Diagnostic and prognostic value of the sex-specific 99th percentile of four high-sensitivity cardiac troponin assays in patients with suspected myocardial infarction.

AIMS: High-sensitivity cardiac troponin (hs-cTn) assays are used for detection of myocardial infarction (MI). Ninety-ninth percentiles show wide inter-assay variation. The use of sex-specific cut-offs is recommended as definitory cut-off for MI. We compared diagnostic performance and prognostic value of sex-specific 99th percentiles of four hs-cTn assays in patients with suspected MI. METHODS AND RESULTS: Concentrations of four hs-cTn assays were measured at presentation and after 3 h in patients with suspected MI. Final diagnoses were adjudicated according to the 4th Universal Definition of MI. Unisex and sex-specific 99th percentiles were evaluated as diagnostic cut-offs following the ESC 0/3 h algorithm. These cut-offs were used in Cox-regression analyses to investigate the association with a composite endpoint of MI, revascularization, cardiac rehospitalization, and death. Non-ST-elevation MI was diagnosed in 368 of 2718 patients. Applying the unisex 99th percentile, Elecsys hs-cTnT provided highest negative predictive value (NPV) of 99.7 and a positive predictive value (PPV) of 75.9. The analysed hs-cTnI assays showed slightly lower NPVs and comparable PPVs [Architect (NPV 98.0, PPV of 71.4); Atellica (NPV 97.7, PPV of 76.1); Pathfast (NPV 97.7, PPV of 66.6)]. Application of sex-specific 99th percentiles did not significantly affect diagnostic performance. Concentrations above 99th percentile were independent predictors for impaired long-term outcome (hazard ratios 1.2-1.5, P < 0.001). CONCLUSION: We describe a good diagnostic accuracy of four hs-cTn assays using the assay-specific 99th percentile for detection of MI. Application of sex-specific 99th percentiles did neither affect diagnostic performance nor prognostic value significantly. Finally, values above the 99th percentile were associated with poor long-term outcome.

Diagnostic performance of a device for acoustic heart sound analysis in patients with suspected myocardial infarction.

BACKGROUND: As only a small proportion of patients with chest pain suffers from myocardial infarction (MI), safe rule-out of MI is of immense importance. Recently an ultrasensitive microphone performing diastolic heart sound analysis (CADScorSystem) for rule-out of coronary artery disease (CAD) has emerged. In this explorational study, we aimed to evaluate the feasibility of the CADScorSystem for diagnosis of MI in the setting of a large emergency department. METHODS: Patients presenting to the emergency department with suspected MI were included. Acoustic heart sound analysis was performed in all patients and automated CAD-score values were calculated via a device-embedded algorithm, which also requires inclusion of three clinical variables: age, sex and presence of hypertension. Patients additionally received serial high-sensitive troponin T measurement measurements to assess the final diagnosis according to third Universal Definition of Myocardial Infarction applying the European Society of Cardiology 0 hour/3 hours algorithm. Diagnostic parameters for MI, considering different CAD-score cut-offs, were computed. RESULTS: Of 167 patients, CAD-scores were available in 61.1%. A total of eight patients were diagnosed with MI. At a cut-off value of <20, CAD-score had a negative predictive value (NPV) of 90.7 (78.4-96.3). The corresponding positive predictive value (PPV) was 6.8 (2.7-16.2). For the adjusted CAD-score (age, sex, hypertension), at a cut-off value of <20, NPV was 90.0 (59.6-99.5) with a PPV of 10.8 (5.3-20.6). CONCLUSION: In this explorative analysis, a transcutaneous ultrasensitive microphone for heart sound analysis resulted in a high NPV analogous to the findings in rule-out of stable CAD in elective patients yet inferior to serial high-sensitivity cardiac troponin measurements and does not seem feasible for application in an emergency setting for rule-out of MI. TRIAL REGISTRATION NUMBER: NCT02355457.

Validation of a 0/1 h Algorithm for Rapid Diagnosis of Myocardial Infarction Using a High-Sensitivity Troponin I Assay.

