Jaffe, Allan S.

Abstract Background Low-density lipoprotein cholesterol (LDL-C) is used to assess atherosclerotic cardiovascular disease (ASCVD) risk and to manage lipid-lowering therapy. Proprotein convertase subtilisin/kexin (type 9) serine protease (PCSK9) inhibitors decrease LDL-C by up to 70% when used in conjunction with statins. Due to cost, insurance companies restrict their use. To be eligible for PCSK9 therapy, a patient must have pre-existing ASCVD and LDL-C > 70 mg/dL, while on a maximally tolerated dose of statins. Most clinical laboratories calculate LDL-C by the Friedewald Equation (FWLDL-C), which utilizes results from the standard lipid panel (total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C)). However, this often leads to an underestimation of LDL-C, especially when TG concentrations are elevated. More accurate equations have recently been developed, such as the Martin (MLDL-C), Sampson-NIH (SLDL-C) and extended Martin (ext-MLDL-C) equations. Using LDL-C determined by the beta-quantification reference method (BQ), we developed the following enhanced version of the Sampson-NIH Equation (eSLDL-C), which includes apoB as an independent variable: eSLDL-C = TC/1.15-(HDL-C)/1.25-TG/6.98-(TG × NonHDL-C)/1115 + TG2/8903.23 + (TG × ApoB)/1237 + ApoB/4.54–4.73 Methods Results for clinically ordered ApoB, BQ, and lipid panels were used. To test the accuracy of the various equations, we compared BQLDL-C to FWLDL-C, MLDL-C, extMLDL-C, SLDL-C and eSLDL-C by regression analysis (N = 12 101, TG < 800). Accuracy of each equation was compared to the BQ reference method for classifying patients (LDL-C ≤ 150, n = 9374) as either being below or above the 70 mg/dL treatment decision threshold for PCSK9 therapy. Results The eSLDL-C equation performed substantially better than the other equations for estimating low LDL-C (BQLDL-C ≤ 100 mg/dL, TG 5–800 mg/dL, n = 4115), with a mean absolute difference (MAD) of 3.80 mg/dL (compared to SLDL-C: 6.05; FWLDL-C: 8.71; MLDL-C: 6.43; extMLDL-C: 6.39). It also had the best overall normalized Matthew’s Correlation Coefficient (nMCC) for the best balance of sensitivity and specificity for identifying patients that are above the 70 mg/dL treatment threshold (eSLDL-C-94.7% (92.2% spec, 98.5% sen), SLDL-C-90.7% (94.8% spec, 95.5% sen), FWLDL-C-88.2% (98.0% spec, 92.7% sen), MLDL-C-90.3% (88.9% spec, 96.5% sen), and extMLDL-C-90.1% (88.4% spec, 96.5% sen)). In our dataset with 1125 subjects being below the 70 mg/dL threshold by BQLDL-C, FWLDL-C misclassified an additional 601 subjects below this threshold (Negative Predictive Value 65%). MLDL-C and extMLDL-C misclassified 289 subjects falsely low, whereas eSLDL-C only has 126 subjects falsely classified lower than the 70 mg/dL threshold. Conclusion We show that the enhanced Sampson-NIH equation, which includes apoB, estimates low LDL-C more accurately than other equations. The use of the new equation would improve access to those patients who might benefit from PCSK9 therapy but have falsely low LDL-C by the FWLDL-C equation or other LDL-C equations. The new equation is also more specific than the MLDL-C and extMLDL-C equations and would, therefore, also reduce the overutilization of PCSK9 therapy by these particular equations for those patients who do not require it, according to the reference BQ method and current guidelines.

Abstract Background Elevated Lp(a) is an independent risk factor for atherosclerotic (ASCVD) events and associates with aortic stenosis. Accurate immunochemical measurement of Lp(a) is complicated by heterogeneity of Lp(a) molecular size. The objective of this study was to validate the analytical performance of an electrophoretic assay for measurement of ApoB-containing lipoprotein particles including Lp(a)-P, LDL-P, and VLDL-P and to compare results to other standard clinical methods. Method Lp(a)-P, LDL-P, and VLDL-P were quantified by electrophoretic serum separation followed by immuno-staining with an ApoB antibody using the SPIFE Touch (Helena Laboratories, Beaumont, TX). Stability was evaluated by comparison to results at time zero (n = 10). Precision was assessed by 5 measurements twice daily for five days. Limit of quantitation (LoQ) was determined by 20 replicate measurements. Linearity was assessed by mixing high and low concentrations at various ratios. Accuracy was assessed by split sample comparison (n = 126) with Helena Laboratories. Lp(a)-P and LDL-P results were compared to nuclear magnetic resonance (NMR) using a Bruker Ascend 600 NMR (Bruker, Billerica, MA) with AXINON software (numares, AG, Regensberg, Germany) (n = 114). Lp(a)-P is included with LDL-P by NMR. Therefore, the SPIFE Lp(a)-P + LDL-P was compared to NMR LDL-P. SPIFE Lp(a)-P was compared directly to Roche cobas c501 Lp(a) immunoassay calibrated to molar units (Roche Diagnostics, Indianapolis, IN) (n = 126). Results The analytical performance of Lp(a)-P, LDL-P, and VLDL-P measured on the SPIFE Touch met all acceptance criteria. Bias to the reference method was <20% with R2 > 0.98. All analytes were stable 14 days refrigerated and 14 days frozen. Lipoprotein particle measurements on SPIFE Touch correlated to those obtained by both NMR and Roche assays. Conclusion The analytical performance of the SPIFE Touch for measuring the concentration of ApoB-containing lipoproteins is acceptable. Further studies are needed to determine clinical implications and utility compared to NMR and Roche assays.

