Transmyocardial laser revascularization (TMLR) has been proposed to improve the clinical situation of these patients.

OBJECTIVES

To assess the efficacy and safety of TMLR versus optimal medical treatment in patients with refractory angina in alleviating the severity of angina and improving survivorship and heart function.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials on The Cochrane Library (Issue 2 2007), MEDLINE (January 2006 to June 2007), EMBASE ( 2004 to June 2007) and ongoing studies were sought using the metaRegister of Controlled Trials database (mRCT) and ClinicalTrials.gov databases. No languages restrictions were applied. Reference lists of relevant papers were also checked.

SELECTION CRITERIA

Studies were selected if they fulfilled the following criteria: randomized controlled trials of TMLR, by thoracotomy, in patients with angina grade III-IV who were excluded from other revascularization procedures. From a total of 181 references, 20 papers were selected, reporting data from seven studies.

DATA COLLECTION AND ANALYSIS

Two reviewers abstracted data from selected papers; . The reviewers performed independently both quality assessment and data extraction. Selected studies present methodological weaknesses. None of them fulfilled all the quality criteria.

MAIN RESULTS

Seven studies (1137 participants of which 559 randomized to TMLR) were included. Overall, 43.8 % of patients in the treatment group decreased two angina classes as compared with 14.8 % in the control group, odds ratio (OR) of 4.63 (95% confidence interval (CI) 3.43 to 6.25), and heterogeneity was statistically significant. Mortality by intention-to-treat analysis at both 30 days (4.0 % in the TMLR group and 3.5 % in the control group) and 1 year (12.2 % in the TMLR group and 11.9 % in the control group) was similar in both groups. The 30-days mortality as treated was 6.8% in TMLR group and 0.8% in the control group, showing a statistically significant difference. The pooled OR was 3.76 (95% CI 1.63 to 8.66), because of the higher mortality in patients crossing from standard treatment to TMLR.

AUTHORS' CONCLUSIONS

There is insufficient evidence to conclude that the clinical benefits of TMLR outweigh the potential risks. The procedure is associated with a significant early mortality.

Transmyocardial laser revascularization: from randomized trials to clinical practice. A review of techniques, evidence-based outcomes, and future directions

Cardiac surgeons are increasingly faced with a more complex patient who has developed a pattern of diffuse coronary artery disease that cannot be completely revascularized by CAGB alone. Considering the increased operative and long-term cardiac risks predicted by incomplete revascularization, and the documented operative and long-term benefits associated with sole therapy and adjunctive TMR in randomized patients with diffuse coronary artery disease, increased use of sole therapy and adjunctive TMR therapy is warranted.

Transmyocardial laser revascularization

It has been almost a decade since transmyocardial laser revascularization (TMR) was approved for clinical use in the United States. The safety of TMR was demonstrated initially with nonrandomized studies in which TMR was used as the only treatment for patients with severe angina. TMR efficacy was proven after multiple randomized controlled trials. These revealed significant angina relief compared to maximum medical therapy in patients with diffuse coronary disease not amenable to conventional revascularization. In light of these results, TMR has been used as an adjunct to coronary artery bypass grafting (CABG). By definition, patients treated with this combined therapy have more severe coronary disease and comorbidities that are associated with end-stage atherosclerosis. Combination CABG + TMR has resulted in symptomatic improvement without additional risk. The likely mechanism whereby TMR has provided benefit is the angiogenesis engendered by the laser-tissue interaction. Improved perfusion and concomitant improvement in myocardial function have been observed post-TMR. Additional therapies to enhance the angiogenic response include combining TMR with stem cell-based treatments, which appear to be promising future endeavors.

Long-term results following percutaneous myocardial laser therapy

OBJECTIVES

The usefulness and safety of percutaneous myocardial laser therapy in selected patients have been identified in previous 1-year randomized trial reports, including that from a double-blind, sham-controlled trial we independently conducted. We aimed to determine whether the 1-year effects are maintained through a long-term, longitudinal follow-up.

METHODS

Patients (n=77) with chronic, stable, medically refractory angina (class III or IV) not amenable to conventional revascularization and with evidence of reversible ischemia, ejection fraction > or =25%, and myocardial wall thickness > or =8 mm were treated with percutaneous myocardial laser. After the 1-year follow-up and disclosure of all randomized assignments as prespecified in the respective study protocol, patients were followed up longitudinally for a mean of 3 years for angina class, left ventricular ejection fraction, medication usage, and adverse events.

