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J B Muhlestein

Publications and source records attributed to J B Muhlestein.

At least 19 recordsLinked to original sources
PubMed2005

Generating genetic risk scores from intermediate phenotypes for use in association studies of clinically significant endpoints.

While previous results of genetic association studies for common, complex diseases (eg., coronary artery disease, CAD) have been disappointing, examination of multiple related genes within a physiologic pathway may provide improved resolution. This paper describes a method of calculating a genetic risk score (GRS) for a clinical endpoint by integrating data from many candidate genes and multiple intermediate phenotypes (IPs). First, the association of all single nucleotide polymorphisms (SNPs) to an IP is determined and regression beta-coefficients are used to calculate an IP-specific GRS for each individual, repeating this analysis for every IP. Next, the IPs are assessed by a second regression as predictors of the clinical endpoint. Each IP's individual GRS is then weighted by the regression beta-coefficients from the second step, creating a single, composite GRS. As an example, 3,172 patients undergoing coronary angiography were evaluated for 3 SNPs from the cholesterol metabolism pathway. Although these data provide only a preliminary example, the GRS method detected significant differences in CAD by GRS group, whereas separate genotypes did not. These results illustrate the potential of the GRS methodology for multigenic risk evaluation and suggest that such approaches deserve further examination in common, complex diseases such as CAD.

Coronary Disease↗
PubMed2001

Usefulness of in-hospital prescription of statin agents after angiographic diagnosis of coronary artery disease in improving continued compliance and reduced mortality.

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.

Aged↗
PubMed2001

Prospective study of pathogen burden and risk of myocardial infarction or death.

BACKGROUND: We previously demonstrated that the risk of coronary artery disease (CAD) increased in relation to the number of pathogens (the "pathogen burden") in a cross-sectional study. In the present prospective study with a different patient cohort, we evaluated the effect of pathogen burden on the risk of myocardial infarction (MI) or death among CAD patients. METHODS AND RESULTS: IgG antibodies to cytomegalovirus (CMV), hepatitis A virus (HAV), herpes simplex virus type 1 (HSV1), HSV type 2 (HSV2), Chlamydia pneumoniae and Helicobacter pylori, and C-reactive protein (CRP) levels were tested in baseline blood samples from 890 patients who had significant CAD on angiography. The mean follow-up period was 3 years. The baseline prevalence of antibodies directed against CMV, HAV, HSV1, or HSV2, but not C pneumoniae and H pylori, was significantly higher among patients who subsequently developed MI or death than among control subjects. After adjustment for traditional risk factors, number of diseased vessels, and clinical presentation, relative hazards (95% confidence limits) for MI or death were 2.0 (1. 4 to 3.2) for CMV, 1.6 (1.1 to 2.3) for HAV, and 1.5 (1.0 to 2.2) for HSV2. Increasing pathogen burden was significantly associated with increasing risk of MI or death in a dose-response fashion. Adjusted relative hazards of MI or death associated with pathogen burden were significant among individuals with low or high CRP levels. CONCLUSIONS: The results suggest that infection plays an important role in incident MI or death and that the risk posed by infection is independently related to the pathogen burden.

Adult↗
PubMed2001

Femoral arterial puncture management after percutaneous coronary procedures: a comparison of clinical outcomes and patient satisfaction between manual compression and two different vascular closure devices.

