Allan Schwartz

Intracoronary irradiation: Dose response for the prevention of restenosis in swine

PURPOSE Restenosis after percutaneous transluminal coronary angioplasty represents, in part, a proliferative response of vascular smooth muscle at the site of injury. We have previously shown that high-dose radiation (20 Gy), delivered via an intracoronary 192Ir source, causes focal medial fibrosis and markedly impairs the restenosis process after balloon angioplasty in swine. This study sought to delineate the dose-response characteristics of this effect. METHODS AND MATERIALS Forty juvenile swine underwent coronary angiography; a segment of the left coronary artery was chosen as a target for balloon injury. In 30 swine, a 2 cm ribbon of 192Ir was positioned at the target segment and 20, 15, or 10 Gy were delivered to the vessel wall (10 animals/dose). Subsequently, overdilatation balloon angioplasty was performed at the irradiated segment. In 10 control swine, overdilatation balloon angioplasty was performed without previous irradiation. Thirty-eight animals survived until sacrifice at 30 +/- 3 days. Histopathological analysis was performed by a pathologist in a blinded manner. The area of maximal luminal compromise within the target segment was analyzed via computer-assisted planimetry. RESULTS Neointimal area was decreased by 71.4% at 20 Gy and by 58.3% at 15 Gy compared with control animals (p < 0.05 for both). A stimulatory effect on smooth muscle cell proliferation was noted at 10 Gy, with a 123% increase in neointimal area compared with controls (p < 0.05). Mean percent area stenosis was also reduced by 63% at 20 Gy and by 74.8% at 15 Gy compared with controls (p < 0.05 for both). CONCLUSIONS Intracoronary irradiation prior to overstretch balloon angioplasty markedly reduces neointima formation; this effect is dose dependent, with evidence of a significant stimulatory effect at 10 Gy. The effective therapeutic dose range for the prevention of restenosis in this model begins at approximately 15 Gy delivered to the vessel wall.

Elevated Levels of Plasma C-Reactive Protein Are Associated With Decreased Graft Survival in Cardiac Transplant Recipients

BackgroundInflammation may be involved in the origin of transplant coronary artery disease. We hypothesized that plasma levels of C-reactive protein (CRP) and interleukin-6 (IL-6), markers for systemic inflammation, would correlate with cardiac transplant graft survival. Methods and ResultsWe studied 99 consecutive cardiac transplant recipients who were referred for routine endomyocardial biopsy and/or surveillance coronary angiography. Plasma levels of CRP and IL-6 were measured by their respective ELISAs. Patients were divided into 2 groups: those who died or required retransplantation and those who survived without the need for retransplantation. During the follow-up period of 5.0±2.7 years (range, 0.2 to 15.1 years) after transplant, 20 patients died and 9 required retransplantation. There was no significant difference in age, race, sex, cause of native myopathy, presence of diabetes, or use of aspirin, statins, or calcium channel blockers between the 2 groups. Although IL-6 did not relate to graft failure, CRP level was predictive of allograft failure (P =0.003). The risk of allograft failure increased 36% for every 2-fold increase in CRP level. Moreover, CRP levels also correlated significantly with the frequency of grade 3 rejection (P =0.02). In multivariate analysis, when combined with other significant predictors such as donor age and sex mismatching of the graft, CRP still significantly predicted graft failure (P =0.025) with a 32% increase in the risk of graft failure for every 2-fold increase in CRP level. ConclusionsThese findings suggest that elevated plasma levels of CRP are associated with subsequent allograft failure in cardiac transplant recipients.

Primum non nocere: the case for watchful waiting in asymptomatic "severe" degenerative mitral regurgitation.

