Autologous bone marrow mononuclear cell transplantation and coronary bypass surgery for treatment of ischemic heart failure

Background: Worldwide, the leading cause of morbidity and mortality is heart failure. It is most often caused by coronary artery disease (CAD) and myocardial infarction (MI), which causes death of myocardial tissue. Although coronary interventions such as coronary bypass graft surgery (CABG) can restore blood flow to ischemic areas, and established pharmacotherapy for heart failure exists, no treatment available in the clinics can regenerate the dead cardiomyocytes. For surgical treatment, patients with heart failure represent a challenge, as they are prone to surgical complications, and suitable preoperative imaging modalities to assess possible benefit from surgery are few. Aims: Cell therapies have recently emerged as a possible alternative for treating heart failure. We wanted to explore the capacity of autologous bone marrow mononuclear cells to regenerate myocardial tissue as an adjunct to CABG. The aim was to assess the therapy s safety and detect the cells possible effects on cardiac function and viability. In addition, we investigated whether it would be possible to predict benefit from CABG in these heart-failure patients with 3-vessel CAD with the aid of combined nuclear imaging data. For this, we used 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) to measure cardiac viability, and 99m-technetium-tetrofosmin single-photon emission computed tomography (99mTc-SPECT) to measure cardiac perfusion. Methods: Between 2006 and 2010, we enrolled 104 patients scheduled for CABG who suffered from CAD and ischemic heart failure. Preoperatively, pharmacotherapy was optimized, after which 39 patients still had left ventricular ejection fraction (LVEF) ≤45%. These patients received injections of bone marrow mononuclear cells (BMMCs) (N=20) or vehicle (N=19) intraoperatively into the myocardial infarction border area in a randomized and double-blind manner. During surgery and at the intensive care unit (ICU), the patients hemodynamics, arterial blood gases, systemic venous oxygen level, blood glucose, acid-base balance, lactate, hemoglobin, body temperature, and diuresis as well as medications needed were monitored and recorded every four hours throughout the first postoperative 24 hours. BMMC effects on the heart were evaluated by use of pre- and 1-year postoperative cardiac magnetic resonance imaging (MRI), FDG-PET, and 99mTc-SPECT and by measuring pro-B-type amino-terminal natriuretic peptide (proBNP) levels. As we later decided to extend the follow-up, these same variables, except for nuclear imaging data, as well as current quality of life were measured at a late follow-up visit in 2013. For this, we could contact 36 of the 39 patients recruited for the original study, of which 30 participated in the extended follow-up. Preoperatively, we also analyzed FDG-PET and 99mTc-SPECT data by using three quantitative techniques with a software tool to measure defects with hypoperfused but viable and non-viable myocardium in 15 control patients. One method used solely PET, two others combined PET and SPECT at different thresholds. As a reference, we used change in LV function and volume by MRI. Results: During the first-year follow-up, improvement was similar in both groups in LVEF, the predefined primary end-point measure (P=0.59), and similar improvement also occurred in local wall thickening (WT) (P=0.68) in the injected segments. Neither changes in viability by PET and SPECT and levels of proBNP differed between these groups. Myocardial scar size by MRI in injected segments rose by a median of 5.1% in the control group (interquartile range, IQR -3.3 to 10.8) but fell by 13.1% in the BMMC group (IQR -21.4 to -6.5) (P=0.0002). During surgery and ICU stay, hemodynamics, arterial blood gases, systemic venous oxygen level, blood glucose, acid-base balance, lactate, hemoglobin, body temperature, and diuresis and levels of medications administered were similar between the study groups. For the extended follow-up, the median period was 60.7 months (IQR 45.1 to 72.6). No statistically significant difference was observable in change in proBNP values or in quality of life between groups. LVEF in both groups remained similarly improved (P=0.647), as also did WT (P=0.434). For controls, scar size in injected segments increased with a median of 2% (IQR -7 to 19); for BMMC patients it remained reduced with a median change of -17% (IQR -30 to -6) (P=0.011). When assessing the benefit-predictive capacity of the two techniques combining FDG-PET and 99mTc-SPECT with different thresholds and one technique using FDG-PET data only, no correlation appeared with preoperative PET- or PET-SPECT-derived viable or non-viable tissue, when compared with global functional outcome (change in LVEF) or local change in WT. Conclusions: In patients with 3-vessel disease and heart failure, the three techniques using SPECT perfusion and PET viability imaging data failed to predict the functional benefit received from CABG. Thus, these imaging modalities may provide no additional advantage to preoperative patient selection, which should be considered when planning treatment for this patient group in the clinics. In the treatment of chronic ischemic heart failure, during surgery and perioperatively in the ICU, both intramyocardial BMMC and placebo injections appear safe. Although failing to affect cardiac function, combining intramyocardial BMMC therapy with CABG can sustainably reduce scar size.