BACKGROUND: Vascular access site management is crucial to safe, efficient and comfortable diagnostic or interventional transfemoral percutaneous coronary procedures. Two new femoral access site closure devices, Perclose and Angio-Seal , have been proposed as alternative methods to manual compression (MC). We compared these two devices and tested them in reference to standard MC for safety, effectiveness and patient preference. METHODS: Prospective demographic, peri-procedural, and late follow-up data for 1,500 patients undergoing percutaneous coronary procedures were collected from patients receiving femoral artery closure by MC (n = 469), Perclose (n = 492), or Angio-Seal (n = 539). Peri-procedural, post-procedural, and post-hospitalization endpoints were: 1) safety of closure method; 2) efficacy of closure method; and 3) patient satisfaction. RESULTS: Patients treated with Angio-Seal experienced shorter times to hemostasis (p < 0.0001, diagnostic and interventional) and ambulation (diagnostic, p = 0.05; interventional, p < 0.0001) than those treated with Perclose. Those treated with Perclose experienced greater access site complications (Perclose vs. Angio-Seal, p = 0.008; Perclose vs. MC, p = 0.06). Patients treated with Angio-Seal reported greater overall satisfaction, better wound healing and lower discomfort (each vs. Perclose or vs. MC, all p < or = 0.0001). For diagnostic cath only, median post-procedural length of stay was reduced by Angio-Seal (Angio-Seal vs. MC, p < 0.0001; Angio-Seal vs. Perclose, p = 0.009). No difference was seen in length of stay for interventional cases. CONCLUSIONS: Overall, Angio-Seal performed better than Perclose or MC in reducing time to ambulation and length of stay among patients undergoing diagnostic procedures. There was a higher rate of successful deployment and shorter time to hemostasis for Angio-Seal, and this was accomplished with no increase in bleeding complications throughout the follow-up. Additionally, Angio-Seal performed better than Perclose in exhibiting a superior 30-day patient satisfaction and patient assessment of wound healing with less discomfort.

Abciximab↗
PubMed2000

Statin therapy, lipid levels, C-reactive protein and the survival of patients with angiographically severe coronary artery disease.

OBJECTIVES: The joint predictive value of lipid and C-reactive protein (CRP) levels, as well as a possible interaction between statin therapy and CRP, were evaluated for survival after angiographic diagnosis of coronary artery disease (CAD). BACKGROUND: Hyperlipidemia increases risk of CAD and myocardial infarction. For first myocardial infarction, the combination of lipid and CRP levels may be prognostically more powerful. Although lipid levels are often measured at angiography to guide therapy, their prognostic value is unclear. METHODS: Blood samples were collected from a prospective cohort of 985 patients diagnosed angiographically with severe CAD (stenosis > or =70%) and tested for total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and CRP levels. Key risk factors, including initiation of statin therapy, were recorded, and subjects were followed for an average of 3.0 years (range: 1.8 to 4.3 years) to assess survival. RESULTS: Mortality was confirmed for 109 subjects (11%). In multiple variable Cox regression, levels of TC, LDL, HDL and the TC:HDL ratio did not predict survival, but statin therapy was protective (adjusted hazard ratio [HR] = 0.49, p = 0.04). C-reactive protein levels, age, left ventricular ejection fraction and diabetes were also independently predictive. Statins primarily benefited subjects with elevated CRP by eliminating the increased mortality across increasing CRP tertiles (statins: HR = 0.97 per tertile, p-trend = 0.94; no statins: HR = 1.8 per tertile, p-trend < 0.0001). CONCLUSIONS: Lipid levels drawn at angiography were not predictive of survival in this population, but initiation of statin therapy was associated with improved survival regardless of the lipid levels. The benefit of statin therapy occurred primarily in patients with elevated CRP.

Aged↗
PubMed2000

Cytomegalovirus seropositivity and C-reactive protein have independent and combined predictive value for mortality in patients with angiographically demonstrated coronary artery disease.