BACKGROUND: Current guidelines recommend 0/1 h algorithms using high-sensitivity cardiac troponin (hs-cTn) for fast diagnosis of myocardial infarction (MI). Yet, for some assays, existing data is limited. We aimed to evaluate the diagnostic performance and the prognostic value of a rapid 0/1 h algorithm for the Access hs-cTnI assay. METHODS: In consecutive patients presenting with suspected MI, we measured concentrations of Access hs-cTnI at presentation and after 1 hour. Final diagnosis was adjudicated independently by 2 cardiologists. Parameters for diagnostic performance were calculated, applying the recently derived European Society of Cardiology (ESC) 0/1 h algorithm for Access hs-cTnI. Additionally, we assessed the prognostic utility of Access hs-cTnI for the composite end point of all-cause mortality and incident MI at 3 years. RESULTS: In 1879 patients, 257 non-ST-elevation MIs occurred. Application of the 0/1 h algorithm classified 44.5% as rule-out, 20.3% as rule-in, and triaged 35.1% to the observe group. High rule-out safety was confirmed with a sensitivity of 97.7% (95% CI, 95.0%-99.1%) and a negative predictive value of 99.3% (95% CI, 98.4%-99.7%). Rule-in capacity was moderate with a specificity of 88.0% (95% CI, 86.3%-89.6%) and a positive predictive value of 50.8% (95% CI, 45.7%-55.9%). After exclusion of patients with ST-elevation MI the results showed strong prognostic value, even after adjustment for cardiovascular risk factors and comorbidities, with adjusted hazard ratios of 2.51 (95% CI, 1.56-4.04) in the observe and 3.55 (95% CI, 2.18-5.79) in the rule-in group for the composite end point of all-cause mortality and incident MI at 3 years, compared to ruled-out patients. CONCLUSION: The ESC 0/1 h algorithm for Access hs-cTnI allows safe and efficient triage of patients with suspected MI and has strong prognostic utility up to 3 years after the initial evaluation.

Differences in measurement of high-sensitivity troponin in an on-demand and batch-wise setting.

BACKGROUND: Most studies assessing the diagnostic value of high-sensitivity troponin in the diagnosis of myocardial infarction used batch-wise analyses of frozen samples for high-sensitivity troponin measurements. Whether the accuracy of these batch-wise high-sensitivity troponin measurements described in diagnostic studies is comparable to clinical routine is unknown. METHODS: We enrolled 937 patients presenting with suspected myocardial infarction in this prospective cohort study. Measurements of high-sensitivity troponin I (Abbott Architect) and high-sensitivity troponin T (Roche) were performed in two settings: (a) on-demand in clinical routine using fresh blood samples; and (b) in batches using frozen blood samples from the same individuals at three timepoints (0 hours, 1 hour and 3 hours after presentation). RESULTS: Median troponin levels were not different between on-demand and batch-wise measurements. Troponin levels in the range of 0 to 40 ng/L showed a very high correlation between the on-demand and batch setting (Pearson correlation coefficient (r) was 0.92-0.95 for high-sensitivity troponin I and 0.96 for high-sensitivity troponin T). However, at very low troponin levels (0 to 10 ng/L) correlation between the two settings was moderate (r for high-sensitivity troponin I 0.59-0.66 and 0.65-0.69 for high-sensitivity troponin T). Application of guideline-recommended rapid diagnostic algorithms showed similar diagnostic performance with both methods. CONCLUSIONS: Overall on-demand and batch-wise measurements of high-sensitivity troponin provided similar results, but their correlation was moderate, when focusing on very low troponin levels. The application of rapid diagnostic algorithms was safe in both settings.Trial Registration: www.clinicaltrials.gov (NCT02355457).

Predictive Value of Serial ECGs in Patients with Suspected Myocardial Infarction.

