Impact of elevated HbA1c on long-term mortality in patients presenting with acute myocardial infarction in daily clinical practice: insights from a 'real world' prospective registry of the Zwolle Myocardial Infarction Study Group.

BACKGROUND: Long-term clinical outcome is less well known in up to presentation persons unknown with diabetes mellitus who present with acute myocardial infarction and elevated glycosylated haemoglobin (HbA1c) levels on admission. We aimed to study the prognostic impact of deranged HbA1c at presentation on long-term mortality in patients not known with diabetes, presenting with acute myocardial infarction. METHODS: A single-centre, large, prospective observational study in patients with and without known diabetes admitted to our hospital for ST-segment elevation myocardial infarction (STEMI) and non-STEMI. Newly diagnosed diabetes mellitus was defined as HbA1c of 48 mmol/l or greater and pre-diabetes mellitus was defined as HbA1c between 39 and 47 mmol/l. The primary endpoint was all-cause mortality at short (30 days) and long-term (median 52 months) follow-up. RESULTS: Out of 7900 acute myocardial infarction patients studied, 1314 patients (17%) were known diabetes patients. Of the 6586 patients without known diabetes, 3977 (60%) had no diabetes, 2259 (34%) had pre-diabetes and 350 (5%) had newly diagnosed diabetes based on HbA1c on admission. Both short-term (3.9% vs. 7.4% vs. 6.0%, p<0.001) and long-term mortality (19% vs. 26% vs. 35%, p<0.001) for both pre-diabetes patients as well as newly diagnosed diabetes patients was poor and comparable to known diabetes patients. After multivariate analysis, newly diagnosed diabetes was independently associated with long-term mortality (hazard ratio 1.72, 95% confidence interval 1.27-2.34, P=0.001). CONCLUSIONS: In the largest study to date, newly diagnosed or pre-diabetes was present in 33% of acute myocardial infarction patients and was associated with poor long-term clinical outcome. Newly diagnosed diabetes (HbA1c ⩾48 mmol/mol) is an independent predictor of long-term mortality. More attention to early detection of diabetic status and initiation of blood glucose-lowering treatment is necessary.

The IFCC Reference Measurement System for HbA1c: a 6-year progress report.

BACKGROUND: The IFCC Reference Measurement System for hemoglobin (Hb)A(1c) (IFCC-RM) has been developed within the framework of metrologic traceability and is embedded in a network of 14 reference laboratories. This paper describes the outcome of 12 intercomparison studies (periodic evaluations to control essential elements of the IFCC-RM). METHODS: Each study included: unknown samples (to test individual network laboratories); known samples (controls); recently manufactured calibrators (to check calculated assigned value); stored calibrators (to test stability) and a calibration-set (to calibrate the IFCC-RM). The unknown samples are measured by use of the IFCC-RM and the designated comparison methods [DCMs; the National Glycohemoglobin Standardization Program (NGSP) in the US, Japanese Diabetes Society/Japanese Society for Clinical Chemistry (JDS/JSCC) in Japan, and Mono-S in Sweden] are used to investigate the stability of the Master Equation (ME), the relationship between IFCC-RM and DCMs. RESULTS: A total of 105 IFCC-RM data sets were evaluated: 95 were approved, 5 were not, and for 5 no data were submitted. Trend analysis of the MEs, expressed as change in percentage HbA(1c) per year, revealed 0.000% (NGSP, not significant), -0.030%, (JDS/JSCC; significant) and -0.016% (Mono-S; not significant). Evaluation of long-term performance revealed no systematic change over time; 2 laboratories showed significant bias, 1 poor reproducibility. The mean HbA(1c) determined by laboratories performing mass spectrometry (MS) was the same as the mean determined by laboratories using capillary electrophoresis (CE), but the reproducibility at laboratories using CE was better. One batch of new calibrators was not approved. All stored calibrators were stable. CONCLUSION: A sound reference system is in place to ensure continuity and stability of the analytical anchor for HbA(1c).

