High-Sensitivity Cardiac Troponin I Measurement for Risk Stratification in a Stable High-Risk Population

High-sensitivity cardiac troponin T levels and secondary events in outpatients with coronary heart disease from the Heart and Soul Study

IMPORTANCE

Levels of high-sensitivity cardiac troponin T (hs-cTnT) predict secondary cardiovascular events in patients with stable coronary heart disease.

OBJECTIVES

To determine the association of hs-cTnT levels with structural and functional measures of heart disease and the extent to which these measures explain the relationship between hs-cTnT and secondary events.

DESIGN

We measured serum concentrations of hs-cTnT and performed exercise treadmill testing with stress echocardiography in a prospective cohort study of outpatients with coronary heart disease who were enrolled from September 11, 2000, through December 20, 2002, and followed up for a median of 8.2 years.

SETTING

Twelve outpatient clinics in the San Francisco Bay Area.

PARTICIPANTS

Nine hundred eighty-four patients with stable coronary heart disease.

MAIN OUTCOMES AND MEASURES

Cardiovascular events (myocardial infarction, heart failure, or cardiovascular death), determined by review of medical records and death certificates.

RESULTS

Of 984 participants, 794 (80.7%) had detectable hs-cTnT levels. At baseline, higher hs-cTnT levels were associated with greater inducible ischemia and worse left ventricular ejection fraction, left atrial function, diastolic function, left ventricular mass, and treadmill exercise capacity. During follow-up, 317 participants (32.2%) experienced a cardiovascular event. After adjustment for clinical risk factors, baseline cardiac structure and function, and other biomarkers (N-terminal portion of the prohormone of brain-type natriuretic peptide and C-reactive protein levels), each doubling in hs-cTnT level remained associated with a 37% higher rate of cardiovascular events (hazard ratio, 1.37 [95% CI, 1.14-1.65]; P = .001).

CONCLUSIONS AND RELEVANCE

In outpatients with stable coronary heart disease, higher hs-cTnT levels were associated with multiple abnormalities of cardiac structure and function but remained independently predictive of secondary events. These findings suggest that hs-cTnT levels may detect an element of risk that is not captured by existing measures of cardiac disease severity.

Troponin T, N-terminal pro-B-type natriuretic peptide, and incidence of stroke: the atherosclerosis risk in communities study

BACKGROUND AND PURPOSE

Increased levels of plasma troponins and natriuretic peptides are associated with increased risk of cardiovascular disease, but only limited information exists on these biomarkers and stroke occurrence. In a prospective epidemiological study, we tested the hypothesis that high-sensitivity troponin T (TnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are associated positively with incidence of stroke.

METHODS

The Atherosclerosis Risk in Communities (ARIC) Study measured plasma TnT and NT-proBNP in 10 902 men or women initially free of stroke and followed them for a mean of 11.3 years for stroke occurrence (n=507).

RESULTS

Both biomarkers were associated positively with total stroke, nonlacunar ischemic, and especially cardioembolic stroke, but not with lacunar or hemorrhagic stroke. For example, after adjustment for prevalent risk factors and cardiac diseases, the hazard ratios (95% CIs) for jointly high values of TnT and NT-proBNP (versus neither biomarker high) were 2.70 (1.92-3.79) for total stroke and 6.26 (3.40-11.5) for cardioembolic stroke. Associations with stroke appeared somewhat stronger for NT-proBNP than TnT. Strikingly, ≈ 58% of cardioembolic strokes occurred in the highest quintile of prestroke NT-proBNP, and 32% of cardioembolic strokes occurred in participants who had both NT-proBNP in the highest quintile and were known by ARIC to have atrial fibrillation sometime before their cardioembolic stroke occurrence.

CONCLUSIONS

In the general population, elevated plasma TnT and NT-proBNP concentrations are associated with increased risk of cardioembolic and other nonlacunar ischemic strokes.

Prognostic value of cardiac troponin I measured with a highly sensitive assay in patients with stable coronary artery disease

OBJECTIVES

The aims of this study were to assess the prognostic value of cardiac troponin I levels, measured with a new high-sensitivity assay, in low-risk patients with stable coronary artery disease (CAD) and to contrast its determinants and prognostic merit with that of high-sensitivity cardiac troponin T (hs-TnT).