The electrocardiogram (ECG) is an important diagnostic tool for patients with suspected acute myocardial infarction (AMI). Current guidelines recommend serial ECGs in case of persisting symptoms. We aimed to analyze the predictive value of ischemic ECG-signs in patients with suspected AMI. Patients presenting to the emergency department with suspected AMI were included. All patients with ST-elevation AMI were excluded from analyses. Patients received 12-lead-ECG and high-sensitive Troponin T (hs-TnT)-measurement at admission and after 3 h. Four groups were defined: no ischemic signs in either ECG; new ischemic signs in the second ECG; resolved ischemic signs in the second ECG; and persistent ischemic signs in both ECGs. Patients were followed for 2 years to assess the composite endpoint of all-cause-mortality, AMI, and coronary revascularization. Using a 30-day landmark analysis, a Cox regression with ischemic signs as the variable of interest, adjusted by cardiovascular risk factors, was calculated. Of 1675 patients, 1321 showed no ischemic signs, in 25 new-, in 92 resolved- and in 237 patients, persistent ischemic signs were documented. Patients with persistent ischemic signs had significantly worse outcomes, compared to those without. Compared to no ischemic signs, adjusted hazard ratios for the combined endpoint were 0.81 (95% CI 0.20, 3.31; p-value = 0.77) for new-, 0.59 (95% CI 0.26, 1.34; p-value = 0.21) for resolved-, and 1.47 (95% CI 1.102, 2.13; p-value = 0.041) for persistent ischemic signs. In patients with suspected AMI, persistent ischemic ECG-signs are predictive of a higher rate of all-cause-mortality, AMI, and revascularization.

Clinical application of the 4th Universal Definition of Myocardial Infarction.

AIMS: The recently released 4th version of the Universal Definition of Myocardial Infarction (UDMI) introduces an increased emphasis on the entities of acute and chronic myocardial injury. We applied the 4th UDMI retrospectively in patients presenting to the emergency department with symptoms potentially indicating myocardial infarction (MI) to investigate its effect on diagnosis and prognosis. METHODS AND RESULTS: We included 2302 patients presenting to the emergency department with symptoms suggestive of MI. The final diagnosis was adjudicated sequentially according to the 3rd and 4th UDMI. Reclassification after readjudication was assessed. Established diagnostic algorithms for patients with suspected MI were applied to compare diagnostic accuracy. All patients were followed to assess mortality, recurrent MI, revascularization, and rehospitalization to investigate the effect of the 4th UDMI on prognosis. After readjudication, 697 patients were reclassified. Most of these patients were reclassified as having acute (n = 78) and chronic myocardial injury (n = 585). Four hundred and thirty-four (18.9%) patients were diagnosed with MI, compared with 501 (21.8%) MIs when adjudication was based on the 3rd UDMI. In the non-MI population, patients with myocardial injury (n = 663) were older, more often female and had worse renal function compared with patients without myocardial injury (n = 1205). Application of diagnostic algorithms for patients with suspected MI revealed a high accuracy after readjudication. Reclassified patients had a substantially higher rate of cardiovascular events compared with not-reclassified patients, particularly patients reclassified to the category of myocardial injury. CONCLUSION: By accentuating the categories of acute and chronic myocardial injury the 4th UDMI succeeds to identify patients with higher risk for cardiovascular events and poorer outcome and thus seems to improve risk assessment in patients with suspected MI. Application of established diagnostic algorithms remains safe when using the 4th UDMI.

Differences in measurement of high-sensitivity troponin in an on-demand and batch-wise setting.

BACKGROUND: Most studies assessing the diagnostic value of high-sensitivity troponin in the diagnosis of myocardial infarction used batch-wise analyses of frozen samples for high-sensitivity troponin measurements. Whether the accuracy of these batch-wise high-sensitivity troponin measurements described in diagnostic studies is comparable to clinical routine is unknown. METHODS: We enrolled 937 patients presenting with suspected myocardial infarction in this prospective cohort study. Measurements of high-sensitivity troponin I (Abbott Architect) and high-sensitivity troponin T (Roche) were performed in two settings: (a) on-demand in clinical routine using fresh blood samples; and (b) in batches using frozen blood samples from the same individuals at three timepoints (0 hours, 1 hour and 3 hours after presentation). RESULTS: Median troponin levels were not different between on-demand and batch-wise measurements. Troponin levels in the range of 0 to 40 ng/L showed a very high correlation between the on-demand and batch setting (Pearson correlation coefficient (r) was 0.92-0.95 for high-sensitivity troponin I and 0.96 for high-sensitivity troponin T). However, at very low troponin levels (0 to 10 ng/L) correlation between the two settings was moderate (r for high-sensitivity troponin I 0.59-0.66 and 0.65-0.69 for high-sensitivity troponin T). Application of guideline-recommended rapid diagnostic algorithms showed similar diagnostic performance with both methods. CONCLUSIONS: Overall on-demand and batch-wise measurements of high-sensitivity troponin provided similar results, but their correlation was moderate, when focusing on very low troponin levels. The application of rapid diagnostic algorithms was safe in both settings. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02355457).

