Matthew Topel

Effect of progenitor cell mobilization with granulocyte-macrophage colony-stimulating factor in patients with peripheral artery disease: a randomized clinical trial.

IMPORTANCE Many patients with peripheral artery disease (PAD) have walking impairment despite therapy. Experimental studies in animals demonstrate improved perfusion in ischemic hind limb after mobilization of bone marrow progenitor cells (PCs), but whether this is effective in patients with PAD is unknown. OBJECTIVE To investigate whether therapy with granulocyte-macrophage colony-stimulating factor (GM-CSF) improves exercise capacity in patients with intermittent claudication. DESIGN, SETTING, AND PARTICIPANTS In a phase 2 double-blind, placebo-controlled study, 159 patients (median [SD] age, 64 [8] years; 87% male, 37% with diabetes) with intermittent claudication were enrolled at medical centers affiliated with Emory University in Atlanta, Georgia, between January 2010 and July 2012. INTERVENTIONS Participants were randomized (1:1) to received 4 weeks of subcutaneous injections of GM-CSF (leukine), 500 μg/day 3 times a week, or placebo. Both groups were encouraged to walk to claudication daily. MAIN OUTCOMES AND MEASURES The primary outcome was peak treadmill walking time (PWT) at 3 months. Secondary outcomes were PWT at 6 months and changes in circulating PC levels, ankle brachial index (ABI), and walking impairment questionnaire (WIQ) and 36-item Short-Form Health Survey (SF-36) scores. RESULTS Of the 159 patients randomized, 80 were assigned to the GM-CSF group. The mean (SD) PWT at 3 months increased in the GM-CSF group from 296 (151) seconds to 405 (248) seconds (mean change, 109 seconds [95% CI, 67 to 151]) and in the placebo group from 308 (161) seconds to 376 (182) seconds (change of 56 seconds [95% CI, 14 to 98]), but this difference was not significant (mean difference in change in PWT, 53 seconds [95% CI, -6 to 112], P = .08). At 3 months, compared with placebo, GM-CSF improved the physical functioning subscore of the SF-36 questionnaire by 11.4 (95% CI, 6.7 to 16.1) vs 4.8 (95% CI, -0.1 to 9.6), with a mean difference in change for GM-CSF vs placebo of 7.5 (95% CI, 1.0 to 14.0; P = .03). Similarly, the distance score of the WIQ improved by 12.5 (95% CI, 6.4 to 18.7) vs 4.8 (95% CI, -0.2 to 9.8) with GM-CSF compared with placebo (mean difference in change, 7.9 [95% CI, 0.2 to 15.7], P = .047). There were no significant differences in the ABI, WIQ distance and speed scores, claudication onset time, or mental or physical component scores of the SF-36 between the groups. CONCLUSIONS AND RELEVANCE Therapy with GM-CSF 3 times a week did not improve treadmill walking performance at the 3-month follow-up. The improvements in some secondary outcomes with GM-CSF suggest that it may warrant further study in patients with claudication. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01041417.

Differential effects of nebivolol and metoprolol on arterial stiffness, circulating progenitor cells, and oxidative stress

Unlike traditional beta receptor antagonists, nebivolol activates nitric oxide. We hypothesized that therapy with nebivolol compared with metoprolol would improve arterial stiffness, increase levels of circulating progenitor cells (PC), and decrease oxidative stress (OS). In a randomized, double-blind, cross-over study, 30 hypertensive subjects received either once daily nebivolol or metoprolol succinate for 3 months each. Pulse wave velocity and augmentation index were measured using tonometry. Flow cytometry was used to measure circulating PC. OS was measured as plasma aminothiols. Measurements were performed at baseline, and repeated at 3 and 6 months. No significant differences were present between the levels of OS, arterial stiffness, and PC numbers during treatment with metoprolol compared with nebivolol. In subgroup analyses of beta-blocker naïve subjects (n = 19), nebivolol reduced pulse wave velocity significantly compared with metoprolol (-1.4 ± 1.9 vs. -0.1 ± 2.2; P = .005). Both nebivolol and metoprolol increased circulating levels of CD34+/CD133 + PC similarly (P = .05), suggesting improved regenerative capacity.

