Effect of a Proposed Modification of the Type 1 and Type 2 Myocardial Infarction Definition on Incidence and Prognosis

Remimazolam attenuates myocardial ischemia-reperfusion injury by inhibiting the NF-ĸB pathway of macrophage inflammation

BACKGROUND

Inflammation is a major contributing factor in myocardial ischemia/reperfusion (I/R) injury, and targeting macrophage inflammation is an effective strategy for myocardial I/R therapy. Though remimazolam is approved for sedation, induction, and the maintenance of general anesthesia in cardiac surgery, its effect on cardiac function during the perioperative period has not been reported. Therefore, this research aimed to explore the impact of remimazolam on inflammation during myocardial ischemia/reperfusion (I/R) injury.

METHODS

An in vivo myocardial I/R mice model and an in vitro macrophage inflammation model were used to confirm remimazolam's cardiac protective effect. In vivo, we used echocardiography, hematoxylin and eosin (HE), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining to determine remimazolam's therapeutic effects on myocardial I/R injury and inflammation. In vitro, we employed enzyme-linked immunosorbent assay (ELISA), Western blot, Real-time Quantitative PCR (qPCR), flow cytometry, and immunofluorescence staining to assess inflammatory responses, especially remimazolam's effects on macrophage polarization after I/R. Furthermore, molecular docking was used to identify its potential binding targets on the inflammatory pathway to explore the mechanism of remimazolam.

RESULTS

Remimazolam exhibited significant anti-myocardial I/R injury activity by inhibiting macrophage-mediated inflammation to reduce myocardial infarction, enhancing cardiac function. In addition, macrophage depletion counteracted improved cardiac function by remimazolam treatment. Mechanistically, the activated NF-ĸB signaling pathway and phosphorylation of p50 and p65 were repressed for anti-inflammatory effect. Consistently, two binding sites on p50 and p65 were identified by molecular docking to affect their phosphorylation of the Ser, Arg, Asp, and His residues, thus regulating NF-κB pathway activity.

CONCLUSION

Our results unveil the therapeutic potential of remimazolam against myocardial I/R injury by inhibiting macrophages polarizing into the M1 type, alleviating inflammation.

Pseudo-targeted metabolic profile differences between emergency patients with type 1 and type 2 myocardial infarction diagnosed by optical coherence tomography

BACKGROUND

It is difficult to distinguish type 2 myocardial infarction (T2MI) from type 1 myocardial infarction (T1MI), although their management varies.

OBJECTIVES

Using optical coherence tomography (OCT) and pseudo-targeted metabolomics to identify biomarkers, investigate metabolic differences, and establish a T2MI subclassification.

METHODS

Among 1519 patients with MI, 97 T2MI patients are identified who are 1:1 matched with 97 T1MI patients after considering age, gender, ST-segment elevation, time from onset to coronary angiography, and hs-cTnI on admission by propensity score matching. Plasma pseudo-targeted metabolomics at baseline was determined.

RESULTS

The clinical characteristics of the two groups were comparable, while the T1MI showed more severe coronary lesions than T2MI according to OCT imaging. 90 differential metabolites were identified between the two groups, among 1027 endogenous metabolites in 20 classes. N-Acetyl-L-Leucine, free fatty acid (15:1), Thymidine-5'-triphosphate, Mevalonic acid 5-pyrophosphate, and five oligopeptides were candidate biomarkers (AUC ≥ 0.85) distinguishing T2MI from T1MI. 12 KEGG pathways showed significant differences, mainly involving amino acid, nucleotide, and their derivatives metabolism, and signaling pathways such as mTOR, cGMP-PKG, and cAMP. Other differences were observed in TCA cycle (P = 0.08) and ROS (P = 0.05). Proteolysis and coronary heart disease risk lipid level were lower in T2MI. T2MI had a decrease of differential abundance score in almost all the KEGG enrichment pathways. Furthermore, T2MI can be subdivided into three subtypes by hierarchical cluster analysis of AUCs with causes/triggers of T2MI.

CONCLUSIONS

There are significant metabolic profile differences between T1MI and T2MI. Several candidate metabolic biomarkers can effectively distinguish the two groups.

CLINICAL TRIAL REGISTRATION

ClinicalTrials. gov NCT03297164.

