Karri Penttilä

C-reactive protein, fibrinogen, interleukin-6 and tumour necrosis factor-α in the prognostic classification of unstable angina pectoris

BACKGROUND. Inflammatory process has been found to play an important role in the pathogenesis of coronary heart disease (CHD) and in the prognosis of CHD patients. AIM. The aim of this study was to investigate the prognostic value of C-reactive protein (CRP), fibrinogen, interleukin (IL)-6 and tumour necrosis factor-α (TNF-α) in patients with unstable angina pectoris (UAP), including factor analysis to assess their joint effects. METHODS. The study comprised 263 consecutive patients (159 men, 104 women; median age 68 years) with UAP. Blood samples for the acute-phase protein and cytokine determinations were drawn on admission. RESULTS. Coronary mortality during the median follow-up time of 17 months was 6-fold higher in the highest tertile for CRP and IL-6 and 3.5-fold higher in the highest tertile for fibrinogen and TNF-α than in the respective combined lower tertiles. Factor analysis produced two underlying factors, ie the ‘inflammation’ factor, including CRP, fibrinogen and IL-6, and the ‘injury’ factor, including troponin T, creatine kinase MB mass and TNF-α. In Cox models, both of these factors were independent predictors of the risk of coronary death and major coronary events (coronary death or nonfatal myocardial infarction). CONCLUSIONS. Elevated levels of acute-phase proteins and cytokines, particularly CRP and IL-6, are strong predictors of the risk of serious coronary events in patients with UAP.

Differences in the diagnosis of myocardial infarction by troponin T compared with clinical and epidemiologic criteria

We investigated the difference in the number of myocardial infarction (MI) diagnoses based on troponin T compared with clinical and epidemiologic (modified FINnish Multinational MONItoring of trends and determinants in CArdiovascular diseases) diagnoses, and the prognosis of patients with discordant diagnoses. Five hundred fifty-nine consecutive patients (315 men and 244 women, median age 69 years) were admitted to the hospital with a suspected acute coronary syndrome. Median follow-up time was 17 months. Of the 559 patients, 127 had a clinical and 137 an epidemiologic diagnosis of MI. When a diagnosis of MI was primarily based on troponin T (>0.10 microg/L), the number of MIs was 169, which increased by 33% compared with the number of MIs by clinical diagnosis, and by 23% compared with those by epidemiologic diagnosis. However, troponin T was not elevated in 13% of the 127 patients with the clinical diagnosis and in 14% of the 137 patients with the epidemiologic diagnosis of MI. Among patients in whom clinical diagnosis of MI was not made, the prognosis with regard to coronary death or nonfatal MI was not significantly worse in patients with troponin T >0.10 microg/L than < or =0.10 microg/L (hazard ratio 1.07; 95% confidence interval 0.62 to 1.84). In patients with a suspected acute coronary syndrome, troponin T-based diagnostics leads to an increase in the number of patients diagnosed with MI compared with clinical or epidemiologic diagnosis. The prognostic impact of troponin T in patients without clinical diagnosis of MI based on elevations in conventional enzyme activities needs further study in larger series of patients.

Laboratory Diagnosis of Patients with Acute Chest Pain

Abstract The enzyme activities of creatine kinase (CK), its isoenzyme MB (CK-MB) and of lactate dehydrogenase isoenzyme 1 (LD-1) have been used for years in diagnosing patients with chest pain in order to differentiate patients with acute myocardial infarction (AMI) from non-AMI patients. These methods are easy to perform as automated analyses, but they are not specific for cardiac muscle damage. During the early 90s the situation changed. First creatine kinase MB mass (CK-MB mass) replaced the measurement of CK-MB activity. Subsequently cardiac-specific proteins troponin T (cTnT) and troponin I (cTnI) appeared on the scene, displacing LD-1 analysis. However, troponin concentrations in blood increase only from four to six hours after onset of chest pain. Therefore a rapid marker such as myoglobin, fatty acid binding protein or glycogen phosphorylase BB could be used in early diagnosis of AMI. On the other hand, CK-MB isoforms alone may also be useful in rapid diagnosis of cardiac muscle damage. Myoglobin, CK-MB mass, cTnT and cTnI are nowadays widely used in diagnosing patients with acute chest pain. Myoglobin is not cardiac-specific and therefore requires supplementation with some other analyses such as troponins to support the myoglobin value. Troponins are very highly cardiac-specific. Only the sera of some patients with severe renal failure, which requires hemodialysis, have elevated cTnT and /or cTnI without there being any evidence of cardiac damage. On the other hand, the latest studies have shown that elevated troponin levels in sera of hemodialysis patients point to an increased risk of future cardiac events in a similar manner to the elevated troponin values in sera of patients with unstable angina pectoris. In addition, the bedside tests for cTnT and cTnI alone or together with myoglobin and CK-MB mass can be used instead of quantitative analyses in the diagnosis of patients with chest pain. These rapid tests are easy to perform and they do not require expensive instrumentation. For routine clinical laboratory practice we suggest that in diagnosis of patients with chest pain, myoglobin and CK-MB mass measurements should be performed whenever they are requested (24 h/day) and cTnT or cTnI on admission to the hospital and then 4–6 and 12 hours later.