“ The physician must … have two special objects in view with regard to disease, namely, to do good or to do no harm ” — Hippocrates 1 The optimal surgical treatment for severe mitral regurgitation resulting from degenerative disease (flail or prolapse caused by myxomatous change or fibroelastic deficiency) is mitral repair.2–5 Although the decision to intervene on a symptomatic patient is relatively straightforward, current guidelines also define other triggers for surgery in patients who are asymptomatic.6,7 In the absence of symptoms, left ventricular (LV) dysfunction, defined as an LV ejection fraction (LVEF) of 30% to 60% or an LV end-systolic diameter (LVESD) of ≥40 mm6 (>45 mm7), is a class I indication. Class IIa indications in the asymptomatic patient with preserved LV function include atrial fibrillation and pulmonary hypertension (pulmonary artery systolic pressure >50 mm Hg at rest or >60 mm Hg after exercise). It is also deemed reasonable (class IIa6 or IIb7) to regard the presence of severe mitral regurgitation as a sole and sufficient indication for surgery provided that the likelihood of repair is high (≥90%)6 and operative risk is low.7 This last recommendation has generated considerable debate because no randomized controlled trial has defined the best treatment for asymptomatic patients with severe degenerative mitral regurgitation. Proponents of prophylactic repair favor an aggressive surgical approach, whereas opponents lobby for a strategy of close medical follow-up until conventional triggers are met (watchful waiting). Here, we present our argument for watchful waiting. Response by Enriquez-Sarano and Sundt see p 813 Because by definition a strategy of prophylactic surgery in asymptomatic patients cannot improve their sense of well-being, it must be associated with better surgical and/or clinical outcomes relative to a triggered strategy. It is our position that this benefit has …

Circulating Levels of IL-1β, a Prothrombotic Cytokine, are Elevated in Unstable Angina Versus Stable Angina

Background: Multiple studies support a role for inflammation in the pathogenesis of coronary atherosclerosis and unstable cardiac syndromes. However, of the known proinflammatory cytokines, only elevated plasma levels of interleukin-6 have been linked to unstable angina. We sought to examine the plasma levels of other major proinflammatory cytokines in similar clinical settings and to determine the extent of the relationship between inflammation and unstable coronary syndromes by measuring the levels of various proinflammatory cytokines in patients with stable and unstable angina.Methods: We measured plasma levels of interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6) in 97 patients: 67 with stable angina, 24 with unstable angina, and 15 healthy controls.Results: Mean levels of IL-1β were significantly higher in patients with unstable angina as compared to patients with stable angina (p = .009). Levels of IL-6 were significantly higher than control patients for both stable angina and unstable angina patients (p = .031 and .006, respectively). No significant differences were found in the levels of TNF-α.Conclusions: Our results suggest that both IL-1β and IL-6 contribute to the pathogenesis of unstable angina, and that the profile of circulating plasma levels of proinflammatory cytokines differs in unstable angina from that in stable angina.Abbreviated Abstract. Multiple studies support a role for inflammation in the pathogenesis of coronary atherosclerosis and unstable cardiac syndromes. We measured plasma levels of interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6) in patients with stable and unstable coronary syndromes. Levels of IL-1β and IL-6 were found to be elevated in patients with unstable coronary syndromes. No significant differences were found in the levels of TNF-α. Our results suggest that both IL-1β and IL-6 contribute to the pathogenesis of unstable angina.

Sequence-independent inhibition of in vitro vascular smooth muscle cell proliferation, migration, and in vivo neointimal formation by phosphorothioate oligodeoxynucleotides.

Phosphorothioate oligodeoxynucleotides (PS oligos) are antisense (sequence-specific) inhibitors of vascular smooth muscle cell (SMC) proliferation when targeted against different genes. Recently an aptameric G-quartet inhibitory effect of PS oligos has been demonstrated. To determine whether PS oligos manifest non-G-quartet, non-sequence-specific effects on human aortic SMC, we examined the effects of S-dC28, a 28-mer phosphorothioate cytidine homopolymer, on SMC proliferation induced by several SMC mitogens. S-dC28 significantly inhibited SMC proliferation induced by 10% FBS as well as the mitogens PDGF, bFGF, and EGF without cytotoxicity. Moreover, S-dC28 abrogated PDGF-induced in vitro migration in a modified micro-Boyden chamber. Furthermore, S-dC28 manifested in vivo antiproliferative effects in the rat carotid balloon injury model. S-dC28 suppressed neointimal cross-sectional area by 73% and the intima/media area ratio by 59%. Therefore, PS oligos exert potent non-G-quartet, non-sequence-specific effects on in vitro SMC proliferation and migration as well as in vivo neointimal formation.

The lymphocytic infiltration in calcific aortic stenosis predominantly consists of clonally expanded T cells.

