Diagnosis of type 1 and type 2 myocardial infarction using a high-sensitivity cardiac troponin I assay with sex-specific 99th percentiles based on the third universal definition of myocardial infarction classification system.

BACKGROUND: The frequency and characteristics of myocardial infarction (MI) subtypes per the Third Universal Definition of MI (TUDMI) classification system using high-sensitivity (hs) cardiac troponin assays with sex-specific cutoffs is not well known. We sought to describe the diagnostic characteristics of type 1 (T1MI) and type 2 (T2MI) MI using an hs-cardiac troponin I (hs-cTnI) assay with sex-specific cutoffs. METHODS: A total of 310 consecutive patients with serial cTnI measurements obtained on clinical indication were studied with contemporary and hs-cTnI assays. Ninety-ninth percentile sex-specific upper reference limits (URLs) for the hs-cTnI assay were 16 ng/L for females and 34 ng/L for males. The TUDMI consensus recommendations were used to define and adjudicate MI based on each URL. RESULTS: A total of 127 (41%) patients had at least 1 hs-cTnI exceeding the sex-specific 99th percentiles, whereas 183 (59%) had hs-cTnI within the reference interval. Females had more myocardial injury related to supply/demand ischemia than males (39% vs 18%, P = 0.01), whereas males had more multifactorial or indeterminate injury (52% vs 33%, P = 0.05). By hs-cTnI, there were 32 (10%) acute MIs, among which 10 (3%) were T1MI and 22 (7%) were T2MI. T2MI represented 69% (22 out of 32) of all acute MIs, whereas T1MI represented 31% (10 out of 32). Ninety-five patients (31%) had an increased hs-cTnI above the 99th percentile but did not meet criteria for acute MI. The most common triggers for T2MI were tachyarrhythmias, hypotension/shock, and hypertension. By contemporary cTnI, more MIs (14 T1MI and 29 T2MI) were diagnosed. By contemporary cTnI, there were 43 MIs, 14 T1MI, and 29 T2MI. CONCLUSIONS: Fewer MI diagnoses were found with the hs-cTnI assay, contrary to the commonly accepted idea that hs-cTnI will lead to excessive false-positive diagnoses.

Large-Scale Scientific Study Led by a Professional Organization during the COVID-19 Pandemic: Operations, Best Practices, and Lessons Learned.

In 2021, the Association for Diagnostics & Laboratory Medicine (ADLM) (formerly the American Association for Clinical Chemistry [AACC]) developed a scientific study that aimed to contribute to the understanding of SARS-CoV-2 immunity during the evolving course of the pandemic. This study was led by a group of expert member volunteers and resulted in survey data from 975 individuals and blood collection from 698 of those participants. This paper describes the formulation and execution of this large-scale scientific study, encompassing best practices and insights gained throughout the endeavor.

Tolerance for three commonly administered COVID-19 vaccines by healthcare professionals.

Importance: Most healthcare institutions require employees to be vaccinated against SARS-CoV-2 and many also require at least one booster. Objective: We determine the impact of vaccine type, demographics, and health conditions on COVID-19 vaccine side effects in healthcare professionals. Design: A COVID-19 immunity study was performed at the 2021 American Association for Clinical Chemistry Annual Scientific meeting. As part of this study, a REDCap survey with cascading questions was administered from September 9, 2021 to October 20, 2021. General questions included participant demographics, past and present health conditions, smoking, exercise, and medications. COVID-19 specific questions asked about SARS-CoV-2 vaccine status and type, vaccine-associated side effects after each dose including any boosters, previous infection with COVID-19, diagnostic testing performed, and type and severity symptoms of COVID-19. Results: There were 975 participants (47.1% male, median age of 50 years) who completed the survey. Pfizer was the most commonly administered vaccine (56.4%) followed by Moderna (32.0%) and Johnson & Johnson (7.1%). There were no significant differences in vaccine type received by age, health conditions, smoking, exercise, or type or number of prescription medications. Side effects were reported more frequently after second dose (e.g., Moderna or Pfizer) (54.1%) or single/only dose of Johnson & Johnson (47.8%). Males were significantly more likely to report no side effects (p < 0.001), while females were significantly more likely to report injection site reactions (p < 0.001), fatigue (p < 0.001), headache (p < 0.001), muscle pain (p < 0.001), chills (p = 0.001), fever (p = 0.007), and nausea (p < 0.001). There was a significant upward trend in participants reporting no side effects with increasing age (p < 0.001). There were no significant trends in side effects among different races, ethnicities, health conditions, medications, smoking status or exercise. In multivariate logistic regressions analyses, the second dose of Moderna was associated with a significantly higher risk of side effects than both the second dose of Pfizer and the single dose of Johnson & Johnson. Conclusions and relevance: Younger people, females, and those receiving the second dose of Moderna had more COVID-19 vaccine side effects that per self-report led to moderate to severe limitations. As reported in other studies, the increase in side effects from Moderna may be explained by higher viral mRNA concentrations but be associated with additional protective immunity.

Myeloperoxidase improves risk stratification in patients with ischemia and normal cardiac troponin I concentrations.

