Christoph Bickel

Sensitive Troponin I Assay in Early Diagnosis of Acute Myocardial Infarction

BACKGROUND Cardiac troponin testing is central to the diagnosis of acute myocardial infarction. We evaluated a sensitive troponin I assay for the early diagnosis and risk stratification of myocardial infarction. METHODS In a multicenter study, we determined levels of troponin I as assessed by a sensitive assay, troponin T, and traditional myocardial necrosis markers in 1818 consecutive patients with suspected acute myocardial infarction, on admission and 3 hours and 6 hours after admission. RESULTS For samples obtained on admission, the diagnostic accuracy was highest with the sensitive troponin I assay (area under the receiver-operating-characteristic curve [AUC], 0.96), as compared with the troponin T assay (AUC, 0.85) and traditional myocardial necrosis markers. With the use of the sensitive troponin I assay (cutoff value, 0.04 ng per milliliter) on admission, the clinical sensitivity was 90.7%, and the specificity was 90.2%. The diagnostic accuracy was virtually identical in baseline and serial samples, regardless of the time of chest-pain onset. In patients presenting within 3 hours after chest-pain onset, a single sensitive troponin I assay had a negative predictive value of 84.1% and a positive predictive value of 86.7%; these findings predicted a 30% rise in the troponin I level within 6 hours. A troponin I level of more than 0.04 ng per milliliter was independently associated with an increased risk of an adverse outcome at 30 days (hazard ratio, 1.96; 95% confidence interval, 1.27 to 3.05; P=0.003). CONCLUSIONS The use of a sensitive assay for troponin I improves early diagnosis of acute myocardial infarction and risk stratification, regardless of the time of chest-pain onset.

Plasma concentrations and genetic variation of matrix metalloproteinase 9 and prognosis of patients with cardiovascular disease.

Background—Matrix metalloproteinase (MMP)-9 secretion by macrophages and other inflammatory cells accelerates atherosclerotic progression and destabilizes vulnerable plaque in animal models. However, epidemiological data evaluating the prognostic impact of circulating concentrations and functional genetic variations of MMP-9 are lacking. Methods and Results—In a prospective study of 1127 patients with documented coronary artery disease, we measured baseline plasma MMP-9 levels and determined the MMP-9/C-1562T and MMP-9/R279Q genotypes. During the follow-up period (mean of 4.1 years), 97 patients died from cardiovascular (CV) causes. Median concentrations of MMP-9 were significantly higher among patients who experienced a fatal CV event than among those who did not (62.2 versus 47.8 ng/mL;P <0.0001). The crude hazard risk ratio of CV death associated with increasing quartiles of MMP-9 was 1.4 (95% CI, 1.2 to 1.8;P <0.0001), and after adjustment for clinical and therapeutic confounders, it was 1.3 (95% CI, 1.1 to 1.6;P =0.005). Additional adjustment for highly sensitive CRP, interleukin-6, fibrinogen, and interleukin-18 revealed a hazard risk ratio to 1.2 (95% CI, 0.9 to 1.6;P =0.15). The T allele of the C-1562T polymorphism was associated with increased MMP-9 levels in a fairly codominant fashion (P =0.004). Although none of the polymorphisms was significantly related with future CV death, there was a significant association (P =0.02) between the R279Q polymorphism and CV events in patients with stable angina. Conclusions—Plasma MMP-9 concentration was identified as a novel predictor of CV mortality in patients with coronary artery disease. Whether it provides independent prognostic information compared with other inflammatory markers will have to be additionally assessed.

Interleukin-18 Is a Strong Predictor of Cardiovascular Death in Stable and Unstable Angina