Global standardization of glycated hemoglobin measurement: the position of the IFCC Working Group.

The measurement of glycated hemoglobin is central in the monitoring of glycemic control in patients with diabetes. There are at least 30 different laboratory assays commercially available to measure the proportion of HbA1c in blood. In 1995 the IFCC established a Working Group (IFCC WG-HbA1c) to achieve international standardization of HbA1c measurement. The main achievements can be summarized as follows: a) a reference measurement procedure has been established with purified primary calibrators; b) a network of reference laboratories has been developed worldwide; and c) work has begun on implementation of traceability to the IFCC reference system. The IFCC WG-HbA1c recognizes the recommendation of the IFCC-IUPAC Committee on Nomenclature, Properties and Units that the analyte measured by the IFCC reference measurement procedure has been defined as betaN1-deoxyfructosyl-hemoglobin and that the recommended measurement units are mmol/mol. The IFCC WG-HbA1c recommends maintaining the use of the name HbA1c in clinical practice.

A comparison of dual vs. triple antiplatelet therapy in patients with non-ST-segment elevation acute coronary syndrome: results of the ELISA-2 trial.

AIMS: To compare dual vs. triple antiplatelet pre-treatment in patients with non-ST-elevation acute coronary syndrome (NSTE ACS) who were planned for early catheterization. METHODS AND RESULTS: A total of 328 consecutive patients with NSTE ACS were included and were randomized to pre-treatment with dual (n = 166, aspirin, clopidogrel 600 mg) or triple antiplatelet therapy (n = 162, aspirin, clopidogrel 300 mg, and Tirofiban). The primary endpoint was enzymatic infarct size, defined as cumulative LDH release (LDHQ(48)). Initial TIMI flow of the culprit vessel was a pre-specified secondary endpoint. Angiography was performed in 98% of patients at a median of 23 h after admission. Enzymatic infarct size (median, 25-75%) was 166 (60-349) IU/L in the triple group compared with 193 (75-466) IU/L in the dual group (P = 0.2). Initial TIMI 3 flow of the culprit vessel was significantly more often observed after triple antiplatelet therapy (67 vs. 47%, P = 0.002). At 30 days follow-up, myocardial infarction (MI) occurred in 46% of patients in the triple antiplatelet group, compared with 57% in the dual antiplatelet group, P = 0.052. No significant difference in bleeding was present. CONCLUSION: This study showed that in patients with NSTE ACS, triple antiplatelet pre-treatment was associated with a non-significant reduction in enzymatic infarct size, a significantly better initial perfusion of the culprit vessel, and a trend towards a better survival without death or MI. Further, large-scale studies should be performed to find whether the beneficial trend in favour of triple antiplatelet pre-treatment can be reproduced.

Pre-treatment with clopidogrel and postprocedure troponin elevation after elective percutaneous coronary intervention.

Elevated troponin after elective percutaneous coronary intervention (PCI) has been associated with a worse prognosis. Pretreatment with clopidogrel may be beneficial in patients undergoing PCI. Therefore, a prospective observational study was conducted to address the potential role of clopidogrel in reducing troponin release after elective PCI. TroponinT was measured 12 hours after elective PCI in 656 patients without elevated troponin before PCI. To assess the independent association between pre-treatment with clopidogrel and increased troponin, multivariate analyses were performed. Mean age of the 656 patients was 63.5 years (SD 10.2), 194 patients (30%) were female and 114 patients (17.4%) had diabetes. In 217 patients (33%) troponin was increased after PCI. Of the 330 patients who were not pre-treated with clopidogrel, 118 patients (34%) had increased troponin after the PCI compared to 99 patients (30%) of the 326 patients who were treated with clopidogrel longer than 24 hours before the procedure (p = 0.14). Stratified analyses showed that patients with older age (p = 0.03), previous PCI (p = 0.013), angina CCS 4 (p = 0.03) and multivessel disease (p = 0.04) had a significantly lower risk of troponin increase after pre-treatment with clopidogrel compared to patients without pre-treatment. After adjusting for differences in the other variables, patients who were pre-treated with clopidogrel had a significant lower risk of post-PCI increase of troponin T (odds ratio 0.69, 95% confidence interval 0.49-0.99). Pre-treatment with clopidogrel is associated with a significantly lower incidence of increased troponin after elective PCI. Combined with results of other studies, pre-treatment should be advised in patients waiting for elective PCI.

