Cost-effectiveness of a microvolt T-wave alternans screening strategy for implantable cardioverter-defibrillator placement in the MADIT-II-eligible population.

OBJECTIVES: This study was designed to compare the cost-effectiveness of implantable cardioverter-defibrillator (ICD) placement with and without risk stratification with microvolt T-wave alternans (MTWA) testing in the MADIT-II (Second Multicenter Automatic Defibrillator Implantation Trial) eligible population. BACKGROUND: Implantable cardioverter-defibrillators have been shown to prevent mortality in the MADIT-II population. Microvolt T-wave alternans testing has been shown to be effective in risk stratifying MADIT-II-eligible patients. METHODS: On the basis of published data, cost-effectiveness of three therapeutic strategies in MADIT-II-eligible patients was assessed using a Markov model: 1) ICD placement in all; 2) ICD placement in patients testing MTWA non-negative;, and 3) medical management. Outcomes of expected cost, quality-adjusted life-years (QALYs), and incremental cost-effectiveness were determined for patient lifetime. RESULTS: Under base-case assumptions, providing ICDs only to those who test MTWA non-negative produced a gain of 1.14 QALYs at an incremental cost of 55,700 dollars when compared to medical therapy, resulting in an incremental cost-effectiveness ratio (ICER) of 48,700 dollars/QALY. When compared with a MTWA risk-stratification strategy, placing ICDs in all patients resulted in an ICER of 88,700 dollars/QALY. Most (83%) of the potential benefit was achieved by implanting ICDs in the 67% of patients who tested MTWA non-negative. Results were most sensitive to the effectiveness of MTWA as a risk-stratification tool, MTWA negative screen rate, cost and efficacy of ICD therapy, and patient risk for arrhythmic death. CONCLUSIONS: Risk stratification with MTWA testing in MADIT-II-eligible patients improves the cost-effectiveness of ICDs. Implanting defibrillators in all MADIT-II-eligible patients, however, is not cost-effective, with one-third of patients deriving little additional benefit at great expense.     

Progesterone oxidation by cytochrome P450 2D isoforms in the brain

The existence of cytochrome P450 2D isoforms in the brain has been demonstrated, although their physiological functions remain to be elucidated. In this study we demonstrated that recombinant rat cytochrome P450 2D1 and 2D4 and human cytochrome P450 2D6 possess progesterone 6 beta- and 16 alpha- hydroxylation activities; 2 beta- and 21-hydroxylation activities; and 2 beta-, 6 beta-, 16 alpha- and 21-hydroxylation activities, respectively. Cytochrome P450 2D4 had the lowest K(m) value and the highest maximum velocity value toward these activities. Progesterone 2 beta- and 21-hydroxylation activities were also detected in rat brain microsomes, and these activities were completely inhibited by anticytochrome P450 2D antibodies. The presence of endogenous 2 beta- and 21-hydroxyprogesterones in rat brain tissues was also demonstrated. The mRNAs of cytochrome P450 2D4, CYP11A, and 3 beta-hydroxysteroid dehydrogenase were detected in the rat brain, suggesting that progesterone was generated from cholesterol by CYP11A and 3 beta-hydroxysteroid dehydrogenase and then underwent hydroxylation to hydroxyprogesterones by cytochrome P450 2D4 in rat brain. Collectively, our findings support the idea that cytochrome P450 2D may be involved in the regulation (metabolism and/or synthesis) of endogenous neuroactive steroids, such as progesterone and its derivatives, in brain tissues.     