Right bundle branch block in patients with suspected myocardial infarction.

AIMS:: The new European Society of Cardiology guideline for ST-segment elevation myocardial infarction recommends that left and right bundle branch block should be considered equal for recommending urgent angiography in patients with suspected myocardial infarction. We aimed to evaluate this novel recommendation in two prospective studies of patients with suspected myocardial infarction. METHODS AND RESULTS:: We included 4067 patients presenting to the emergency department with suspected myocardial infarction. All patients had an ECG recorded immediately upon admission. Patients were classified as having right bundle branch block (RBBB), left bundle branch block (LBBB), bifascicular block (BFB) or no bundle branch block. All patients were followed for up to two years to assess mortality. In the overall population 125 (3.1%) patients had RBBB, 281 (6.9%) LBBB and 60 (1.5%) BFB. The final diagnosis of myocardial infarction was adjudicated in 20.8% (RBBB), 28.5% (LBBB), 23.3% (BFB) and 21.6% (no complete block) of patients. The mortality rate after one year was 10.7% (RBBB), 7% (LBBB), 17.5% (BFB) and 3.2% (no complete block). The adjusted hazard ratios were 1.29 (95% confidence interval (CI) 0.71-2.34; P=0.40) for RBBB, 1.71 (95% CI 1.17-2.50; P=0.006) for LBBB and 2.27 (95% CI 1.28-4.05; P=0.005) for BFB. CONCLUSION:: Our results support the new European Society of Cardiology ST-segment elevation myocardial infarction guideline describing RBBB as a high risk for mortality in patients with suspected myocardial infarction. However, the data challenge the concept of RBBB as a trigger of acute angiography because the likelihood of myocardial infarction in a chest pain unit setting is equally frequent in patients without bundle branch block.

Evaluation of a new ultra-sensitivity troponin I assay in patients with suspected myocardial infarction.

AIMS: Troponin is the gold-standard for diagnostic evaluation of patients with suspected myocardial infarction (MI). We aimed to evaluate the diagnostic and prognostic performance of a new ultra-sensitivity troponin I (us-TnI) assay in patients with suspected MI. METHODS AND RESULTS: 1534 patients with suspected MI were included. Us-TnI measurements were performed directly on admission and after one hour. One-year rates of mortality and incident MI were assessed. For diagnostic evaluation the negative and positive predictive value (NPV/PPV) using admission us-TnI concentrations and 0/1h delta were calculated. For rule-out an NPV > 99.5% (100% for single-admission-value) and for rule-in a PPV > 80% was targeted. Internal derivation/validation was used. In the derivation dataset 155/767 (20.2%) patients were diagnosed with having non-ST-elevation MI (NSTEMI). For rule-out of NSTEMI an us-TnI < 1 ng/L directly on admission resulted in an NPV of 100.0% (CI 98.2-100.0). Using serial sampling an admission us-TnI < 2 ng/L and a 0/1h delta < 1 ng/L resulted in an NPV of 99.7% (CI 98.4-100.0) and ruled-out NSTEMI in 46.8% of all patients. The respective one-year rate of death or MI was 0.6%. For rule-in of NSTEMI an us-TnI ≥ 25 ng/L on admission or a 0/1h delta ≥ 6 ng/L resulted in a PPV of 81.3% (CI 73.7-87.5) and ruled-in NSTEMI in 18.5% of all patients. The one-year event rate was 12.7%. Results were similar in 767 patients from the validation cohort. CONCLUSION: Application of an us-TnI assay allows the accurate triage of a large proportion of patients with suspected MI using a 0/1h algorithm. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02355457).

Impact of age on the performance of the ESC 0/1h-algorithms for early diagnosis of myocardial infarction.