BACKGROUND: We assessed the ability of myeloperoxidase (MPO) to identify the risk for major adverse cardiac events (MACE) in patients who present with ischemic symptoms suggestive of acute coronary syndrome and have a normal cardiac troponin I (cTnI) value. METHODS: We used Siemens (n = 400) and Abbott (n = 350) assays to measure MPO and cTnI in plasma samples from 400 patients. Event rates (myocardial infarction, cardiac death, percutaneous coronary intervention, coronary artery bypass grafting) were estimated by the Kaplan-Meier method and compared with the log-rank statistic. RESULTS: At the 30-day follow-up, the adjusted hazard ratios for MACE were 3.9 (P < 0.001) for increased cTnI and 2.7 (P = 0.006) for increased MPO for the Siemens assays and were 5.5 (P < 0.001) for increased cTnI and 2.9 (P = 0.001) for increased MPO for the Abbott assays. Similar findings were observed with 6 months of follow-up. Patients who initially had a normal cTnI value and an increased Siemens MPO value demonstrated a higher rate of MACE at 30 days than those in whom both values were normal (16.1% vs 3.6%, P = 0.002) and 6 months (18.1% vs 5.0%, P = 0.002). Similarly, patients who had an increased Abbott MPO result demonstrated a higher MACE rate at 30 days (12.3% vs 3.9%, P = 0.03) and at 6 months (16.2% vs 5.1%, P = 0.01) than those with normal values. CONCLUSIONS: A combination of MPO and cTnI allowed the identification of a greater proportion of patients at risk for MACE than the use of cTnI alone. Increased MPO values remained predictive of future cardiac events even when the cTnI value was normal.

Searching for a BNP standard: Glycosylated proBNP as a common calibrator enables improved comparability of commercial BNP immunoassays.

BACKGROUND: Circulating B-type natriuretic peptide (BNP) is widely accepted as a diagnostic and risk assessment biomarker of cardiac function. Studies suggest that there are significant differences in measured concentrations among different commercial BNP immunoassays. The purpose of our study was to compare BNP-related proteins to determine a form that could be used as a common calibrator to improve the comparability of commercial BNP immunoassay results. METHODS: BNP was measured in 40 EDTA-plasma samples from acute and chronic heart failure patients using five commercial BNP assays: Alere Triage, Siemens Centaur XP, Abbott I-STAT, Beckman Access2 and ET Healthcare Pylon. In parallel with internal calibrators from each manufacturer, six preparations containing BNP 1-32 motif a) synthetic BNP, b) recombinant BNP (E. coli), c) recombinant nonglycosylated proBNP (E. coli), d) recombinant His-tagged (N-terminal) nonglycosylated proBNP (E. coli), e) recombinant glycosylated proBNP (HEK cells), and f) recombinant glycosylated proBNP (CHO cells) were also used as external calibrators for each assay. RESULTS: Using the internal standards provided by manufacturers and for five of six external calibrators, up to 3.6-fold differences (mean 1.9-fold) were observed between BNP immunoassays (mean between-assay CV 24.5-47.2%). A marked reduction of the between-assay variability was achieved, when glycosylated proBNP expressed in HEK cells was used as the common calibrator for all assays (mean between-assay CV 14.8%). CONCLUSIONS: Our data suggest that recombinant glycosylated proBNP could serve as a common calibrator for BNP immunoassays to reduce between-assay variability and achieve better comparability of BNP concentrations of commercial BNP immunoassays.

Cardiac troponin changes to distinguish type 1 and type 2 myocardial infarction and 180-day mortality risk.

AIMS: To determine the ability of serial cardiac troponin (cTnI) changes (delta) to distinguish type 1 and type 2 myocardial infarction (MI) (excluding all ST-segment elevation MIs (STEMIs)) and describe the diagnostic accuracy and 180-day mortality in MI versus no-MI patients. METHODS AND RESULTS: Serial cTnIs were measured in 1112 consecutive patients without STEMI and within 6h of presentation to a United States emergency department: 856 (77%) with no MI, 66 (6%) type 1 MI, and 190 (17%) type 2 MI. Of the 0 to 3h and 0 to 6h absolute and relative cTnI changes, only the distribution of absolute change from 0 to 6h was significantly different between type 1 and type 2 MI: median (interquartile range) 311 (1430) ng/l vs. 80 (330) ng/l, p=0.03. Neither the absolute concentration change nor the absolute percent change from either 0 h to 3h (areas under the curves (AUCs) 0.57 and 0.54 respectively) or 0 h to 6h (AUCs 0.60 and 0.51) improved on the performance of the individual cTnI results at 3h (AUC 0.60) or 6h (AUC 0.62), respectively. After adjusting for age, and histories of heart failure and renal insufficiency, those with type 2 MI (hazard ratio 2.9, 95% confidence interval (CI) 1.4-5.9, p=0.004) and those with no index MI and cTnI(max0-6h) > 34 ng/l (2.5, CI 1.1-6.0, p=0.04) had increased risk of death within 180 days compared with those with no MI and cTnI(max 0-6h) ≤ 34 ng/l. CONCLUSION: Delta cTnI did not aid in distinguishing type 1 MI from the more common type 2 MI. Patients diagnosed with type 2 MIs, which represented more than half of all index MIs, had increased risk of death after discharge.