Optimal Cutoff Levels of More Sensitive Cardiac Troponin Assays for the Early Diagnosis of Myocardial Infarction in Patients With Renal Dysfunction

A novel troponin I rule-out value below the upper reference limit for acute myocardial infarction

OBJECTIVE

To determine cut-off values for a recently introduced high sensitive cardiac troponin assay (hs-cTnI) which provide similar sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) for acute myocardial infarction (AMI) as known cut-off values for an hs-cTnT assay.

METHODS

A prospective observational study was performed. Hs-cTnT (Roche) and hs-cTnI (Abbott) were measured in consecutive patients with symptoms suggestive of AMI. Representative measurements (obtained at least 3 h after chest pain has started) and serial measurements with a time delay between 2.5 h and 4.5 h were used to determine cut-off levels. Two independent clinicians adjudicated the final diagnosis.

RESULTS

1490 patients were included in the study of whom 114 (8%) received a final diagnosis of AMI. Receiver operating characteristics analysis showed no statistically significant differences in the areas under the curve between the two assays. Cut-off values for representative hs-TnI were found to be as follows: rule-out: 10 ng/L (sensitivity: 98.2%; 95% CI 95.7% to 100.0% and NPV: 99.8%; 99.5% to 100.0%); rule-in: 70 ng/L (specificity: 90.8%; 89.3% to 92.4% and PPV: 39.7%; 36.1% to 43.3%). For serial measurements we found a Δ rule-out cut-off value of 20 ng/L (sensitivity: 94.9%; 88.0% to 100.0% and NPV: 98.7%; 96.9% to 100.0%) and Δ rule-in cut-off values of 100 ng/L (specificity: 92.7%; 87.9% to 95.8% and PPV: 57.6%; 39.4% to 74.0%) and 300% (specificity: 93.8%; 90.4% to 97.2% and PPV: 61.3%; 51.1% to 71.5%).

CONCLUSIONS

Cut-off values for hs-cTnI measurements are determined which allow a similar diagnostic classification as compared with hs-cTnT. Importantly, for a rule-out paradigm this cut-off value is unmistakably lower than the upper reference limit.

Troponin elevations in patients with chronic cardiovascular disease: An analysis of current evidence and significance

Serum troponin elevation above the 99^th percentile of the upper reference limit in healthy subjects (<0.01 ng/ml measured using currently available high-sensitivity cardiac troponin laboratory assays) is required to establish the diagnosis the diagnosis of myocardial necrosis in acute cardiovascular syndromes, as well as guide prognosis and therapy. In the perioperative period, for patients with cardiac disease undergoing noncardiac surgery, it is a particularly critical biomarker universally used to assess the myocardial damage. The value of troponin testing and elevation (as well as its significance) in patients with chronic cardiac valvular, vascular, and renal disease is relatively less well understood. This evidence-based review seeks to examine the currently available data assessing the significance of troponin elevation in certain chronic valvular and other disease states.

Coronary Angiographic Findings in Acute Ischemic Stroke Patients With Elevated Cardiac Troponin: The Troponin Elevation in Acute Ischemic Stroke (TRELAS) Study

BACKGROUND

A relevant proportion of patients with acute ischemic stroke (AIS) have elevated levels of cardiac troponins (cTn). However, the frequency of coronary ischemia as the cause of elevated cTn is unknown. The aim of our study was to analyze coronary vessel status in AIS patients with elevated cTn compared with patients presenting with non-ST-segment-elevation acute coronary syndrome (NSTE-ACS).

METHODS AND RESULTS

Among 2123 consecutive patients with AIS prospectively screened at 2 tertiary hospitals, 13.7% had cTn elevation (>50 ng/L). According to a prespecified sample size estimation, 29 patients with AIS (median age, 76 years [first-third quartiles, 70-82 years]; 52% male) underwent conventional coronary angiography and were compared with age- and sex-matched patients with NSTE-ACS. The primary end point was presence of coronary culprit lesions on coronary angiograms as analyzed by independent interventional cardiologists blinded for clinical data. Median cTn on presentation did not differ between patients with AIS or NSTE-ACS (95 versus 94 ng/L; P=0.70). Compared with patients with NSTE-ACS, patients with AIS were less likely to have coronary culprit lesions (7 of 29 versus 23 of 29; P<0.001) or any obstructive coronary artery disease (15 of 29 versus 25 of 29; P=0.02; median number of vessels with >50% stenosis, 1 [first-third quartiles, 0-2] versus 2 [first-third quartiles, 1-3]; P<0.01).

CONCLUSIONS

Coronary culprit lesions are significantly less frequent in AIS patients compared with age- and sex-matched patients with NSTE-ACS despite similar baseline cTn levels. Half of all AIS patients had no angiographic evidence of coronary artery disease. Further studies are needed to clinically identify the minority of patients with AIS and angiographic evidence of a culprit lesion.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01263964.

Current approaches for the diagnosis, risk stratification and interventional treatment of patients with acute coronary syndromes without st-segment elevation

This article reviews current approaches to diagnosis and determination of the individual risk of patients with acute coronary syndrome without ST-segment elevation. Guidelines for determining the choice of treatment strategy and the time slots for its implementation are discussed. We describe the technical features of the implementation of interventional treatment in this group of patients; the choice of methods of myocardial revascularization is discussed.