The diagnosis of cardiac ischemia remains a challenge in contemporary emergency medicine. A blood-borne biomarker is an attractive alternative to cardiac imaging or stress testing as it would be cheaper and logistically faster to obtain. A number of candidate biomarkers have been proposed for the detection of cardiac ischemia; however, only Ischemia Modified Albumin (IMA) has been released for clinical use. IMA is a good discriminator between ischemic and non-ischemic patients. Changes in IMA concentration have shown to occur during coronary angioplasty-induced ischemia. Clinical studies indicate that IMA appears to offer on admission an early test which can be combined with electrocardiographic findings and cardiac troponin measurements for the early exclusion of acute coronary syndrome. IMA is an independent predictor of short and long term adverse outcomes in patients with acute chest pain. However, this test is relatively new and uncertainties remain. Elevations of IMA occur in conditions other than chest pain, thus questioning its specificity. The mechanism of IMA formation and the precise entity being measured are not fully known. Nevertheless, IMA measurement remains the only current clinical biomarker which may be used for the diagnosis of patients suspected of cardiac ischemia.

The novel coronavirus SARS-CoV-2 causes the disease COVID-19, a severe acute respiratory syndrome. COVID-19 is now a global pandemic and public health emergency due to rapid human-to-human transmission. The impact is far-reaching, with enforced social distancing and isolation, detrimental effects on individual physical activity and mental wellbeing, education in the young and economic impact to business. Whilst most COVID-19 patients demonstrate mild-to-moderate symptoms, those with severe disease progression are at a higher risk of mortality. As more is learnt about this novel disease, it is becoming evident that comorbid cardiovascular disease is associated with a greater severity and increased mortality. Many patients positive for COVID-19 demonstrate increased concentrations of cardiac troponin, creating confusion in clinical interpretation. While myocardial infarction is associated with acute infectious respiratory disease, the majority of COVID-19 patients demonstrate stable cTn rather than the dynamically changing values indicative of an acute coronary syndrome. Although full understanding of the mechanism of cTn release in COVID-19 is currently lacking, this mini-review assesses the limited published literature with a view to offering insight to pathophysiological mechanisms and reported treatment regimens.

Cardiac troponin T and I (cTnT, cTnI) are sensitive biochemical markers of myocardial cell necrosis and have been adopted as the gold standard tests for acute myocardial infarction. Subtle elevations in cTn above the detection limits of the currently available commercial assays confers poor prognosis. These markers are superior to classical enzyme markers of necrosis due to their cardiospecificity. The diagnosis of drug-induced cardiac toxicity using the classical enzymes is problematic due to the high elevations of these markers in skeletal muscle necrosis. cTnT and cTnI are now being adopted as sensitive biomarkers of drug-induced cardiac toxicity.

Objective: Ischemia-modified albumin (IMA®) is a novel marker for assessing cardiac ischaemia. We assessed the relationship between total albumin concentrations and IMA in serum to investigate whether interpretation of IMA was albumin-dependent. Subjects and Methods: 298 serum samples were assayed for total albumin (albumin), using bromcresol purple, and IMA, using an indirect colorimetric assay. Correlations were investigated for the whole data set and for two subgroups, those samples with low albumin (≤34 g/l) and those with albumin within the reference interval. Results: There was a significant (r = –0.888, p < 0.0001) negative correlation between IMA and albumin both over the entire range of albumin concentrations and in the low albumin concentration subgroup (r = –0.85, p < 0.0001); however, there was less significant correlation in the subgroup with albumin within the reference interval (r = –0.37, p < 0.0001). Conclusion: A negative correlation exists between IMA and albumin concentrations; however, there is less significant correlation when albumin is within the reference interval. IMA concentrations determined in patients with albumin concentrations ≤34 g/l should be interpreted with some caution.

Background Elevated serum cardiac troponin T (cTnT) and I (cTnI) can occur in patients with chronic kidney disease. Differences in cTn concentrations between cTnT and cTnI have been reported but the mechanism of such discrepancy has not been investigated. This study investigates the clearance of cTn with the aid of an in vitro model of haemodialysis (HD). Methods Serum was obtained before and after a single session of dialysis from 53 patients receiving HD and assayed for cTnT and cTnI. An in vitro model of the dialysis process was used to investigate the mechanism of clearance of cTn during HD. Results Serum cTnI was significantly lower (p=0.043) following a session of HD whereas cTnT concentrations were similar to those obtained before HD. Using an in vitro model of dialysis, it was demonstrated that cTnI is not dialysed from the vascular compartment but adheres to the dialyser membrane. Conclusions The adherence of cTnI to the dialyser membrane is responsible for the observed decrease in serum cTnI following a session of dialysis. The adherence of cTnT or T-I-C complex to the dialyser membrane could not be demonstrated and supports the observation that pre-HD and post-HD serum concentrations of cTnT are similar.

Galectin-3 is secreted from macrophages and binds and activates fibroblasts forming collagen. Tissue fibrosis is central to the progression of chronic heart failure (CHF). We performed a European multicentered evaluation of the analytical performance of the two-step routine and Short Turn-Around-Time (STAT) galectin-3 immunoassay on the ARCHITECT i1000SR, i2000SR, and i4000SR (Abbott Laboratories). We evaluated the assay precision and dilution linearity for both routine and STAT assays and compared serum and plasma, and fresh vs. frozen samples. The reference interval and biological variability were also assessed. Measurable samples were compared between ARCHITECT instruments and between the routine and STAT assays and also to a galectin-3 ELISA (BG Medicine). The total assay coefficient of variation (CV%) was 2.3%-6.2% and 1.7%-7.4% for the routine and STAT assays, respectively. Both assays demonstrated linearity up to 120 ng/mL. Galectin-3 concentrations were higher in plasma samples than in serum samples and correlated well between fresh and frozen samples (R=0.997), between the routine and STAT assays, between the ARCHITECT i1000 and i2000 instruments and with the galectin-3 ELISA. The reference interval on 627 apparently healthy individuals (53% male) yielded upper 95th and 97.5th percentiles of 25.2 and 28.4 ng/mL, respectively. Values were significantly lower in subjects younger than 50 years. The galectin-3 routine and STAT assays on the Abbott ARCHITECT instruments demonstrated good analytical performance. Further clinical studies are required to demonstrate the diagnostic and prognostic potential of this novel marker in patients with CHF.