Prospective evaluation of the role of routine cardiac troponin T measurement to identify left ventricular ejection fraction < 40% after first myocardial infarction

Clinically Acquired High Sensitivity Cardiac Troponin T is a Poor Predictor of Reduced Left Ventricular Ejection Fraction After ST Elevation Myocardial Infarction: A National Cohort Study-ANZACS-QI 65

OBJECTIVE

Cardiac troponins (cTn) have been used historically to estimate infarct size in ST elevation myocardial infarction (STEMI). Within a resource constrained health care environment, cTn could therefore be used for prioritisation of patients for cardiac imaging, in particular echocardiography. We aimed to determine how useful routinely collected cTn would be in predicting significant left ventricular (LV) impairment.

METHODS

All patients in the All New Zealand Acute Coronary Syndrome Quality Improvement (ANZACS-QI) registry with their first episode of STEMI between January 2013 and November 2018, who had high sensitivity troponin T measured, were included. We excluded patients with no left ventricular ejection fraction (LVEF) assessment, known LV dysfunction, or prior myocardial infarction.

RESULTS

In total, 3,698 patients were included in the analysis. A higher mean hsTnT (admission and peak) was seen in patients with more severely impaired LV function but there was significant overlap in the range of hsTnT between the different LVEF categories. Cardiac troponins demonstrated poor discriminative ability to either predict or exclude significant LV impairment (LVEF <40%). At an optimal cutpoint of 3,405 ng/L, peak hsTnT had a sensitivity of 56.5% (95% confidence interval [CI] 42-62%), a specificity of 65.3% (95% CI 62-79%) and an area under the receiver operating curve of 0.62 (95% CI 0.60-0.64).

CONCLUSION

This is the largest study comparing clinically measured troponin levels and LV function in patients presenting with STEMI. A definite, but weak, association was seen between peak troponin and the degree of LV dysfunction, with significant overlap in troponin levels between levels of myocardial dysfunction. Routinely acquired troponin is not suitable for clinical use as a method of prioritising patients for cardiac imaging.

Association between Variation of Troponin and Prognosis of Acute Myocardial Infarction before and after Primary Percutaneous Coronary Intervention

Background

Circulating levels of cardiac troponin I (cTnI) after ST-segment elevation myocardial infarction (STEMI) were considered as prognostic factors for predicting the incidence of major adverse cardiovascular events (MACE). △cTnI is the difference between peak cTnI after primary percutaneous coronary intervention (PPCI) and cTnI on initial admission.

Purpose

This study aimed to assess the relationship between △cTnI, the ratio of △cTnI to cTnI on initial admission, and the incidence of MACE during the follow-up period.

Methods

A total of 2596 patients with cTnI measured upon admission and one-time measurement of cTnI during hospitalization were enrolled.

Results

In the adjusted models of the survival receiver operating characteristic (ROC) curve, △cTnI and the ratio of △cTnI to cTnI on initial admission have stronger discrimination power of MACE (area under curve (AUC) 0.730 and 0.717) compared with peak cTnI after PPCI and cTnI at admission (AUC 0.590, 0.546). Multivariate Cox regression analysis identified △cTnI (hazard ratio (HR) 1.018, 95% confidence interval (CI) 1.001 to 1.035) as a relevant factor for MACE during follow-up. △cTnI was divided into quartiles, and maximum △ cTnI between 4.845 and 19.073 ng/ml comprised more patients with anterior wall myocardial infarction (p < 0.001), higher GRACE score (p = 0.038), CK-MB (p = 0.023), and Myoglobin (p < 0.001). On the K–M survival curves, the incidence of MACE, mortality, and angina pectoris were significantly higher in the group with maximum △cTnI (p = 0.035, 0.049, 0.026).

Conclusion

The △cTnI level and the ratio of △cTnI have stronger discrimination power of predicting the incidence of MACE. The group with maximum △cTnI has higher incidence of MACE, mortality, and angina pectoris during the follow-up period.

Sub-acute cardiac magnetic resonance to predict irreversible reduction in left ventricular ejection fraction after ST-segment elevation myocardial infarction: A DANAMI-3 sub-study

AIMS

To predict irreversible reduction in left ventricular ejection fraction (LVEF) during admission for ST-segment elevation myocardial infarction (STEMI) using cardiac magnetic resonance (CMR) in addition to classical clinical parameters. Irreversible reduction in LVEF is an important prognostic factor after STEMI which necessitates medical therapy and implantation of prophylactic implantable cardioverter defibrillator (ICD).

