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Gallium nitride (GaN) transistors, first introduced in the 1990s, have become key building blocks for many commercial and military electronics systems. The high radio frequency (RF) power generating capability of GaN is one of its most attractive features, but if they are not properly thermally managed, severe RF performance degradation can occur, such as reduced gain, reduced output power, and lower efficiency. This paper introduces a recently developed microfluidic cooling technique and presents experimental results quantifying the RF performance benefits to a high frequency RF GaN high power amplifier. It is shown that, when compared to state-of-the-art conventional liquid cooling, the new microfluidic cooling technique improved a GaN monolithic microwave integrated circuit amplifier’s gain by over 4 dB, its maximum output power by over 8 dB and its power added efficiency by 3% to 5% points. [ABSTRACT FROM AUTHOR]

Background: Uric acid is a nontraditional risk factor implicated in the development of coronary artery disease (CAD). This study prospectively evaluated the predictive value of serum uric acid (SUA) levels for mortality after angiographic diagnosis of CAD. Methods: Blood samples were collected from 1,595 consecutive, consenting patients with significant, angiographically defined CAD (stenosis 70%). Baseline and procedural variables were recorded and levels of SUA were measured. Patients were followed to death or to the time of contact (mean 2.6 years, range 1.8-5.0 years). Results: Patients averaged 65 +/- 11 years of age, 78% were male and 170 subjects died during the follow-up period. In univariate analysis of prospectively defined quintiles, SUA predicted all-cause mortality (fifth quintile vs. first four quintiles: hazard ratio 1.9, p < 0.001). In multivariable Cox regression controlling for 20 covariables, independent predictive value for mortality was retained by SUA (hazard ratio 1.5, confidence interval 1.02-2.1, p = 0.04). In subgroup analysis based on diuretic use status, SUA independently predicted mortality among patients not using diuretics, while SUA was not a significant predictor of mortality among those who used diuretics. Conclusions: In patients with significant, angiographically defined CAD, SUA predicted mortality independent of traditional risk factors. This suggests that elevated SUA may be a risk factor for mortality in patients with significant cardiovascular disease and may be a stronger secondary than primary risk factor in CAD. [ABSTRACT FROM AUTHOR]

Background: Despite recent advances in the treatment and prevention of cardiovascular disease, a treatment gap for secondary prevention medications still exists. Objective: To develop and implement a program ensuring appropriate prescription of aspirin, statins, β-blockers, angiotensin-converting enzyme inhibitors, and warlarin at hospital discharge. Design: A nonrandomized before-after study comparing patients hospitalized before (1996-1998) and after (1999-2002) implementation of a discharge medication program (DMP). Patients were followed for up to 1 year. Setting: The 10 largest hospitals in the Utah-based Intermountam Health Care system. Patients: In the pre-DMP and DMP time periods, 26 000 and 31 465 patients, respectively, were admitted to cardiovascular services (n = 57465). Measurements: Prescription of indicated medications at hospital discharge; post discharge death or readmission. Results: By 1 year, the rate of prescription of each medication increased significantly to more than 90% (P< 0.001); this rate was sustained. At 1 year, unadjusted absolute event rates for readmission and death, respectively, were 210 per 1000 person-years and 96 per 1000 person-years before OMP implementation and 191 per 1000 person-years and 70 per 1000 person-years afterward. Relative risk for death and readmission at 30 days decreased after OMP implementation; hazard ratios (HRs) for death and readmission were 0.81 (95% CI, 0.73 to 0.89) and 0.92 (CI, 0.87 to 0.99) (P < 0.001 and P = 0.017, respectively). At I year, risk for death continued to decrease (hazard ratio, 0.79 [CI, 0.75 to 0.84]; P < 0.001) while risk for readmission stabilized (hazard ratio, 0.94 [CI, 0.90 to 0.98]; P= 0.002), probably because survivors had more opportunities to be readmitted. Limitations: The study design was observational and nonrandomized, and the authors could not control for potential confounders or determine the extent to which secular trends accounted for the observed improvements. Conclusions: A relatively simple quality improvement program aimed at enhancing the prescription of appropriate discharge medications among cardiovascular patients is feasible and can be sustained within an integrated multihospital system. Such a program may be associated with improvements in cardiovascular readmission rates and mortality. [ABSTRACT FROM AUTHOR]

