Baseline hsTnT Research Articles

Correlation of concentrations of high-sensitivity troponin T and high-sensitivity C-reactive protein with plaque progression as measured by CT coronary angiography

BackgroundElevated levels of inflammatory biomarkers are associated with increased cardiovascular morbidity and mortality. ObjectiveWe sought to determine whether elevated concentrations of high-sensitivity troponin T (hs-TnT) and high-sensitivity C-reactive protein (hs-CRP) predict progression of coronary artery disease (CAD) as determined by coronary CT angiography (coronary CTA). MethodsPatients presenting to the emergency department with acute chest pain who initially showed no evidence of an acute coronary syndrome underwent baseline and follow-up coronary CTA (median follow-up, 23.9 months) using identical acquisition and reconstruction parameters. Coronary CTA data of each major coronary artery were co-registered. Cross-sections were assessed for the presence of calcified and noncalcified plaques. Progression of atherosclerotic plaque and change of plaque composition from noncalcified to calcified plaque was evaluated and correlated to levels of hs-TnT and hs-CRP at the time of the baseline CT. ResultsFifty-four patients (mean age, 54.1 years; 59% male) were included, and 6775 cross-sections were compared. CAD was detected in 12.2 ± 21.2 cross-sections per patient at baseline. Prevalence of calcified plaque increased by 1.5 ± 2.4 slices per patient (P < .0001) over the follow-up period. On average, 1.6 ± 3.6 slices with new noncalcified plaque were found per patient (P < .0001) and 0.7 ± 1.7 slices with pre-existing noncalcified plaque had progressed to calcified plaque (P < .0001). After multivariate adjustment, change of overall CAD burden was predicted by baseline hs-TnT and hs-CRP (r = 0.29; P = .039 and r = 0.40; P = .004). Change of plaque composition was associated with baseline hs-TnT (r = 0.29; P = .03). ConclusionConcentrations of hs-TnT and hs-CRP are weakly associated with a significant increase in CAD burden and change in plaque composition over 24 months independent of baseline risk factors.

Abstract 18710: Improvements in Glycemic Control in Type 2 Diabetes Do Not Lead to Reductions in Circulating Cardiac Troponin

Objective: Concentrations of cardiac troponin T, when measured with a high-sensitivity assay (hsTnT), have emerged as a strong marker of cardiovascular mortality, and are frequently elevated in patients with type 2 diabetes. Whether glycemic control affects concentrations of this marker is unknown. Methods and Results: We measured hsTnT in patients from the LANCET trial, a 14 week, 2x2 factorial, randomized, placebo-controlled trial of insulin glargine and metformin in early type 2 diabetes. Baseline and 14-week follow up samples were available from 438 participants. At baseline, 408 out of 438 (93.2%) had detectable circulating hsTnT, while 59 (13.5%) had hsTnT levels above the established upper reference limit (≥ 14 ng/L). At baseline, the median (IQR) HbA1c was 6.9% (6.3-7.7%) with no significant differences by treatment group. Statistically significant associations with baseline natural logarithm transformed hsTnT were noted for age (ρ=0.09, P&lt;0.05), but not fasting glucose, HbA1c, body mass index, interleukin-6, or high-sensitivity C-reactive protein (each P&gt;0.26). After 14 weeks of randomly allocated therapy, we observed a significant reduction in HbA1c in all treatment groups except placebo (Figure). In models adjusted for baseline hsTnT and baseline antihyperglycemic therapy we observed no over all change in hsTnT by random treatment allocation (P=0.92) and no individual treatment group differences relative to placebo (Figure; each P≥0.37). Conclusions: These data suggest that aggressive glucose control with insulin glargine, metformin, or the combination does not alter concentrations of circulating cardiac troponin T. Our findings are concordant with the results of large randomized controlled trials showing that glycemic control alone may not suffice to substantively lower cardiovascular risk. (Clinicaltrials.gov Identifier: NCT00366301 )