Coronary artery embolism and acute coronary syndrome: A critical appraisal of existing data

The occurrence of coronary artery embolism (CE) has been associated with various clinical conditions, including aortic and mitral prosthetic heart valve implantation, atrial fibrillation (AF), dilated cardiomyopathy, neoplasia, infective endocarditis, atrial septal defect, cardiac tumors, and hypercoagulable states. CE is also a rare cause of myocardial infarction (MI), with a prevalence of about 5%, a figure probably underestimated. The purpose of this article was to determine the current state of knowledge on acute coronary syndrome (ACS) related to CE. We thus performed a comprehensive structured literature search of the MEDLINE database for articles published between 1 January 1990 and 31 December 2021. The diagnosis of CE remains difficult despite the currently used Shibata classification, which is based on major criteria, including angiographic characteristics: globular filling defects, saddle thrombi or multiple filling defects and absence of atherosclerosis in the coronary arteries. Suspected or confirmed CE requires the identification of an etiology. There are only two published series on CE, including about 50 cases each. The three main causes in these series were: 1) atrial fibrillation (73% vs 28.3%), 2) cardiomyopathy (9.4% vs 25%) and 3) malignancy (9.6% vs 15.1%). Finally, 26.3% of the MI patients with CE had no identifiable cause of CE. When anatomically possible, analyzing the thrombus after thrombectomy may help. MI due to CE requires systematic assessment of other locations, i.e. multiple coronary and extracardiac locations. Simultaneous systemic embolization to the brain (67%), limbs (25%), kidneys (25%) or spleen (4%) is frequent, occurring in approximately 25% of CE-related MI. In the setting of acute MI, CE is associated with significant morbidity and mortality. Coronary artery thromboembolism is a rare, non-atherosclerotic, cause of ACS, and prospective studies are needed to evaluate a systematic diagnostic approach and personalized therapeutic strategies.

Diagnostic and prognostic impact of new pathophysiology-based categorization of type 1 and type 2 myocardial infarction: data from the French RICO survey

BACKGROUND

A new classification of type 1 and 2 myocardial infarction (MI) derived from the fourth universal definition of MI (UDMI) has been recently proposed, based on pathophysiology of coronary artery disease (CAD). We assessed the impact of this new MI categorization on epidemiology and outcomes, considering type 1 MI (T1MI) and type 2 MI (T2MI), with and without CAD.

METHODS

Retrospective study including all consecutive patients hospitalized for an acute MI in a multicenter database (RICO). MI was defined according to current UDMI. Rates and outcomes of T1MI and T2MI were addressed according to the new classification.

RESULTS

Among the 4,573 patients included in our study, 3,710 patients (81.1%) were initially diagnosed with T1M1 and 863 (18.9%) with T2MI. After reclassification, 96 T2MI patients were moved into the T1MI category. Out of the remaining 767 patients with T2MI, 567 underwent coronary angiography, and were adjudicated as type 2A MI (68.6%) with obstructive CAD, and type 2B MI (31.4%) without obstructive CAD. When compared with T1MI and T2BMI, T2AMI patients had worse in-hospital outcomes, including severe heart failure (P < .001), atrial fibrillation or flutter (P < .001) and severe bleeding (P < .001). Kaplan-Meier 1-year survival curves showed higher all-cause and CV causes mortality in T2AMI patients compared to T1MI and T2BMI (P < .001). In multivariate Cox regression analysis, type of MI was independent predictor of death.

CONCLUSION

Our large observational multicenter study shows major disparities in mortality according to type of MI and support the relevance of the new MI classification to improve risk classification, taking into account CAD in T2MI. Our findings may help identifying specific phenotypes and considering personalized diagnostic and management strategies.

Preexisting atrial fibrillation and myocardial infarction: only 10% of infarcts directly linked to atrial fibrillation

The aim of the study was to evaluate the incidence and prognosis of type 1 myocardial infarction (T1MI) and type 2 MI (T2MI) in patients with acute MI and known atrial fibrillation (AF) to identify MI directly linked to AF. Among the 669 patients, four patients with hyperthyroidism were excluded, and among the remaining 665 patients, about two-thirds were diagnosed with T1MI, and the remaining third were diagnosed with T2MI. AF was the direct cause of MI in 9.8% of our overall population [1.8% of T1MI type C (coronary embolism), 4.9% of T2MI type A and 3.1% of T2MI type B]. Among patients with T2MI, 30-day mortality was lower when the trigger was AF than for the other triggers, for both type 2A (6% vs. 11%) and type 2B (0% vs. 13%). Most cases of AF-related MI are, thus, T2MI, for which therapeutic guidelines are lacking. Given the diverse triggers in T2MI, a specific approach using etiological patterns is needed to properly determine the optimal therapeutic.