Aims: We aimed to evaluate the impact of age on the performance of the European Society of Cardiology (ESC) 0/1h-algorithms and to derive and externally validate alternative cut-offs specific to older patients. Methods and results: We prospectively enrolled patients presenting to the emergency department (ED) with symptoms suggestive of acute myocardial infarction in three large diagnostic studies. Final diagnoses were adjudicated by two independent cardiologists. High-sensitivity cardiac troponin (hs-cTn) T and I concentrations were measured at presentation and after 1 h. Patients were stratified according to age [<55 years (young), ≥55 to <70 years (middle-age), ≥70 years (old)]. Rule-out safety of the ESC hs-cTnT 0/1h-algorithm was very high in all age-strata: sensitivity 100% [95% confidence interval (95% CI) 94.9-100] in young, 99.3% (95% CI 96.0-99.9) in middle-age, and 99.3% (95% CI 97.5-99.8) in old patients. Accuracy of rule-in decreased with age: specificity 97.0% (95% CI 95.8-97.9) in young, 96.1% (95% CI 94.5-97.2) in middle-age, and 92.7% (95% CI 90.7-94.3) in older patients. Triage efficacy decreased with increasing age (young 93%, middle-age 80%, old 55%, P < 0.001). Similar results were found for the ESC hs-cTnT 0/1h-algorithm. Alternative, slightly higher cut-off concentrations optimized for older patients maintained very high safety of rule-out, increased specificity of rule-in (P < 0.01), reduced overall efficacy for hs-cTnT (P < 0.01), while maintaining efficacy for hs-cTnI. Findings were confirmed in two validation cohorts (n = 2767). Conclusion: While safety of the ESC 0/1h-algorithms remained very high, increasing age significantly reduced overall efficacy and the accuracy of rule-in. Alternative slightly higher cut-off concentrations may be considered for older patients, particularly if using hs-cTnI. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT00470587, number NCT00470587 and NCT02355457 (BACC).

Prospective Validation of the 0/1-h Algorithm for Early Diagnosis of Myocardial Infarction.

BACKGROUND: The safety of the European Society of Cardiology (ESC) 0/1-h algorithm for rapid rule-out and rule-in of non-ST-segment elevation myocardial infarction (NSTEMI) using high-sensitivity cardiac troponin (hs-cTn) has been questioned. OBJECTIVES: This study aimed to validate the diagnostic performance of the 0/1-h algorithm in a large multicenter study. METHODS: The authors prospectively enrolled unselected patients in 6 countries presenting to the emergency department with symptoms suggestive of NSTEMI. Final diagnosis was centrally adjudicated by 2 independent cardiologists. Hs-cTnT and hs-cTnI blood concentrations were measured at presentation and after 1 h. Safety of rule-out was quantified by the negative predictive value (NPV) for NSTEMI, accuracy of rule-in by the positive predictive value (PPV), and overall efficacy by the proportion of patients triaged towards rule-out or rule-in within 1 h. RESULTS: Prevalence of NSTEMI was 17%. Among 4,368 patients with serial hs-cTnT measurements available, safety of rule-out (NPV 99.8%, 2,488 of 2,493), accuracy of rule-in (PPV 74.5%, 572 of 768), and overall efficacy were high by assigning three-fourths of patients either to rule-out (57%, 2,493 to 4,368) or rule-in (18%, 768 to 4,368). Similarly, among 3,500 patients with serial hs-cTnI measurements, safety of rule-out (NPV 99.7%, 1,528 of 1,533), accuracy of rule-in (PPV 62.3%, 498 of 800), and overall efficacy were high by assigning more than two-thirds of patients either to rule-out (44%, 1,533 of 3,500) or rule-in (23%, 800 of 3,500). Excellent safety was confirmed in multiple subgroup analyses including patients presenting early (≤3 h) after chest pain onset. CONCLUSIONS: The ESC 0/1-h algorithm using hs-cTnT and hs-cTnI is very safe and effective in triaging patients with suspected NSTEMI. (Advantageous Predictors of Acute Coronary Syndromes Evaluation [APACE]; NCT00470587; and Biomarkers in Acute Cardiac Care [BACC]; NCT02355457).

Relations of Sex to Diagnosis and Outcomes in Acute Coronary Syndrome.