BACKGROUND: The role of inflammation in coronary artery disease (CAD) is being increasingly recognized. Markers of inflammation (eg, C-reactive protein [CRP]) and infection (eg, seropositivity to Chlamydia pneumoniae, cytomegalovirus [CMV], and Helicobacter pylori) have been proposed as risk factors for CAD, but these associations require further evaluation. METHODS AND RESULTS: We prospectively tested whether CRP levels and IgG seropositivity to C pneumoniae, CMV, and H pylori are predictors of subsequent mortality in 985 consecutive patients with angiographically demonstrated CAD (stenosis >/=70%). Patients were followed for an average of 2.7 years (range 1.5 to 4.0 years). Patients averaged 65 years of age; 77% were men; and 110 (11.2%) died during follow-up. CRP levels were significantly elevated in nonsurvivors compared with survivors (mean CRP 3.1 mg/dL versus 1.5 mg/dL, P:=0.003). After controlling for all known baseline variables, the 2nd and 3rd tertiles of CRP compared with the 1st produced a Cox hazard ratio (HR) for mortality of 2.4 (P:=0.001). Of the 3 infectious markers tested, only seropositivity to CMV (HR=1.9, P:<0.05) was predictive of mortality. The majority of mortality risk associated with elevated CRP or CMV seropositivity occurred when both risk factors were present (P: for trend <0.0001). Other independent predictors of increased risk of mortality were age (HR=1.07 per year, P:<0.0001), left ventricular ejection fraction (HR=0.97 per percent, P:<0.0001), and diabetes mellitus (HR=1.7, P:=0.02). CONCLUSIONS: CMV seropositivity and elevated CRP, especially when in combination, are strong, independent predictors of mortality in patients with CAD. This suggests an interesting hypothesis that a chronic, smoldering infection (CMV) might have the capacity to accelerate the atherothrombotic process.

Aged↗
PubMed2000

Randomized secondary prevention trial of azithromycin in patients with coronary artery disease: primary clinical results of the ACADEMIC study.

BACKGROUND: Chlamydia pneumoniae is associated with coronary artery disease (CAD), although its causal role is uncertain. A small preliminary study reported a >50% reduction in ischemic events by azithromycin, an antibiotic effective against C pneumoniae, in seropositive CAD patients. We tested this prospectively in a larger, randomized, double-blind study. METHODS AND RESULTS: CAD patients (n=302) seropositive to C pneumoniae (IgG titers >/=1:16) were randomized to placebo or azithromycin 500 mg/d for 3 days and then 500 mg/wk for 3 months. The primary clinical end point included cardiovascular death, resuscitated cardiac arrest, nonfatal myocardial infarction (MI), stroke, unstable angina, and unplanned coronary revascularization at 2 years. Treatment groups were balanced, and azithromycin was generally well tolerated. During the trial, 47 first primary events occurred (cardiovascular death, 9; resuscitated cardiac arrest, 1; MI, 11; stroke, 3; unstable angina, 4; and unplanned coronary revascularization, 19), with 22 events in the azithromycin group and 25 in the placebo group. There was no significant difference in the 1 primary end point between the 2 groups (hazard ratio for azithromycin, 0.89; 95% CI, 0.51 to 1.61; P:=0.74). Events included 9 versus 7 occurring within 6 months and 13 versus 18 between 6 and 24 months in the azithromycin and placebo groups, respectively. CONCLUSIONS: This study suggests that antibiotic therapy with azithromycin is not associated with marked early reductions (>/=50%) in ischemic events as suggested by an initial published report. However, a clinically worthwhile benefit (ie, 20% to 30%) is still possible, although it may be delayed. Larger (several thousand patient), longer-term (>/=3 to 5 years) antibiotic studies are therefore indicated.

Adult↗
PubMed2000

Plasma homocysteine predicts mortality independently of traditional risk factors and C-reactive protein in patients with angiographically defined coronary artery disease.

