Oliver Danne

Prognostic implications of elevated whole blood choline levels in acute coronary syndromes.

Troponins I and T represent the current biomarker standard for diagnosis of myocardial infarction. Even small increases of cardiac troponins have prognostic implications, but not all patients at risk are correctly classified, particularly at admission. We identified elevated whole-blood choline as a promising marker and performed a prospective study of 327 patients with a suspected acute coronary syndrome that focused on the analysis of troponin-negative patients. Diagnostic classification of patients and the definition of troponin cutoffs were performed according to the new European Society of Cardiology/American College of Cardiology criteria. Blood was sampled serially and choline was measured using high-performance liquid chromatography mass spectrometry in whole blood. Patients were followed for 30 days. In patients with negative troponin I test results at admission (n = 250), choline was a predictor of cardiac death and nonfatal cardiac arrest (hazard ratio 6.0, p = 0.003), life-threatening arrhythmias (hazard ratio 3.75, p = 0.004), heart failure (hazard ratio 2.87, p = 0.002), and coronary angioplasty (hazard ratio 2.57, p = 0.001). In multivariate analysis of troponin-negative patients, choline was the strongest predictor of cardiac death or arrest (odds ratio 6.05, p = 0.01). Choline was not a marker for myocardial necrosis but indicated high-risk unstable angina in patients without acute myocardial infarction (sensitivity 86.4%, specificity 86.2%). Thus, an increased concentration of choline at hospital admission is a predictor of adverse cardiac events in patients with suspected acute coronary syndromes. Whole blood choline may be useful for early risk stratification of these patients, particularly if troponin results are negative on admission.

Effect of Collection Tube Type and Preanalytical Handling on Myeloperoxidase Concentrations

BACKGROUND Myeloperoxidase (MPO) has shown potential as a marker for cardiovascular disease. Limited studies have been published with a variety of sample types, resulting in a wide range of MPO values. Little is known or understood about the impact of collection tube type and preanalytical handling of specimens for MPO determination. METHOD MPO concentration was determined by use of the ARCHITECT(R) MPO research use assay, which is currently under development. Samples were collected into multiple anticoagulant collection tubes from donors and patients presenting to the emergency department with symptoms of acute coronary syndromes. Whole blood was stored on ice or at room temperature for predetermined time periods. We also evaluated serum and plasma after centrifugation followed by storage at room temperature, 2-8 degrees C, and below -10 degrees C. RESULTS Baseline sample concentrations were dependent on collection tube type as well as handling conditions. MPO concentrations were consistently higher in samples collected in serum and heparin plasma tubes than in samples in EDTA or citrate tubes. Spike recovery was acceptable in all sera and plasma tested, indicating that the increased MPO concentrations were not due directly to an anticoagulant interference. CONCLUSIONS The collection tube type and preanalytical handling are critical for accurate and consistent MPO measurement. The preferred anticoagulant and tubes are the EDTA or EDTA plasma preparation tube. MPO concentrations in samples collected in these tubes are stable before centrifugation as whole blood as well as plasma after processing.

Development of an optimized multimarker strategy for early risk assessment of patients with acute coronary syndromes

BACKGROUND A multitude of biomarkers have been suggested for early risk-assessment in patients admitted to the emergency department with suspected acute coronary syndromes. We used logistic regression synergistically with classification and regression tree (CART) analysis to define a multimarker strategy and the cut-off values and sequencing needed to optimize risk stratification in a low to moderate risk population of the emergency department. METHODS 432 unselected patients (59.7+/-14.5 y, 60.4% male) admitted to the emergency department (ED) with acute coronary syndromes (ACS) were enrolled. Cardiac troponin I (cTnI), N-terminal pro-B-Type natriuretic peptide (NT-proBNP), high sensitivity C-reactive protein (hsCRP), placental growth factor (PlGF), lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and D-dimers were measured by immunoassay and whole blood choline (WBCHO) and plasma choline (PLCHO) were measured using LC/MS from baseline samples. Logistic regression and CART analysis were used to define the importance of the various biomarkers tested and to define their hierarchy with respect to the prediction of major adverse cardiac events (MACE; cardiac death, non-fatal MI, unstable angina, CHF requiring admission, urgent PCI and CABG) over the 42-day follow-up period. RESULTS A combination of NT-proBNP, WBCHO and Lp-PLA2 with cutoffs identified by CART-analysis was optimal for risk-stratification and superior to all other possible combinations of markers. Increased concentrations of both NT-proBNP (>1400 ng/l) and WBCHO (>21 micromol/l) identified patients with very high risk (RR=2.4, 39% primary endpoint) while low concentrations of NT-proBNP (< or = 1400 ng/l), WBCHO (< or = 17 micromol/l) and LP-PLA2 (< or = 210 microg/l) indicated very low risk (0% primary endpoint). WBCHO > 17 micromol/l additionally identified a subgroup with intermediate risk (RR=3.0, 13.5% primary endpoint) in patients with NT-proBNP concentrations < or = 1400 ng/l. Troponin when increased was highly prognostic but was not often positive in this early cohort. CONCLUSIONS A multimarker strategy defined synergistically by logistic regression and by classification and regression tree (CART) analysis can stratify patients into risk groups ranging from very low risk (0% MACE) to very high risk (39.5% MACE) based on admission values.