Patterns and outcomes of invasive management of type 2 myocardial infarction in the United States

BACKGROUND

Type 2 myocardial infarction (MI) occurs due to a mismatch in myocardial oxygen supply and demand without unstable coronary artery disease. We sought to identify patterns, predictors and outcomes of invasive management of type 2 MI in the USA.

METHODS

Adults aged ≥18 years hospitalized with type 2 MI were identified in a cross-sectional study from the 2018 National Inpatient Sample. Invasive management was defined as invasive coronary angiography or revascularization. Patient, hospital and geographic characteristics associated with invasive management were identified by multivariable logistic regression. Propensity-matched cohorts were generated to evaluate associations between invasive vs. conservative management and mortality.

RESULTS

We identified 268 850 admissions with type 2 MI in 2018. Type 2 MI patients had a high burden of comorbidities and were commonly admitted with diagnoses of circulatory (39.7%), infectious (23.1%) or respiratory (10.8%) illness. Only 11.2% of type 2 MI were managed invasively, of which 17.9% underwent coronary revascularization. Odds of invasive management were higher with commercial insurance [adjusted OR (aOR) 1.39; 95% confidence interval (CI), 1.27-1.52] and lower with Medicaid (aOR 0.86; 95% CI, 0.76-0.96) vs. Medicare. Significant heterogeneity in invasive management of type 2 MI was observed by geographic region (range 7.2-13.8%), independent of patient and hospital factors. Invasive management was associated with lower in-hospital mortality than conservative management overall (3.9 vs. 9.1%; P < 0.001) and in propensity-matched analyses (OR, 0.70; 95% CI, 0.59-0.84).

CONCLUSION

Invasive management of type 2 MI varies by insurance status and geography, highlighting uncertainty regarding optimal management and potential disparities in clinical care.

Characteristics and Outcomes of Type 2 Myocardial Infarction

Question

What are the characteristics and outcomes of type 2 myocardial infarction (T2MI) compared with type 1 myocardial infarction (T1MI) in patients presenting to the emergency department (ED) with acute chest discomfort?

Findings

In this cohort study 6253 patients, 251 patients (4.0%) and 1027 patients (16.4%) were diagnosed with T2MI and T1MI, respectively, and had comparable all-cause and cardiovascular mortality at 2 years. Tachyarrhythmia and hypertension were responsible for more than two-thirds of patients with T2MI and had lower mortality compared with patients with hypotension, hypoxemia, or anemia.

Meaning

Improved understanding of the specifics of patients with T2MI should help improve management strategies.

Importance

In contrast to type 1 myocardial infarction (T1MI) caused by atherothrombosis, characteristics and outcomes of type 2 myocardial infarction (T2MI) caused by supply-demand mismatch are incompletely understood.

Objective

To explore the characteristics and outcomes of patients with T2MI compared with those with T1MI.

Design, Setting, and Participants

In a prospective, international, multicenter cohort study including 12 emergency departments (EDs) in 5 European countries, unselected patients presenting with acute chest discomfort were enrolled from April 2006 to April 2018. Follow-up was done by telephone or in written form 3, 12, and 24 months after hospital discharge. Data were analyzed from April 2006 to April 2020.

Interventions

The final diagnoses of T2MI and T1MI were centrally adjudicated according to the Fourth Universal Definition of Myocardial Infarction by 2 independent cardiologists, including the pathophysiological trigger of T2MI.

Main Outcomes and Measures

Patient characteristics and outcomes, including 2-year all-cause and cardiovascular mortality and future T2MI and T1MI events.

Results

Of 6253 included patients, 2078 (33.2%) were women, and the median (IQR) age was 61 (48-74) years. Among 6253 patients with acute chest discomfort, the final adjudicated diagnosis was T2MI in 251 patients (4.0%), with tachyarrhythmia and hypertension responsible for two-thirds of cases, and T1MI in 1027 patients (16.4%). All-cause and cardiovascular mortality were comparable at 2 years (T2MI: adjusted hazard ratio, 1.0; 95% CI, 0.7-1.5; T1MI: adjusted hazard ratio, 0.7; 95% CI, 0.4-1.1). Patients with tachyarrhythmia or hypertension as their underlying trigger of T2MI had a lower mortality compared with patients with hypotension, hypoxemia, or anemia. Future T2MI was more likely among patients with index T2MI compared with patients with index T1MI (hazard ratio, 3.2; 95% CI, 1.4-7.5). Similarly, future T1MI was more likely to occur among patients with index T1MI (hazard ratio, 3.0; 95% CI, 1.2-7.4).