METHODS AND RESULTS

A post-hoc analysis of DANAMI-3 trial program (Third DANish Study of Optimal Acute Treatment of Patients With ST-elevation Myocardial Infarction) which recruited 649 patients who had CMR performed during index hospitalization and after 3 months. Patients were divided into two groups according to CMR-LVEF at 3 months: Group 1 with LVEF≤35% and Group 2 with LVEF>35%. Group 1 included 15 patients (2.3%) while Group 2 included 634 patients (97.7%). A multivariate analysis showed that: Killip class >1 (OR 7.39; CI:1.47-36.21, P = 0.01), symptom onset-to-wire ≥6 h (OR 7.19; CI 1.07-50.91, P = 0.04), LVEF≤35% using index echocardiography (OR 7.11; CI: 1.27-47.43, P = 0.03), and infarct size ≥40% of LV on index CMR (OR 42.62; CI:7.83-328.29, P < 0.001) independently correlated with a final LVEF≤35%. Clinical models consisted of these parameters could identify 7 out of 15 patients in Group 1 with 100% positive predictive value.

CONCLUSION

Together with other clinical measurements, the assessment of infarct size using late Gadolinium enhancement by CMR during hospitalization is a strong predictor of irreversible reduction in CMR_LVEF ≤35. That could potentially, after validation with future research, aids the selection and treatment of high-risk patients after STEMI, including implantation of prophylactic ICD during index hospitalization.

Higher incidence of hypotension episodes in women during the sub-acute phase of ST elevation myocardial infarction and relationship to covariates

OBJECTIVE

The introduction of primary percutaneous coronary intervention (PPCI) has modified the profile of ST elevation myocardial infarction (STEMI) patients. Occurrence and prognostic significance of hypotension episodes are not known in PPCI treated STEMI patients. It is also not known whether and/or how the hypotension episodes correlate with the degree of myocardial damage and whether there are any sex differences.

METHODS

Data of 293 consecutive STEMI patients (189 males) treated by PPCI and without cardiogenic shock were analyzed. Blood pressure was measured noninvasively. A hypotensive episode was defined as a systolic blood pressure below 90 mmHg over a period of at least 30 minutes.

RESULTS

A hypotensive episode was observed in 92 patients (31.4%). Female sex was the strongest independent predictor of hypotension episodes (p < 0.0001), while there was no relationship to electrocardiographic STEMI localization. Hypotensive patients had significantly higher levels of troponin T and brain natriuretic peptide; hypotensive episodes were particularly frequent in women with increased troponin T. Treatment with angiotensin-converting enzyme inhibitor (ACEI), angiotensin receptor blocker (ARB) and betablockers was less frequent in hypotensive patients. After a mean 20-month follow-up, all-cause mortality did not differ between hypotensive patients and others. However, mortality in hypotensive patients who did not tolerate ACEI/ARB therapy was significantly higher compared to other hypotensive patients (p = 0.016).

CONCLUSION

Hypotension episodes are not uncommon in the sub-acute phase of contemporarily treated STEMI patients with a striking difference between sexes-female sex was the strongest independent predictor of hypotension episodes. Hypotensive episodes may lead to a delay in pharmacotherapy which influences prognosis. Higher incidence of hypotension in women could at least partially explain the sex-related differences in the use of cardiovascular pharmacotherapy which was repeatedly observed in various studies.

How Well Do Laboratories Adhere to Recommended Clinical Guidelines for the Management of Myocardial Infarction: The CARdiac MArker Guidelines Uptake in Europe Study (CARMAGUE)

BACKGROUND

We undertook an assessment of current use of evidence-based guidelines for the use of cardiac biomarkers in Europe (EU) and North America (NA).

METHODS

In 2013–2014 a web-based questionnaire was distributed via NA and EU biochemical societies. Questions covered cardiac biomarkers measured, analytical methods used, decision thresholds, and use of decision-making protocols. Results were collated using a central database and analyzed using comparative and descriptive nonparametric statistics.

RESULTS

In EU, returns were obtained from 442 hospitals, 50% central or university hospitals, and 39% from local hospitals from 35 countries with 395/442 (89%) provided an acute service. In NA there were 91 responses (63.7% central or university hospitals, 19.8% community hospitals) with 76/91 (83.5%) providing an acute service. Cardiac troponin was the preferred cardiac biomarker in 99.5% (EU) and 98.7% (NA), and the first line marker in 97.7% (EU) and 97.4% (NA). There were important differences in the choice of decision limits and their derivations. The origin of the information was also significantly different, with EU vs NA as follows: package insert, 61.9% vs 40%; publications, 17.1% vs 15.0%; local clinical or analytical validation choice, 21.0% vs 45.0%; P = 0.0003.