Standardization of HbA1c and Optimal Range of Monitoring.

The IFCC has established a working group on HbA1c standardization, which developed a reference system to act as basis for global standardization of all glycohemoglobin/HbA1c assays. The reference system is based on HbA1c, defined as beta-N-1-deoxy fructosyl haemoglobin as component. Two reference methods specifically measure the glycated N-terminal residue of the beta chain of haemoglobin. The assay principle is peptide mapping after proteolytic cleavage of the molecule followed by measurement of the ratio of the glycated and non-glycated ss-N-terminal hexapeptides by HPLC/MS or HPLC/CE. An international network of 12 reference laboratories is in place. An overall CV below 2% is achieved in comparison studies, which guarantees a reliable value assignment to secondary reference materials. For implementation of the system, the relationship between IFCC and the existing Designated Comparison Methods in the US (NGSP), Sweden (MonoS) and Japan was calculated in seven method comparisons. In all cases, the correlation was exactly the same, making recalculation of the various systems to one IFCC reference system possible. IFCC values will be a reference range of 3-4% HbA1c with a target value of optimal treatment of 5% and change of therapy proposed at values >6%. The last item of the IFCC WG on HbA1c standardization is the adjustment of all the commercial methods to this new reference system. Three method comparison studies with all the major manufacturer methods were performed. This allowed us to first anchor all commercial methods to the IFCC reference system and thereafter recalculate the results to the new IFCC system. Secondary reference materials and a transfer protocol are provided to enable manufacturers to adjust their routine tests to the new reference system. The IFCC reference system for HbA1c will make it possible to improve the performance of routine HbA1c assays. The goal of this improved analytical performance is a within and between run CV of 2%. If this can be achieved, then the HbA1c results can be incorporated into the diagnostic strategies for detecting diabetes mellitus.

The impact of glucose-insulin-potassium infusion in acute myocardial infarction on infarct size and left ventricular ejection fraction [ISRCTN56720616].

BACKGROUND: Favorable clinical outcomes have been observed with glucose-insulin-potassium infusion (GIK) in acute myocardial infarction (MI). The mechanisms of this beneficial effect have not been delineated clearly. GIK has metabolic, anti-inflammatory and profibrinolytic effects and it may preserve the ischemic myocardium. We sought to assess the effect of GIK infusion on infarct size and left ventricular function, as part of a randomized controlled trial. METHODS: Patients (n = 940) treated for acute MI by primary percutaneous coronary intervention (PCI) were randomized to GIK infusion or no infusion. Endpoints were the creatinine kinase MB-fraction (CK-MB) and left ventricular ejection fraction (LVEF). CK-MB levels were determined 0, 2, 4, 6, 24, 48, 72 and 96 hours after admission and the LVEF was measured before discharge. RESULTS: There were no differences between the two groups in the time course or magnitude of CK-MB release: the peak CK-MB level was 249 +/- 228 U/L in the GIK group and 240 +/- 200 U/L in the control group (NS). The mean LVEF was 43.7 +/- 11.0 % in the GIK group and 42.4 +/- 11.7% in the control group (P = 0.12). A LVEF < or = 30% was observed in 18% in the controls and in 12% of the GIK group (P = 0.01). CONCLUSION: Treatment with GIK has no effect on myocardial function as determined by LVEF and by the pattern or magnitude of enzyme release. However, left ventricular function was preserved in GIK treated patients.

Late-life anemia is associated with increased risk of recurrent falls.