Background: High-sensitivity (hs) cardiac troponin (cTn) assays quantifies cTn in most healthy men and women. Whether quantifiable cTn concentrations below the 99 th percentile upper-reference limit have short term prognostic implications in emergency department (ED) patients remains uncertain. Methods: Multicenter (n=22) United States (US) cohort of ED patients undergoing at least one hs-cTnT measurement (CV Data Mart Biomarker cohort). For this assay, the lowest reportable concentration is <6 ng/L. Sex-specific 99 th percentiles of 10 ng/L for women and 15 ng/L for men were used. The primary outcome was index hospitalization mortality. Results: A total of 85610 patients were examined, including 43043 women and 42567 men. A total of 775 index hospitalization deaths (0.91%) occurred, including 361 (0.84%) in women and 414 (0.97%) in men. Among women, baseline hs-cTnT concentrations were non-quantifiable (<LoQ) in 37.5%, quantifiable (LoQ-99 th ) in 21.6%, and increased >99 th percentile in 40.9%. Among men, baseline hs-cTnT concentrations were non-quantifiable (<LoQ) in 20.0%, quantifiable (LoQ-99 th ) in 37.4%, and increased >99 th percentile in 42.6%. Patients with higher concentrations were more likely to be older and had more comorbidities. Continuous baseline hs-cTnT (log) were associated with a higher odds of index hospitalization mortality (OR 1.26, 95% CI 1.24-1.28). Following multivariable analyses, quantifiable hs-cTnT (LoQ-99 th ) also were associated with index hospitalization mortality in all patients (OR 2.07, 95% 1.22-3.53), and in both women (OR 3.13, 95% CI 1.51-6.50) and men (OR 2.17, 95% 1.28-3.69) (Figure). Conclusions: Hs-cTnT concentrations within the reference range are more common in men than in women. Quantifiable hs-cTnT concentrations within the sex-specific reference range are associated with a higher risk of index hospitalization mortality, with a larger prognostic effect in women than in men.

Background: The 2021 ACC/AHA chest pain guidelines recommend risk scores such as HEAR (History, Electrocardiogram, Age, Risk Factors) for short term risk-stratification yet limited data exists integrating them with high-sensitivity cardiac troponin T (hs-cTnT). Methods: Retrospective, multicenter (n=2), observational, U.S. cohort study of consecutive ED patients without ST-elevation myocardial infarction (MI) who had at least one hs-cTnT (limit of quantitation, LoQ, <6 ng/L, and sex-specific 99 th percentiles of 10 ng/L for women and 15 ng/L for men) measurement on clinical indication in whom HEAR scores (0-8) were calculated. The composite major adverse cardiovascular (MACE) outcome was 30-day MI and death. Results: Among 1,979 ED patients undergoing hs-cTnT measurement, 1045 (53%) were classified as low-risk (0-3), 914 (46%) as intermediate-risk (4-6), and 20 (1%) as high-risk (7-8) based on HEAR scores. HEAR scores were not associated with an increased risk of 30-day MACE after adjusted analyses. Outcomes according to risk-strata based on HEAR scores and baseline hs-cTnT are shown in Table 1. Patients with quantifiable hs-cTnT (LoQ-99 th ) had an increased risk for 30-day MACE (3.4%) despite being estimated to be low-risk (0-3) per HEAR scores. Conversely, those with serial hs-cTnT<99 th percentile remained at low-risk (range 0% to 1.2%) for 30-day MACE across HEAR score strata. Conclusions: HEAR scores are of limited value in those with baseline hs-cTnT<LoQ or hs-cTnT>99 th percentile where hs-cTnT identifies very low and high-risk patients irrespective of HEAR scores. In those with baseline quantifiable hs-cTnT within the reference range (<99 th percentile), a higher risk (>1%) for 30-day MACE exists even in those with low HEAR scores. With serial hs-cTnT measurements, HEAR scores overestimate risk when hs-cTnT remains <99 th percentile.

