Long-term outcomes after transmyocardial revascularization

Synergistic Effect of Transmyocardial Revascularization and Platelet-Rich Plasma on Improving Cardiac Function After Coronary Artery Bypass Grafting

Background Coronary artery disease (CAD) is a global health burden, contributing to mortality and morbidity. A proportion of patients with CAD suffer from diffuse CAD, where conventional revascularization techniques such as percutaneous coronary intervention and coronary artery bypass grafting (CABG) may be insufficient to adequately restore myocardial perfusion. Transmyocardial revascularization (TMR) uses a laser to create microscopic channels in the myocardium, inducing inflammation, angiogenesis, and neovascularization to improve perfusion to ischemic regions. Platelet-rich plasma (PRP) is an autologous concentrate of platelets that contains a myriad of growth factors and bioactive proteins, which have been shown to promote tissue regeneration and wound healing. The combination of TMR and PRP therapies has been proposed to synergistically enhance myocardial revascularization and functional recovery in patients with advanced CAD undergoing surgical revascularization. Methods This study evaluated the efficacy of combining TMR and PRP with CABG in improving cardiac function in diffuse CAD patients. Fifty-two patients were randomized to CABG alone (n = 16), CABG+TMR (n = 17), CABG+PRP (n = 10), and CABG+TMR+PRP (n = 9). TMR was performed using a holmium:YAG laser to create 10 channels in the inferolateral left ventricular wall. PRP was prepared from autologous whole blood and injected into the myocardium adjacent to the TMR channels. Cardiac function was assessed using speckle-tracking echocardiography preoperatively, postoperatively, and at one-year follow-up. Adverse events, including post-operative atrial fibrillation, acute kidney injury, and readmissions, were also recorded. Statistical analyses were performed to compare outcomes between the treatment groups. Results The CABG+TMR+PRP group showed significantly improved global longitudinal strain (GLS) at one year compared to CABG alone (mean GLS -15.96 vs -12.09, p = 0.02). Post-operative left ventricular ejection fraction trended higher in the TMR+PRP group (57.78%) vs other groups, but not significantly. Post-operative atrial fibrillation was higher in the TMR+PRP group (67% vs 25%, p = 0.04), potentially reflecting increased inflammation. No significant differences were observed in other adverse events. Conclusions The results of this study suggest a synergistic benefit of combining TMR and PRP therapies as an adjunct to CABG in patients with diffuse CAD. The significant improvement in GLS at one year in the TMR+PRP group compared to CABG alone indicates enhanced myocardial remodeling and functional recovery, which may translate to improved long-term outcomes. The higher incidence of postoperative atrial fibrillation in the TMR+PRP group warrants further investigation but may reflect the heightened inflammatory response necessary for angiogenesis and tissue regeneration. Prospective, randomized controlled trials with larger sample sizes and longer follow-up periods are needed to validate these findings and optimize treatment protocols. Nonetheless, concomitant TMR+PRP therapy represents a promising approach to augmenting myocardial revascularization and recovery in patients with advanced CAD undergoing surgical revascularization.

Association of postoperative complications and outcomes following coronary artery bypass grafting

BACKGROUND

The long-term effects of postoperative complications following coronary artery bypass grafting (CABG) are unknown.

METHODS

Medicare-linked records from the Society of Thoracic Surgeons Adult Cardiac Surgery Database were queried for isolated CABG records from 2007 through 2012. Unadjusted and adjusted associations between individual postoperative complications and both mortality and all-cause rehospitalization were evaluated to 7 years using Cox proportional-hazards models and cumulative incidence functions. Because of nonproportional hazards, associations are presented as early (0 to 90 days) and late (90 days to 7 years).

RESULTS

Of the 294,533 isolated CABG patients who had records linked to Medicare for long-term follow-up (median age, 73 years; 30% female), 120,721 (41%) experienced at least 1 of the complications of interest, including new-onset atrial fibrillation (30.0%), prolonged ventilation (12.3%), renal failure (4.5%), reoperation (3.5%), stroke (1.9%), and sternal wound infection (0.4%). Each of the 6 postoperative complications was associated with a significantly increased risk of mortality and rehospitalization to 7 years despite adjustment for baseline characteristics and the presence of multiple complications. Although the predominant effect of postoperative complications was observed in the first 90 days, the increased risk-adjusted hazard for death and rehospitalization continued through 7 years.

CONCLUSIONS

Postoperative complications are associated with an increased risk of both early and late mortality and all-cause rehospitalization, particularly during the "value" window within 90 days of CABG. These findings underscore the need to develop avoidance strategies as well as cost-adjustment methods for each of these complications.

Midterm outcomes of transmyocardial laser revascularization with intramyocardial injection of adipose derived stromal cells for severe refractory angina

Introduction

Refractory angina has limited effective therapeutic options and often contributes to frequent hospitalizations, morbidity and impaired quality of life.

Aim

We sought to examine midterm results of a bio-interventional therapy combining transmyocardial laser revascularization (TMLR) and intramyocardial injection of adipose derived stem cells (ADSC) in patients with refractory angina not amenable to percutaneous or surgical revascularization.