Background—Interleukin (IL)-18 plays a central role in orchestrating the cytokine cascade and accelerates atherosclerosis and plaque vulnerability in animal models. However, epidemiological data evaluating the role of IL-18 levels in atherosclerosis are lacking. Methods and Results—In a prospective study of 1229 patients with documented coronary artery disease, we measured baseline serum concentrations of IL-18 and other markers of inflammation. During the follow-up period (median, 3.9 years), 95 patients died of cardiovascular causes. Median serum concentrations of IL-18 were significantly higher among patients who had a fatal cardiovascular event than among those who did not (68.4 versus 58.7 pg/mL;P <0.0001). The hazard risk ratio of future cardiovascular death increased with increasing quartiles of IL-18 (hazard risk ratio, 1.46; 95% CI 1.21 to 1.76;P for trend <0.0001). After adjustment for most potential confounders, including the strong predictor ejection fraction as well as the inflammatory variables IL-6, high-sensitive C-reactive protein, and fibrinogen, this relation remained almost unchanged, such that patients within the highest quartile of IL-18 had a 3.3-fold increase in hazard risk compared with those in the first quartile (95% CI, 1.3 to 8.4, P =0.01). This relation was observed in patients with stable angina and patients with unstable angina at baseline. Conclusions—Serum IL-18 level was identified as a strong independent predictor of death from cardiovascular causes in patients with coronary artery disease regardless of the clinical status at admission. This result strongly supports recent experimental evidence of IL-18–mediated inflammation leading to acceleration and vulnerability of atherosclerotic plaques.

Asymmetric Dimethylarginine and the Risk of Cardiovascular Events and Death in Patients With Coronary Artery Disease: Results from the AtheroGene Study

As a competitive inhibitor of endothelial nitric oxide synthase, asymmetric dimethylarginine (ADMA) has been related to atherosclerotic disease. Little is known about the prognostic impact of baseline ADMA determination. In a prospective cohort of 1908 patients with coronary artery disease, we assessed baseline serum concentration of ADMA in 1874 consecutive patients with coronary artery disease. One hundred fourteen individuals developed the primary end point of death from cardiovascular causes or nonfatal myocardial infarction during a mean follow-up of 2.6±1.2 years. Median concentrations of ADMA levels were higher among individuals who subsequently developed the primary end point than among those who did not (0.70 versus 0.63 &mgr;mol/L; P<0.001). The risk of future cardiovascular event was associated with increasing thirds of baseline ADMA (P for trend, <0.001) such that individuals in the highest third at entry had a hazard ratio 2.48 times higher than those in the lowest third (95% confidence interval, 1.52 to 4.06; P<0.001). This relationship remained nearly unchanged after adjustment for most potential confounders. Prediction models that simultaneously incorporated ADMA, B-type natriuretic peptide, C-reactive protein, and creatinine in addition to traditional risk factors revealed B-type natriuretic peptide (hazard ratio, 1.96; 95% confidence interval, 1.3 to 3.0; P=0.002) and ADMA (hazard ratio, 1.90; 95% confidence interval, 1.3 to 2.8; P=0.001) as the strongest risk predictors. High levels of baseline ADMA independently predict future cardiovascular risk. ADMA has prognostic value beyond traditional risk factors and novel biomarkers and might guide therapeutic strategies.

Serial Changes in Highly Sensitive Troponin I Assay and Early Diagnosis of Myocardial Infarction

CONTEXT Introduction of highly sensitive troponin assays into clinical practice has substantially improved the evaluation of patients with chest pain. OBJECTIVE To evaluate the diagnostic performance of a highly sensitive troponin I (hsTnI) assay compared with a contemporary troponin I (cTnI) assay and their serial changes in the diagnosis of acute myocardial infarction (AMI). DESIGN, SETTING, AND PATIENTS A total of 1818 patients with suspected acute coronary syndrome were consecutively enrolled at the chest pain units of the University Heart Center Hamburg, the University Medical Center Mainz, and the Federal Armed Forces Hospital Koblenz, all in Germany, from 2007 to 2008. Twelve biomarkers including hsTnI (level of detection, 3.4 pg/mL) and cTnI (level of detection, 10 pg/mL) were measured on admission and after 3 and 6 hours. MAIN OUTCOME MEASURES Diagnostic performance for AMI of baseline and serial changes in hsTnI and cTnI results at 3 hours after admission to the emergency department. RESULTS Of the 1818 patients, 413 (22.7%) were diagnosed as having AMI. For discrimination of AMI, the area under the receiver operating characteristic (ROC) curve was 0.96 (95% CI, 0.95-0.97) for hsTnI on admission and 0.92 (95% CI, 0.90-0.94) for cTnI on admission. Both were superior to the other evaluated diagnostic biomarkers. The use of hsTnI at admission (with the diagnostic cutoff value at the 99th percentile of 30 pg/mL) had a sensitivity of 82.3% and a negative predictive value (for ruling out AMI) of 94.7%. The use of cTnI (with the diagnostic cutoff value at the 99th percentile of 32 pg/mL) at admission had a sensitivity of 79.4% and a negative predictive value of 94.0%. Using levels obtained at 3 hours after admission, the sensitivity was 98.2% and the negative predictive value was 99.4% for both hsTnI and cTnI assays. Combining the 99th percentile cutoff at admission with the serial change in troponin concentration within 3 hours, the positive predictive value (for ruling in AMI) for hsTnI increased from 75.1% at admission to 95.8% after 3 hours, and for cTnI increased from 80.9% at admission to 96.1% after 3 hours. CONCLUSIONS Among patients with suspected acute coronary syndrome, hsTnI or cTnI determination 3 hours after admission may facilitate early rule-out of AMI. A serial change in hsTnI or cTnI levels from admission (using the 99th percentile diagnostic cutoff value) to 3 hours after admission may facilitate an early diagnosis of AMI.