Introduction: Differentiating type 2 myocardial infarction (T2MI) from myocardial injury can be difficult. The presence of objective evidence of acute myocardial ischemia may facilitate the identification of high-risk T2MI patients. Methods: Retrospective, observational cohort post-hoc analysis of adult emergency department patients undergoing hs-cTnT measurement. Patients with ≥1 hs-cTnT>99th percentile were adjudicated following the Fourth Universal Definition of MI. Patients were categorized as “subjective T2MI” when ischemic symptoms were the lone criteria supporting T2MI, or “objective T2MI” when there was ≥1 objective clinical feature (electrocardiography, imaging, angiography) of acute myocardial ischemia. The primary outcome was mortality. Results: A total of 857 patients were included, amongst which 55 (6.4%) were classified as subjective T2MI, 36 (4.2%) as objective T2MI, and 702 (82%) as myocardial injury. Among objective T2MIs, the most common criteria were ischemic electrocardiographic changes (n=29). Median (IQR) maximum hs-cTnT were 24 (18, 43) ng/L in myocardial injury, 34 (19, 80) in subjective T2MI, and 74 (35, 237) in objective T2MI. Those with objective T2MI had a higher risk of mortality during the index presentation (17% vs. 1.7%, p<0.0001; HR 11.1 95% CI 3.7-33.4) and at 2-year follow-up (47% vs. 31%, p=0.04; HR 1.92, 95% CI 1.17-3.14) than those with myocardial injury (Figure). Objective T2MI had a higher mortality than subjective T2MI at index presentation (17% vs. 2.0%, p=0.01) and at 1- (25% vs. 9.1%, p=0.04) and 3-months (31% vs. 13%, p=0.04) follow-up. There were no mortality differences between subjective T2MI and myocardial injury. Conclusions: In patients diagnosed with T2MI, those with objective evidence of myocardial ischemia have significantly worse outcomes compared to those with myocardial injury and subjective T2MI. A more rigorous definition of T2MI might be a more effective way to define this important entity.

Introduction: Early identification of Acute Myocardial Injury can prompt rapid triage and appropriate interventions to improve clinical outcomes. Over 10 million patients present at the ED with chest-pain, with the majority due to non-cardiac causes, resulting in unnecessary burdens for Emergency Departments (ED). An instant non-invasive method to measure cardiac troponin (cTn) would therefore be of great benefit. Identified need: All Guidelines recommend the use of high sensitivity (HS) cTn for the diagnosis of acute coronary syndromes (ACS). Current biochemical biomarker testing relies on labeling the cTn with turnaround times often an hour or more. Point-of-care solutions reduce the test time, but still depend on the proper handling of samples and blood processing techniques that could lead to difficulties. Tropsensor provides a non-invasive alternative to standard of care (SOC) hs-cTn measurements without the need for a blood draw. The molecular infrared spectroscopy-based transdermal device provides a cTn readout within 5 minutes and allows for serial measurements without any of the delays or complications of blood draws. Methods: A 26-patient (consented and IRB approved) study was conducted at Zuckerberg San Francisco General Hospital with recruitment based on ACS-related presenting symptoms at the ED. Wrist-worn Tropsensor was used on the patients while the corresponding troponin was determined using a high sensitivity (SOC) assay (Siemens ADVIA Centaur) via a blood draw. Results and conclusions: A Pearson’s correlation of 82% with the hs-cTnI was observed. AMI diagnosis sensitivity was 100%, Specificity=50%, PPV=81.8%, NPV=100% and accuracy=84.6%. The Tropsensor modality seems to provide data similar to that of a hs-cTn assay. If so, it would accelerate the assessment of patients presenting with chest pain. By not requiring a blood draw, the Tropsensor could provide a rapid, safe, standardized and reliable source for cTn while allowing bedside serial trending. It thus has the potential to streamline cardiac care workflow by ruling-out many non-cardiac patients and identifying those with high values who are at risk. Such an approach has the potential to facilitate appropriate patient triage towards early discharge of emergent treatment.