CONCLUSIONS

There are significant differences between EU and NA use of cardiac biomarkers. This probably relates to different availability of assays between EU and NA (such as high-sensitivity troponin assays) and different laboratory practices on assay introduction (greater local evaluation of assay performance occurred in NA).

Sensitive troponin assays

Sensitive troponin assays have been developed to meet the diagnostic goals set by the universal definition of myocardial infarction (MI). The analytical advantages of sensitive troponin assays include improved analytical imprecision at concentrations below the 99th percentile and the ability to define a reference distribution fully. Clinically, the improved sensitivity translates into the ability to diagnosis MI earlier, possibly within 3 h from admission and the ability to use the rate of change of troponin (Δ troponin) for diagnosis. Very sensitive assays may, in appropriately selected populations (perhaps with the addition of Δ troponin), allow diagnosis on hospital admission or within 1–2 h of admission. An elevated troponin level occurring in patients without suspected acute coronary syndromes has, in all studies to date in which outcome has been examined, been shown to indicate an adverse prognosis whatever the underlying clinical diagnosis. Failure of elevation means a good prognosis allowing early, safe hospital discharge, whereas a raised value requires investigation and should help prevent clinically significant pathology being overlooked. Sensitive troponins do present a challenge to the laboratory and the clinician. For the laboratory, the diagnosis of MI requires a change in troponin value. For the clinician, the challenge is to shift from a simplistic yes/no diagnosis of MI based on a single troponin value to a diagnosis that utilises early troponin changes as part of the clinical picture, and to relate the new class of detectable troponin elevation in patients with ischaemic myocardial disease to existing clinical guidelines and trial evidence.

Biomarkers of cardiovascular damage

Acute coronary syndromes (ACS) are due to the rupture or erosion of atheromatous plaques. This produces, depending on plaque size, vascular anatomy and degree of collateral circulation, progressive tissue ischaemia which may progress to cardiomyocyte necrosis. This may then result in cardiac remodelling. Serum biomarkers are available which can be used for diagnosis of all of these stages. Markers to detect myocardial ischaemia at the pre-infarction stage are potentially the most interesting but also the most challenging. An ischaemia marker offers the opportunity to intervene to prevent progression to infarction. The problems with potential ischaemia markers are specificity and the reference diagnostic standard against which they can be judged. To date, only one, ischaemia-modified albumin(R), has reached the point where clinical studies can be performed. The measurement of the cardiac troponins, cardiac troponin T and cardiac troponin I, have become recognised as the diagnostic reference standard for myocardial necrosis. The sensitive nature of these tests has also revealed that myocardial necrosis is also found in a range of other clinical situations, highlighting the need to use all clinical information for diagnosis of acute myocardial infarction. The measurement of B-type natriuretic peptides can be shown to be diagnostic and prognostic in both ACS and detecting the sequelae of post-infarction myocardial insufficiency. The role of the B-type natriuretic peptides in detection of cardiac failure, both acute and chronic, is well defined but remains the subject of further studies, in ACS.

Biomarkers of Cardiovascular Damage and Dysfunction—An Overview

Acute coronary syndromes (ACS) are due to the rupture or erosion of atheromatous plaques. This produces, depending on plaque size, vascular anatomy and degree of collateral circulation, progressive tissue ischaemia which may progress to cardiomyocyte necrosis and subsequent cardiac remodelling. Cardiac biomarkers can be used for diagnosis and assessment of all of these stages. Markers to detect myocardial ischaemia at the pre-infarction stage are potentially the most interesting but also the most challenging. An ischaemia marker offers the opportunity to intervene to prevent progression to infarction. The challenges with potential ischaemia markers are specificity and the diagnostic reference standard for assessment. To date, only one, ischaemia modified albumin, has reached the point where clinical studies can be performed. The measurement of the cardiac troponins, cardiac troponin T and cardiac troponin I, has become the diagnostic standard as the biomarker of myocardial necrosis. The sensitive nature of troponin measurement has also revealed that myocardial necrosis is also found in a range of other clinical situations. This illustrates the need to use all clinical information for diagnosis of acute myocardial infarction. The measurement of B type natriuretic peptides can be shown to be diagnostic and prognostic for both acute ACS and detecting the sequelae of post infarction myocardial insufficiency. The role of the B type natriuretic peptides in detection of cardiac failure, acute and chronic, is well defined. Their role in ACS remains the subject of further studies.

Diagnostic and prognostic role of cardiac troponin I (cTnI) measured on the DPC Immulite

OBJECTIVE

To evaluate the diagnostic and prognostic role of the Immulite cTnI assay for the detection of acute coronary syndromes (ACS).