Choline in acute coronary syndrome: an emerging biomarker with implications for the integrated assessment of plaque vulnerability

Whole-blood choline, plasma choline and serum choline are emerging biomarkers in acute coronary syndrome related to coronary plaque instability with platelet thrombus formation and ischemia. Whole-blood choline is an early predictor for cardiac events, which adds to troponins, natriuretic peptides and inflammatory markers. Serum choline is highly predictive for myocardial infarction and discriminates high- from low-risk subgroups in troponin-positive patients. Choline is a candidate marker to aid decision making in the emergency room in the upcoming era of sensitive troponin tests and the growing need to differentiate between ischemic and nonischemic etiologies of troponin elevations. The integrated approach of in vitro choline measurement in combination with advanced techniques of in vivo choline imaging represents a novel future strategy for detecting vulnerable plaques. This paper provides an up-to-date review of choline in acute coronary syndrome including key aspects of pathophysiology, analytical methods, clinical studies and implications for the integrated assessment of plaque vulnerability.

Choline in Whole Blood and Plasma: Sample Preparation and Stability

BACKGROUND Choline is critical for a variety of biological functions and has been investigated as a biomarker for various pathological conditions including acute coronary syndrome. METHODS A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was used to quantify choline in whole blood and plasma in freshly collected samples prepared with ultrafiltration or protein precipitation. We investigated the effects of preanalytical variables including types of anticoagulants and storage temperature and time. RESULTS We observed no significant differences in whole-blood choline concentration in EDTA-anticoagulated vs heparin-anticoagulated samples: mean (SD) difference 0.9% (3.2%), P = 0.80. For plasma, choline concentrations with heparin in 5 of 12 volunteers were >10% higher than with EDTA, P = 0.01. One freeze-thaw cycle led to significant mean (SD) increases in choline concentrations in heparin whole blood, 19.3% (11.4%), P <0.01, and the effect was not significant for other sample types studied (P >0.33). For freshly collected samples stored at ambient temperature, choline concentrations in all types of samples increased with storage time. For EDTA whole blood, EDTA plasma, and heparin plasma, the choline concentration increased for the first 60 min and then stabilized. For heparin whole blood, the choline concentration continued to increase linearly with storage time for >4 h, at which time the choline concentrations were increased by approximately 50%. CONCLUSIONS Sample collection, storage, and sample preparation procedures are critical for clinical measurements of choline in whole blood and plasma.

Left ventricular hypertrophy and diastolic dysfunction: Their relation to coronary heart disease

SummaryDiastolic dysfunction is an early sign in the temporal sequence of ischemic events in coronary heart disease. The ischemic cascade, beginning with an oxygen demand supply imbalance and metabolic alterations, identifies diastolic disorders of the left ventricle (LV) as an early phenomenon, sometimes before systolic dysfunction, electrocardiographic changes, or chest pain occur. Although the physiology of diastolic function is complex, the factors contributing to diastolic disturbances can be differentiated intointrinsic andextrinsic LV abnormalities. Intrinsic mechanisms include (a) impaired LV relaxation, (b) the complex of LV hypertrophy, and (c) increased LV asynchrony. Myocardial hypertrophy leads to an increase of the myocardial mass/volume ratio, and the degree of hypertrophy is the main determinant of chamber stiffness. The main, if not unique, determinant of myocardial diastolic tissue distensibility is the structure and concentration of the collagen. Consequently, tissue stiffness is increased in coronary disease by reparative interstitial fibrosis or scar following myocardial infarction. In myocardial hypertrophy the LV collagen concentration is elevated due to reactive fibrosis. An increase in regional asynchrony of LV contraction and relaxation is a result of regional ischemia as well as of LV hypertrophy and tissue fibrosis. Factors extrinsic to the LV causing diastolic disorders include (a) increased central blood volume, which will increase left ventricular pressure without altering the LV pressure-volume relation, and (b) ventricular interaction mediated by pericardial restraint, which may cause a parallel upward shift of the diastolic LV pressure-volume relation. Improved insight into the mechanisms of LV relaxation and filling characteristics help in the treatment of LV diastolic dysfunction.