Material and methods

We included 15 patients with severe refractory angina and anterior wall ischemia who were ineligible for revascularization strategies. Adipose tissue was harvested and purified, giving the stem cell concentrate. All patients underwent left anterior thoracotomy and TMLR using a low-powered holmium : yttrium–aluminum–garnet laser and intramyocardial injection of ADSC using a combined delivery system.

Results

No deaths or major adverse cardiovascular or cerebrovascular events were observed in the 6-month follow-up. Mean ejection fraction increased from 35% to 38%, and mean Canadian Cardiovascular Society Angina Score decreased from 3.2 to 1.4, with decreased necessity of nitrate usage. Seventy-three percent of patients reported health improvement particularly regarding general health and bodily pain. Improvement in endocardial movement, myocardial thickening and stroke volume index (35.26 to 46.23 ml/m²) on cardiac magnetic resonance imaging (MRI) was observed in 3 patients who had repeat CMR imaging after 6 months.

Conclusions

Our study suggested that interventional therapy combining TMLR with intramyocardial implantation of ADSC may reduce symptoms and improve quality of life in patients with refractory angina. These early findings need further validation in large scale randomized controlled trials.

Clinical outcomes meta-analysis: measuring subendocardial perfusion and efficacy of transmyocardial laser revascularization with nuclear imaging

INTRODUCTION

Randomized and nonrandomized clinical trials have tried to assess whether or not TMR patients experience an increase in myocardial perfusion. However there have been inconsistencies reported in the literature due to the use of different nuclear imaging modalities to test this metric. The primary purpose of this meta-analysis was to determine whether SPECT, MUGA and PET scans demonstrate changes in myocardial perfusion between lased and non-lased subjects and whether laser type affects myocardial perfusion. The secondary purpose was to examine the overall effect of laser therapy on clinical outcomes including survival, hospital re-admission and angina reduction.

METHODS

Sixteen studies were included in the primary endpoint analysis after excluding all other non-imaging TMR papers. Standardized mean difference was used as the effect size for all quantitative outcomes and log odds ratio was used as the effect size for all binary outcomes.

RESULTS

Statistically significant improvements in myocardial perfusion were observed between control and treatment groups in myocardial perfusion at 6-month follow up using PET imaging with a porcine model. However non-significant differences were observed in patients at 3 and 12 months using SPECT, PET or MUGA scans. Both CO₂ and Ho:YAG laser systems demonstrated an increase in myocardial perfusion however this effect was not statistically significant. In addition both laser types displayed statistically significant decreases in patient angina at 3, 6 and 12 months but non-significant increases in survival rates and decreases in hospital re-admissions.

CONCLUSION

In order to properly assess myocardial perfusion in TMR subjects, subendocardial perfusion needs to be analyzed via nuclear imaging. PET scans can provide this level of sensitivity and should be utilized in future studies to monitor and detect perfusion changes in lased and non-lased subjects.

Remodeling an infarcted heart: novel hybrid treatment with transmyocardial revascularization and stem cell therapy

Transmyocardial revascularization (TMR) has emerged as an additional therapeutic option for patients suffering from diffuse coronary artery disease (CAD), providing immediate angina relief. Recent studies indicate that the volume of surgical cases being performed with TMR have been steadily rising, utilizing TMR as an adjunctive therapy. Therefore the purpose of this review is to provide an up-to-date appreciation of the current state of TMR and its future developmental directions on CAD treatment. The current potential of this therapy focuses on the implementation of stem cells, in order to create a synergistic angiogenic effect while increasing myocardial repair and regeneration. Although TMR procedures provide increased vascularization within the myocardium, patients suffering from ischemic cardiomyopathy may not benefit from angiogenesis alone. Therefore, the goal of introducing stem cells is to restore the functional state of a failing heart by providing these cells with a favorable microenvironment that will enhance stem cell engraftment.

Transmyocardial revascularization devices: technology update

Transmyocardial laser revascularization (TMR) emerged as treatment modality for patients with diffuse coronary artery disease not amendable to percutaneous or surgical revascularization. The procedure entails the creation of laser channels within ischemic myocardium in an effort to better perfuse these areas. Currently, two laser devices are approved by the US Food and Drug Administration for TMR – holmium:yttrium–aluminum–garnet and CO₂. The two devices differ in regard to energy outputs, wavelengths, ability to synchronize with the heart cycle, and laser–tissue interactions. These differences have led to studies showing different efficacies between the two laser devices. Over 50,000 procedures have been performed worldwide using TMR. Improvements in angina stages, quality of life, and perfusion of the myocardium have been demonstrated with TMR. Although several mechanisms for these improvements have been suggested, evidence points to new blood vessel formation, or angiogenesis, within the treated myocardium, as the major contributory factor. TMR has been used as sole therapy and in combination with coronary artery bypass grafting. Clinical studies have demonstrated that TMR is both safe and effective in angina relief long term. The objective of this review is to present the two approved laser devices and evidence for the safety and efficacy of TMR, along with future directions with this technology.