Subclinical myocardial necrosis and cardiovascular risk in stable patients undergoing elective cardiac evaluation.

OBJECTIVE: The presence of subclinical myocardial necrosis as a prodrome to longer-term adverse cardiac event risk has been debated. The debate has focused predominantly within patients with acute coronary syndrome, and on issues of troponin assay variability and accuracy of detection, rather than on the clinical significance of the presence of subclinical myocardial necrosis (ie, "troponin leak") within stable cardiac patients. Herein, we examine the relationship between different degrees of subclinical myocardial necrosis and long-term adverse clinical outcomes within a stable cardiac patient population with essentially normal renal function. METHODS AND RESULTS: Sequential consenting patients (N=3828; median creatinine clearance, 100 mL/min/1.73m(2)) undergoing elective diagnostic coronary angiography with cardiac troponin I (cTnI) levels below the diagnostic cut-off for defining myocardial infarction (<0.03 ng/mL) were evaluated. The relationship of subclinical myocardial necrosis with incident major adverse cardiovascular events (defined as any death, myocardial infarction, or stroke) over 3-year follow-up was examined. "Probable" (cTnI 0.001-0.008 ng/mL) and "definite" (cTnI 0.009-0.029 ng/mL) subclinical myocardial necrosis were observed frequently within the cohort (34% and 18%, respectively). A linear relationship was observed between the magnitude of subclinical myocardial necrosis and risk of 3-year incident major adverse cardiovascular events, particularly in those with cTnI 0.009 ng/mL or higher (hazard ratio, 3.00; 95% confidence interval, 2.4-3.8), even after adjustment for traditional risk factors, C-reactive protein, and creatinine clearance. The presence of subclinical myocardial necrosis was associated with elevations in acute phase proteins (C-reactive protein, ceruloplasmin; P<0.01 each) and reduction in systemic antioxidant enzyme activities (arylesterase; P<0.01) but showed no significant associations with multiple specific measures of oxidant stress, and showed borderline associations with myeloperoxidase, a marker of leukocyte activation. CONCLUSIONS: In stable cardiology patients, prodromal subclinical myocardial necrosis is associated with substantially higher long-term risk for major adverse cardiovascular events. The underlying mechanisms contributing to this minimal troponin leak phenomenon warrants further investigation.

Prognostic value of myeloperoxidase in patients with chest pain.

BACKGROUND: Inflammation is linked to adverse outcomes in acute coronary syndromes. Myeloperoxidase, an abundant leukocyte enzyme, is elevated in culprit lesions that have fissured or ruptured in patients with sudden death from cardiac causes. Numerous lines of evidence suggest mechanistic links between myeloperoxidase and both inflammation and cardiovascular disease. METHODS: We assessed the value of plasma levels of myeloperoxidase as a predictor of the risk of cardiovascular events in 604 sequential patients presenting to the emergency department with chest pain. RESULTS: Initial plasma myeloperoxidase levels predicted the risk of myocardial infarction, even in patients who are negative for troponin T (<0.1 ng per milliliter) at base line (P<0.001). Myeloperoxidase levels at presentation also predicted the risk of major adverse cardiac events (myocardial infarction, the need for revascularization, or death) within 30 days and 6 months after presentation (P<0.001). In patients without evidence of myocardial necrosis (defined as those who were negative for troponin T), the base-line myeloperoxidase levels independently predicted the risk of major adverse coronary events at 30 days (unadjusted 2nd, 3rd, and 4th quartile odds ratios, 2.2 [95 percent confidence interval, 1.1 to 4.6], 4.2 [95 percent confidence interval, 2.1 to 8.4], and 4.1 [95 percent confidence interval, 2.0 to 8.4], respectively) and at 6 months. CONCLUSIONS: A single initial measurement of plasma myeloperoxidase independently predicts the early risk of myocardial infarction, as well as the risk of major adverse cardiac events in the ensuing 30-day and 6-month periods. Myeloperoxidase levels, in contrast to troponin T, creatine kinase MB isoform, and C-reactive protein levels, identified patients at risk for cardiac events in the absence of myocardial necrosis, highlighting its potential usefulness for risk stratification among patients who present with chest pain.

Comparative sensitivities between different plasma B-type natriuretic peptide assays in patients with minimally symptomatic heart failure.

Plasma B-type natriuretic peptide (BNP) assays have become widely used to diagnose and manage patients with heart failure. However, differences in assay characteristics may have important implications when BNP is used as a screening test for heart failure at a specific cutoff value. We performed a prospective comparison of 2 commercially available assays--one that is a laboratory-based, microparticle enzyme immunoassay (MEIA) that uses EDTA plasma specimens and one that is a point-of-care (POC), single-use fluorescence immunoassay that uses EDTA--anticoagulated whole blood or plasma specimens-in patients with heart failure and healthy controls. Despite the overall concordance between different SNP assays for the diagnosis of heart failure, their sensitivities may differ when compared at the approved diagnostic cutoff value of 100 pg/mL. At this cutoff value, the MEIA on AxSYM demonstrated greater sensitivity than POC Triage BNP assay in minimally symptomatic patients with heart failure. Therefore, for screening purposes, cutoff values for plasma BNP or N-terminal pro-BNP levels should be specific for each assay to optimize test performance. These findings suggest that there is a relationship between the decision statistics used in screening for left ventricular dysfunction and the type of diagnostic assay used.

Plasma ceruloplasmin, a regulator of nitric oxide activity, and incident cardiovascular risk in patients with CKD.