Myoglobin, creatine kinase MB isoforms and creatine kinase MB mass in early diagnosis of myocardial infarction in patients with acute chest pain.

OBJECTIVES Measurements of myoglobin and creatine kinase (CK)-MB isoforms have been suggested to be sensitive tests for the early diagnosis of myocardial infarction (MI). We have investigated the utility of myoglobin, creatine kinase (CK)-MB isoforms and creatine kinase MB mass (CK-MBm) in early diagnosis of MI using cardiac troponin T (cTnT) positivity as a reference. DESIGN AND METHODS The study population comprised 440 patients who had had chest pain for less than 12 h. Patients were divided into cTnT negative (cTnT-) or cTnT positive (cTnT+) patients (concentration of cTnT >0.1 microg/L at two different time points during 72 h). RESULTS At the time of admission to the emergency department receiver operating characteristics (ROC) curves of CK-MB isoforms and CK-MBm were not better than that of myoglobin. Six hours after admission CK-MB isoforms and CK-MBm provided statistically significantly larger areas under the curve (AUC) than myoglobin (p < 0.01). When ROC curves were related to the onset of chest pain (< 3 h, 3-6 h, and > 6 h) there were no significant differences between the cardiac markers studied. CONCLUSIONS According to the present findings, CK-MB isoforms or myoglobin offer no advantage over CK-MBm as early markers of myocardial infarction.

Adaptation of the Troponin T ELISA Test to a Microplate Immunoassay Reader

Troponin T concentration in serum is usually measured by the automated method developed by Boehringer Mannheim for the ES-series of analysers. These instruments need at least 140 microliters of serum and 700 microliters of reagents for a single analysis, which takes 90 min. We describe an alternative procedure, using streptavidin-coated microtitre plates, troponin T reagents of Boehringer Mannheim and an ELISA-reader to measure the concentration of troponin T. The present assay needs only 30 microliters of sample and 200 microliters of reagents, and it takes 75 min; the detection limit is 0.10 microgram/l. We also assessed the microtitre plate method for sensitivity and precision and compared the results with those measured by an ES-300 automatic analyser. Both methods have the same measurement range for troponin T of 0.1 to 15 micrograms/l. For daily routine use of the microtitre plate method we recommend duplicate determinations.

Methods, units and quality requirements for the analysis of haemoglobin A1c in diabetes mellitus

The formation of glycohemoglobin, especially the hemoglobin A1c (HbA1c) fraction, occurs when glucose becomes coupled with the amino acid valine in the β-chain of Hb; this reaction is dependent on the plasma concentration of glucose. Since the early 1970s it has been known that diabetics display higher values OF HbA1C because they have elevated blood glucose concentrations. Thus HbA1c has acquired a very important role in the treatment and diagnosis of diabetes mellitus. After the introduction of the first quantitative measurement OF HbA1C, numerous methods for glycohemoglobin have been introduced with different assay principles: From a simple mini-column technique to the very accurate automated high-pressure chromatography and lastly to many automated immunochemical or enzymatic assays. In early days, the results of the quality control reports for HbA1c varied extensively between laboratories, therefore in United States and Canada working groups (WG) of the Diabetes Controls and Complications Trial (DCCT) were set up to standardize the HbA1c assays against the DCCT/National Glycohemoglobin Standardization Program reference method based on liquid chromatography. In the 1990s, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) appointed a new WG to plan a reference preparation and method for the HBA1c measurement. When the reference procedures were established, in 2004 IFCC recommended that all manufacturers for equipment used in HbA1c assays should calibrate their methods to their proposals. This led to an improvement in the coefficient of variation (CV%) associated with the assay. In this review, we describe the glycation of Hb, methods, standardization of the HbA1c assays, analytical problems, problems with the units in which HbA1c values are expressed, reference values, quality control aspects, target requirements for HbA1c, and the relationship of the plasma glucose values to HbA1c concentrations. We also note that the acceptance of the mmol/mol system for HbA1c as recommended by IFCC, i.e., the new unit and reference ranges, are becoming only slowly accepted outside of Europe where it seems that expressing HbA1c values either only in per cent units or with parallel reporting of percent and mmol/mol will continue. We believe that these issues should be resolved in the future and that it would avoid confusion if mmol/mol unit for HbA1c were to gain worldwide acceptance.

Adaptation of the Diazyme Direct Enzymatic HbA1c Assay for a microplate reader at room temperature

Abstract Background: Measurement of hemoglobin A1c (HbA1c) is a key diagnostic criterion and a key parameter for the follow-up of the treatment of diabetes mellitus. Typically, immunochemical assays of HbA1c are performed in clinical chemistry analyzers. In this study, we applied the HbA1c assay on a microplate reader at room temperature. Methods: HbA1c samples were measured using the Direct Enzymatic HbA1c Assay™ from Diazyme Laboratories (Poway, CA, USA) using a Plate Chameleon™ Microplate Reader (Hidex Co., Turku, Finland) according to the manufacturers protocol and a modification of the method to room temperature. The Tosoh G7 HPLC method for HbA1c (Tosoh Co., Tokyo, Japan) was used as a comparative method. Results: There was good correlation of HbA1c results when the assay was performed at room temperature (+22°C) compared with that at +37°C (r=0.987). The modified method was linear over the HbA1c range 4%–14%. Analysis of HbA1c results from 50 blood samples by the modified method showed good agreement with the HPLC method (r=0.990). Conclusions: The modified Diazyme Direct Enzymatic HbA1c Assay™ appears to work as good at +22°C as that performed according to manufacturers protocol at +37°C.