BACKGROUND: Plasma homocysteine (tHCY) has been associated with coronary artery disease (CAD). We tested whether tHCY also increases secondary risk, after initial CAD diagnosis, and whether it is independent of traditional risk factors, C-reactive protein (CRP), and methylenetetrahydrofolate reductase (MTHFR) genotype. METHODS AND RESULTS: Blood samples were collected from 1412 patients with severe angiographically defined CAD (stenosis >/=70%). Plasma tHCY was measured by fluorescence polarization immunoassay. The study cohort was evaluated for survival after a mean of 3.0+/-1.0 years of follow-up (minimum 1.5 years, maximum 5.0 years). The average age of the patients was 65+/-11 years, 77% were males, and 166 died during follow-up. Mortality was greater in patients with tHCY in tertile 3 than in tertiles 1 and 2 (mortality 15.7% versus 9.6%, P:=0.001 [log-rank test], hazard ratio [HR] 1.63). The relative hazard increased 16% for each 5-micromol/L increase in tHCY (P:<0.001). In multivariate Cox regression analysis, controlling for univariate clinical and laboratory predictors, elevated tHCY remained predictive of mortality (HR 1.64, P:=0.009), together with age (HR 1. 72 per 10-year increment, P:<0.0001), ejection fraction (HR 0.84 per 10% increment, P:=0.0001), diabetes (HR 1.98, P:=0.001), CRP (HR 1. 42 per tertile, P:=0.004), and hyperlipidemia. Homozygosity for the MTHFR variant was weakly predictive of tHCY levels but not mortality. CONCLUSIONS: In patients with angiographically defined CAD, tHCY is a significant predictor of mortality, independent of traditional risk factors, CRP, and MTHFR genotype. These findings increase interest in tHCY as a secondary risk marker and in secondary prevention trials (ie, with folate/B vitamins) to determine whether reduction in tHCY will reduce risk.

Aged↗
PubMed2000

Randomized trial of contrast media utilization in high-risk PTCA: the COURT trial.

BACKGROUND: Previous in vitro and in vivo studies have suggested an association between thrombus-related events and type of contrast media. Low osmolar contrast agents appear to improve the safety of diagnostic and coronary artery interventional procedures. However, no data are available on PTCA outcomes with an isosmolar contrast agent. METHODS AND RESULTS: A multicenter prospective randomized double-blind trial was performed in 856 high-risk patients undergoing coronary artery intervention. The objective was to compare the isosmolar nonionic dimer iodixanol (n=405) with the low osmolar ionic agent ioxaglate (n=410). A composite variable of in-hospital major adverse clinical events (MACE) was the primary end point. A secondary objective was to evaluate major angiographic and procedural events during and after PTCA. The composite in-hospital primary end point was less frequent in those receiving iodixanol compared with those receiving ioxaglate (5.4% versus 9.5%, respectively; P=0.027). Core laboratory defined angiographic success was more frequent in patients receiving iodixanol (92.2% versus 85. 9% for ioxaglate, P=0.004). There was a trend toward lower total clinical events at 30 days in patients randomized to iodixanol (9.1% versus 13.2% for ioxaglate, P=0.07). Multivariate predictors of in-hospital MACE were use of ioxaglate (P=0.01) and treatment of a de novo lesion (P=0.03). CONCLUSIONS: In this contemporary prospective multicenter trial of PTCA in the setting of acute coronary syndromes, there was a low incidence of in-hospital clinical events for both treatment groups. The cohort receiving the nonionic dimer iodixanol experienced a 45% reduction in in-hospital MACE when compared with the cohort receiving ioxaglate.

Aged↗
PubMed2000

Antibiotic therapy for treatment of Chlamydia to prevent coronary heart disease events.

Evidence is mounting that infectious agents might be involved in atherosclerosis. Therefore, antibiotic therapy might be helpful in its prevention. Early pilot therapeutic trials have targeted Chlamydia pneumoniae because it has the most evidence associating it with atherosclerosis. Small, randomized pilot trials that test the effect of macrolide therapy on future clinical events in patients with coronary artery disease have already shown promising but mixed results. Large clinical trials are presently underway that should provide more definitive information regarding the use of antibiotics in coronary artery disease. Until the results of these studies are available, it is not recommended that antibiotic therapy be routinely utilized for the treatment or prevention of complications of atherosclerosis.

Animals↗
PubMed2000

Chronic infection and coronary artery disease.