Comparative Impact of Multiple Biomarkers and N-Terminal Pro-Brain Natriuretic Peptide in the Context of Conventional Risk Factors for the Prediction of Recurrent Cardiovascular Events in the Heart Outcomes Prevention Evaluation (HOPE) Study

Background— Individual markers of inflammation may add incremental predictive value in the context of conventionally available risk factors. We evaluated the ability of 9 inflammatory biomarkers, microalbuminuria, and N-terminal pro-brain natriuretic peptide (Nt-proBNP) to improve cardiovascular risk prediction beyond that obtained from traditional risk factors in a secondary-prevention population. Methods and Results— We measured biomarkers representing the acute-phase reaction (C-reactive protein, fibrinogen, and interleukin-6), proinflammatory pathways (soluble tumor necrosis factor receptor-1 and -2, soluble interleukin-1 receptor antagonist, and interleukin-18), endothelial activation (soluble vascular adhesion molecule-1 and soluble intercellular adhesion molecule-1), Nt-proBNP, and microalbuminuria in 3199 study individuals of the Heart Outcomes Prevention Evaluation (HOPE) Study and assessed their association with risk of myocardial infarction, stroke, or cardiovascular death (primary outcome, n=501) over 4.5 years of follow-up. In a backward Cox regression procedure that included risk factors and biomarkers, Nt-proBNP (hazard ratio [HR] 1.72 per increment SD, 95% CI 1.39 to 2.12; P<0.0001), soluble intercellular adhesion molecule-1 (HR 1.46, 95% CI 1.19 to 1.80; P=0.0003), microalbuminuria (HR 1.55, 95% CI 1.22 to 1.98; P=0.0004), soluble interleukin-1 receptor antagonist (HR 1.30, 95% CI 1.05 to 1.61; P=0.02), and fibrinogen (HR 1.31, 95% CI 1.05 to 1.62; P=0.02) remained significantly related to the primary outcome. Only inclusion of Nt-proBNP provided incremental information above that obtained by models of traditional risk factors. Conclusions— Although levels of various inflammatory biomarkers are significantly related to future cardiovascular risk, their incremental predictive value is modest. A model consisting of simple traditional risk factors and Nt-proBNP provided the best clinical prediction in the secondary-prevention population.

Copeptin Improves Early Diagnosis of Acute Myocardial Infarction

OBJECTIVES Early identification of myocardial infarction in chest pain patients is crucial to identify patients at risk and to maintain a fast treatment initiation. BACKGROUND The aim of the current investigation is to test whether determination of copeptin, an indirect marker for arginin-vasopressin, adds diagnostic information to cardiac troponin in early evaluation of patients with suspected myocardial infarction. METHODS Between January 2007 and July 2008, patients with suspected acute coronary syndrome were consecutively enrolled in this multicenter study. Copeptin, troponin T (TnT), myoglobin, and creatine kinase-myocardial band were determined at admission and after 3 and 6 h. RESULTS Of 1,386 (66.4% male) enrolled patients, 299 (21.6%) had the discharge diagnosis of acute myocardial infarction, 184 (13.3%) presented with unstable angina, and in 903 (65.2%) an acute coronary syndrome could be excluded. Combined measurement of copeptin and TnT on admission improved the c-statistic from 0.84 for TnT alone to 0.93 in the overall population and from 0.77 to 0.9 in patients presenting within 3 h after chest pain onset (CPO) (p < 0.001). In this group the combination of copeptin with a conventional TnT provided a negative predictive value of 92.4%. CONCLUSIONS In triage of chest pain patients, determination of copeptin in addition to troponin improves diagnostic performance, especially early after CPO. Combined determination of troponin and copeptin provides a remarkable negative predictive value virtually independent of CPO time and therefore aids in early and safe rule-out of myocardial infarction.