RESULTS

No procedural mortality, myocardial infarction, or cerebral embolism occurred. Pericardiocentesis was required in two patients (2.6%). Cardiac event-free survival was 88% at 1 year and 66% at late follow-up. Mean Canadian Cardiovascular Society angina class was significantly improved from baseline (3.2+/-0.4) at 1 year (2.2+/-1.1, P<0.001) and at a mean of 3 years (1.9+/-1.2, P<0.001). Nitrate usage was significantly reduced at late follow-up; however, ejection fraction did not change over time. In a multivariate analysis, angina improvement at 1 year was found to be a significant independent predictor of both survival and angina improvement at late follow-up.

CONCLUSION

We conclude that percutaneous myocardial laser therapy in selected patients with severe, medically refractory angina not treatable with conventional revascularization induces significant and sustained symptomatic benefit.

Evaluation of diagnostic imaging technologies and therapeutics devices: better information for better decisions: proceedings of a multidisciplinary workshop

We are entering an era in which the success of biomedical science and the increasing understanding of the value of evidence for practice are in a state of tension. This tension is especially notable in the device arena, in which the short life cycles and iterative nature of development are at odds with current design constructs of the types of clinical trials that provide evidence for medical decision making. The financial pressure arising from strained budgets and expanding costs from the aging of the population and the continued development of new technology heightens the need for a focus on new approaches. Given this background, a group of experts representing constituencies with different perspectives were convened for a day and a half to discuss key issues and their potential solutions. Because of the complex and heterogeneous nature of the environments in which devices are used, the meeting focused on 3 broad, general uses of devices: imaging, risk stratification, and therapeutics. The goal of the meeting was to develop a preliminary list of ideas that could be framed as researchable questions or constructs for consideration by policy makers that ultimately might lead to improvements in the current system. Across diagnostic imaging, risk stratification devices, and therapeutic devices, the crosscutting issues can be identified: We need better methods of collaborative funding and priority setting, improved and more flexible methods, and new approaches to the integration of federal agencies in overseeing the system.

Perioperative management of patients undergoing transmyocardial laser revascularization

Advanced revascularization strategies continue to uncover a growing number of patients with symptomatic diffuse coronary artery disease. Transmyocardial laser revascularization (TMR) provides significant benefit in terms of improved quality of life and more complete revascularization for these difficult to treat patients when TMR is used as sole therapy or in combination with coronary artery bypass grafting. The safe clinical application of this important procedure relies on diligent perioperative management with appropriate patient selection, intraoperative care that avoids myocardial ischemia, and postoperative pain control along with expeditious reinstitution of antianginal medications. The treatment paradigms learned with the safe application of TMR should prove useful as new therapies to extend our revascularization options are developed.

Transmyocardial laser revascularization as an adjunct to coronary artery bypass grafting

Many patients with angina related to coronary artery disease respond to medical management or can be completely revascularized using available percutaneous coronary interventions or coronary artery bypass grafting (CABG). There is evidence, however, to indicate that up to 25% of patients are incompletely revascularized following CABG and that incomplete revascularization is a significant independent predictor of early and late mortality and adverse events. Transmyocardial revascularization (TMR) is a surgical option for patients with debilitating angina due to coronary artery disease in areas of the heart not amenable to complete revascularization using conventional treatments. In randomized, 1-year controlled trials with long-term follow-up and in additional clinical experience, TMR performed adjunctively to CABG in patients who would be incompletely revascularized by CABG alone has yielded significantly improved clinical outcomes. Based on these published results, the Society of Thoracic Surgeons has issued a practice guideline recommending adjunctive TMR in this difficult patient group.

Guidelines for the Clinical Use of Transmyocardial Laser Revascularization

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 (CABG) are clinically challenging. Transmyocardial laser revascularization (TMR), as sole therapy or as an adjunct to CABG, may be appropriate therapy for these patients. The recommendations are based on a review of the available evidence including expert consensus opinions. The author follows the format of the American Heart Association and the American College of Cardiology guidelines for diagnostic and therapeutic procedures. There are class I indications for sole therapy TMR and class IIA indications for TMR as an adjunct to CABG. TMR is indicated for selected patients: as sole therapy for a subset of patients with refractory angina. It also may be effective as an adjunct to CABG for a subset of patients with angina who cannot be completely revascularized surgically.