OBJECTIVES: To examine whether anemia is associated with a higher incidence of recurrent falls. DESIGN: Prospective cohort study. SETTING: Community-dwelling sample in The Netherlands. PARTICIPANTS: Three hundred ninety-four participants aged 65 to 88 from the Longitudinal Aging Study Amsterdam. MEASUREMENTS: Anemia was defined according to World Health Organization criteria as a hemoglobin concentration less than 12 g/dL in women and less than 13 g/dL in men. Falls were prospectively determined using fall calendars that participants filled out weekly for 3 years. Recurrent fallers were identified as those who fell at least two times within 6 months during the 3-year follow-up. RESULTS: Of the 394 persons, 11.9% (18 women and 29 men) had anemia. The incidence of recurrent falls was 38.3% of anemic persons versus 19.6% of nonanemic persons (P=.004). After adjustment for sex, age, body mass index, and diseases, anemia was significantly associated with a 1.91 times greater risk for recurrent falls (95% confidence interval=1.09-3.36). Poor physical function (indicated by muscle strength, physical performance, and limitations) partly mediated the association between anemia and incidence of recurrent falls. CONCLUSION: Late-life anemia is common and associated with twice the risk of recurrent falls. Muscle weakness and poor physical performance appear to partly mediate this association.

Achieved platelet aggregation inhibition after different antiplatelet regimens during percutaneous coronary intervention for ST-segment elevation myocardial infarction.

OBJECTIVES: To evaluate the extent of platelet aggregation inhibition in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI), treated with different antiplatelet agents and dosages. BACKGROUND: The extent of platelet aggregation inhibition is an independent predictor of major cardiac events after elective PCI. In STEMI patients undergoing PCI, routine dose of antiplatelet agents may be associated with less effective platelet aggregation inhibition. METHODS: Patients were treated with clopidogrel before angiography and randomized to abciximab, tirofiban, high-dose tirofiban, or no glycoprotein (GP) IIb/IIIa inhibitor; GP IIb/IIIa inhibitor bolus, followed by maintenance infusion, was administered after angiography, but before PCI. Platelet aggregation inhibition was assessed before angiography, immediately after PCI, and 1 and 6 h afterwards. RESULTS: The total study population consisted of 112 patients. Platelet aggregation inhibition was variable for individuals and suboptimal for all agents, particularly in the periprocedural period. Only with high-dose tirofiban, mean periprocedural platelet aggregation inhibition exceeded 80%. Angiographic parameters after PCI were not different between the groups. No relationship was found between the level of platelet aggregation and parameters of PCI success (Thrombolysis In Myocardial Infarction frame count and myocardial blush grade), after combining the data from all four groups studied. CONCLUSIONS: Platelet aggregation inhibition in STEMI patients undergoing PCI, treated with antiplatelet agents, is variable and suboptimal for all agents and dosages studied. Only with high-dose tirofiban, mean periprocedural platelet aggregation inhibition exceeded 80%. However, no relationship of platelet aggregation inhibition and angiographic outcome was found in this patient cohort.

The predictive value of cumulative lactate dehydrogenase release within the first 72 h of acute myocardial infarction in patients treated with primary angioplasty.

BACKGROUND: In patients with acute myocardial infarction, estimation of infarct size by cumulative lactate dehydrogenase release at 72 h (LDHQ(72)) is a simple and widely used method. Our objective was to study the value of estimating infarct size, by the cumulative release of LDH over 72, 60, 48 and 36 h in predicting left ventricular ejection fraction (LV(ef)) and cardiac death at 1 year. METHODS: In the Zwolle Infarction Study infarct size estimated as LDHQ was calculated in 1224 patients treated with primary percutaneous coronary intervention for acute myocardial infarction between December 1993 and June 2001. Patients were categorized as having small (LDHQ(72)<800 U/L), medium (LDHQ(72) 800-2500 U/L) or large (LDHQ(72)>2500 U/L) myocardial infarction. RESULTS: LDHQ(72) was closely correlated with LDHQ(60), LDHQ(48) and LDHQ(36) (r = 0.998, 0.993 and 0.987, respectively, P <0.0001). The relations between LDHQ infarct size classification and mean LV(ef) (51% vs 45% vs 35%, P <0.001) or cardiac death at 1 year (0-0.3% vs 0.7-1% vs 6-8%) showed a similar pattern, irrespective of whether LDH was measured up to 36, 48, 60 or 72 h. CONCLUSION: Infarct size classification based on LDHQ(36) is an objective and widely available method for early risk stratification in patients treated with primary angioplasty for acute ST-segment elevation myocardial infarction.