Conclusions and Relevance

Among patients with T2MI, tachyarrhythmia and hypertension were responsible for more than two-thirds of T2MI cases. While T2MI and T1MI had comparable all-cause and cardiovascular mortality at 2 years, patients with tachyarrhythmia or hypertension as their underlying trigger of T2MI had a lower mortality compared with patients with hypotension, hypoxemia, or anemia. Future T2MI occurred 3-fold more frequently among patients with T2MI vs T1MI as the index event. Improved understanding of the specifics of patients with T2MI should help improve management strategies.

Characteristics and Outcomes of Type 1 versus Type 2 Perioperative Myocardial Infarction After Noncardiac Surgery

BACKGROUND

Perioperative myocardial infarction is frequently attributed to type 2 myocardial infarction, a mismatch in myocardial oxygen supply-demand without unstable coronary artery disease. Our aim was to identify characteristics, management, and outcomes of perioperative type 1 versus type 2 myocardial infarction among surgical inpatients.

METHODS

Adults age ≥45 years hospitalized for noncardiac surgery were identified in the United States. Perioperative myocardial infarction were identified using International Classification of Diseases, 10th revision (ICD-10) codes. Clinical characteristics, invasive myocardial infarction management, mortality, and readmissions were assessed by myocardial infarction subtype.

RESULTS

Among 4,755,382 surgical hospitalizations, we identified 38,975 perioperative myocardial infarctions (0.82%), with type 2 infarction in 42%. Patients with type 2 myocardial infarction were older, more likely to be women, and less likely to have cardiovascular comorbidities compared with type 1 myocardial infarction. Fewer patients with type 2 myocardial infarction underwent invasive management than type 1 myocardial infarction (6.7% vs 28.8%, P < .001). Type 2 myocardial infarction mortality was lower than type 1 myocardial infarction mortality (12.1% vs 17.4%, P < .001; adjusted odds ratio [aOR] 0.51, 95% confidence interval [CI] 0.45-0.59). Invasive management of perioperative myocardial infarction was associated with lower mortality in type 1 (aOR 0.56, 95% CI 0.49-0.74) but not type 2 (aOR 1.19, 95% CI 0.77-1.85) myocardial infarction. Among survivors, there was no difference in 90-day hospital readmission between type 2 and type 1 perioperative myocardial infarction (36.5% vs 36.1%, P = .72).

CONCLUSIONS

Type 2 myocardial infarctions account for approximately 40% of perioperative myocardial infarctions. Patients with type 2 perioperative myocardial infarction are less likely to undergo invasive management and have lower mortality compared with those with type 1 perioperative myocardial infarction.

Synthesis of Ziziphus spina-christi (Jujube) Root Methanol Extract Loaded Functionalized Silver Nanoparticle (ZS-Ag-NPs); Physiochemical Characterization and Effect of ZS-Ag-NPs on Adipocyte Maturation, Adipokine and Vascular Smooth Muscle Cell Interaction

In this research, a simple, green approach was employed to synthesize silver nanoparticles with the aid of Ziziphus spina-christi (L.) methanol root extract, which can act as a reducing, capping agent to treat obesity and inflammation. Globally, Ziziphus spina-christi (Jujube) root is used in traditional therapy as a lipolysis promoter. GC-MS results confirmed the availability of kaempferol (flavonol), cannabinol and indole-3-carboxylic acid in Ziziphus spina-christi root methanol extract (ZSE). ZSE silver nanoparticles (ZS-Ag-NPs) were synthesized and their effect on mitochondrial fatty acid oxidation capacity and adipokine levels in maturing adipocytes were analyzed. Maturing adipocytes treated with 0.4 µg/dL of ZSE and ZS-Ag-NPs significantly reduced the lipid content in adipocytes by 64% and 82%, respectively. In addition, lipolysis-related genes such as LPL (1.9 fold), HSL (2.3 fold), PGC-1α (3 fold), UCP-1 (4.1 fold), PRDM16 (2 fold) and PPARα (2.7 fold) increased significantly in ZS-Ag-NPs treated maturing adipocytes. The ZS-Ag-NPs treatment significantly decreased insulin resistance and metabolic inflammation-related LTB4-R, TNF-α, IL-4 and STAT-6 mRNA levels. Mitochondrial thermogenesis stimulating capacity of ZS-Ag-NPs was further confirmed by the significantly enhanced CREB-1 and AMPK protein levels in adipocytes. Furthermore, ZS-Ag-NPs treated adipokines (condition media, CM) were treated with human umbilical vein endothelial cells (HUVECs) to determine cytotoxicity and pro-inflammatory stimulus capacity. We found that ZS-Ag-NPs treated adipocyte CM effectively increased mRNA expression levels of the vascular endothelial cell growth factor (VEGF), and down-regulated oxidative stress (LPO, eNOS, and HO) and vascular cell inflammation (ICAM, VCAM, TNF-α, IL-1β, and NF-κB). In conclusion, ZS-Ag-NPs displayed an action at the molecular level in mitochondrial fatty acid oxidation, decreased adipokine secretion in adipocytes, and enhanced vascular endothelial cell growth. This molecular mechanical action of ZS-Ag-NPs reduced effectively obesity progressions and metabolic inflammatory pathogenesis associated with aging.