BACKGROUND: The atypical presentation of women with acute coronary syndrome (ACS) has been related to delayed diagnosis and treatment, which may explain worse outcome compared with men. METHODS AND RESULTS: We analyzed pooled data of 2520 patients of 2 prospective cohorts in terms of differences in presentation and management of women and men suggestive of ACS. Using logistic regression, we established 2 diagnostic models and tested their diagnostic performance in both sexes separately. Sex-specific differences in management of patients with ACS were ascertained and a 2-year follow-up was performed. Women were older than men (median 67 versus 61 years, P=0.001), had more often dyspnea (22% versus 18%, P=0.024), nausea or vomiting (26% versus 16%, P=0.001) and radiating chest pain (47% versus 40%, P=0.001). Classical risk factors (smoking, diabetes mellitus, dyslipidemia or known coronary artery disease) were less frequent in women. Diagnostic models showed no significant sex-related differences in diagnostic performance in a "first contact" setting (medical history and symptoms) or after "complete triage" (including ECG and biomarkers). Women with ACS underwent coronary angiography (73.8% versus 84.3%, P<0.001) and revascularization (53.8% versus 70.1%, P<0.001) less frequently. Two-year incidence of myocardial infarction and death was similar in both sexes, but revascularization and cardiac rehospitalization were more frequent in men. CONCLUSIONS: In a large cohort of patients with suspected ACS, sex differences in clinical presentation did not impair diagnostic accuracy. Two-year outcomes were comparable. Our findings suggest a benefit of chest pain units to minimize sex differences in ACS management and prognosis. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifiers: NCT02355457 (BACC), NCT03227159 (stenoCardia).

Discrimination of patients with type 2 myocardial infarction.

AIMS: The differentiation of type 1 and type 2 myocardial infarction (T1MI, T2MI) is important, but challenging in the emergency department. We aimed to investigate the clinical characteristics and cardiovascular outcome of T2MI patients and to develop a clinical decision tool to differentiate T1MI and T2MI patients. METHODS AND RESULTS: We prospectively enrolled 1548 patients with suspected MI. All patients were followed for up to 2 years to assess mortality. We used logistic regression with backward step-down selection to determine the most important predictors of T2MI. Based on these regression coefficients, we developed a diagnostic prediction model (score) to diagnose T2MI. T2MI was the final diagnosis of 99 patients. Patients with T2MI showed a high 1-year mortality rate (13.8%), which equals that of T1MI patients (9.4%). Female sex (Beta 1.27 [95% confidence interval; CI 0.67-1.90]), not having radiating chest pain (Beta 1.62 [CI 0.96-2.34]) and a baseline high-sensitivity troponin I concentration ≤ 40.8 ng/L (Beta 1.30 [CI 0.74-1.89]) were the strongest predictors for T2MI. Their combination resulted in an area under the curve of 0.71 to discriminate T1MI and T2MI. The binary score based on this model assigns one point to each of the predictors. Patients with the highest score value of 3 had a 72% probability of T2MI. CONCLUSION: T2MI patients are a heterogeneous population with high-cardiovascular risk. A score based on laboratory and clinical parameters might help to differentiate T1MI and T2MI patients. The additional use of this score in clinical routine needs to be investigated prospectively. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02355457).

Cardiovascular Biomarkers in Hypertensive Patients with Medical Treatment-Results from the Randomized TEAMSTA Protect I Trial.

BACKGROUND: High blood pressure (BP) is associated with an increased rate of cardiovascular events and mortality. Cardiovascular biomarkers are able to predict long-term risk in the general population, particularly in diseased cohorts. We undertook an investigation of the effect of 2 different antihypertensive treatments on cardiovascular biomarkers in a randomized trial. METHODS: The TEAMSTA study included 481 hypertensive patients. They were randomized to either 80-mg telmisartan + 5-mg amlodipine (TA) or 40-mg olmesartan + 12.5-mg hydrochlorothiazide (OH). The trial was performed as a prospective, randomized, double-blinded, controlled, single-center study. We measured BP, high-sensitivity cardiac troponin I (hs-cTnI), high-sensitivity cardiac troponin T (hs-cTnT), B-type natriuretic peptide (BNP), and N-terminal-pro-BNP (NT-proBNP) before randomization and after 6 months. RESULTS: Individuals were randomized into 2 groups: 230 individuals to the OH-group and 251 to the TA-group. After 6 months of treatment, a reduction in BP (systolic/diastolic) was seen, from 135.2/85.2 mmHg to 122.5/75.7 mmHg with similar effects in both groups. hs-cTnT concentrations were measureable in 26.2% of the study population, while hs-cTnI was detected in 98.3%. hs-cTnI concentrations were significantly reduced from 4.6 to 4.2 ng/L in the overall population, from 4.7 to 4.4 ng/L in the OH-group, and from 4.6 to 4.0 ng/L in the TA-group (all P < 0.001). No significant changes of hs-cTnT were observed. BNP and NT-proBNP concentrations decreased from 15.0 to 12.4 ng/L (P < 0.001) and from 64.8 to 53.3 ng/L (P < 0.001), respectively, after 6 months. CONCLUSIONS: The reduction in BP was associated with a decrease of high-sensitivity troponin I, BNP, and NT-proBNP concentrations, which might represent a cardiovascular risk reduction. CLINICAL TRIAL REGISTRATION: EudraCT 2009-017010-68.