Impact of Unstable Angina on Outcomes of Transmyocardial Laser Revascularization Combined With Coronary Artery Bypass Grafting

BACKGROUND

For sole therapy transmyocardial laser revascularization (TMR), unstable angina has been demonstrated to be a significant independent predictor of operative mortality. The objective of this study was to investigate the preoperative risk profile of patients undergoing TMR plus coronary artery bypass graft surgery (CABG) and to determine the impact of unstable angina on outcomes.

METHODS

Using The Society of Thoracic Surgeons National Cardiac Database from 1998 to 2003, 5,618 patients underwent TMR plus CABG. These patients were compared with 932,715 patients who underwent CABG only operations.

RESULTS

The TMR plus CABG patients had a significantly higher incidence of diabetes (50% versus 34%), renal failure (7% versus 5%), peripheral vascular disease (20% versus 16%), reoperative surgery (26% versus 9%), three-vessel coronary artery disease (80% versus 71%), hyperlipidemia (73% versus 62%; p < 0.001 for all comparisons). The incidence of preoperative unstable angina was similar (46% versus 47%). The unadjusted perioperative mortality was 3.8% for TMR plus CABG patients. When unstable angina patients were removed, the observed mortality for TMR plus CABG was decreased to 2.7%.

CONCLUSIONS

It is likely that patients who undergo TMR plus CABG have a higher prevalence of diffuse coronary disease based on their preoperative demographics. Despite the increased risk associated with such anatomy, the mortality rate was not significantly increased when TMR was added to CABG in an effort to provide a more complete revascularization. As was noted from the outcomes of sole therapy TMR, in unstable angina patients, TMR plus CABG carries a higher risk, but this risk is not significantly different from that of such patients treated with CABG alone.

Mid-Term Results After Thoracoscopic Transmyocardial Laser Revascularization

BACKGROUND

Transmyocardial revascularization is a surgical therapy for the relief of severe angina in patients who are not suitable candidates for coronary artery bypass graft surgery or percutaneous coronary interventions. Historically, surgical techniques employed a left thoracotomy with or without thoracoscopic assist for visualization. This study evaluated the feasibility and midterm outcomes after transmyocardial laser revascularization performed using a completely thoracoscopic, closed chest approach.

METHODS

Patients (9 men [90%] and 1 woman [10%]) at a mean age of 66 +/- 10 years who were ineligible for coronary artery bypass graft surgery or percutaneous coronary intervention underwent sole therapy transmyocardial laser revascularization using a completely thoracoscopic surgical approach using a holmium:yttrium-aluminum-garnet laser system. Preoperatively, patients had a mean ejection fraction of 0.51 +/- 0.09 and a mean angina class of 3.7 +/- 0.5.

RESULTS

A mean of 30 +/- 2.4 channels were created during mean laser and operative procedure times of 14 +/- 2.9 and 133 +/- 32 minutes, respectively. Patients were extubated at a mean of 7.6 +/- 12 hours and were discharged from the hospital at a mean of 5.4 +/- 3.4 days. There were no hospital deaths or major complications. At a mean of 8.4 +/- 5.5 months postoperatively, all patients survived and significant clinical improvement with a mean angina class of 1.3 +/- 0.5 (p < 0.001).

CONCLUSIONS

A completely thoracoscopic surgical approach is feasible for sole therapy transmyocardial revascularization that affords improved visualization over a limited thoracotomy approach. Limited complications and significant clinical improvement after the procedure were observed. With minimal port manipulation, there is an opportunity for decreased postoperative pain; however, larger studies are warranted to verify this hypothesis.