Cardiovascular Biomarkers in the Early Discrimination of Type 2 Myocardial Infarction

Importance

Rapid and accurate noninvasive discrimination of type 2 myocardial infarction (T2MI), which is because of a supply-demand mismatch, from type 1 myocardial infarction (T1MI), which arises via plaque rupture, is essential, because treatment differs substantially. Unfortunately, this is a major unmet clinical need, because even high-sensitivity cardiac troponin (hs-cTn) measurement provides only modest accuracy.

Objective

To test the hypothesis that novel cardiovascular biomarkers quantifying different pathophysiological pathways involved in T2MI and/or T1MI may aid physicians in the rapid discrimination of T2MI vs T1MI.

Design, Setting, and Participants

This international, multicenter prospective diagnostic study was conducted in 12 emergency departments in 5 countries (Switzerland, Spain, Italy, Poland, and the Czech Republic) with patients presenting with acute chest discomfort to the emergency departments. The study quantified the discrimination of hs-cTn T, hs-cTn I, and 17 novel cardiovascular biomarkers measured in subsets of consecutively enrolled patients against a reference standard (final diagnosis), centrally adjudicated by 2 independent cardiologists according to the fourth universal definition of MI, using all information, including cardiac imaging and serial measurements of hs-cTnT or hs-cTnI.

Results

Among 5887 patients, 1106 (18.8%) had an adjudicated final diagnosis of MI; of these, 860 patients (77.8%) had T1MI, and 246 patients (22.2%) had T2MI. Patients with T2MI vs those with T1MI had lower concentrations of biomarkers quantifying cardiomyocyte injury hs-cTnT (median [interquartile range (IQR)], 30 (17-55) ng/L vs 58 (28-150) ng/L), hs-cTnI (median [IQR], 23 [10-83] ng/L vs 115 [28-576] ng/L; P < .001), and cardiac myosin-binding protein C (at presentation: median [IQR], 76 [38-189] ng/L vs 257 [75-876] ng/L; P < .001) but higher concentrations of biomarkers quantifying endothelial dysfunction, microvascular dysfunction, and/or hemodynamic stress (median [IQR] values: C-terminal proendothelin 1, 97 [75-134] pmol/L vs 68 [55-91] pmol/L; midregional proadrenomedullin, 0.97 [0.67-1.51] pmol/L vs 0.72 [0.53-0.99] pmol/L; midregional pro-A-type natriuretic peptide, 378 [207-491] pmol/L vs 152 [90-247] pmol/L; and growth differentiation factor 15, 2.26 [1.44-4.35] vs 1.56 [1.02-2.19] ng/L; all P < .001). Discrimination for these biomarkers, as quantified by the area under the receiver operating characteristics curve, was modest (hs-cTnT, 0.67 [95% CI, 0.64-0.71]; hs-cTn I, 0.71 [95% CI, 0.67-0.74]; cardiac myosin-binding protein C, 0.67 [95% CI, 0.61-0.73]; C-terminal proendothelin 1, 0.73 [95% CI, 0.63-0.83]; midregional proadrenomedullin, 0.66 [95% CI, 0.60-0.73]; midregional pro-A-type natriuretic peptide, 0.77 [95% CI, 0.68-0.87]; and growth differentiation factor 15, 0.68 [95% CI, 0.58-0.79]).