BACKGROUND AND OBJECTIVES: Increased serum levels of the acute-phase reactant ceruloplasmin predict adverse clinical outcomes in the setting of acute coronary syndromes and heart failure, but their role in patients with CKD is unclear. This study investigated the relationship of ceruloplasmin with clinical outcomes in CKD, especially with regard to traditional cardiac biomarkers. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Serum ceruloplasmin levels in consecutive study participants with CKD (n=654; estimated GFR<60 ml/min per 1.73 m(2)) as well as a control group of non-CKD participants matched for age and sex (n=250) were measured. Study participants were enrolled during 2001-2006 from a population of patients presenting for elective diagnostic coronary angiography and prospectively followed for 3 years (median follow-up=1095 days) to determine incident major adverse cardiac events (defined as a composite of death, nonfatal myocardial infarction, and stroke). RESULTS: Serum ceruloplasmin levels in CKD patients were elevated versus controls (median [interquartile range]; 25.5 [21.8-29.6] versus 22.7 [19.7-26.5] mg/dl; P<0.001) and associated with increased risk of future major adverse cardiac events (hazard ratio, 1.35; 95% confidence interval, 1.0 to 1.82; P=0.04). After adjusting for traditional risk factors, higher serum ceruloplasmin was still associated with higher risk of major adverse cardiac events at 3 years (hazard ratio, 1.61; 95% confidence interval, 1.15 to 2.25; P=0.01). CONCLUSION: In CKD patients, increased serum ceruloplasmin, a regulator of nitric oxide activity, is associated with increased risk of long-term adverse cardiovascular events, even after multivariable model adjustment for traditional clinical and biologic risk factors.

Diminished antioxidant activity of high-density lipoprotein-associated proteins in chronic kidney disease.

BACKGROUND: Decreased serum arylesterase activity, catalyzed by the high-density lipoprotein-associated paraoxonase (PON)-1, is associated with increased oxidant stress and atherosclerosis risk. We sought to determine the prognostic value of serum PON-1 activity, as monitored by PON or arylesterase activities, in subjects with chronic kidney disease (CKD), particularly in relation to established cardiac biomarkers. METHODS AND RESULTS: Serum arylesterase and PON activities were measured in sequential subjects with CKD (n=630; estimated glomerular filtration rate [eGFR] <60 mL/min per 1.73 m(2)) and an age- and sex-matched control group of non-CKD subjects (n=315) presenting for cardiac evaluations and prospectively followed for incident (3-year) major adverse cardiac events (composite of death, nonfatal myocardial infarction, and stroke). Serum arylesterase activity in CKD subjects was lower compared with that in non-CKD control subjects [median (interquartile range) 94 (77 to 112) versus 103 (85 to 121) µmol(L·min) per mL, P<0.001]; similarly, PON activity in CKD subjects was lower compared with that in non-CKD control subjects [median (interquartile range) 474 (275 to 936) versus 586 (301 to 1118) nmol(L·min) per mL, P<0.001]. Lower serum arylesterase (hazard ratio 1.8, 95% CI 1.26 to 2.57, P<0.01) was a predictor of poorer outcomes. After adjusting for traditional risk factors and medication use, lower serum arylesterase (hazard ratio 1.55, 95% CI 1.08 to 2.23, P<0.05) still conferred an increased risk of major adverse cardiac events at 3 years. CONCLUSIONS: In patients with CKD, decreased serum arylesterase activity, a measure of diminished antioxidant properties of PON-1, predicts higher risk of incident long-term adverse cardiovascular events (heart attack, stroke, or death) in multivariable models adjusting for established clinical and biochemical risk factors.

Diminished antioxidant activity of high-density lipoprotein-associated proteins in systolic heart failure.

BACKGROUND: Diminished serum arylesterase activity, catalyzed by the high-density lipoprotein-associated paraoxonase-1, is associated with heightened systemic oxidative stress and atherosclerosis risk. In the present study, we sought to determine the prognostic role of serum arylesterase activity in subjects with systolic heart failure, particularly in relation to established cardiac biomarkers. METHODS AND RESULTS: We measured serum arylesterase activity in 760 subjects with impaired left ventricular systolic function (left ventricular ejection fraction <50%), and prospectively followed major adverse cardiac events (including death, nonfatal myocardial infarction, and stroke) for 3 years. In our study cohort (mean age, 64±11 years; 74% men; median left ventricular ejection fraction, 35%; median creatinine clearance, 96 mg/dL), mean serum arylesterase activity (98±25 µmol/L/min/mL) was lower compared with that in healthy control subjects (mean, 115±26 µmol/L/min/mL, P<0.01) but higher compared with advanced decompensated heart failure subjects (mean, 69±22 µmol/L/min/mL, P<0.01). Within our cohort, there was modest correlation between serum arylesterase activity and high-density lipoprotein cholesterol (r=0.33, P<0.01) as well as B-type natriuretic peptide (r=-0.23, P<0.01). Lower serum arylesterase activity was a strong predictor of poorer outcomes (hazard ratio, 2.94; 95% confidence interval, 1.54, 5.62; P<0.001). After adjusting for traditional risk factors, medication use, B-type natriuretic peptide, and creatinine clearance, lower serum arylesterase still conferred an increased risk of major adverse cardiac events at 3 years (hazard ratio, 2.69; 95% confidence interval, 1.37 to 5.28; P=0.004). CONCLUSIONS: In patients with systolic heart failure, decreased serum arylesterase activity, a measure of diminished antioxidant properties of high-density lipoprotein, predicts higher risk of incident long-term adverse cardiac event independent of established clinical and biochemical risk factors.