High-Sensitivity Troponin T and Risk Stratification in Patients With Atrial Fibrillation During Treatment With Apixaban or Warfarin

The aim of this study was to evaluate the prognostic value of high-sensitivity troponin T (hs-TnT) in addition to clinical risk factors and the CHA2DS2VASc (congestive heart failure, hypertension, 75 years of age and older, diabetes mellitus, previous stroke or transient ischemic attack, vascular disease, 65 to 74 years of age, female) risk score in patients with atrial fibrillation (AF). The level of troponin is a powerful predictor of cardiovascular events and mortality. A total of 14,897 patients with AF were randomized to treatment with apixaban or warfarin in the ARISTOTLE (Apixaban for the Prevention of Stroke in Subjects With Atrial Fibrillation) trial. The associations between baseline hs-TnT levels and outcomes were evaluated using adjusted Cox regression models. Levels of hs-TnT were measurable in 93.5% of patients; 75% had levels >7.5 ng/l, 50% had levels >11.0 ng/l, and 25% had levels >16.7 ng/l. During a median 1.9-year period, the annual rates of stroke or systemic embolism ranged from 0.87% in the lowest hs-TnT quartile to 2.13% in the highest hs-TnT quartile (adjusted hazard ratio [HR]: 1.94; 95% confidence interval [CI]: 1.35 to 2.78; p = 0.0010). The annual rates in the corresponding groups ranged from 0.46% to 4.24% (adjusted HR: 4.31; 95% CI: 2.91 to 6.37; p < 0.0001) for cardiac death and from 1.26% to 4.21% (adjusted HR: 1.91; 95% CI: 1.43 to 2.56; p = 0.0001) for major bleeding. Adding hs-TnT levels to the CHA2DS2VASc score improved the C statistic from 0.620 to 0.635 for stroke or systemic embolism (p = 0.0226), from 0.592 to 0.711 for cardiac death (p < 0.0001), and from 0.591 to 0.629 for major bleeding (p < 0.0001). Apixaban reduced rates of stroke, mortality, and bleeding regardless of the hs-TnT level. Levels of hs-TnT are often elevated in patients with AF. The hs-TnT level is independently associated with an increased risk of stroke, cardiac death, and major bleeding and improves risk stratification beyond the CHA2DS2VASc risk score. The benefits of apixaban as compared with warfarin are consistent regardless of the hs-TnT level. (Apixaban for the Prevention of Stroke in Subjects With Atrial Fibrillation [ARISTOTLE]; NCT00412984).

Cardiomyocyte Injury Assessed by a Highly Sensitive Troponin Assay and Sudden Cardiac Death in the Community: The Cardiovascular Health Study

This study sought to determine the association between markers of cardiomyocyte injury in ambulatory subjects and sudden cardiac death (SCD). The pathophysiology of SCD is complex but is believed to be associated with an abnormal cardiac substrate in most cases. The association between biomarkers of cardiomyocyte injury in ambulatory subjects and SCD has not been investigated. Levels of cardiac troponin T, a biomarker of cardiomyocyte injury, were measured by a highly sensitive assay (hsTnT) in 4,431 ambulatory participants in the Cardiovascular Health Study, a longitudinal community-based prospective cohort study. Serial measures were obtained in 3,089 subjects. All deaths, including SCD, were adjudicated by a central events committee. Over a median follow-up of 13.1 years, 246 participants had SCD. Baseline levels of hsTnT were significantly associated with SCD (hazard ratio [HR] for +1 log(hsTnT): 2.04, 95% confidence interval [CI]: 1.78 to 2.34]. This association persisted in covariate-adjusted Cox analyses accounting for baseline risk factors (HR: 1.30, 95% CI: 1.05 to 1.62), as well as for incident heart failure and myocardial infarction (HR: 1.26, 95% CI: 1.01 to 1.57). The population was also categorized into 3 groups based on baseline hsTnT levels and SCD risk [fully adjusted HR: 1.89 vs. 1.55 vs. 1 (reference group) for hsTnT ≥12.10 vs. 5.01 to 12.09 vs. ≤ 5.00 pg/ml, respectively; p trend = 0.005]. On serial measurements, change in hsTnT levels was also associated with SCD risk (fully adjusted HR for +1 pg/ml per year increase from baseline: 1.03, 95% CI: 1.01 to 1.06). The findings suggest an association between cardiomyocyte injury in ambulatory subjects and SCD risk beyond that of traditional risk factors.