Valve lesions in degenerative calcific aortic stenosis (CAS), a disorder affecting 3% of those older than 75 years, are infiltrated by T lymphocytes. We sought to determine whether the αβ TCR repertoire of these valve-infiltrating lymphocytes exhibited features either of a polyclonal nonselective response to inflammation or contained expanded clones suggesting a more specific immune process. TCR β-chain CDR3-length distribution analysis using PCR primers specific for 23 Vβ families performed in eight individuals with CAS affecting tri- or bileaflet aortic valves revealed considerable oligoclonal T cell expansion. In five cases, β-chain nucleotide sequencing in five selected Vβ families showed that an average of 92% of the valve-infiltrating T cell repertoire consisted of expanded T cell clones, differing markedly in composition from the relatively more polyclonal peripheral CD8 or CD4 T cell subsets found even in this elderly population. Twenty-four of the valve-infiltrating T cell clones also had the same clone identified in blood, some of which were highly expanded. Interestingly, 22 of these 24 shared clones were CD8 in lineage (p = 1.5 × 10−12), suggesting a possible relationship to the expanded CD8+CD28− T cell clones frequently present in the elderly. Additionally, the sequences of several TCR β-chain CDR3 regions were homologous to TCR β-chains identified previously in allograft arteriosclerosis. We infer that these findings are inconsistent with a nonselective secondary response of T cells to inflammation and instead suggest that clonally expanded αβ T cells are implicated in mediating a component of the valvular injury responsible for CAS.

Percutaneous Mitral Valve Repair in the Initial EVEREST Cohort Evidence of Reverse Left Ventricular Remodeling

Background— Percutaneous repair of mitral regurgitation (MR) permits examination of the effect of MR reduction without surgery and cardiopulmonary bypass on left ventricular (LV) dimensions and function. The goal of this analysis was to determine the extent of reverse remodeling at 12 months after successful percutaneous reduction of MR with the MitraClip device. Methods and Results— Of 64 patients with 3 and 4+ MR who achieved acute procedural success after treatment with the MitraClip device, 49 patients had moderate or less MR at 12-month follow-up. Their baseline and 12-month echocardiograms were compared between the group with and without LV dysfunction. In patients with persistent MR reduction and pre-existing LV dysfunction, there was a reduction in LV wall stress, reduced LV end-diastolic volume, LV end-systolic volume and increase in LV ejection fraction in contrast to those with normal baseline LV function, who showed reduction in LV end-diastolic volume, LV wall stress, no change in LV end-systolic volume, and a fall in LV ejection fraction. Conclusions— Patients with pre-existing LV dysfunction demonstrate reverse remodeling and improved LV ejection fraction after percutaneous mitral valve repair. Clinical Trial Registration— URL: . Unique identifiers: [NCT00209339][1], [NCT00209274][2]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00209339&atom=%2Fcirccvim%2F6%2F4%2F522.atom [2]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00209274&atom=%2Fcirccvim%2F6%2F4%2F522.atomBackground—Percutaneous repair of mitral regurgitation (MR) permits examination of the effect of MR reduction without surgery and cardiopulmonary bypass on left ventricular (LV) dimensions and function. The goal of this analysis was to determine the extent of reverse remodeling at 12 months after successful percutaneous reduction of MR with the MitraClip device. Methods and Results—Of 64 patients with 3 and 4+ MR who achieved acute procedural success after treatment with the MitraClip device, 49 patients had moderate or less MR at 12-month follow-up. Their baseline and 12-month echocardiograms were compared between the group with and without LV dysfunction. In patients with persistent MR reduction and pre-existing LV dysfunction, there was a reduction in LV wall stress, reduced LV end-diastolic volume, LV end-systolic volume and increase in LV ejection fraction in contrast to those with normal baseline LV function, who showed reduction in LV end-diastolic volume, LV wall stress, no change in LV end-systolic volume, and a fall in LV ejection fraction. Conclusions—Patients with pre-existing LV dysfunction demonstrate reverse remodeling and improved LV ejection fraction after percutaneous mitral valve repair. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifiers: NCT00209339, NCT00209274.

Circulating Activated and Effector Memory T Cells Are Associated with Calcification and Clonal Expansions in Bicuspid and Tricuspid Valves of Calcific Aortic Stenosis