On a variety of fronts, chronic infection has been found to be significantly associated with the development of atherosclerosis and the clinical complications of unstable angina, myocardial infarction, and stroke. For the most part, these are still just associations. Specific causative relationships on par with that determined between H. pylori and peptic ulcer disease have not yet been established. Potential mechanisms whereby chronic infections may play a role in atherogenesis are myriad. In the case of C. pneumoniae, the effect may result from direct vessel wall colonization, which may damage the vessel directly or indirectly by initiating immunologic responses. In other cases, the effect may simply be that of enhancing the preexisting chronic inflammatory response of the body to standard risk factors, such as hyperlipidemia. Even though the infectious agent may not directly infect the vessel wall, it may perform its critical role from afar. Chronic infection might also influence preexisting plaque by enhancing T cell activation or other inflammatory responses that may participate in the destabilization of the intimal cap. Chronic infection may play a role in the initiation, progression, or destabilization of atherosclerotic plaques. The infectious agents with the most evidence to support a causative role in atherosclerosis include C. pneumoniae and cytomegalovirus. Evidence is mounting for a variety of other potential agents, including H. pylori, various periodontal agents, and even hepatitis A. Future studies are expected to elucidate further the pathophysiologic relationship between chronic infection and atherosclerosis and to evaluate the potential of a variety of treatment approaches, including antibiotics.

Animals↗
PubMed2000

A common variant of the AMPD1 gene predicts improved cardiovascular survival in patients with coronary artery disease.

OBJECTIVE: We tested whether a common AMPD1 gene variant is associated with improved cardiovascular (CV) survival in patients with coronary artery disease (CAD). BACKGROUND: Reduced activity of adenosine monophosphate deaminase (AMPD) may increase production of adenosine, a cardioprotective agent. A common, nonsense, point variant of the AMPD1 gene (C34T) results in enzymatic inactivity and has been associated with prolonged survival in heart failure. METHODS: Blood was collected from 367 patients undergoing coronary angiography. Genotyping was done by polymerase chain reaction amplification and restriction enzyme digestion, resulting in allele-specific fragments. Coronary artery disease was defined as > or =70% stenosis of > or =1 coronary artery. Patients were followed prospectively for up to 4.8 years. Survival statistics compared hetero- (+/-) or homozygotic (-/-) carriers with noncarriers. RESULTS: Patients were 66 +/- 10 years old; 79% were men; 22.6% were heterozygous and 1.9% homozygous for the variant AMPD1(-) allele. During a mean of 3.5 +/- 1.0 years, 52 patients (14.2%) died, 37 (10.1%) of CV causes. Cardiovascular mortality was 4.4% (4/90) in AMPD1(-) allele carriers compared with 11.9% (33/277) in noncarriers (p = 0.046). In multiple variable regression analysis, only age (hazard ratio, 1.11/year, p < 0.001) and AMPD1(-) carriage (hazard ratio, 0.36, p = 0.053) were independent predictors of CV mortality. CONCLUSIONS: Carriage of a common variant of the AMPD1 gene was associated with improved CV survival in patients with angiographically documented CAD. The dysfunctional AMPD1(-) allele may lead to increased cardiac adenosine and increased cardioprotection during ischemic events. Adenosine monophosphate deaminase-1 genotyping should be further explored in CAD for prognostic, mechanistic and therapeutic insights.

AMP Deaminase↗
PubMed2000

Collaborative multidisciplinary workshop report: clinical antimicrobial trials for primary and secondary prevention of atherosclerotic cardiovascular disease.

The task assigned to the working group on Clinical Antimicrobial Trials for Primary and/or Secondary Prevention of Atherosclerotic Cardiovascular Disease was to evaluate the need for additional clinical antibiotic trials of a primary or secondary nature for the treatment of atherosclerotic heart disease and to suggest possible designs for future trials. In addition, the working group was to define the role of collaboration in answering research questions.

Anti-Bacterial Agents↗
PubMed2000

Chlamydia pneumoniae-induced atherosclerosis in a rabbit model.