Abstract: Background: Some components of the complete blood count and basic metabolic profile are commonly used risk predictors. Many of their components are not commonly used, but they might contain independent risk information. This study tested the ability of a risk score combining all components to predict all-cause mortality. Methods: Patients with baseline complete blood count and basic metabolic profile measurements were randomly assigned (60%/40%) to independent training (N = 71,921) and test (N = 47,458) populations. A third population (N = 16,372) from the Third National Health and Nutrition Examination Survey and a fourth population of patients who underwent coronary angiography (N = 2558) were used as additional validation groups. Risk scores were computed in the training population for 30-day, 1-year, and 5-year mortality using age- and sex-adjusted weights from multivariable modeling of all complete blood count and basic metabolic profile components. Results: Area under the curve c-statistics were exceptional in the training population for death at 30 days (c = 0.90 for women, 0.87 for men), 1 year (c = 0.87, 0.83), and 5-years (c = 0.90, 0.85) and in the test population for death at 30 days (c = 0.88 for women, 0.85 for men), 1 year (c = 0.86, 0.82), and 5 years (c = 0.89, 0.83). In the test, the Third National Health and Nutrition Examination Survey, and the angiography populations, risk scores were highly associated with death (P <.001), and thresholds of risk significantly stratified all 3 populations. Conclusion: In large patient and general populations, risk scores combining complete blood count and basic metabolic profile components were highly predictive of death. Easily computed in a clinical laboratory at negligible incremental cost, these risk scores aggregate baseline risk information from both the popular and the underused components of ubiquitous laboratory tests. [Copyright &y& Elsevier]

Objectives: This study evaluated the effect of statin therapy on mortality in individuals with significant coronary artery disease (CAD) stratified by age.Background: Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) significantly reduce morbidity and mortality in individuals with CAD. Unfortunately, the large statin trials excluded individuals over 80 years old, and it is therefore unknown whether very elderly individuals benefit from statins as do younger individuals.Methods: A cohort of 7,220 individuals with angiographically defined significant CAD (> or =70%) was included. Statin prescription was determined at hospital discharge. Patients were followed up for 3.3 +/- 1.8 years (maximum 6.8). Patients were grouped by age (<65, 65 to 79, and > or =80 years) to determine whether statin therapy reduced mortality in an age-dependent manner.Results: Average age was 65 +/- 12 years; 74% were male; and 31% had a postmyocardial infarction status. Overall mortality was 16%. Elderly patients were significantly less likely to receive statins than younger patients (> or =80 years: 19.8%; 65 to 79 years: 21.1%; <65 years: 28.0%; p < 0.001). Mortality was decreased among statin recipients in all age groups: > or =80 years: 29.5% among patients not taking a statin versus 8.5% of those taking a statin (adjusted hazard ratio [HR] 0.50, p = 0.036); 65 to 79 years: 18.7% vs. 6.0% (HR 0.56, p < 0.001); and <65 years: 8.9% vs. 3.1% (HR 0.70, p = 0.097).Conclusions: Statin therapy is associated with reduced mortality in all age groups of individuals with significant CAD, including very elderly individuals. Although older patients were less likely to receive statin therapy, they received a greater absolute risk reduction than younger individuals. More aggressive statin use after CAD diagnosis may be indicated, even in older patients. [ABSTRACT FROM AUTHOR]

Despite well-documented clinical benefit of the use of statins in patients with coronary artery disease (CAD) and even mild lipid elevations, studies have documented the presence of a significant "treatment gap" between those patients in whom treatment is indicated and those patients who actually receive it. It has been proposed that a prescription for statin therapy given to indicated patients at the time of initial angiographic diagnosis of CAD has the potential to improve long-term medication compliance, but this requires further evaluation. We prospectively followed 600 patients with angiographically demonstrated CAD (diameter stenosis > or = 70%) who met the National Cholesterol Education Project (NCEP) guidelines for statin therapy for an average of 3.0 years (range 2.0 to 4.6). Patients were an average of 65 years of age, 78% were men, 77% presented initially with acute ischemic syndrome, and 64 (10.7%) died during follow-up. Overall, 105 patients (18%) were discharged from the initial hospitalization with a statin prescription. At long-term follow-up, the number of patients taking statins had increased to 47%. However, long-term statin compliance was significantly higher among patients initially discharged with a statin prescription than those who were not (77% vs 40%; p < 0.0001). Additionally, those patients discharged with a statin prescription had significantly reduced mortality rate at long-term follow-up (5.7% vs 11.7%; p = 0.05). Cox hazard regression analysis, controlling for all known clinical baseline variables, confirmed the absence of a prehospital discharge statin prescription to be an independent predictor of increased mortality (hazard ratio 2.4) with a statistical trend (p = 0.06). Thus, this study demonstrates that after angiographic diagnosis of CAD, prescription of appropriate statin therapy at the time of hospital discharge improves long-term statin compliance and may significantly enhance survival. [ABSTRACT FROM AUTHOR]