Preprocedural high-sensitive Troponin strongly predicts survival after Transcatheter Aortic Valve Implantation (TAVI)

Transcatheter aortic valve implantation/replacement (TAVI/TAVR) has become a valuable therapeutic tool in the treatment of inoperable or high risk patients with severe aortic stenosis. Several risk scores have been proposed to evaluate the perioperative and long-term risk of patients undergoing TAVI. However, exact estimation of risk remains difficult. We thus sought to investigate whether biomarkers may improve risk stratification. We prospectively included 111 consecutive patients undergoing TAVI at our institution from 02/2011 until 05/2012. 107 patients were available for follow-up. 61.7% were females, mean age was 81.63 years (±6.34y), and 56.1% were treated via transfemoral access. Since elevated troponin T levels have been associated with adverse outcome in various forms of cardiac disease, high sensitive troponin T (hsTnT) and other clinical and biochemical parameters were measured 24h before TAVI. Mean logistic Euroscore was 21.4% (±14.0%), and mean STS score was 6.6% (±4.1%). Mean follow-up was 249 days (±158d). The primary endpoint was all-cause mortality. A total of 21 deaths (19.6%) occurred during follow up. 30-day mortality was 7.5%. Median baseline hsTnT values were 23.5 ng/ml (IQR 12.9-48.4 ng/ml). hsTnT, NTproBNP, Euroscore, pre- and postprocedural aortic regurgitation (AR) were significantly associated with outcome. Interestingly, a multivariate analysis revealed that only hsTnT (HR upper quartile 5.1 vs. lower quartiles, CI 2.06-12.54, p<0.001) and to a lesser extent preprocedural AR (HR=2.30, CI 1.33-3.99, p=0.003) independently predict survival time. Taken together, elevation of hsTnT pre-TAVI is a novel and strong predictor of death in TAVI patients.

Abstract 18505: High-sensitive Troponin T Levels Independently Predict Survival in TAVI Patients

TAVI (transcatheter aortic valve implantation) has become a valuable therapeutic tool in the treatment of inoperable or high risk patients with severe aortic stenosis. Several risk scores have been proposed to estimate the perioperative and long-term risk of patients undergoing TAVI. However, exact estimation of perioperative and long term risk remains difficult. We thus sought to investigate whether biomarkers may improve risk stratification in this setting. We included 111 consecutive patients undergoing TAVI (using Edwards Sapien and Sapien XT prostheses) at our institution from February 2011 until May 2012. 109 patients were available for complete follow up. 61% were females, mean age was 80.6 years (+/- 11.0 years), 55% were treated via transfemoral access. Since elevated troponin T levels have been associated with adverse outcome in various forms of cardiac disease, high sensitive troponin T (hsTNT) values and other parameters were measured a day before TAVI (baseline) and 1, 3, and 7 days post-procedure. Mean EF was 48.3% (+/- 10.3%) and mean logistic Euroscore 20.8% (+/- 13.1%). Mean follow-up was 163 days (+/-144 days), The primary endpoint was all-cause mortality and a total of 18 deaths (16.51%) occurred. 30 day mortality was 6.4% (7/109). Median baseline hsTNT values were 22.7 ng/ml with an interquartile range (IQR) of 12-47 ng/ml. Cox regression analyses including age, sex, procedural access site, NYHA class, renal function [creatinine], NTproBNP, STS score, and logistic Euroscore revealed only baseline hsTNT (HR for upper quartile 6.32 vs. quartiles 1-3, CI 2.15-18.55, p=0.001) and the baseline creatinine level (HR=1.89 per quartile, CI 1.02-3.48, p=0.043) as independent prognostic parameters for cumulative mortality. At 72 hours post-TAVI, hsTNT increased to a median of 178 ng/ml, IQR 88.7-361.52 ng/ml. hsTNT levels at day 3 were associated with adverse outcome, but did not offer additional prognostic information when compared to preprocedural hsTNT levels. However, the individual raise in hsTNT at day 3 is associated with the incidence of cumulative death (p=0.034). In conclusion, elevated hsTNT the day before TAVI is an independent risk predictor of all-cause death in TAVI patients.