Association Between Living in Food Deserts and Cardiovascular Risk

Background— Food deserts (FD), neighborhoods defined as low-income areas with low access to healthy food, are a public health concern. We evaluated the impact of living in FD on cardiovascular risk factors and subclinical cardiovascular disease (CVD) with the hypothesis that people living in FD will have an unfavorable CVD risk profile. We further assessed whether the impact of FD on these measures is driven by area income, individual household income, or area access to healthy food. Methods and Results— We studied 1421 subjects residing in the Atlanta metropolitan area who participated in the META-Health study (Morehouse and Emory Team up to Eliminate Health Disparities; n=712) and the Predictive Health study (n=709). Participants’ zip codes were entered into the United States Food Access Research Atlas for FD status. Demographic data, metabolic profiles, hs-CRP (high-sensitivity C-reactive protein) levels, oxidative stress markers (glutathione and cystine), and arterial stiffness were evaluated. Mean age was 49.4 years, 38.5% male and 36.6% black. Compared with those not living in FD, subjects living in FD (n=187, 13.2%) had a higher prevalence of hypertension and smoking, higher body mass index, fasting glucose, and 10-year risk for CVD. They also had higher hs-CRP (P=0.014), higher central augmentation index (P=0.015), and lower glutathione level (P=0.003), indicative of increased oxidative stress. Area income and individual income, rather than food access, were associated with CVD risk measures. In a multivariate analysis that included food access, area income and individual income, both low-income area and low individual household income, were independent predictors of a higher 10-year risk for CVD. Only low individual income was an independent predictor of higher hs-CRP and augmentation index. Conclusions— Although living in FD is associated with a higher burden of cardiovascular risk factors and preclinical indices of CVD, these associations are mainly driven by area income and individual income rather than access to healthy food.

Association between oxidative stress and atrial fibrillation

BACKGROUND Oxidative stress (OS) may be a key mechanism underlying the development of atrial fibrillation (AF) in experimental studies, but data in humans remain limited. OBJECTIVE Systemic OS can be estimated by measurements of circulating levels of the aminothiols including glutathione, cysteine, and their oxidized products. We tested the hypothesis that the redox potentials of glutathione (EhGSH) and cysteine will be associated with prevalent and incident AF. METHODS Plasma levels of aminothiols were measured in 1439 patients undergoing coronary angiography, of whom 148 (10.3%) had a diagnosis of AF. After a median follow-up of 6.3 years, 104 of 917 patients (11.5%) developed incident AF. Multivariate logistic regression and Cox regression models were used to determine whether OS markers were independent predictors of prevalent and incident AF after adjustment for traditional risk factors, heart failure, coronary artery disease, and high-sensitivity C-reactive protein level. RESULTS For each 10% increase in EhGSH, the odds of prevalent AF was 30% higher (odds ratio [OR] 1.3; 95% confidence interval [CI] 1.1-1.7; P = .02) and 90% higher (OR 1.9; 95% CI 1.3-2.7; P = .004) when the median was used as a cutoff. The EhGSH level above the median was more predictive of chronic AF (OR 4.0; 95% CI 1.3-12.9; P = .01) than of paroxysmal AF (OR 1.7; 95% CI 1.1-2.7; P = .03). Each 10% increase in EhGSH level was associated with a 40% increase in the risk of incident AF (hazard ratio 1.4; 95% CI 1.1-1.7; P = .01). CONCLUSION Increased OS measured by the redox potentials of glutathione is associated with prevalent and incident AF. Therapies that modulate OS need to be investigated to treat and prevent AF.

Progenitor Cells and Clinical Outcomes in Patients With Heart Failure

Background Endogenous regenerative capacity, assessed as circulating progenitor cell (PC) numbers, is an independent predictor of adverse outcomes in patients with cardiovascular disease. However, their predictive role in heart failure (HF) remains controversial. We assessed the relationship between the number of circulating PCs and the pathogenesis and severity of HF and their impact on incident HF events. Methods and Results We recruited 2049 adults of which 651 had HF diagnosis. PCs were enumerated by flow cytometry as CD45med+ blood mononuclear cells expressing CD34, CD133, vascular endothelial growth factor receptor-2, and chemokine (C-X-C motif) receptor 4 epitopes. PC subsets were lower in number in HF and after adjustment for clinical characteristics in multivariable analyses, a low CD34+ and CD34+/CXCR+ cell count remained independently associated with a diagnosis of HF (P<0.01). PC levels were not significantly different in reduced versus preserved ejection fraction patients. In 514 subjects with HF, there were 98 (19.1%) all-cause deaths during a 2.2±1.5-year follow-up. In a Cox regression model adjusting for clinical variables, hematopoietic-enriched PCs (CD34+, CD34+/CD133+, and CD34+/CXCR4+) were independent predictors of all-cause death (hazard ratio 2.0, 1.6, 1.6-fold higher mortality, respectively; P<0.03) among HF patients. Endothelial-enriched PCs (CD34+/VEGF+) were independent predictors of mortality in patients with HF with preserved ejection fraction only (hazard ratio, 5.0; P=0.001). Conclusions PC levels are lower in patients with HF, and lower PC counts are strongly and independently predictive of mortality. Strategies to increase PCs and exogenous stem cell therapies designed to improve regenerative capacity in HF, especially, in HF with preserved ejection fraction, need to be further explored.