IFCC reference system for measurement of hemoglobin A1c in human blood and the national standardization schemes in the United States, Japan, and Sweden: a method-comparison study.

BACKGROUND: The national programs for the harmonization of hemoglobin (Hb)A(1c) measurements in the US [National Glycohemoglobin Standardization Program (NGSP)], Japan [Japanese Diabetes Society (JDS)/Japanese Society of Clinical Chemistry (JSCC)], and Sweden are based on different designated comparison methods (DCMs). The future basis for international standardization will be the reference system developed by the IFCC Working Group on HbA(1c) Standardization. The aim of the present study was to determine the relationships between the IFCC Reference Method (RM) and the DCMs. METHODS: Four method-comparison studies were performed in 2001-2003. In each study five to eight pooled blood samples were measured by 11 reference laboratories of the IFCC Network of Reference Laboratories, 9 Secondary Reference Laboratories of the NGSP, 3 reference laboratories of the JDS/JSCC program, and a Swedish reference laboratory. Regression equations were determined for the relationship between the IFCC RM and each of the DCMs. RESULTS: Significant differences were observed between the HbA(1c) results of the IFCC RM and those of the DCMs. Significant differences were also demonstrated between the three DCMs. However, in all cases the relationship of the DCMs with the RM were linear. There were no statistically significant differences between the regression equations calculated for each of the four studies; therefore, the results could be combined. The relationship is described by the following regression equations: NGSP-HbA(1c) = 0.915(IFCC-HbA(1c)) + 2.15% (r(2) = 0.998); JDS/JSCC-HbA(1c) = 0.927(IFCC-HbA(1c)) + 1.73% (r(2) = 0.997); Swedish-HbA(1c) = 0.989(IFCC-HbA(1c)) + 0.88% (r(2) = 0.996). CONCLUSION: There is a firm and reproducible link between the IFCC RM and DCM HbA(1c) values.

Evaluation of portable blood glucose meters. Problems and recommendations.

Various guidelines are in use for validating blood glucose meters. There are currently no analytical guidelines for validating procedures available for non-invasive or minimally invasive blood glucose meters. As a result manufacturers of these meters need to comply with different regulations in different countries with concomitant high costs. Some of the differences between different guidelines will be discussed in this article and recommendations for improvement will be presented.

Laboratory tests in diagnosis and management of diabetes mellitus. Practical considerations.

The clinical laboratory plays an essential role in both the diagnosis and therapeutic monitoring of diabetes mellitus. Here, a short review of the main laboratory parameters used in the monitoring of diabetes--glucose (including point-of-care testing), HbA1c and microalbuminuria--is presented. The impact of pre-analytical and analytical performance criteria on the clinical decision making process is discussed.

A comparison of two invasive strategies in patients with non-ST elevation acute coronary syndromes: results of the Early or Late Intervention in unStable Angina (ELISA) pilot study. 2b/3a upstream therapy and acute coronary syndromes.