We sought to delineate further the immunological significance of T lymphocytes infiltrating the valve leaflets in calcific aortic stenosis (CAS) and determine whether there were associated alterations in circulating T cells. Using clonotypic TCR β-chain length and sequence analysis we confirmed that the repertoire of tricuspid CAS valves contains numerous expanded T cell clones with varying degrees of additional polyclonality, which was greatest in cases with severe calcification. We now report a similar proportion of clonal expansions in the much younger bicuspid valve CAS cases. Peripheral blood flow cytometry revealed elevations in HLA-DR+ activated CD8 cells and in the CD8+CD28nullCD57+ memory-effector subset that were significantly greater in both bicuspid and tricuspid CAS cases with more severe valve calcification. Lesser increases of CD4+CD28null T cells were identified, principally in cases with concurrent atherosclerotic disease. Upon immunostaining the CD8 T cells in all valves were mainly CD28null, and CD8 T cell percentages were greatest in valves with oligoclonal repertoires. T cell clones identified by their clonotypic sequence as expanded in the valve were also found expanded in the circulating blood CD28nullCD8+ T cells and to a lesser degree in the CD8+CD28+ subset, directly supporting the relationship between immunologic events in the blood and the valve. The results suggest that an ongoing systemic adaptive immune response is occurring in cases with bicuspid and tricuspid CAS, involving circulating CD8 T cell activation, clonal expansion, and differentiation to a memory-effector phenotype, with trafficking of T cells in expanded clones between blood and the valve.

Plasma Levels of Tissue Plasminogen Activator and Plasminogen Activator Inhibitor-1 Are Correlated With the Presence of Transplant Coronary Artery Disease in Cardiac Transplant Recipients

Hemostatic factors are involved in the pathogenesis of native coronary artery disease. However, their role in transplant coronary artery disease is less established. To assess the role of hemostatic factors in transplant coronary artery disease we studied 52 consecutive cardiac transplant patients. The presence of transplant coronary artery disease was determined by angiography. Plasma levels of tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), von Willebrand Factor (vWF), and fibrin D-dimer were determined by enzyme-linked immunosorbent assays. Serum lipids were measured by enzymatic methods. Patients with transplant coronary artery disease had higher circulating t-PA (8.6 +/- 0.8 vs. 5.4 +/- 0.6 ng/ml, p = 0.021) and PAI-1 antigen concentrations (38.0 +/- 3.4 vs 25.8 +/- 2.2 ng/ml, p = 0.037). t-PA and PAI-1 antigen concentrations correlated with the severity of angiographic disease (R = 0.34; p = 0.014 for t-PA, and R = 0.45; p = 0.001 for PAI-1). Serum cholesterol levels were higher in patients with transplant coronary artery disease (221 +/- 7.6 vs 191 +/- 9.2 mg/dl, p = 0.039). Serum triglycerides were also higher in patients with transplant coronary artery disease by angiography (246 +/- 38.3 vs 139 +/- 20.8 mg/dl, p = 0.050). Multivariate analysis identified t-PA antigen (p = 0.003) and triglyceride levels (p = 0.038) as independent predictors for the presence of transplant coronary artery disease. We conclude that cardiac transplant patients with evidence of transplant coronary artery disease on coronary angiography have altered hemostatic function which is reflected by elevated levels of circulating t-PA and PAI-1 antigens. The interaction of the hemostatic system and serum lipids in the development of transplant coronary artery disease warrants further study.

T-Cell Lymphokines, Interleukin-4 and Gamma Interferon, Modulate the Induction of Vascular Smooth Muscle Cell Tissue Plasminogen Activator and Migration by Serum and Platelet-Derived Growth Factor

Platelet-derived growth factor (PDGF)-induced smooth muscle cell (SMC) fibrinolysis is necessary for SMC migration. In order to determine whether the T-cell lymphokines interleukin-4 (IL-4) and gamma interferon (gamma-IFN) affect SMC fibrinolysis and migration, we examined the effects of human recombinant IL-4 and gamma-IFN on human aortic SMC tissue-type plasminogen activator (TPA), urokinase-type plasminogen activator (UPA), and plasminogen activator inhibitor type-1 (PAI-1) antigen production, as determined by enzyme-linked immunosorbent assays. Although IL-4 had no direct effect on SMC TPA antigen, IL-4 potentiated SMC TPA antigen levels and activity in conditioned media and cellular lysates in media containing 2% fetal bovine serum but did not change UPA or PAI-1 production. gamma-IFN attenuated IL-4 augmentation of SMC TPA antigen production in conditioned media, although gamma-IFN itself had no direct effects on SMC TPA and PAI-1 antigen production. IL-4 augmented PDGF induction of SMC TPA antigen. gamma-IFN inhibited PDGF induction of SMC TPA antigen and IL-4 potentiation of this process. gamma-IFN diminished the promigratory effects of both IL-4 and PDGF on in vitro SMC migration. Tranexamic acid, a plasmin inhibitor, abrogated the stimulation of SMC migration by IL-4. Therefore, IL-4 and gamma-IFN modulate the induction of SMC TPA and SMC migration by 2% fetal bovine serum and PDGF.