In order to establish a causative relationship between Chlamydia pneumoniae and atherosclerosis, animal models have been proposed. In a rabbit model, arterial intimal thickening has been induced by direct intravascular and intranasal inoculation with C. pneumoniae. C. pneumoniae infection can induce significant acceleration of atherosclerosis in a mildly hyperlipidemic rabbit model but is prevented by treatment with azithromycin. Together these preliminary rabbit experiments suggest that C. pneumoniae may play a causative role in atherosclerosis. More animal studies are underway that are designed to address further mechanistic and therapeutic questions regarding the association between C. pneumoniae and atherosclerosis.

Animals↗
PubMed2000

The ACADEMIC study in perspective (Azithromycin in coronary artery disease: elimination of myocardial infection with Chlamydia).

Chlamydia pneumoniae, a common cause of respiratory infection, is vasotropic and frequently found in human atheromas. Whether it plays a causal role in coronary artery disease (CAD) is uncertain. The effects of 3 months of azithromycin treatment or placebo were tested in 302 patients with chronic CAD seropositive to C. pneumoniae at 3-6 months. Azithromycin reduced a global rank sum score of 4 inflammatory markers (C-reactive protein [CRP], interleukin [IL]-1, IL-6, tumor necrosis factor-alpha; P=.011) and a global rank sum change score (+/-SD) (from 535+/-201 to 587+/-190; P=.027) at 6 (but not 3) months. Change scores for CRP and IL-6 and median IL-1 levels were lower. C. pneumoniae IgG and IgA antibody titers were unchanged. Clinical cardiovascular events at 6 months did not differ between groups (azithromycin, 9; placebo, 7). Infections were reduced and drug was well tolerated. Thus, azithromycin caused modest but significant reductions in markers of inflammation, but differences in clinical events were not evident at 6 months. However, power was limited and conclusions should await results of the 2-year evaluation and larger studies.

Aged↗
PubMed2000

The effect of chronic azithromycin therapy on soluble endothelium-derived adhesion molecules in patients with coronary artery disease.

In patients with coronary artery disease (CAD), azithromycin therapy is associated with decreased cytokine levels and overall reduction of inflammation. Chlamydia pneumoniae (C.Pn) is a common pathogen that may be an important factor in the development and progression of atherosclerosis. Cell-adhesion molecules have an important role in recruitment of inflammatory cells during plaque development and are expressed by endothelial cells on activation. We sought to define the effect of treatment with azithromycin on circulating levels of soluble vascular cell-adhesion molecule (VCAM-I), intercellular adhesion molecule (ICAM-1), and E-selectin in patients with CAD. Plasma concentrations of VCAM-1, ICAM-1, and E-selectin were measured in 40 patients with documented CAD and a positive (> or = 1:16) immunoglobulin G (IgG) titer against C.Pn, 20 subjects with normal coronary arteries, and 14 healthy volunteers. Patients were assigned randomly to receive either 500 mg/wk of azithromycin or placebo for 3 months. Serum samples were obtained at baseline, at 3 months, and during the follow-up visit at 6 months. Patients with documented CAD exhibited elevation of VCAM-1 (535 +/- 227 ng/ ml; p = 0.0001) and E-selectin (69 +/- 29 ng/ml; p = 0.006), but not ICAM-1 (321 +/- 65 ng/ml) concentrations as compared with the patients with angiographically proven normal coronary arteries (252 +/- 80; 50 +/- 22; and 311 +/- 40 ng/ml) and healthy controls (110 +/- 18; 29 +/- 2; and 238 +/- 47 ng/ml, respectively). Prolonged treatment with azithromycin did not significantly affect the plasma levels of soluble VCAM-1, ICAM-1, and E-selectin. Soluble markers of endothelial activation are markedly increased in patients with documented CAD as compared with those with normal coronary arteries and healthy controls. Despite substantial heterogeneity in plasma E-selectin, ICAM-1, and VCAM-1 levels, long-term azithromycin treatment did not affect plasma levels of these adhesion molecules, indicative of endothelial activation, over a period of 6 months.

Adult↗