Cardiac high‐sensitivity troponin T measurement: A layer of complexity in managing haemodialysis patients

To determine: (i) the proportion of stable asymptomatic haemodialysis patients with elevated troponin; (ii) stability of troponin values after dialysis and over a 2-week interval; and (iii) whether high-sensitivity troponin T (hsTnT) was associated with higher prevalence of cardiovascular risk factors or cardiovascular disease in these patients. We measured hsTnT and the fourth generation troponin I before and after dialysis in 103 stable in-centre haemodialysis patients without ischaemic symptoms. Patients were divided into quartiles to test for associations with established cardiovascular risk factors or disease. hsTnT was above the 99th percentile for the general population in 99% of haemodialysis patients compared with only 13% elevation for the troponin I assay (P < 0.001). Median pre-dialysis hsTnT concentrations were unchanged after a 2-week interval (69 vs 69 ng/L, P = 0.55) but fell slightly immediately following dialysis (69 vs 61 ng/L, P < 0.001). Established coronary artery disease (59% vs 22%), peripheral vascular disease (38% vs 4%) and diabetes (18% vs 7%) were more prevalent (P < 0.05) in those in the highest quartile for hsTnT compared with those in the lowest quartile. Almost all in-centre haemodialysis patients have elevated troponin T in their baseline stable state and this appears unchanged over a 2-week interval. Such a high rate of baseline elevation of hsTnT may lead to confusion in managing acute coronary syndrome in this group of patients, particularly when symptoms are atypical. We recommend that if Troponin I assay is unavailable then baseline hsTnT concentrations are measured periodically in all haemodialysis patients.

Elevated Baseline Cardiac Troponin Levels in the Elderly—Another Variable to Consider?

Background: High-sensitivity Troponin T (hs-TnT) is now widely employed in the diagnosis of myocardial infarction. Inappropriate “rule in” or delayed “rule out” of myocardial infarction has significant consequences. It is therefore important to understand factors that influence baseline levels of hs-TnT. We sought to determine the impact of increasing age on baseline hs-TnT levels.

Comparison of diagnostic accuracy between three different rules of interpreting high sensitivity troponin T results

With the introduction of high sensitivity troponin-T (hs-TnT) assay, clinicians face more patients with 'positive' results but without myocardial infarction. Repeated hs-TnT determinations are warranted to improve specificity. The aim of this study was to compare diagnostic accuracy of three different interpretation rules for two hs-TnT results taken 6 h apart. After adjusting for clinical differences, hs-TnT results were recoded according to the three rules. Rule1: hs-TnT >13 ng/L in at least one determination. Rule2: change of >20 % between the two measures. Rule3: change >50 % if baseline hs-TnT 14-53 ng/L and >20 % if baseline >54 ng/L. The sensitivity, specificity and ROC curves were compared. The sensitivity analysis was used to generate post-test probability for any test result. Primary outcome was the evidence of coronary critical stenosis (CCS) on coronary angiography in patients with high-risk chest pain. 183 patients were analyzed (38.3 %) among all patients presenting with chest pain during the study period. CCS was found in 80 (43.7 %) cases. The specificity was 0.62 (0.52-0.71), 0.76 (0.66-0.84) and 0.83 (0.74-0.89) for rules 1, 2 and 3, respectively (P < 0.01). Sensitivity decreased with increasing specificity (P < 0.01). Overall diagnostic accuracy did not differ among the three rules (AUC curves difference P = 0.12). Sensitivity analysis showed a 25 % relative gain in predicting CCS using rule 3 compared to rule 1. Changes between two determinations of hs-TnT 6 h apart effectively improved specificity for CCS presence in high-risk chest pain patients. There was a parallel loss in sensitivity that discouraged any use of such changes as a unique way to interpret the new hs-TnT results.

