By means of a graphical method the influence of the analytical variation and the discrimination limit (DL) on the diagnostic power of the maximum serum myoglobin value observed from 4 to 12 h after onset of symptoms in 291 patients suspected for myocardial infarction (AMI) was examined. The prevalence of AMI was 0.45 and the male to female ratio 2:1. Serum myoglobin (S-myoglobin) was measured by a radioimmunoassay (RIA) with a coefficient of analytical variation (CVA) of 9%. For the distributions of the log values of maximum S-myoglobin for AMI patients and non-AMI patients straight lines were obtained on a probit scale. A statistically significant difference was found between the distributions for females and males without AMI, whereas no difference was found between females and males with AMI. The distributions of patients with and without AMI overlapped markedly giving a high number of misclassifications. The minimum fraction of misclassifications among all patients admitted occurred at a DL of 325 micrograms/l and was 0.16. When S-myoglobin is used for the purpose of early diagnosis of AMI the DL should be chosen so that the fraction of false negative patients is small. Consequently the fraction of false positive patients will be relatively high. At a DL of, for example, 175 micrograms/l, the false negative fraction was 0.06 of all patients with AMI (sensitivity 0.94), and the fraction of false positive patients was 0.35 (specificity 0.65).(ABSTRACT TRUNCATED AT 250 WORDS)
6 long distance runners from the Danish marathon elite and 6 non-runners completed test runs of 28 and 12 km, respectively, Distance runners and non-runners showed the same responses in platelet function. We found a significant decrease in ADP induced platelet aggregability, a decreased serotonin release induced by ADP and collagen and an increase in platelet factor 4 immediately following the run. The antithrombin I11 levels remained constant. Euglobulin lysis time was shortened (by approximately 50 %) and the plasminogen levels significantly increased. The last 2 findings indicate an equal increase in fibrinolytic activity during distance running in both groups. While short term, strenuous exercise induces platelet hyperaggregation, long term distance running induces a state of exhaustion of platelet aggregation capacity.
In patients with symptomatic severe AS treated with TAVI, the presence of COPD neither affects overall survival nor survival from cardiac death. Patients with COPD had, however, both higher pre- and postoperative NYHA class compared with patients without COPD, but NYHA class improvement from pre- to postintervention was equivalent in both groups.
A latex agglutination test for detection of elevated levels of myoglobin in serum has been studied, and its clinical value in diagnosis of acute myocardial infarction (AMI) has been evaluated on a retrospective material of fifty-five patients consecutively admitted to hospital on suspicion for AMI within 4 h after onset of symptoms. The analysis time was less than 10 min. There was no evidence of interference with other related proteins, as judged from analysis of sera with high content of aspartate and alanine aminotransferase, lactate dehydrogenase and creatine kinase, nor was the test sensitive to haemolysis. However, unspecific agglutination was seen with some sera containing a high concentration of rheumatoid factors. In sera with known concentrations of myoglobin, quantitated by a radioimmunoassay, the test was negative in all sera below 80 micrograms/l (n = 187), and positive in all sera above 140 micrograms/l (n = 209). In the range 80-140 micrograms/l the latex test could be either positive or negative (n = 105). The day-to-day reproducibility was high in the ranges below 80 micrograms/l and above 140 micrograms/l, but range 80-140 micrograms/l. In the diagnosis of AMI the predictive value of a positive result was 0.64, and the predictive value of a negative result was 1.0. The latex agglutination test is therefore clinically useful as an emergency test, and as a very early and sensitive indicator for AMI. Patients with a negative test result during the first 12 h after debut of symptoms can with great certainty be identified as not suffering from AMI, whereas patients with a positive test result should be monitored by further laboratory analyses.
In a retrospective study of 307 patients with suspected acute myocardial infarction (AMI) the diagnostic value of S-myoglobin quantitation was compared with S-creatine kinase (CK, EC 2.7.3.2).The results were compared with the final diagnoses, which were made according to the WHO criteria. A reference group of healthy blood donors and children hospitalized for removal of adenoids was investigated. Children (2-16 years) had significantly lower myoglobin levels (25f10 pg/l) than adults (19-65 years, 411t 17 pg/l). In the children a positive correlation was found between age and S-myoglobin concentration but not in adults. Women (34k17 pg/l) had lower S-myoglobin concentration than men (47k 15 pg/l). The difference in sensitivity for deteo tion of AMI by S-myoglobin or S-CK analyses is not significant when the results from blood samples drawn on admission and on the following three mornings are compared, but myoglobin can be detected earlier in serum than CK after an AMI. If only the results from blood samples drawn on admission are compared, the S-myoglobin analysis had a significantly higher sensitivity than the CK analysis. The S-myoglobin analysis had a lower specificity than the CK analysis, and i.m. injections were found to be an important reason for false positive results. S-myoglobin may be of value in the very early verification of AMI, but the frequent blood sampling and the low specificity are problematic. The simultaneous quantitation of S-myoglobin and the heart specific CK isoenzyme fraction (MB) seems to be a good combination.
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