High-sensitivity assays for troponin in patients with cardiac disease.

Troponin is a widely used biomarker in patients with cardiac disease. The use of troponin is well established in patients with suspected acute myocardial infarction (AMI), but troponin measurement is also used in other acute and nonacute settings. In patients with suspected AMI, early decision-making is crucial to allow rapid treatment and further diagnostic evaluation. Current guidelines recommend serial measurements of troponin with a cut-off concentration at the 99th percentile to triage patients in the emergency department. Newer, high-sensitivity assays for troponin enable the detection of distinctly lower concentrations. Using these assays and very low cut-off concentrations, several rapid diagnostic strategies have been reported to improve diagnosis in acute cardiac care. Furthermore, noncoronary and nonacute applications of troponin assays - for example as a biomarker in patients with heart failure, pulmonary embolism, or stable coronary artery disease - are on the horizon and might improve individual risk stratification. In this Review, we provide an overview on the development of high-sensitivity assays for troponin, and their application in patients with cardiac disease.

Early diagnosis of acute myocardial infarction using high-sensitivity troponin I.

OBJECTIVE: There is a clinical need for early and accurate diagnosis of acute myocardial infarction (AMI). Current European Society of Cardiology (ESC) guidelines recommend diagnosis of non-ST-elevation AMI based on serial troponin measurements. We aimed to challenge the ESC guidelines using 1) a high-sensitivity troponin I (hs-TnI) baseline cutoff, 2) an absolute hs-TnI change after 1 hour and 3) additional application of an ischemic ECG. METHODS: 1,516 patients with suspected AMI presenting to the emergency department were included. Hs-TnI was measured directly at admission, after 1 and 3 hours. We investigated baseline concentrations, absolute changes of hs-TnI and additional application of an ischemic ECG to diagnose AMI. A positive predictive value (PPV) of more than 85% was targeted. RESULTS: The median age of the study population was 65 years; 291 patients were diagnosed with AMI. The PPV of the 3-hours ESC algorithm was 85.5% (CI 79.7, 90.1) and 65.8% (CI 60.5,70.8) for the 1-hour algorithm. Using a high baseline hs-TnI concentration of 150 ng/L resulted in a PPV of 87.8% (CI 80.9,92.9). Alternatively, a hs-TnI change of 20 ng/L after 1 hour, resulted in a PPV of 86.5% (80.9,91.0), respectively for the diagnosis of AMI. Additional use of an ischemic ECG increased the PPV to 90.5% (CI 83.2,95.3), while reducing the efficacy. CONCLUSION: The diagnosis of AMI based on hs-TnI is challenging. The application of absolute hs-TnI changes after 1 hour may facilitate rapid rule-in of patients. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02355457).

Challenging the 99th percentile: A lower troponin cutoff leads to low mortality of chest pain patients.

BACKGROUND: Rule-out of non-ST-elevation myocardial infarction is based on consecutive measurements of cardiac troponins using the 99th percentile of the respective assay as cutoff. The new ESC guidelines alternatively offer rapid 1h algorithms with lower cutoffs than the 99th percentile for rule-out of non-ST-elevation myocardial infarction. We aimed to compare a recently introduced 1h algorithm based on a high-sensitivity cardiac troponin I (hs-TnI) cutoff of 6ng/L at 0h and 1h to the current standard of care using the 99th percentile (27ng/L) as cutoff with reference to follow-up events in a large chest pain cohort. METHODS: Hs-TnI was measured at three time points (0h, 1h and 3h) in 1625 patients presenting with suspected myocardial infarction to the emergency department of the University-Medical Center Hamburg-Eppendorf. Seventy-five patients with ST-elevation myocardial infarction were excluded from the analysis. All-cause mortality, cardiac death, acute myocardial infarction, revascularization and cardiac rehospitalization after 12months were assessed. RESULTS: Patients ruled out by the 1h algorithm showed significantly less cardiac rehospitalizations (12.84% vs. 17.66%; p<0.001), and overall mortality (1.30% vs 3.46%, p<0.001) compared to using the 99th percentile as cutoff. The majority of deaths were caused by non-cardiac reasons. Cardiac deaths were rare using the 1h algorithm (0.21%). CONCLUSION: The commonly used 99th percentile as cutoff neglects patients with a high risk in the setting of acute chest pain. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02355457).