Management Options for Angina Refractory to Maximal Medical and Surgical Interventions

Despite the seemingly daily advances in the primary, secondary, and tertiary prevention for coronary artery disease, many patients will ultimately experience progression of their disease and experience angina refractory to further active treatment. In these patients, disabling angina occurs at rest or during simple activities of daily living. When this occurs, symptom management, a predominant focus of nursing, becomes the goal of care. Several medical and surgical alternatives are available to patients with refractory angina. Enhanced external counterpulsation and transmyocardial laser revascularization are Food and Drug Administration approved therapies that can be used to attempt to restore the balance of supply and demand. Modulation of sympathetic tone via procedures such as stellate ganglion blocks has also been employed. Other methods to control the pain are techniques that alter pain perception such as spinal opioids, transcutaneous electrical nerve stimulation, and spinal cord stimulation. Too few patients with refractory angina are referred for any of these palliative therapies. Armed with knowledge regarding these therapies, nurses will be better prepared to provide anticipatory guidance to patients and their families and to support the patient's hope for relief as they cope with this devastating condition.

Meta-analysis of survival and relief of angina pectoris after transmyocardial revascularization

A meta-analysis of 7 randomized trials involving 1,053 patients was performed to evaluate the effect of transmyocardial laser revascularization as the sole procedural intervention on survival and angina relief. At 1 year, transmyocardial laser revascularization produced a significant improvement in angina class (p <0.0001) but no improvement in survival (p = 0.75).

Synergy of old and new technology results in successful revascularization of the anterior myocardium with relief of angina in the absence of suitable targets

BACKGROUND

Diffuse and distal left anterior descending (LAD) coronary disease that is refractory to conventional surgical and/or percutaneous revascularization represents a clinical and economic dilemma. Transmyocardial laser revascularization (TMLR) has improved angina without clear measurable improvement of myocardial perfusion. This study was undertaken to determine if combining a Vineberg implant with TMLR of the LAD distribution enhances myocardial perfusion and relieves symptoms.

METHODS

Twenty-one patients with an obliterated LAD and a viable anterior wall underwent off-pump coronary artery bypass grafting (OPCAB) (2.6 grafts/patient). Eight were studied with preoperative, postoperative-early (4-9 days), and postoperative-late (3-5 months) stress and rest nuclear imaging. In all but 3 cases, the Vineberg implant was modified such that the distal end of the conduit, as it emerged from the muscular tunnel, was anastomosed to any patent LAD segment. The anterior wall, to the left of the LAD, was also instrumented with a Holmium yttriumaluminum- garnet laser (8-16 sites).

RESULTS

There has been 100% follow-up with durations ranging from 6 to 36 months. There were no deaths. All patients had complete relief of their angina. Serial perfusion scans demonstrated a 2-phase improvement in perfusion. Three of the patients underwent angiography of the implant at 6 to 9 months; angiography in each case demonstrated a patent robust conduit. The 1 patient studied at 24 months demonstrated several sites of a myocardial "blush" consistent with neovascularization.

CONCLUSIONS

Although some of the benefits of TMLR/Vineberg may be a consequence of collateral blood flow from other revascularized regions, we believe there to be a synergistic effect on perfusion and angina relief by these combined procedures which may be related to angiogenesis.

Current and future treatment strategies for refractory angina

Patients with refractory angina are not candidates for revascularization and have both class III or IV angina and objective evidence of ischemia despite optimal medical therapy. An estimated 300,000 to 900,000 patients in the United States have refractory angina, and 25,000 to 75,000 new cases are diagnosed each year. This review focuses on treatment strategies for refractory angina and includes the mechanism of action and clinical trial data for each strategy. The pharmacological agents that have been used are ranolazine, ivabradine, nicorandil, L-arginine, testosterone, and estrogen; currently, only L-arginine, testosterone, and estrogen are approved by the Food and Drug Administration. Results with the noninvasive treatments of enhanced external counterpulsation and transcutaneous electrical nerve stimulation are provided. Invasive treatment strategies including spinal cord stimulation, transmyocardial revascularization, percutaneous myocardial revascularization, and gene therapy are also reviewed.

Adjunctive transmyocardial revascularization: five-year follow-up of a prospective, randomized trial

BACKGROUND

In a prospective, randomized trial involving 263 patients who would be incompletely revascularized by coronary artery bypass grafting (CABG) alone, CABG plus transmyocardial revascularization (CABG/TMR) provided an early mortality benefit with similar angina relief compared with CABG alone at 1 year. We evaluated the long-term outcome of patients randomized to CABG/TMR or CABG alone.