Introduction: High-sensitivity cardiac troponin (hs-cTn) assays were first approved for use in the U.S. in 2017. They are the guideline preferred biomarker to evaluate patients with acute chest pain. Few data exist regarding implementation of hs-cTn assays in the U.S. Hypothesis: We hypothesize that use of hs-cTn assays has increased over time and that patients assessed with hs-cTn have a shorter length of stay (LOS) and similar use of cardiac testing. Methods: We examined trends in implementation of hs-cTn assays among participating hospitals in the NCDR Chest Pain MI Registry from 1/1/2019 through 9/30/2021. Excluding STEMI patients, associations between hs-cTn use, in-hospital diagnostic imaging, and patient outcomes were assessed using logistic or negative binomial regression models. Results: Among 550 participating hospitals with 251,000 patients in the registry, implementation of hs-cTn assays increased from 3.3% in Q1, 2019 to 32.6% in Q3, 2021 (P trend <0.0001; Figure ). Implementation was similar by hospital size, type, and geographic location. hs-cTn use was associated with more echocardiography among patients with NSTE-ACS (82% vs. 75%; aOR: 1.43, 95% CI, 1.19-1.73) but not in low-risk chest pain. hs-cTn use was associated with decreased odds of invasive coronary angiography in low-risk patients (3.7% vs. 4.5%; aOR: 0.73, 95% CI, 0.58-0.92) but similar use in NSTE-ACS. There was no association between hs-cTn use and non-invasive stress/CTCA testing. Among NSTE-ACS patients, hs-cTn use was not associated with PCI, CABG, or in-hospital mortality. Use of hs-cTn was associated with shorter LOS (47.6 hours vs. 48 hours; IRR: 0.96, 95% CI, 0.93-0.98). Conclusions: Although implementation of hs-cTn among U.S. hospitals is increasing, most U.S hospitals continue to use less-sensitive troponin assays. hs-cTn use was associated with shorter LOS overall, greater use of echocardiography in NSTE-ACS, and lower use of invasive angiograms in low-risk patients.

Abstract Funding Acknowledgements Type of funding sources: Private hospital(s). Main funding source(s): Mayo Clinic Department of Laboratory Medicine and Pathology. Background Elevated lipoprotein(a) [Lp(a)] is associated with increased risk for atherosclerotic cardiovascular disease (ASCVD). Treatment of patients with elevated Lp(a) usually includes marked reduction in low density lipoprotein cholesterol (LDL-C). However, there are uncertainties about whether all increases in Lp(a) are equivalent in there risk relationship. Purpose The aim of this investigation was to risk stratify patients with elevated Lp(a) mass [Lp(a)-M] based on Lp(a) cholesterol (Lp(a)-C) measurements. We assessed coronary artery disease (CAD) by coronary angiogram and major adverse cardiac events (MACE) in a cohort of patients with elevated Lp(a) mass (≥30mg/dL) over a 15 year followup. Methods Electrophoretic and immunologic assays were used to measure Lp(a)-C and Lp(a)-M, respectively. Univariate and multivariate logistic regression analysis was employed to test for association between Lp(a) and CAD in a cohort patients with elevated Lp(a)-M (≥30mg/dL). The relationship between Lp(a) and time to major cardiac events was evaluated using cox regression analysis. Receiver operator curve (ROC) analyses were used to identify optimal cutoff values for Lp(a)-M and C for predicting CAD in our model. Results We analyzed 179 patients with elevated Lp(a)-M. Cutoff values of 3.3mg/dL for Lp(a)-C and 42.1mg/dL for Lp(a)-M optimally predicted CAD in an ROC analysis. Of these patients, 84 were found to have Lp(a)-C &lt; 3.3mg/dL (low Lp(a)-C), while 95 patients had Lp(a)-C levels ≥ 3.3mg/dL (high Lp(a)-C). High Lp(a)-C was associated with CAD identified on coronary angiography in univariate (OR = 2.17, 95% CI = 1.18 – 4.00, p = 0.013) and multivariate (OR = 3.36, 95% CI = 1.64 – 6.89, p &lt; 0.001) models controlling for traditional risk factors. In univariate analyses high Lp(a)-C was also associated with MACE (HR = 2.38, 95% CI = 1.19 – 4.75, p = 0.01) while Lp(a)-M ≥ 42.1mg/dL (high Lp(a)-M) was not (HR = 1.68, 95% CI = 0.82 – 3.44, p = 0.15) (Table 1, Figure 1). Lp(a)-C remained significantly correlated with MACE after adjusting for traditional risk factors. When included in a model together, Lp(a)-C maintained its significance while Lp(a)-M failed to predict MACE, indicating that Lp(a)-C is a stronger predictor of MACE than Lp(a)-M. Conclusion This study demonstrates that patients with elevated Lp(a)-M and high Lp(a)-C are approximately 2.5 times more likely to encounter MACE over time when compared to patients with elevated Lp(a)-M and low Lp(a)-C. Our investigation suggests that Lp(a)-C can be used to risk stratify patients with elevated Lp(a)-M and identify those at higher risk.