Immediate Rule-Out of Acute Myocardial Infarction Using Electrocardiogram and Baseline High-Sensitivity Troponin I.

AIMS: Serial measurements of high-sensitivity troponin are used to rule out acute myocardial infarction (AMI) with an assay specific cutoff at the 99th percentile. Here, we evaluated the performance of a single admission troponin with a lower cutoff combined with a low risk electrocardiogram (ECG) to rule out AMI. METHODS: Troponin I measured with a high-sensitivity assay (hs-TnI) was determined at admission in 1040 patients presenting with suspected AMI (BACC study). To rule out AMI we calculated the negative predictive value (NPV) utilizing the optimal hs-TnI cutoff combined with a low risk ECG. The results were validated in 3566 patients with suspected AMI [2-h Accelerated Diagnostic Protocol to Assess Patients With Chest Pain Symptoms Using Contemporary Troponins as the Only Biomarker (ADAPT) studies]. Patients were followed for 6 or 12 months. RESULTS: 184 of all patients were diagnosed with AMI. An hs-TnI cutoff of 3 ng/L resulted in a NPV of 99.3% (CI 97.3-100.0), ruling out 35% of all non-AMI patients. Adding the information of a low risk ECG resulted in a 100% (CI 97.5-100.0) NPV (28% ruled out). The 2 validation cohorts replicated the high NPV of this approach. The follow-up mortality in the ruled out population was low (0 deaths in BACC and Stenocardia, 1 death in ADAPT). CONCLUSIONS: A single hs-TnI measurement on admission combined with a low risk ECG appears to rule out AMI safely without need for serial troponin testing. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02355457).

Diagnosis of Myocardial Infarction Using a High-Sensitivity Troponin I 1-Hour Algorithm.

IMPORTANCE: Rapid and accurate diagnosis of acute myocardial infarction (AMI) currently constitutes an unmet need. OBJECTIVE: To test a 1-hour diagnostic algorithm to diagnose AMI using a high-sensitivity troponin I assay with a new cutoff level of 6 ng/L. DESIGN, SETTING, AND PARTICIPANTS: The Biomarkers in Acute Cardiac Care study is a prospective study that investigated the application of the troponin I assay for the diagnosis of AMI in 1040 patients presenting to the emergency department with acute chest pain from July 19, 2013, to December 31, 2014. Results were validated in 2 independent cohorts of 4009 patients. Final follow-up was completed on July 1, 2015, and data were assessed from July 2 to December 15, 2015. EXPOSURE: Acute chest pain suggestive of AMI. MAIN OUTCOMES AND MEASURES: Accurate diagnosis or exclusion of AMI and 12-month mortality in patients with acute chest pain. RESULTS: Of the 1040 patients included from the study cohort, 673 (64.7%) were male and had a median age of 65 (interquartile range, 52-75) years. With application of a low troponin I cutoff value of 6 ng/L, the rule-out algorithm showed a high negative predictive value of 99.8% (95% CI, 98.6%-100.0%) after 1 hour for non-ST-segment elevation MI type 1. The 1-hour approach was comparable to a 3-hour approach. Similarly, a rule-in algorithm based on troponin I levels provided a high positive predictive value with 82.8% (95% CI, 73.2%-90.0%). Moreover, application of the cutoff of 6 ng/L resulted in lower follow-up mortality (1.0%) compared with the routinely used 99th percentile (3.7%) for this assay. Two independent cohorts further validated the performance of this algorithm with high negative and positive predictive values. CONCLUSIONS AND RELEVANCE: Patients with possible AMI can be triaged within 1 hour after admission with no loss of safety compared with a 3-hour approach, when a low and sensitive cutoff is applied. This concept enables safe discharge or rapid treatment initiation after 1 hour.