Frederick G.P. Welt

Intramyocardial transplantation of autologous CD34+ stem cells for intractable angina : A phase I/IIa double-blind, randomized controlled trial

Background— A growing population of patients with coronary artery disease experiences angina that is not amenable to revascularization and is refractory to medical therapy. Preclinical studies have indicated that human CD34+ stem cells induce neovascularization in ischemic myocardium, which enhances perfusion and function. Methods and Results— Twenty-four patients (19 men and 5 women aged 48 to 84 years) with Canadian Cardiovascular Society class 3 or 4 angina who were undergoing optimal medical treatment and who were not candidates for mechanical revascularization were enrolled in a double-blind, randomized (3:1), placebo-controlled dose-escalating study. Patients received granulocyte colony-stimulating factor 5 &mgr;g · kg−1 · d−1 for 5 days with leukapheresis on the fifth day. Selection of CD34+ cells was performed with a Food and Drug Administration–approved device. Electromechanical mapping was performed to identify ischemic but viable regions of myocardium for injection of cells (versus saline). The total dose of cells was distributed in 10 intramyocardial, transendocardial injections. Patients were required to have an implantable cardioverter-defibrillator or to temporarily wear a LifeVest wearable defibrillator. No incidence was observed of myocardial infarction induced by mobilization or intramyocardial injection. The intramyocardial injection of cells or saline did not result in cardiac enzyme elevation, perforation, or pericardial effusion. No incidence of ventricular tachycardia or ventricular fibrillation occurred during the administration of granulocyte colony-stimulating factor or intramyocardial injections. One patient with a history of sudden cardiac death/ventricular tachycardia/ventricular fibrillation had catheter-induced ventricular tachycardia during mapping that required cardioversion. Serious adverse events were evenly distributed. Efficacy parameters including angina frequency, nitroglycerine usage, exercise time, and Canadian Cardiovascular Society class showed trends that favored CD34+ cell–treated patients versus control subjects given placebo. Conclusions— A randomized trial of intramyocardial injection of autologous CD34+ cells in patients with intractable angina was completed that provides evidence for feasibility, safety, and bioactivity. A larger phase IIb study is currently under way to further evaluate this therapy.

Inflammation and Restenosis in the Stent Era

Abstract—The pathophysiology of restenosis involves early elements of direct injury to smooth muscle cells, deendothelialization, and thrombus deposition. Over time, this leads to smooth muscle cell proliferation/migration and extracellular matrix deposition. There is an increasing body of evidence to suggest that inflammation plays a pivotal role linking early vascular injury to the eventual consequence of neointimal growth and lumen compromise. The widespread use of coronary stents has fundamentally altered the vascular response to injury by causing a more intense and prolonged inflammatory state. Many of the cellular and molecular elements responsible for leukocyte recruitment have been elucidated, providing potential therapeutic targets for restenosis. This review seeks to provide an integrated view of the pathophysiology of restenosis that explains the central role of inflammation.

Percutaneous Coronary Intervention Versus Coronary Artery Bypass Graft Surgery for Patients With Medically Refractory Myocardial Ischemia and Risk Factors for Adverse Outcomes With Bypass: A Multicenter, Randomized Trial

Abstract BACKGROUND Percutaneous coronary intervention (PCI) and coronary artery bypass graft surgery (CABG) are being applied to high-risk populations, but previous randomized trials comparing revascularization methods have excluded a number of important high-risk groups. OBJECTIVES This five-year, multicenter, randomized clinical trial was designed to compare long-term survival among patients with medically refractory myocardial ischemia and a high risk of adverse outcomes assigned to either a CABG or a PCI strategy, which could include stents. METHODS Patients from 16 Veterans Affairs Medical Centers were screened to identify myocardial ischemia refractory to medical management and the presence of one or more risk factors for adverse outcome with CABG, including prior open-heart surgery, age >70 years, left ventricular ejection fraction RESULTS A total of 232 patients was randomized to CABG and 222 to PCI. The 30-day survivals for CABG and PCI were 95% and 97%, respectively. Survival rates for CABG and PCI were 90% versus 94% at six months and 79% versus 80% at 36 months (log-rank test, p = 0.46). CONCLUSIONS Percutaneous coronary intervention is an alternative to CABG for patients with medically refractory myocardial ischemia and a high risk of adverse outcomes with CABG.

Monocyte Recruitment and Neointimal Hyperplasia in Rabbits: Coupled Inhibitory Effects of Heparin

Among the many effects of heparin independent of its effects on coagulation are inhibition of vascular smooth muscle cell proliferation and regulation of leukocyte-blood vessel interactions. The potential link between these effects was examined in an animal model of vascular injury rich in inflammatory cells: the placement of endovascular metal stents in rabbit iliac arteries. Monocyte adhesion stimulated by early focal thrombus was maximal after 3 days, with infiltrating monocytes and intimal cell proliferation maximal after 7 days. Tissue monocyte number dictated cell proliferation at each time point (R2 = .92, P < .0001). Heparin reduced both early monocyte adhesion as well as monocyte infiltration within the neointima 7 and 14 days after stent placement. Reductions in adherent and tissue monocytes were commensurate with reductions in intimal cell proliferation and intimal thickening. At 14 days, heparins inhibition of mononuclear cell adhesion was correlated with its suppression of intimal thickening (R2 = .82, P < .0001). Monocytes have been hypothesized to serve as markers, initiators, and promoters of arterial occlusive diseases. Heparins ability to inhibit mononuclear cell adhesion and penetration and reduce neointimal size and cell proliferation after vascular injury may further implicate monocytes in the pathogenesis of neointimal hyperplasia after mechanical arterial injury.