Ruling Out Myocardial Infarction with Troponin T and Creatine Kinase MB Mass: Diagnostic and Prognostic Aspects

OBJECTIVE To investigate the time window for ruling out myocardial infarction (MI) with troponin T (TnT) and creatine kinase isoenzyme MB mass (CK-MBm) and the prognosis of patients with ruled-out MI diagnosis. DESIGN The study was based on 397 patients admitted with a suspected acute coronary syndrome but with relief of symptoms within 24 h. RESULTS MI diagnosis was confirmed with elevated TnT (>0.10 microg/l) in 108 patients. in 91% within 12-24 h from the onset of symptoms, and in 99% within 12 h from admission. In 94 of these patients CK-MBm became elevated (>5.0 microg/l). in 95% within 10-12 h from the onset of symptoms, and in 99% within 6 h from admission. Among patients with ruled-out MI diagnosis, the 1-year incidence of recurrent coronary events was 29% in those with positive history of coronary heart disease (CHD) but only 7% in those without prior CHD (p < 0.001). CONCLUSION Using TnT or CK-MBm, MI can be ruled out within 12 h from admission in the majority of patients. Among patients with ruled-out MI diagnosis, positive history of CHD is an important determinant of prognosis.Objective - To investigate the time window for ruling out myocardial infarction (MI) with troponin T (TnT) and creatine kinase isoenzyme MB mass (CK-MBm) and the prognosis of patients with ruled-out MI diagnosis. Design - The study was based on 397 patients admitted with a suspected acute coronary syndrome but with relief of symptoms within 24 h. Results - MI diagnosis was confirmed with elevated TnT (> 0.10 µg/l) in 108 patients, in 91% within 12-24 h from the onset of symptoms, and in 99% within 12 h from admission. In 94 of these patients CK-MBm became elevated (> 5.0 µg/l), in 95% within 10-12 h from the onset of symptoms, and in 99% within 6 h from admission. Among patients with ruled-out MI diagnosis, the 1-year incidence of recurrent coronary events was 29% in those with positive history of coronary heart disease (CHD) but only 7% in those without prior CHD ( p < 0.001). Conclusion - Using TnT or CK-MBm, MI can be ruled out within 12 h from admission in the majority of patients. Among patients with ruled-out MI diagnosis, positive history of CHD is an important determinant of prognosis.

Diagnostic, clinical and laboratory turnaround times in troponin T testing

Abstract Background: At present, measurements of troponins play a key role in the diagnosis of myocardial infarction. There is a consensus that a turnaround time (TAT) of 1 h or less should be achieved for cardiac marker assays. However, little is known about the real delays between the patients arrival at the emergency department (ED) and the reporting of the test. Methods: In the present study, the TATs of a cardiac marker, troponin T (TnT), were analyzed at a central laboratory at Kuopio University Hospital in a population consisting of 215 patients who were admitted to the hospital ED. Four specific time points were recorded: 1) the time of the patients arrival to the ED, 2) the time of the ordering of the test, 3) the time when blood samples arrived at the laboratory, and 4) the time of completion and reporting of the test. Results: The median diagnostic TAT from patients arrival to the reporting of the TnT result was 122 min. The clinical median TAT was 46 min and the laboratory median TAT was 69 min. Laboratory TAT consisted of the preanalytical TAT at the ED (median 14 min), pre- and postanalytical TAT in the laboratory (median 40 min), and the analytical TAT (on average 10 min). The laboratory TAT was approximately half of the complete diagnostic TAT. Conclusions: On the basis of this analysis, we propose new concepts for the TATs in the diagnostic process: diagnostic TAT which consists of clinical and laboratory TAT. The focus should be shifted from the analytical TAT to the diagnostic process as a whole. Clin Chem Lab Med 2008;46:1030–2.

Hemoglobin A1c reported in units and diagnostic cut-offs in relation to the international recommendations.

*Corresponding author: Ilkka Penttilä, Research Institute of Exercise Medicine, Haapaniementie 16, Kuopio 70100, Finland, Phone: +358 40582556e+011, E-mail: ilkka.penttila@uef.fi Karri Penttilä: Finnish Medicines Agency FIMEA, Kuopio, Finland Päivi Holm: FIMLAB Laboratories Ltd, Tampere, Finland Harri Laitinen: Labquality Ltd., Helsinki, Finland Rainer Rauramaa: Kuopio Research Institute of Exercise Medicine, Kuopio, Finland Letter to the Editor