Racial and ethnic variations in caregiver service use

OBJECTIVE: This article examines whether race and ethnicity contribute to the differential use of caregiver support services, when controlling for caregiver and care recipient characteristics, as represented by predisposing, enabling, and need factors included in the Behavioral Model of Health Services Use. METHODS: The study includes 1,508 individuals who provide care to an ill or disabled adult aged 50 or older, identified through a random digit dial telephone survey of California households. Logistic regression analysis is utilized to examine factors that predict use of caregiver support services. RESULTS: Race and ethnicity do not contribute significantly to caregiver service utilization, when controlling for relevant covarying factors such as age, education, emotional support, family contribution, care recipient service use, and care recipient impairment. A significant interaction exists between ethnicity and family closeness, with reduced rates of service use among Asian and Pacific Island caregivers whose families are brought closer by the caregiving experience. DISCUSSION: These findings suggest that racial and ethnic disparities in caregiver service use found at the bivariate level are attributable to covarying predisposing, enabling, and need factors. Further research and theoretical development are suggested to clarify the impact of sociocultural factors on caregiver service use.     

A Critical Role for Thioredoxin-Interacting Protein in Diabetes-Related Impairment of Angiogenesis

Impaired angiogenesis in ischemic tissue is a hallmark of diabetes. Thioredoxin-interacting protein (TXNIP) is an exquisitely glucose-sensitive gene that is overexpressed in diabetes. As TXNIP modulates the activity of the key angiogenic cytokine vascular endothelial growth factor (VEGF), we hypothesized that hyperglycemia-induced dysregulation of TXNIP may play a role in the pathogenesis of impaired angiogenesis in diabetes. In the current study, we report that high glucose–mediated overexpression of TXNIP induces a widespread impairment in endothelial cell (EC) function and survival by reducing VEGF production and sensitivity to VEGF action, findings that are rescued by silencing TXNIP with small interfering RNA. High glucose–induced EC dysfunction was recapitulated in normal glucose conditions by overexpressing either TXNIP or a TXNIP C247S mutant unable to bind thioredoxin, suggesting that TXNIP effects are largely independent of thioredoxin activity. In streptozotocin-induced diabetic mice, TXNIP knockdown to nondiabetic levels rescued diabetes-related impairment of angiogenesis, arteriogenesis, blood flow, and functional recovery in an ischemic hindlimb. These findings were associated with in vivo restoration of VEGF production to nondiabetic levels. These data implicate a critical role for TXNIP in diabetes-related impairment of ischemia-mediated angiogenesis and identify TXNIP as a potential therapeutic target for the vascular complications of diabetes.     

Canadian Cardiovascular Society Guidelines for the Diagnosis and Management of Stable Ischemic Heart Disease

This overview provides a guideline for the management of stable ischemic heart disease. It represents the work of a primary and secondary panel of participants from across Canada who achieved consensus on behalf of the Canadian Cardiovascular Society. The suggestions and recommendations are intended to be of relevance to primary care and specialist physicians with an emphasis on rational deployment of diagnostic tests, expedited implementation of long- and short-term medical therapy, timely consideration of revascularization, and practical follow-up measures.     

Zotarolimus-eluting stent utilization in small-vessel coronary artery disease (ZEUS)

The role of the second-generation zotarolimus-eluting stent RESOLUTE in small-vessel coronary artery disease is unclear. The aim of this study was examine the angiographic results of RESOLUTE in de novo coronary lesions of ≥50 % diameter stenosis in target vessels ≤2.5 mm. From August 2008 to April 2010, 142 symptomatic patients with 159 lesions who fitted the inclusion criteria were treated with RESOLUTE. The mean age of patients was 66 ± 10 years, with male predominance (66 %). Diabetes mellitus was found in 62 (43.7 %) patients, whereas multivessel disease was observed in 105 (73.9 %). The mean stent size and length used were 2.33 ± 0.13 and 22 ± 8 mm, respectively. Follow-up angiography was performed on 143 (89.9 %) lesions in 127 (89.4 %) patients at a mean of 10.3 ± 3.6 months. Angiographic restenosis was found in 9 (6.3 %) lesions; the late loss was 0.26 ± 0.34 mm. At 1-year follow-up there were four cardiovascular deaths, two nonfatal myocardial infarctions, and six repeated revascularizations. The resultant major adverse cardiac event rate was 8.5 %. The use of RESOLUTE to treat small-vessel disease is associated with good clinical and angiographic outcomes at 1 year.