CD14+CD16+ monocytes in coronary artery disease and their relationship to serum TNF-α levels

Monocytes play a central role in the inflammatory disease atherosclerosis. CD14+CD16+ monocytes are considered proinflammatory monocytes, as they have an increased capacity to produce proinflammatory cytokines, such as TNF-α, and are elevated in various inflammatory diseases.We hypothesized that patients with coronary artery disease (CAD) have increased levels of CD14+CD16+ monocytes, and that CD14+CD16+ monocytes are associated with inflammation markers. We investigated CD14+CD16+ monocytes in 247 patients with CAD and 61 control subjects using flow cytometry. In addition serum concentrations of TNF-α, IL-6, and Hs-CRP were assessed. Patients with CAD had higher levels of CD14+CD16+ monocytes than controls (13.6% versus 11.4%; p

Genetic Analysis of the Interleukin-18 System Highlights the Role of the Interleukin-18 Gene in Cardiovascular Disease

Background—Interleukin (IL)-18 plays a key role in atherosclerosis and its complications. The present study investigated the genetic variability of 4 genes of the IL-18 system—IL18, IL18R1, IL18RAP, and IL18BP—in relation to circulating IL-18 levels and cardiovascular mortality. Methods and Results—Twenty-two polymorphisms were genotyped in 1288 patients with coronary artery disease prospectively followed up during a median period of 5.9 years. The end point was death from cardiovascular causes (n=142). Baseline IL-18 levels were predictive of cardiovascular deaths occurring during ≤4 years of follow-up (HR=2.96, 95% CI 1.54 to 5.70, P=0.001 for the top compared with the bottom quartile) but not of later deaths. Haplotypes of the IL18 gene were associated with IL-18 levels (P=0.002) and cardiovascular mortality (P=0.006) after adjustment for cardiovascular risk factors. The same haplotype was associated with both a 9% lowering effect on IL-18 levels and a protective effect on risk (HR=0.57, 95% CI 0.36 to 0.92). IL18 haplotypes explained only 2% of IL-18 variability. Adjustment for baseline IL-18 levels abolished the association of haplotypes with cardiovascular risk. The haplotype associated with phenotypes was the only one carrying the minor allele of the IL18/A+183G polymorphism located in the 3′untranslated region and potentially affecting mRNA stability. The other genes of the system were not related to IL-18 levels or cardiovascular outcome. Conclusion—Variations of the IL18 gene consistently influence circulating levels of IL-18 and clinical outcome in patients with coronary artery disease, which supports the hypothesis of a causal role of IL-18 in atherosclerosis and its complications.

Serum uric acid as an independent predictor of mortality in patients with angiographically proven coronary artery disease

It is a matter of controversy as to whether uric acid is an independent predictor of mortality in patients with coronary artery disease (CAD) or whether it represents only an indirect marker of adverse outcome by reflecting the association between uric acid and other cardiovascular risk factors. Therefore, we studied the influence of uric acid levels on mortality in patients with CAD. In 1,017 patients with angiographically proven CAD, classic risk factors and uric acid levels were determined at enrollment. A follow-up over a median of 2.2 years (maximum 3.1) was performed. Death from all causes was defined as an end point of the study. In CAD patients with uric acid levels <303 micromol/L (5.1 mg/dl) (lowest quartile) compared with those with uric acid levels >433 micromol/L (7.1 mg/dl) (highest quartile), the mortality rate increased from 3.4% to 17.1% (fivefold increase). After adjustment for age, both sexes demonstrated an increased risk for death with increasing uric acid levels (female patients: hazard ratio [HR] 1.30, 95% confidence intervals [CI] 1.14 to 1.49, p < or = 0.001; male patients: HR 1.39 [95% CI 1.21 to 1.59], p < or = 0.001). In multivariate Cox regression analysis performed with 12 variables that influence overall mortality-including diuretic use-elevated levels of uric acid demonstrated an independent, significant positive relation to overall mortality (HR 1.23 [95% CI 1.11 to 1.36], p <0.001) in patients with CAD. Thus, uric acid is an independent predictor of mortality in patients with CAD.