Perioperative myocardial necrosis in patients at high cardiovascular risk undergoing elective non-cardiac surgery

ObjectiveCardiovascular complications are important causes of morbidity and mortality in elective non-cardiac surgery. Although difficult to diagnose, perioperative myocardial infarction (MI) remains prognostically important. High-sensitivity troponin T (hs-TnT) assays allow...

Abstract 9326: Peri-Operative Myocardial Damage in Higher-Risk Patients Undergoing Elective Non-Cardiac Surgery

Introduction: The development of high-sensitivity assays has greatly improved the analytical performance of cardiac troponin, allowing detection of very minor damage to cardiac muscle. High sensitivity troponin (hsTnT) is elevated in subgroups of stable populations, with prognostic significance. We postulated hsTnT would be elevated in a proportion of patients undergoing elective non-cardiac surgery, with this elevation predicting adverse peri-operative events. Aims: The aims of our study were to identify the incidence of elevated hsTnT in patients undergoing non-cardiac surgery, and to determine the association between elevated pre-operative hsTnT and adverse peri-operative events. Methods: Consecutive patients aged ≥45 years undergoing major elective non-cardiac surgery, prescribed anti-platelet therapy for primary or secondary cardiovascular event prevention, were included. Baseline, 24 and 48-hour post-operative hsTnT (Roche Diagnostics, 99th percentile 13ng/L) were collected, an elevation above the 99th percentile or if baseline hsTnT elevated, a delta value of 30%, used to define myocardial damage. Results: Included in the analysis were 160 consecutive patients undergoing elective non-cardiac surgery (mean age 72.3 ± 9.7 years, 66% male). Baseline hsTnT was elevated in 29.5% of all patients. Peri-operative myocardial damage occurred in 28.6% of patients. Independent predictors of peri-operative myocardial damage included age (HR 1.07, 1.02-1.12), intra-operative hypotension (HR 3.65, 1.34-9.91), and pre-operative haemoglobin (Hb) concentration (HR 0.97, 0.95-0.99). Baseline elevated hsTnT did not predict peri-operative myocardial damage. Myocardial infarction as defined by the Universal Definition occurred in only 2.7% of patients. Conclusions: Although pre-operative hsTnT was commonly elevated in this cohort, there was no significant association with post-operative myocardial damage. We found 28% of stable higher-risk patients undergoing elective non-cardiac surgery have hsTnT determined peri-operative myocardial damage. The significant associations of intra-operative hypotension and pre-operative Hb concentration suggest myocardial damage is predominantly due to a supply and demand mismatch.

Prognostic value of cardiac troponin T in patients with moderate to severe heart failure scheduled for cardiac resynchronization therapy

Predicting response to cardiac resynchronization therapy (CRT) is challenging. Highly sensitive cardiac troponin T (hsTnT) might predict response to CRT and identify patients at a high risk of experiencing severe cardiovascular events. We investigated whether baseline levels of hsTnT were associated with response to CRT and with severe cardiovascular events after long-term follow-up. Eighty-one consecutive patients were included according to the current guidelines for CRT. Biochemical, functional, and clinical parameters were assessed at baseline and at 3, 6, and 12 months of follow-up; and mortality/cardiac transplantation after 46 ± 6 months of follow-up was investigated. Cardiac magnetic resonance imaging and echocardiography were used to assess left ventricular function including viability and remodeling. Seventy-five patients completed 12 months of follow-up; and after a follow-up of 46 ± 6 months, a total of 15 patients died, 13 of these from cardiovascular causes, and 7 underwent heart transplantation. Baseline hsTnT <15 ng/L predicted response to CRT and was associated with a more favorable outcome with regard to severe cardiovascular events. Multivariate analysis found that presence of transmural scar tissue/fibrosis on magnetic resonance imaging and use of statins were independently associated with higher concentrations of hsTnT at baseline. There was a strong correlation between hsTnT and N-terminal pro-B-type natriuretic peptide levels. Highly sensitive TnT levels were elevated in the majority of heart failure patients who were scheduled for CRT. The HsTnT levels predicted response to CRT as well as long-time survival.