It is proposed that contrast-induced nephropathy (CN) correlates with the use of increasing contrast volumes during coronary angiography. This supposition has led to the current recommendation to limit the dose of contrast in patients at high risk for renal dysfunction. Limits in contrast dosing may negatively impact the evaluation of patients undergoing cardiac catheterization for myocardial infarction and acute coronary syndrome. The objective of this study was to empirically assess, in a large population, the presence and strength of this correlation. Baseline blood samples and clinical information were obtained from 5256 consenting patients hospitalized for coronary angiography. Levels of serum creatinine were measured pre- and postcatheterization, and the total change in serum creatinine was calculated. Nephropathy was defined as a change of > or =0.5 mg/dL. The total volume of contrast dye (iopamidol, nonionic) used during the angiography procedure was recorded. Logistic regression was used for the primary analysis.The average age was 64 +/- 14 years, and 67% of patients were male. Paradoxically, the incidence of CN was inversely related to the volume in the overall population: 16%, 14%, 8%, and 7% for quartile (Q) 1 (<115 mL), Q2 (115-160 mL), Q3 (161-225 mL), and Q4 (>225 mL) of contrast, respectively (P-trend <0.001). In multivariable regression, this trend toward lower CN remained (Q1 (referent) OR = 1.0, Q2: 1.02, Q3: 0.60, Q4: 0.53, P < 0.001). Other predictors included age, left ventricular ejection fraction, diabetes, and baseline creatinine level (all P < 0.001). For patients at high risk, with a baseline creatinine >2.0 mg/dL (n = 415), contrast volume (Q1: <75 mL, Q2: 75-120 mL, Q3: 121-170 mL, Q4: >170 mL) did not predict either increased or decreased risk of CN (48%, 42%, 49%, 43%, respectively, P-trend = 0.76). This lack of predictive value remained after multivariable adjustment.In this large population, no association was found between the amount of contrast used during angiography and the incidence of CN in patients at initial high risk. The apparent inverse relation of risk with volume in the overall population is likely explained by clinical practice bias. If confirmed, these results may have important clinical implications.

Background: Large randomized clinical trials have demonstrated differences in the efficacy and safety of glycoprotein (GP) IIb/IIIa inhibitors, but little has been published regarding comparisons of these agents in a "real-world" setting., Purpose: This study evaluated the safety and efficacy of GP IIb/IIIa inhibitors in a large population of patients who underwent percutaneous coronary intervention (PCI) during a 5-year period., Methods: Patients undergoing PCI from 2000 through 2004 were eligible for inclusion if they received any single GP IIb/IIIa inhibitor. Patients with significant comorbidities were included. Patients were excluded if they received more than one GP IIb/IIIa inhibitor or underwent catheterization without PCI. Target activated clotting time was 200-250 seconds., Results: Of 5,055 patients undergoing PCI, 4,321 (85%) received a single GP IIb/IIIa inhibitor (abciximab, 1,178; eptifibatide, 1,698; tirofiban, 1,445). Major bleeding complications were rare, ranging from 1.9-3.1%, and transfusion rates were low, ranging from 0.8-2.1%, with no significant differences among the agents evaluated. No significant differences in 1-year mortality, myocardial infarction, urgent target vessel revascularization or composite endpoint rates were identified among the therapeutic agents., Conclusions: In this large study of PCI patients, GP IIb/IIIa inhibition was associated with a low incidence of major bleeding complications and requirement of transfusion. With appropriate management, GP IIb/IIIa inhibitor use can benefit patients undergoing PCI, with minimal risk of bleeding complications.

Background: Coronary artery bypass surgery (CABG) and percutaneous coronary intervention with stenting (PCI-S) are both safe and effective approaches for revascularization in patients with multivessel coronary artery disease. However, conflicting information exists when comparing the efficacy of the two methods. In this study, we examined the outcomes of major adverse cardiovascular events and death for subgroups of typical "real-world" patients undergoing coronary revascularization in the modern era., Methods and Results: Patients were included if they were revascularized by CABG or PCI-S, had > or = 5 years of follow-up, and had > or = 2-vessel disease. Patients were followed for an average of 7.0+/-3.2 years for incidence of death and major adverse cardiovascular events (death, myocardial infarction, or repeat revascularization). Multivariate regression models were used to correct for standard cardiac risk factors including age, sex, hyperlipidemia, diabetes mellitus, family history of coronary artery disease, smoking, hypertension, heart failure, and renal failure. Subgroup analyses were also performed, stratified by age, sex, diabetes, ejection fraction, and history of PCI-S, CABG, or myocardial infarction. A total of 6369 patients (CABG 4581; PCI-S 1788) were included. Age averaged 66+/-10.9 years, 76% were male, and 26% were diabetic. Multivariate risk favored CABG over PCI-S for both death (hazard ratio 0.85; P=0.001) and major adverse cardiovascular events (hazard ratio 0.51; P<0.0001). A similar advantage with CABG was also found in most substrata, including diabetes., Conclusions: In this large observational study of patients undergoing revascularization for multivessel coronary artery disease, a long-term benefit was found, in relationship to both death and major adverse cardiovascular events, for CABG over PCI-S regardless of diabetic status or other stratifications.