Functionally Competent Cardiac Stem Cells Can Be Isolated From Endomyocardial Biopsies of Patients With Advanced Cardiomyopathies

Rationale: Two categories of cardiac stem cells (CSCs) with predominantly myogenic (mCSC) and vasculogenic (vCSC) properties have been characterized in the human heart. However, it is unknown whether functionally competent CSCs of both classes are present in the myocardium of patients affected by end-stage cardiac failure, and whether these cells can be harvested from relatively small myocardial samples. Objective: To establish whether a clinically relevant number of mCSCs and vCSCs can be isolated and expanded from endomyocardial biopsies of patients undergoing cardiac transplantation or left ventricular assist device implantation. Methods and Results: Endomyocardial biopsies were collected with a bioptome from the right side of the septum of explanted hearts or the apical LV core at the time of left ventricular assist device implantation. Two to 5 biopsies from each patient were enzymatically dissociated, and, after expansion, cells were sorted for c-kit (mCSCs) or c-kit and KDR (vCSCs) and characterized. mCSCs and vCSCs constituted 97% and 3% of the c-kit population, respectively. Population doubling time averaged 27 hours in mCSCs and vCSCs; 5×106 mCSCs and vCSCs were obtained in 28 and 41 days, respectively. Both CSC classes possessed significant growth reserve as documented by high telomerase activity and relatively long telomeres. mCSCs formed mostly cardiomyocytes, and vCSCs endothelial and smooth muscle cells. Conclusions: The growth properties of mCSCs and vCSCs isolated from endomyocardial biopsies from patients with advanced heart failure were comparable to those obtained previously from larger myocardial samples of patients undergoing elective cardiac surgery.

Neutrophil, Not Macrophage, Infiltration Precedes Neointimal Thickening in Balloon-Injured Arteries

Abstract—Macrophages are abundant after stent-induced arterial injury. Inhibition of macrophage recruitment blocks neointimal growth in this model. In contrast, after superficial injury from balloon endothelial denudation, macrophages are sparse. However, many anti-inflammatory therapies remain effective against neointimal growth after balloon injury. To investigate further the role of leukocytes after injury, 41 New Zealand White rabbits underwent iliac artery balloon denudation. In 18, subcutaneous pumps were placed to deliver intravenous heparin (0.3 mg/kg per hour). Arteries were harvested at 6 hours and at 3, 7, and 14 days. In 8 animals, either M1/70 (a monoclonal antibody [mAb] against adhesion molecule Mac-1) or a nonspecific IgG was given (5 mg/kg IV bolus and then 1 mg/kg SC QOD), and arteries were harvested at 6 hours and 3 days. Computer-aided morphometry was performed as was immunohistochemistry to assess smooth muscle cell (SMC) proliferation (bromodeoxyuridine-positive cells), neutrophil content (RPN357, mAb against rabbit neutrophil/thymocyte), and macrophage content (RAM-11, mAb against rabbit macrophage). Heparin inhibited neointimal growth at 7 and 14 days (64% and 32.5% reduction, respectively;P <0.05). Neutrophils were observed in the media early after balloon injury, and heparin and M1/70 inhibited this infiltration (82% and 83% reduction, respectively;P <0.05 each) with a coincident inhibition of medial SMC proliferation at 3 days (49% and 84% reduction, respectively;P <0.05 each). Macrophages were absent at all time points. Neutrophil, but not macrophage, infiltration occurs early after endothelial denudation. Inhibition of this process is associated with a reduction in medial SMC proliferation. These data suggest a central role for neutrophils in restenosis and help to explain prior reports of an inhibitory effect of anti-inflammatory therapies on neointimal growth after balloon injury.

The Public Health Hazards of Risk Avoidance Associated With Public Reporting of Risk-Adjusted Outcomes in Coronary Intervention

Public reporting of risk-adjusted outcomes for percutaneous coronary intervention (PCI) procedures has been mandated in New York State for more than a decade. During that time there has been a significant decline in the unadjusted mortality after such procedures. Massachusetts joined New York in 2003 as only the second state to require case level reporting of every coronary interventional procedure performed. In this review, we explore the differences in the populations reported by the 2 states and consider possible risks of public reporting of clinical outcomes after PCI procedures, including the risk of increasing conservatism in the treatment of the sickest patients. We offer a conceptual framework to understand the potential risk-averse behavior of interventional cardiologists subject to public reporting, and offer several proposals to counteract this potential deleterious effect of reporting programs.