Diastolic Blood Pressure and Adverse Outcomes in the TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist) Trial

Background Although diastolic blood pressure (DBP) is independently associated with an increased risk of adverse cardiovascular outcomes in the general population, it is unclear if a similar relationship exists in patients with heart failure with preserved ejection fraction. Methods and Results This analysis included 1703 (mean age, 72±10 years; 50% men; 78% white) patients with heart failure with preserved ejection fraction enrolled in the TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist) Trial from the Americas who were treated for hypertension. Multivariable Cox regression was used to examine the risk of hospitalization for heart failure, death, and cardiovascular death associated with DBP. The relationship between hospitalization for heart failure and DBP was linear, with an increased risk observed with decreasing DBP values (≥90 mm Hg: referent; 80–89 mm Hg: hazard ratio [HR], 1.44; 95% confidence interval [CI], 0.85–2.44; 70–79 mm Hg: HR, 1.18; 95% CI, 0.69–2.01; 60–69 mm Hg: HR, 1.54; 95% CI, 0.90–2.63; <60 mm Hg: HR, 2.12; 95% CI, 1.20–3.74; P=0.0055 for trend). The associations of DBP with death (≥90 mm Hg: HR, 1.86; 95% CI, 1.12–3.06; 80–89 mm Hg: HR, 1.23; 95% CI, 0.89–1.70; 70–79 mm Hg: referent; 60–69 mm Hg: HR, 1.20; 95% CI, 0.90–1.59; <60 mm Hg: HR, 1.68; 95% CI, 1.21–2.33) and cardiovascular death (≥90 mm Hg: HR, 2.02; 95% CI, 1.10–3.71; 80–89 mm Hg: HR, 1.17; 95% CI, 0.77–1.79; 70–79 mm Hg: referent; 60–69 mm Hg: HR, 1.16; 95% CI, 0.80–1.70; <60 mm Hg: HR, 1.85; 95% CI, 1.21–2.82) were nonlinear, with a greater risk of each outcome observed with DBP values ≥90 and <60 mm Hg. Conclusions DBP values ≥90 and <60 mm Hg are associated with a significant risk of adverse outcomes in patients with heart failure with preserved ejection fraction who are treated for hypertension. Further research is needed to determine optimal DBP targets to reduce the risk of adverse events in patients with heart failure with preserved ejection fraction.

Comparisons of the Framingham and Pooled Cohort Equation Risk Scores for Detecting Subclinical Vascular Disease in Blacks Versus Whites

The pooled cohort Atherosclerotic Cardiovascular Disease (ASCVD) risk calculator is designed to improve cardiovascular risk estimation compared with the Framingham Risk Score, particularly in blacks. Although the ASCVD risk score better predicts mortality and incident cardiovascular disease in blacks, less is known about its performance for subclinical vascular disease measures, including arterial stiffness and carotid intima-media thickness. We sought to determine if the ASCVD risk score better identifies subclinical vascular disease in blacks compared with the Framingham risk score. We calculated both the Framingham and ASCVD cohort risk scores in 1,231 subjects (mean age 53 years, 59% female, 37% black) without known cardiovascular disease and measured the extent of arterial stiffness, as determined by pulse wave velocity (PWV), central pulse pressure (CPP), and central augmentation index (CAIx), and subclinical atherosclerosis, as determined by carotid-IMT (C-IMT). Compared with whites, blacks had higher CAIx (23.9 ± 10.2 vs 22.1 ± 9.6%, p = 0.004), CPP (36.4 ± 10.5 vs 34.9 ± 9.8 mmHg, p = 0.014), PWV (7.6 ± 1.5 vs 7.3 ± 1.3 m/s, p = 0.004), and C-IMT (0.67 ± 0.10 vs 0.65 ± 0.10 mm, p = 0.005). In a multivariable analysis including race and Framingham risk score, race remained an independent predictor of all measures of subclinical vascular disease; however, models with race and the ASCVD risk score showed that race was not an independent predictor of subclinical vascular disease. In conclusion, greater subclinical vascular disease in blacks was not estimated by the Framingham risk score. The new ASCVD risk score provided a better estimate of racial differences in vascular function and structure.