High sensitivity troponin outperforms contemporary assays in predicting major adverse cardiac events up to two years in patients with chest pain

Previous studies have shown a risk of subsequent major adverse cardiovascular events (MACEs) in patients with suspected acute coronary syndromes (ACSs) and elevated cardiac troponin. The aim of this study was to compare prognostic utility of high-sensitivity troponin with contemporary troponin assays in such patients. In total, 332 patients with suspected ACS were investigated between November 2006 and April 2007; all were followed for two years. Blood samples were analysed to compare Roche Elecsys high-sensitivity troponin T (hsTnT), Abbott Architect troponin I 3rd generation (TnI 3) and Roche Elecsys troponin T (TnT), for the prediction of MACE (composite of cardiovascular death, non-fatal myocardial infarction and revascularization). Sixty-eight patients (20.5%) experienced MACE between discharge and two years. Receiver operating characteristic (ROC) curve derived area under the ROC curve (95% confidence intervals) for baseline hsTnT were 0.70 (0.63-0.76), TnI 3 0.66 (0.59-0.73) and TnT 0.61 (0.53-0.69). hsTnT (P = 0.001) was superior to TnT and TnI 3 trended (P = 0.094) to superiority but were equivalent to each other. hsTnT best stratified patients with cumulative event rates for two-year MACE of 35.6% for levels ≥99th percentile, 17.9% for levels between the limit of detection (LOD) and 99th percentile and 5.4% for levels <LOD compared with TnI 3: 33.0%, 31.1% and 10.9%, respectively. TnT had MACE rates of 36.7% when ≥99th percentile and 15.4% when <99th percentile (=LOD). hsTnT outperformed contemporary TnI and TnT assays for the prediction of MACE at two years. Those with levels below the LOD for hsTnT identified a group of patients at very low risk for adverse events.

Pre-operative High-sensitive Troponin Concentration in Higher-risk Patients Undergoing Elective Non-cardiac Surgery

Background: Cardiac troponins are the most sensitive biochemical marker of myocardial injury, with newer high-sensitive troponin (hs-TnT) assays allowing the detection of lesser degrees of myocardial damage. Hs-TnT is elevated in approximately 10% of patients with stable coronary artery disease, and is significantly associated with adverse long-term cardiovascular outcomes. The aim of our study was to investigate baseline troponin (both 4th generation and hs-TnT) concentrations in high-risk patients undergoing elective non-cardiac surgery. Methods: Consecutive patients undergoing elective non-cardiac surgery, currently prescribed anti-platelet therapy because they were deemed high risk, were included. Patient demographics and comorbidities were collected. Baseline hs-TnT (Roche Diagnostics, ninety-ninth percentile 13 ng/L, limit of detection 2 ng/L), and fourth generation TnT (Roche Diagnostics, 99th percentile 10 ng/L, limit of detection 10 ng/L) were collected in all patients. Results: One hundred and ten consecutive patients were recruited (mean age: 72 ± 9.7 years, 64% male). Hs-TnT concentration was elevated above the ninety-ninth percentile in 29 (26%) patients, with only seven (6%) elevated using the older fourth generation assay. Multivariate predictors of elevated hs-TnT included; age (r = 0.42, p < 0.01); estimated glomerular filtration rate (r = −0.67, p < 0.01); and haemoglobin (r = −0.42, p < 0.01). A similar trend was observed for ischaemic heart disease history, however this was not statistically significant (p = 0.08). Conclusion: In stable high risk patients undergoing elective non-cardiac surgery, approximately one-quarter will have an elevated pre-operative hs-TnT. Factors associated with this include age, renal dysfunction, and anaemia. Given an elevated hs-TnT in stable populations is associated with worse cardiovascular outcomes, the impact on peri-operative morbidity and mortality merits further evaluation.