METHODS

Thirteen centers that enrolled 83% (218/263) of the patients in the original trial participated in this longitudinal study. Between 1996 and 1998, these centers randomized 218 patients who would be incompletely revascularized by CABG alone because of diffusely diseased target vessels to either holmium:yttrium-aluminum-garnet (holmium:YAG) CABG/TMR (n = 110) or CABG alone (n = 108). Baseline demographics and operative characteristics were similar between groups. Follow-up (mean 5.0 +/- 1.7 years) included survival and blinded angina class assessment.

RESULTS

At this 5-year follow-up both groups experienced significant angina improvement from baseline, however, the CABG/TMR group had a lower mean angina score (0.4 +/- 0.7 vs 0.7 +/- 1.1, p = 0.05), a significantly lower proportion of patients with severe angina (class III/IV: 0% [0/68] vs 10% [6/60], p = 0.009), and a trend towards greater number of angina-free patients (78% [53/68] vs 63% [38/60], p = 0.08), compared with CABG alone patients. Kaplan-Meier survival at 6 years was similar between CABG/TMR and CABG alone patients (76% vs 80%, p = 0.90).

CONCLUSIONS

Five-year follow-up of prospectively randomized patients who would be incompletely revascularized because of diffuse coronary artery disease indicates that the addition of TMR to conventional CABG provides superior angina relief compared to CABG alone.

Transmyocardial Laser Therapy: A Strategic Approach

BACKGROUND

Coronary artery bypass and percutaneous intervention have become the established methods of coronary revascularization in treating angina pectoris. Subsets of angina patients, however, are not amenable to either of these procedures. Transmyocardial laser revascularization (TMR) has been developed as a potential treatment to address such patients, and clinical research to date illustrates the success of TMR for this patient group.

STRATEGIC PLAN SUMMARY

Although the symptoms of ischemic heart disease manifest themselves in a variety of ways, the best results with TMR are seen in patients with severe angina rather than in patients with silent ischemia or congestive heart failure. Potential TMR patients receive diagnostic tests to determine if and where the therapy should be applied. A recent cardiac catheterization is required to document the status of and the coronary-system suitability for the planned intervention. It is not appropriate to assume that a patient with nonbypassable, noninterventional coronary artery disease has to be relegated to medical therapy only. Additionally, echocardiography demonstrates the status of cardiac valves and segmental wall motion activity. This knowledge allows the surgeon to determine the sequence of surgery and if abnormalities are present. Once the decision to use TMR use has been made, there are 2 approaches--sole therapy or adjunctive therapy. TMR is not to be substituted for a feasible bypass graft, but the best time to make this decision may well be during the surgery itself, because grafts that appear surgically feasible on an angiogram may be less feasible after the chest has been opened. The decision to perform sole-therapy TMR in the absence of bypassable vessels clearly must be made before opening the chest. Whether to use cardiopulmonary bypass (CPB) and the sequence in which to perform TMR and bypass grafts are based on surgeon preference. The advantage of performing TMR on CPB is that channels can quickly be lased without pause. A potential advantage of performing TMR before bypass grafts is that "channel leak" (bleeding) can be minimized by the conclusion of the surgery. Complete revascularization has become technically more difficult because of the increasing use of percutaneous approaches and because patients are being referred for coronary artery bypass grafting much later in the course of their coronary disease progression than before. TMR may well be a viable alternative to bypassing a heavily diseased, previously intervened, small-diameter coronary artery. Thus, a model in which myocardial perfusion is considered within the context of the natural circulation can be conceived as an alternative to a model in which circulation is altered by interventional, surgical, and/or transmyocardial methods. TMR has been shown to be effective in accomplishing a complete revascularization when the restoration of circulation to ischemic territories with interventional therapy, bypass surgery, or a combination of both has been ineffective. We recommend that interested users follow this "complete revascularization strategy" algorithm for all ischemic vessels being considered for interventional or surgical treatment. Running each diseased vessel through this thought process will ensure that available treatment options are considered in the optimization of a patient's outcome.

CONCLUSION

The use of TMR for angina relief has evolved into a clinically proven technology that has enabled physicians to address difficult revascularization cases with a therapy that is safe and effective.

The Society of Thoracic Surgeons practice guideline series: transmyocardial laser revascularization

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.