BACKGROUND

New, highly sensitive cardiac troponin assays permit evaluation of the association between troponin levels and outcomes in patients with stable CAD.

METHODS

High-sensitivity cardiac troponin I (hs-TnI) levels at baseline were assessed in 3,623 patients with stable CAD and preserved systolic function enrolled in the PEACE (Prevention of Events With Angiotensin-Converting Enzyme Inhibitor Therapy) trial.

RESULTS

In total, 98.5% of patients had hs-TnI concentrations higher than the detection level (1.2 pg/ml). hs-TnI correlated moderately with hs-TnT (r = 0.44) and N-terminal pro-B-type natriuretic peptide (r = 0.39) but only weakly with age (r = 0.17) and estimated glomerular filtration rate (r = -0.11). During a median follow-up period of 5.2 years, 203 patients died of cardiovascular causes or were hospitalized for heart failure, and 209 patients had nonfatal myocardial infarctions. In analyses adjusting for conventional risk markers, N-terminal pro-B-type natriuretic peptide, and hs-TnT, hs-TnI levels in the fourth compared with the 3 lower quartiles were associated with the incidence of cardiovascular death or heart failure (hazard ratio: 1.84; 95% confidence interval: 1.30 to 2.61; p < 0.001). [corrected]. There was a [corrected] weaker association with nonfatal myocardial infarction (hazard ratio: 1.37; 95% confidence interval: 0.98 to 1.92; p = 0.066). [corrected]. In the same models, hs-TnT concentrations were associated with the incidence of cardiovascular death or heart failure but not of myocardial infarction.

CONCLUSIONS

In patients with stable CAD, hs-TnI concentrations are associated with cardiovascular risk independently of conventional risk markers and hs-TnT. (Prevention of Events With Angiotensin-Converting Enzyme Inhibitor Therapy [PEACE]; NCT00000558).

Troponin T, B-type natriuretic peptide, C-reactive protein, and cause-specific mortality

PURPOSE

We sought to evaluate the associations of high-sensitivity troponin T (Hs-TnT), N-terminal pro-brain natriuretic peptide (NT-proBNP), and high sensitivity C-reactive protein (Hs-CRP) with mortality from any cause, cardiovascular disease (CVD), coronary heart disease (CHD), stroke, cancer, and respiratory disease in the Atherosclerosis Risk in Communities cohort.

METHODS

We included 11,193 participants aged 54 to 74 years, initially free of the conditions being studied, and who had biomarkers measured. Participants were followed for a mean of 9.9 years.

RESULTS

Hazard ratios (HR), adjusted for multiple risk factors, for mortality in participants in the highest Hs-TnT category compared with those with undetectable levels were: Total 3.42 (95% confidence interval [CI], 2.75-4.26); CVD, 7.34 (95% CI, 4.64-11.6); CHD, 6.06 (95% CI, 2.91-12.6); stroke, 3.31 (95% CI, 1.26-8.66); cancer, 1.60 (95% CI, 1.08-2.38); and respiratory, 3.85 (95% CI, 1.39-10.7). Comparing the highest NT-proBNP quintile with those in the lowest quintile, the adjusted HRs for mortality were: Total, 3.05 (95% CI, 2.46-3.77); CVD, 7.48 (95% CI, 4.67-12.0); CHD, 4.07 (95% CI, 2.07-7.98); and stroke, 10.4 (95% CI, 2.26-47.7). Comparing extreme Hs-CRP quintiles, the adjusted HRs for mortality were: Total, 1.61 (95% CI, 1.32-1.97); CVD, 1.76 (95% CI, 1.19-2.62); and respiratory, 3.36 (95% CI, 1.34-8.45). Having multiple markers elevated simultaneously greatly increased cause-specific mortality risks.

CONCLUSIONS

Greater levels of Hs-TnT, NT-proBNP and Hs-CRP are associated with increased risk of death, not just from CVD, but also from some noncardiovascular causes.