Conclusions and Relevance

In this study, biomarkers quantifying myocardial injury, endothelial dysfunction, microvascular dysfunction, and/or hemodynamic stress provided modest discrimination in early, noninvasive diagnosis of T2MI.

Direct comparison of high-sensitivity cardiac troponin T and I in the early differentiation of type 1 vs. type 2 myocardial infarction

AIMS

To directly compare the diagnostic accuracy of high-sensitivity cardiac troponin (hs-cTn) T vs. hs-cTnI in the early non-invasive differentiation of Type 1 myocardial infarction (T1MI) due to plaque rupture and atherothrombosis from Type 2 myocardial infarction (T2MI) due to supply-demand mismatch.

METHODS AND RESULTS

In a prospective multicentre diagnostic study, two independent cardiologists centrally adjudicated the final diagnosis of T1MI vs. T2MI according to the fourth universal definition of myocardial infarction (MI), using all available clinical information including cardiac imaging in patients presenting with acute chest pain. Diagnostic accuracy was quantified by the area under the receiver operating characteristics curve (AUC). The most extensively validated hs-cTnT-Elecsys and hs-cTnI-Architect assays were measured at presentation, 1 h, and 2 h. Among 5887 patients, 1106 (19%) had a final diagnosis of MI, including 860 (78%) T1MI and 246 (22%) T2MI. The AUC of hs-cTnT-Elecsys to differentiate T1MI from T2MI was moderate and comparable to that provided by hs-cTnI-Architect: hs-cTnT-Elecsys AUC-presentation 0.67 [95% confidence interval (CI) 0.64-0.71], AUC-1 h 0.70 (95% CI 0.66-0.74), and AUC-2 h 0.71 (95% CI 0.66-0.75) vs. hs-cTnI-Architect AUC-presentation 0.71 (95% CI 0.67-0.74), AUC-1 h 0.72 (95% CI 0.68-0.76), and AUC-2 h 0.74 (95% CI 0.69-0.78), all P = not significant (NS). Similarly, the AUC of absolute changes was moderate and comparable for hs-cTnT-Elecsys and hs-cTnI-Architect (all P = NS). Cut-off concentrations achieving at least 90% specificity for the differentiation of T1MI vs. T2MI were >114 ng/L for hs-cTnT-Elecsys [odds ratio (OR) 4.2, 95% CI 2.7-6.6] and >371 ng/L for hs-cTnI-Architect (OR 4.0, 95% CI 2.6-6.2).

CONCLUSION

hs-cTnT-Elecsys and hs-cTnI-Architect provided comparable, albeit only moderate, diagnostic accuracy for the early differentiation of T1MI vs. T2MI.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov number, NCT00470587, https://clinicaltrials.gov/ct2/show/NCT00470587.

External Validation and Extension of a Clinical Score for the Discrimination of Type 2 Myocardial Infarction

BACKGROUND

The early non-invasive discrimination of Type 2 versus Type 1 Myocardial Infarction (T2MI, T1MI) is a major unmet clinical need. We aimed to externally validate a recently derived clinical score (Neumann) combing female sex, no radiating chest pain, and high-sensitivity cardiac troponin I (hs-cTnI) concentration ≤40.8 ng/L.

METHODS

Patients presenting with acute chest discomfort to the emergency department were prospectively enrolled into an international multicenter diagnostic study. The final diagnoses of T2MI and T1MI were centrally adjudicated by two independent cardiologists using all information including cardiac imaging and serial measurements of hs-cTnT/I according to the fourth universal definition of MI. Model performance for T2MI diagnosis was assessed by formal tests and graphical means of discrimination and calibration.

RESULTS

Among 6684 enrolled patients, MI was the adjudicated final diagnosis in 1079 (19%) patients, of which 242 (22%) had T2MI. External validation of the Neumann Score showed a moderate discrimination (C-statistic 0.67 (95%CI 0.64-0.71)). Model calibration showed underestimation of the predicted probabilities of having T2MI for low point scores. Model extension by adding the binary variable heart rate >120/min significantly improved model performance (C-statistic 0.73 (95% CI 0.70-0.76, p < 0.001) and had good calibration. Patients with the highest score values of 3 (Neumann Score, 9.9%) and 5 (Extended Neumann Score, 3.3%) had a 53% and 91% predicted probability of T2MI, respectively.

CONCLUSION

The Neumann Score provided moderate discrimination and suboptimal calibration. Extending the Neumann Score by adding heart rate >120/min improved the model's performance.