Percutaneous coronary intervention versus coronary bypass graft surgery for diabetic patients with unstable angina and risk factors for adverse outcomes with bypass: Outcome of diabetic patients in the AWESOME randomized trial and registry

OBJECTIVES This study compared survival after percutaneous coronary intervention (PCI) with survival after coronary artery bypass graft surgery (CABG) among diabetics in the Veterans Affairs AWESOME (Angina With Extremely Serious Operative Mortality Evaluation) study randomized trial and registry of high-risk patients. BACKGROUND Previous studies indicate that CABG may be superior to PCI for diabetics, but no comparisons have been made for diabetics at high risk for surgery. METHODS Over five years (1995 to 2000), 2,431 patients with medically refractory myocardial ischemia and at least one of five risk factors (prior CABG, myocardial infarction within seven days, left ventricular ejection fraction <0.35, age >70 years, or an intra-aortic balloon being required to stabilize) were identified. A total of 781 were acceptable for CABG and PCI, and 454 consented to be randomized. The 1,650 patients not acceptable for both CABG and PCI constitute the physician-directed registry, and the 327 who were acceptable but refused to be randomized constitute the patient-choice registry. Diabetes prevalence was 32% (144) among randomized patients, 27% (89) in the patient-choice registry, and 32% (525) in the physician-directed registry. The CABG and PCI survival rates were compared using Kaplan-Meier curves and log-rank tests. RESULTS The respective CABG and PCI 36-month survival rates for diabetic patients were 72% and 81% for randomized patients, 85% and 89% for patient-choice registry patients, and 73% and 71% for the physician-directed registry patients. None of the differences was statistically significant. CONCLUSIONS We conclude that PCI is a relatively safe alternative to CABG for diabetic patients with medically refractory unstable angina who are at high risk for CABG.

Systemic Inflammation Induced by Lipopolysaccharide Increases Neointimal Formation After Balloon and Stent Injury in Rabbits

Background—Emerging data indicate that the inflammatory response after mechanical arterial injury correlates with the severity of neointimal hyperplasia in animal models and postangioplasty restenosis in humans. The present study was designed to examine whether a nonspecific stimulation of the innate immune system, induced in close temporal proximity to the vascular injury, would modulate the results of the procedure. Methods and Results—Rabbits subjected to iliac artery balloon injury (balloon denudation with or without stent deployment) were injected twice with a bacterial lipopolysaccharide (LPS) (500 ng/rabbit) before and after surgery. The dose was chosen to be sufficient to induce systemic inflammation but not septic shock. A systemic marker of inflammation (serum interleukin-1&bgr; levels measured by ELISA) and monocytic stimulation (CD14 levels on monocytes measured by flow cytometry) were increased after LPS administration. Arterial macrophage infiltration at 7 days after injury was 1.7±1.2% of total cells in controls and 4.2±1.8% in LPS-treated rabbits (n=4, P <0.05). Morphometric analysis of the injured arteries 4 weeks after injury revealed significantly increased luminal stenosis (38±4.2% versus 23±2.6, mean± SEM; n=8, P <0.05) and neointima-to-media ratio (1.26±0.21 versus 0.66± 0.09, P <0.05) in LPS-treated animals compared with controls. This effect was abolished by anti-CD14 Ab administration. Serum interleukin-1&bgr; levels and monocyte CD14 expression were significantly increased in correlation with the severity of intimal hyperplasia. LPS treatment increased neointimal area after stenting from 0.57±0.07 to 0.77± 0.1 mm2 and stenosis from 9±1% to 13±1.7% (n=5, P < 0.05). Conclusions—Nonspecific systemic stimulation of the innate immune system concurrently with arterial vascular injury facilitates neointimal formation, and conditions associated with increased inflammation may increase restenosis.

Leukocyte recruitment and expression of chemokines following different forms of vascular injury

Inflammation plays a central role in restenosis following coronary intervention. Recent human and animal data suggest important differences between the inflammatory responses to simple balloon angioplasty compared with stent implantation. To investigate the mechanisms of these differences, New Zealand white rabbits underwent bilateral iliac artery balloon denudation. Half received intravascular stents. Arteries were harvested at three, seven and 14 days for immunohistochemistry, and 4 hours, 8 hours and 14 days for chemokine mRNA analysis. Leukocyte content was quantifi ed utilizing immunohistochemistry (RPN357, monoclonal antibody (mAb) against rabbit neutrophil; RAM-11, mAb against rabbit macrophage). We analyzed the mRNA levels of the chemokines monocyte chemoattractant protein 1 (MCP-1) and interleukin 8 (IL-8) through semi-quantitative polymerase chain reaction. We demonstrated the spatial pattern of MCP-1 mRNA levels through in situ mRNA hybridization. In balloon-injured arteries, leukocyte recruitment was confi ned to early neutrophil infi ltration. IL-8 and MCP-1 mRNA levels peaked within hours and were undetectable at 14 days. In contrast, in stented arteries, early neutrophil recruitment was followed by prolonged macrophage accumulation. IL-8 and MCP-1 mRNA levels peaked within hours but were still detectable 14 days post injury. Conclusions: In contrast to balloon injury, stent-induced injury results in sustained chemokine expression and leukocyte recruitment. These data may have important implications for antirestenotic strategies.