Troponin I measured by a high-sensitivity assay in patients with suspected reversible myocardial ischemia: data from the Akershus Cardiac Examination (ACE) 1 study

BACKGROUND

Whether cardiac troponin concentrations are increased by reversible myocardial ischemia is controversial. Differences in the structure of cardiac troponin I (cTnI) and cTnT may have implications for diagnostic utility.

METHODS

cTnI was measured with a prototype high-sensitivity (hs) assay in 198 patients referred for myocardial perfusion imaging (MPI) before exercise stress testing, immediately after, and 1.5 and 4.5 h later. We categorized patients according to MPI results and compared hs-cTnI concentrations with hs-cTnT concentrations.

RESULTS

Baseline hs-cTnI was higher in patients with reversible myocardial ischemia (n = 19) vs the other patients (n = 179): median 4.4 (quartiles 1-3: 2.3-7.1) vs 2.5 (1.4-4.3) ng/L, P = 0.003. Baseline hs-cTnI and hs-cTnT concentrations were correlated (r = 0.46, P < 0.001) and the areas under the ROC curve for hs-cTnI and hs-cTnT in diagnosing reversible ischemia were similar: 0.71 vs 0.69, P = 0.77. Whereas hs-cTnI increased immediately after exercise (P < 0.001 vs baseline measurements) in patients without ischemia, it increased after 4.5 h in patients with reversible ischemia (P = 0.01). The increment in hs-cTnI concentrations was comparable between groups; thus, measuring hs-cTnI after exercise stress testing did not improve diagnostic accuracy over baseline measurements, and hs-cTnI concentrations were not found to be associated with reversible myocardial ischemia in multivariate analysis. By linear regression analysis, age, male sex, history of hypertension, angiotensin-converting enzyme inhibitor use, and lower left ventricular ejection fraction were associated with higher baseline hs-cTnI concentrations.

CONCLUSIONS

In patients referred to MPI, hs-cTnI concentrations were not closely associated with reversible myocardial ischemia, but rather were influenced by variables associated with structural alterations of the myocardium.

Cardiac Troponin T Measured by a High-Sensitivity Assay Predicts Recurrent Cardiovascular Events in Stable Coronary Heart Disease Patients with 8-Year Follow-up

BACKGROUND

The clinical relevance of slightly increased circulating troponin concentrations in patients with stable coronary heart disease (CHD) several weeks after an acute event or CABG has not been fully evaluated.

METHODS

Baseline plasma concentrations of troponin T were measured with a high-sensitivity assay (hs-cTnT) (Roche Elecsys) in a cohort of 1050 CHD patients from 30 to 70 years of age. The prognostic value of hs-cTnT on a combined cardiovascular disease (CVD) end point after adjustment for covariates was determined with Cox proportional hazards modeling.

RESULTS

The median hs-cTnT concentration was 10.9 ng/L (interquartile range, 5.1–18.9 ng/L). Increased hs-cTnT concentrations were associated with an older age, history of hypertension and diabetes, more advanced coronary artery disease, and other CHD risk factors. Furthermore, hs-cTnT concentration was strongly correlated with N-terminal pro–B-type natriuretic peptide (NT-proBNP) and cystatin C (ρ = 0.61, and ρ = 0.32, respectively; both P values &lt;0.0001). During a median follow-up of 8.1 years, 150 patients (14.3%) experienced a secondary CVD event. In a multivariate model, hs-cTnT was associated with a hazard ratio (HR) for secondary events of 2.83 (95% CI, 1.68–4.79) when the extreme quartiles were compared. Further adjustment for cystatin C, NT-proBNP, and C-reactive protein attenuated this association only slightly (HR, 2.27; 95% CI, 1.31–3.95); P for trend &lt; 0.002). ROC curve analysis of a clinical model that added hs-cTnT to a baseline model showed nonsignificant improvement in the area under the curve (0.69 vs 0.67), whereas the net reclassification improvement was 17.2% (P = 0.029).

CONCLUSIONS

Slightly increased hs-cTnT concentrations in stable CHD patients are associated with several cardiovascular disorders and predict long-term CVD events.