BACKGROUND: Only few studies specifically addressed the effect of timing of angiography and/or pre-treatment with a glycoprotein 2b/3a receptor blocker in patients with non-ST elevation acute coronary syndromes (ACS) who undergo invasive treatment. METHODS: In a 2-year period, 220 patients with non-ST elevation ACS, were randomized to early angiography without tirofiban pre-treatment (Early strategy) or to delayed angiography after 24-48h pre-treatment with tirofiban (Late strategy). The first 48h after admission, CKmb levels were measured and enzymatic infarct size (LDHQ(48)) was assessed by the area under the LDH release curve. When PCI was performed beyond 48h, CKmb was measured 6 and 12h afterwards. RESULTS: Median time to angiography was 6 (Early) and 50 (Late) hours. PCI was performed in 130 patients (59%). In these patients, a patent (TIMI 2 or 3 flow) culprit vessel was more often present in the Late group compared to the Early group (66% vs 82% p=0.05). In patients with an elevated CKmb (n=96, 44%), LDHQ(48)was significantly lower in patients who underwent angiography after pre-treatment with tirofiban (629+/-503U/L (Early) vs 432+/-441U/L (Late), p=0.02). No difference in clinical outcome between the groups was observed at 30 days follow-up. CONCLUSION: This pilot study showed that a strategy of delayed angiography with concomitant pre-treatment with tirofiban is associated with improved angiographic outcomes and less initial enzyme release, compared to a strategy of immediate angiography without 2b/3a inhibitor pre-treatment. The use of an end point parameter, which assess total enzyme release over a given period of time, might be of special value in patients with non-ST elevation ACS, who undergo very early invasive treatment.

A solid-phase blocking ELISA for detection of type O foot-and-mouth disease virus antibodies suitable for mass serology.

A simple solid-phase blocking ELISA for the detection of antibodies directed against type O foot-and-mouth disease virus (FMDV) was developed. The ELISA was validated using field sera collected from cattle, pigs and sheep originating from FMDV infected and non-infected Dutch farms, reference sera obtained from the World Reference Laboratory for foot-and-mouth disease at the Institute for Animal Health, Pirbright Laboratory, UK and sera from experimentally infected animals. Testing 2664 sera collected from non-infected cattle, pigs and sheep resulted in a specificity of 96%. A sensitivity relative to the virus neutralisation test (VNT) of >99% was achieved when testing 148 positive cattle, goat and sheep sera collected from FMDV-infected Dutch farms. All international reference sera scored consistently correct. The ELISA also correctly scored 398 of 409 positive experimentally derived sera. The sensitivity and specificity of this monoclonal antibody-based ELISA for detection of type O FMDV antibodies is sufficient for use as a screening ELISA. During the 2001 epidemic in the Netherlands, 8000 serum samples per day were regularly tested in this ELISA. The samples scoring positive were then tested by neutralisation for confirmation thus making optimum use of the neutralisation testing capacity.

Approved IFCC reference method for the measurement of HbA1c in human blood.

HbA1C is the stable glucose adduct to the N-terminal group of the beta-chain of HbA0. The measurement of HbA1c in human blood is most important for the long-term control of the glycaemic state in diabetic patients. Because there was no internationally agreed reference method the IFCC Working Group on HbA1c Standardization developed a reference method which is here described. In a first step haemoglobin is cleaved into peptides by the enzyme endoproteinase Glu-C, and in a second step the glycated and non-glycated N-terminal hexapeptides of the beta-chain obtained are separated and quantified by HPLC and electrospray ionisation mass spectrometry or in a two-dimensional approach using HPLC and capillary electrophoresis with UV-detection. Both principles give identical results. HbA1c is measured as ratio between the glycated and non-glycated hexapeptides. Calibrators consisting of mixtures of highly purified HbA1c and HbA0 are used. The analytical performance of the reference method has been evaluated by an international network of reference laboratories comprising laboratories from Europe, Japan and the USA. The intercomparison studies of the network showed excellent results with intra-laboratory CVs of 0.5 to 2% and inter-laboratory CVs of 1.4 to 2.3%. Possible interferences have been carefully investigated. Due to the higher specificity of the reference method the results are lower than those generated with most of the present commercial methods which currently are calibrated with unspecific designated comparison methods. The new reference method has been approved by the member societies of the International Federation of Clinical Chemistry and Laboratory Medicine and will be the basis for the future uniform standardization of HbA1c routine assays worldwide.