MR-based calf muscle perfusion index correlates with treadmill exercise test parameters in patients with peripheral arterial disease

Background The functional impairment caused by peripheral arterial disease (PAD) is difficult to evaluate objectively and quantitatively. Current methods used to assess the efficacy of therapeutic interventions in patients with PAD are limited by variability and changes representing the placebo effect. Recently, Gadolinium-enhanced first-pass (FP) MRI has emerged as a new method to assess perfusion in peripheral muscles at peak exercise. We seek to demonstrate that calf muscle perfusion index measured with FP MRI at peak exercise correlates with treadmill exercise measures of ischemia in patients with PAD.

High‐Sensitivity Troponin I Levels and Coronary Artery Disease Severity, Progression, and Long‐Term Outcomes

Background The associations between high‐sensitivity troponin I (hsTnI) levels and coronary artery disease (CAD) severity and progression remain unclear. We investigated whether there is an association between hsTnI and angiographic severity and progression of CAD and whether the predictive value of hsTnI level for incident cardiovascular outcomes is independent of CAD severity. Methods and Results In 3087 patients (aged 63±12 years, 64% men) undergoing cardiac catheterization without evidence of acute myocardial infarction, the severity of CAD was calculated by the number of major coronary arteries with ≥50% stenosis and the Gensini score. CAD progression was assessed in a subset of 717 patients who had undergone ≥2 coronary angiograms >3 months before enrollment. Patients were followed up for incident all‐cause mortality and incident cardiovascular events. Of the total population, 11% had normal angiograms, 23% had nonobstructive CAD, 20% had 1‐vessel CAD, 20% had 2‐vessel CAD, and 26% had 3‐vessel CAD. After adjusting for age, sex, race, body mass index, smoking, hypertension, diabetes mellitus history, and renal function, hsTnI levels were independently associated with the severity of CAD measured by the Gensini score (log 2 ß=0.31; 95% confidence interval, 0.18–0.44; P<0.001) and with CAD progression (log 2 ß=0.36; 95% confidence interval, 0.14–0.58; P=0.001). hsTnI level was also a significant predictor of incident death, cardiovascular death, myocardial infarction, revascularization, and cardiac hospitalizations, independent of the aforementioned covariates and CAD severity. Conclusions Higher hsTnI levels are associated with the underlying burden of coronary atherosclerosis, more rapid progression of CAD, and higher risk of all‐cause mortality and incident cardiovascular events. Whether more aggressive treatment aimed at reducing hsTnI levels can modulate disease progression requires further investigation.

Sex Differences in Circulating Progenitor Cells

Background Lower levels of circulating progenitor cells (PCs) reflect impaired endogenous regenerative capacity and are associated with aging, vascular disease, and poor outcomes. Whether biologic sex and sex hormones influence PC numbers remains a subject of controversy. We sought to determine sex differences in circulating PCs in both healthy persons and patients with coronary artery disease, and to determine their association with sex hormone levels. Methods and Results In 642 participants (mean age 48 years, 69% women, 23% black) free from cardiovascular disease, we measured circulating PC counts as CD45med+ mononuclear cells coexpressing CD34 and its subsets expressing CD133, chemokine (C‐X‐C motif) receptor 4, and vascular endothelial growth factor receptor 2 epitopes using flow cytometry. Testosterone and estradiol levels were measured. After adjustment for age, cardiovascular risk factors, and body mass, CD34+ (β=−23%, P<0.001), CD34+/CD133+ (β=−20%, P=0.001), CD34+/chemokine (C‐X‐C motif) receptor 4–positive (β=−24%, P<0.001), and CD34+/chemokine (C‐X‐C motif) receptor 4–positive/CD133+ (β=−21%, P=0.001) PC counts, but not vascular endothelial growth factor receptor 2‐positive PC counts were lower in women compared with men. Estradiol levels positively correlated with hematopoietic, but not vascular endothelial growth factor receptor 2‐ positive PC counts in women (P<0.05). Testosterone levels and PC counts were not correlated in men. These findings were replicated in an independent cohort with prevalent coronary artery disease. Conclusions Women have lower circulating hematopoietic PC levels compared with men. Estrogen levels are modestly associated with PC levels in women. Since PCs are reflective of endogenous regenerative capacity, these findings may at least partly explain the rise in adverse cardiovascular events in women with aging and menopause.