Clinical Use and Measurement of Cardiac Troponin (cTn)

Cardiac troponins are cardio-specific and are widely used for the early diagnosis and triage of patients with acute coronary syndromes in conjunction with clinical history, electrocardiographic changes and imaging. Troponin is also useful for the prediction of outcomes in acute coronary syndromes, renal failure, sepsis, and critically ill patients. New developments in assay technology, designated as high sensitivity troponins, permit detection of lower levels of troponin in most healthy individuals, earlier diagnosis of myocardial infarction, and prognosis of stable coronary disease in the community.

Biomarkers for Predicting Serious Cardiac Outcomes at 72 Hours in Patients Presenting Early after Chest Pain Onset with Symptoms of Acute Coronary Syndromes

BACKGROUND

Most outcome studies of patients presenting early to the emergency department with potential acute coronary syndromes have focused on either the index diagnosis of myocardial infarction (MI) or a composite end point at a later time frame (30 days or 1 year). We investigated the performance of 9 biomarkers for an early serious outcome.

METHODS

Patients (n = 186) who presented to the emergency department within 6 h of chest pain onset had their presentation serum sample measured for the following analytes: creatine kinase, creatine kinase isoenzyme MB, enhanced AccuTnI troponin I (Beckman Coulter), high-sensitivity cardiac troponin T (hs-cTnT), ischemia-modified albumin, interleukin-6, investigation use only hs-cTnI (Beckman Coulter), N-terminal pro–B-type natriuretic peptide, and cardiac troponin I (Abbott AxSym). We followed patients until 72 h after presentation and determined whether they experienced the following serious cardiac outcomes: MI, heart failure, serious arrhythmia, refractory ischemic cardiac pain, or death. ROC curves were analyzed to determine the area under the ROC curve (AUC) and optimal cutoffs for the biomarkers.

RESULTS

The AUCs for the hs-cTnI assay (0.86; 95% CI, 0.76–0.96), the AccuTnI assay (0.86; 95% CI, 0.78–0.95), and the hs-cTnT assay (0.82; 95% CI, 0.71–0.94) assays were significantly higher than those for the other 6 assays (AUC values ≤0.71 for the rest of the biomarkers, P &lt; 0.05). The ROC curve–derived optimal cutoffs were ≥19 ng/L (diagnostic sensitivity, 80%; specificity, 88%), ≥0.018 μg/L (diagnostic sensitivity, 75%; specificity, 86%), and ≥32 ng/L (diagnostic sensitivity, 68%; specificity, 92%) for the hs-cTnI, AccuTnI, and hs-cTnT assays, respectively.

CONCLUSIONS

The optimal cutoffs for predicting serious cardiac outcomes in this low-risk population are different from the published 99th percentiles. Larger studies are required to verify these findings.

Circulating Troponin As Measured by a Sensitive Assay for Cardiovascular Risk Assessment in Primary Prevention

BACKGROUND

Measuring circulating cardiac troponin using novel sensitive assays has revealed that even minute elevations are associated with increased mortality in patients with coronary artery disease or even in the general population. Less well defined, however, is the incremental value of measuring circulating cardiac troponin I (cTnI) by a sensitive assay for risk assessment in primary prevention.

METHODS

We measured circulating concentrations of cTnI, N-terminal pro–B-type natriuretic peptide (NT-proBNP), and high-sensitivity C-reactive protein (hsCRP) in 5388 individuals free of known cardiovascular disease recruited into the DETECT study, a prospective longitudinal population-based cohort study. We determined the prognostic implications for incident major adverse cardiovascular events (MACE) during 5 years of follow-up.

RESULTS

Circulating cTnI was detectable in 19% of the subjects. Increased cTnI concentrations were associated with established risk factors for atherosclerosis and demonstrated a graded relationship with all-cause mortality and incident MACE during 5-year follow-up. A single measurement of cTnI significantly improved risk prediction over established risk factors, and also added prognostic information, when adjusted for serum concentrations of NT-proBNP and hsCRP.

CONCLUSIONS

Minute increases in cTnI are associated with increased mortality and incident MACE in a large primary prevention cohort and, thus, identify contributors to cardiovascular risk not fully captured by traditional risk factor assessment.