Validation of NACB and IFCC guidelines for the use of cardiac markers for early diagnosis and risk assessment in patients with acute coronary syndromes

BACKGROUND International guidelines have been established for the use of cardiac markers in the early diagnosis and risk assessment of patients with acute coronary syndromes. METHODS A single center, prospective observational study was conducted in a tertiary care university hospital on 200 consecutive patients with suspected acute myocardial infarction (AMI). Blood was drawn on admission and after 2, 4, 8, 12 and 24 h for the measurement of CK-MB/CK activity, myoglobin, CK-MB mass and troponin I. A 6-week follow-up was undertaken for the combined end point of acute coronary syndrome and death. RESULTS Myoglobin showed an early diagnostic sensitivity of 0.65 on admission, 0.90 after 2 h and 0.92 after 4 h compared with 0.46, 0.74 and 0.88 for CK-MB/CK activity. The combination of myoglobin and cTnI increased the diagnostic value compared with myoglobin alone on admission, 2 and 4 h later. In multivariate analysis, cTnI and CK-MB/CK mass, but not myoglobin and CK-MB/CK activity, were shown to be independent predictors on the 6-week follow-up. CONCLUSIONS Repetitive myoglobin measurements within 4 h of admission, combined with at least one early troponin test, was shown to be the strategy of choice in early AMI diagnosis and prognosis assessment.

Ischemia-Modified Albumin, Free Fatty Acids, Whole Blood Choline, B-Type Natriuretic Peptide, Glycogen Phosphorylase BB, and Cardiac Troponin

There is increasing need to make accurate early diagnosis and rule out acute coronary syndromes (ACS) in patients who present to the emergency department (ED) with chest pain. Accurate diagnosis will reduce the number of inappropriate management decisions, and the number of malpractice lawsuits relating to these decisions. Early diagnosis will facilitate faster entry to treatment protocols such as anticoagulant and antiplatelet therapies resulting in reduced morbidity, mortality, and hospital length of stay. Rapid rule-out of ischemia will facilitate discharge of patients at no or low risk for cardiovascular complications and alleviate the diminishing resources available to EDs. Although the presence of ST-segment depressions on the electrocardiogram (ECG) is evidence of ischemia, the ECG is nondiagnostic in the majority of unstable angina patients. Radionuclide imaging is a sensitive marker for ischemia, but is expensive and requires a high degree of technical expertise.

The role of myeloperoxidase (MPO) for prognostic evaluation in sensitive cardiac troponin I negative chest pain patients in the emergency department

Background: The diagnostic work-up of patients with acute chest pain in the emergency department (ED) is a challenging task. Serial troponin testing is required to rule-out acute myocardial infarction. Objective: To evaluate the value of myeloperoxidase (MPO) testing in sensitive cardiac troponin I (cTnI) negative patients with suspected acute coronary syndromes (ACS) in the routine setting of an ED. Methods: MPO was assessed in 432 consecutive patients presenting to the ED with ACS. In 266 patients, serial blood samples were available. After 6 weeks, major adverse cardiac events (MACE) were assessed. MPO and cTnI were measured in all available samples. For cTnI, a sensitive assay was used. Cut-off values were derived from an independent sample of 300 healthy volunteers. Results: Incidence of MACE in our population was 13%. MPO levels revealed sensitivity (Sens) of 82.1% and specificity (Spec) of 37.2% for MACE compared with 60.7% Sens and 61.4% Spec for sensitive cTnI. In serial sensitive cTnI negative patients (n=218), MACE incidence was 6.4%. MPO continued to demonstrate significant discriminatory power for the prognosis of MACE. Multivariate analyses confirmed these findings. Conclusion: MPO has an independent prognostic value overall and most notably in patients tested negative with a higher sensitive cardiac troponin I assay. MPO could be a promising biomarker for the initial evaluation of patients in chest pain units and is worth further investigation.

Effect of the Glycoprotein IIb/IIIa Inhibitor Tirofiban on Concentrations of Whole Blood Choline in Acute Coronary Syndromes

Background Whole blood choline (WBCHO) concentrations reflect phospholipase D activation pathways involved in coronary plaque vulnerability and platelet activation suppressed by glycoprotein IIb/IIIa receptor (GP IIb/IIIa) inhibitors, but it is unknown whether this treatment affects serial WBCHO levels. Methods We performed a retrospective matched pairs analysis of 32 patients with acute coronary syndrome treated either with standard therapy alone or with tirofiban plus standard therapy with serial measurements of WBCHO. Results The median level of choline decreased after 4 to 6 hours in the tirofiban group (21.2 μmol/L) while the median level in the group without tirofiban increased (29.3 μmol/L) and WBCHO was significantly lower in tirofiban treated patients ( P =0.039). Over time, the decrease of WBCHO was significant in the tirofiban group only ( P =0.006). Conclusions Our results suggest that in patients with acute coronary syndrome, tirofiban treatment is associated with a significant reduction of WBCHO concentration.