POPULATION

150 males and 63 females with a median age of 63 years, range 28 to 88, and an interquartile range of 18 years were admitted within 24 h of chest pain and non-ST segment elevation ACS were studied. The median onset of symptoms was 3 h (range 0-23).

METHODS

Venous samples were taken on admission (t = 0) and at 24 h (t = 24). The serum samples were assayed for CK, CK-MB and cTnT on an Elecsys 1010 (Roche Diagnostics, Lewes, UK). The cTnT assay CV was 5.5% at 0.32 microg/l and 5.4% at 6.0 microg/l, and the detection limit was 0.01 microg/l with an upper limit of 25 microg/l. For cTnI using the Immulite (DPC, Gwynedd, Wales), the detection limit was 0.1 microg/l, and the upper limit was 180 microg/l. Final diagnostic categorization was performed by both WHO and European Society of Cardiology criteria using cTnT as the diagnostic cardiac biomarker. Patients were followed for the major adverse cardiac events (MACE), endpoints cardiac death, AMI or need for urgent revascularization. ROC curves were constructed using final diagnosis. Outcome prediction was assessed by ROC curves and Kaplan-Meier survival curves.

RESULTS

Both methods had equivalent diagnostic efficiency using WHO criteria for AMI. When ESC criteria were used the AUC for admission and 24 h cTnT and cTnI values were 0.945 vs. 0.910, P = 0.20 and 0.998 vs. 0.937, P = 0.005, respectively. Both methods predicted outcome as either death or MI or MACE and were not significantly different.

CONCLUSION

The Immulite cTnI assay can be used for diagnosis and risk stratification in patients admitted with non-ST segment elevation acute coronary syndromes.

Clinical effect of recalibration of the roche cardiac troponin T assay

OBJECTIVE

To assess the effect of recalibration of the Roche 3rd-generation cTnT assay with recombinant human cardiac troponin T (cTnT) standards on clinical decision limits.

MATERIALS AND METHODS

Serum samples from 77 patients (66 +/- 16 years) admitted to the coronary care unit were assayed using the 2nd- and 3rd-generation cTnT assays.

RESULTS

There was excellent agreement (r = 0.99 Spearman, 95% CI 0.99-1.0; p <or= 0.0001, n = 153) between the 2nd- and 3rd-generation cTnT assays across the analytical range, but there was a curvilinear relationship between values. There was concordance between the 2nd- and 3rd-generation cTnT values in the range from 0 to 0.2 microg/l. Above 0.2 microg/l, however, there were increasing but predictable differences.

CONCLUSION

There was no statistical difference between the 2nd- and 3rd-generation cTnT assays, demonstrated by a linear relationship below 0.2 microg/l. This confirms that the 3rd-generation assay was calibrated to that of the 2nd-generation assay in the range of 0-0.2 microg/l. The detection limit and upper reference limit of normal will be unaffected by this change in calibration. A non-linear relationship at higher 2nd-generation concentrations (0.2-25.0 microg/l) was observed. Clinical decision limits up to 0.2 microg/l, associated with increased cardiac risk, are unaffected by the assay calibration, but values greater than 0.2 microg/l are affected.

Measurement of troponin I 48h after admission as a tool to rule out impaired left ventricular function in patients with a first myocardial infarction

Few studies have evaluated cardiac troponin I (cTnI) as a marker for infarct size and left ventricular (LV) dysfunction. Here we investigated the ability of a single-point cTnI, measured with a second-generation assay (Access AccuTnI), to estimate infarct size and assess LV function in patients with a first myocardial infarction (AMI). cTnI measurements were performed 12 and 48h after admission in 63 consecutive AMI patients. LV function was evaluated by gated single-photon emission computed tomography (SPECT) and infarct size was estimated by CK-MB peak and SPECT myocardial perfusion. LV function and infarct size were evaluated by SPECT before hospital discharge. SPECT was also repeated 3months later. Significant correlations (p<0.001) were found between cTnI at 12 and 48h and both the peak CK-MB (r=0.61 and r=0.82, respectively) and the perfusion defect size at SPECT (r=0.55 and r=0.61, respectively). cTnI at 12 and 48h were inversely related (p<0.001) to LV ejection fraction (LVEF) assessed both early (r=–0.45 and r=–0.57, respectively) and 3months after AMI (r=–0.51 and r=–0.69, respectively). cTnI >14.8 μg/L at 48h predicted an LVEF <40% at 3months with a sensitivity of 100% [95% confidence interval (CI) 73.5–100%], specificity of 65% (CI 49–79%), and a negative predictive value of 100%. Our findings demonstrate that a single cTnI measurement 48h after admission is useful for ruling out impaired LV function in a routine clinical setting.