Highly sensitive troponin T assay in normotensive patients with acute pulmonary embolism

To assess the role of cardiac troponin T (cTnT) levels on admission using a new, highly sensitive assay (hsTnT) in the risk assessment of normotensive patients with acute pulmonary embolism (PE). We prospectively studied 156 consecutive normotensive patients with confirmed PE. The prognostic value of hsTnT at baseline was compared with the conventional cTnT troponin assay and with N-terminal pro-brain natriuretic peptide concentrations. Long-term follow-up was available for 153 patients (98.1%). Highly sensitive troponin T values ranged from 0.001 to 357.2 pg/mL [median 27.2 (25th-75th percentile 9.4-69.4) pg/mL]. Overall, 100 patients (64%) had hsTnT > or =14 pg/mL. Baseline hsTnT was higher in patients with an adverse 30-day outcome (> or =1: death, need for catecholamines, endotracheal intubation, or cardiopulmonary resuscitation) compared with an uncomplicated course [71.7 (35.5-117.9) vs. 26.4 (9.2-68.2) pg/mL; P = 0.027]. The cut-off value of 14 pg/mL showed an excellent prognostic sensitivity and negative predictive value (both 100%). In comparison, as many as 50% of the patients with an adverse early outcome would have been misclassified as low risk by cTnT (cut-off 0.03 ng/mL). Logistic regression indicated a two-fold increase in the risk of an adverse outcome for each increase of hsTnT by 1SD of the natural logarithm (P = 0.037). Patients with elevated hsTnT levels had a reduced probability of long-term survival (P = 0.029 by log-rank); by Cox's regression analysis, hsTnT was the only laboratory biomarker predicting an elevated risk of death over the long term. Highly sensitive troponin T assays may be capable of improving risk stratification of non-high-risk PE.

Nine Years of Unprotected Left Main Stem Coronary Stenting at Christchurch Hospital

assays have been developed which can detect much lower levels of troponin. Methods: 441 patients with chest pain suggestive of acutemyocardial infarction (AMI)were recruited between November 2006 and May 2007; all were followed for 2 years. Serial blood samples were analysed to compare Roche high sensitivity troponin T (hsTNT)with latest generation Abbott troponin I (TNI) and Roche TNT for the prediction of MACE, defined as composite of cardiovascular death, myocardial infarction or revascularization. Results: 91 patients (20.6%) experienced MACE at 2 years. ROC curve AUC for baseline hsTNT was 0.71 (0.66–0.75), TNI was 0.66 (0.61–0.71) and TNT was 0.62 (0.56–0.67). hsTNT out-performs TNT (p= 0.001) but there is no statistical difference between hsTNT and TNI or TNI andTNT.Hazard ratios (HR) forMACEwere 11.4 (2.8–46.9) for hsTNT, 2.9 (1.9–4.6) for TNI and 2.5 (1.6–3.8) for TNT. WhenHRareadjusted foranypatient characteristic shown to be independent predictors ofMACE (in this study independent predictors were age, prior history of ischaemic heart disease and index admission diagnosis of AMI), only hsTNTconveyedadditional risk,HR, 5.2 (1.2–23.1,p= 0.03). Conclusions: hsTNT outperforms conventional assays in prediction of MACE as seen by ROC curve analysis and Cox proportional hazards modelling and is the only troponin to add prognostic utility when adjusted for all baseline characteristics.

Highly Sensitive Cardiac Troponin T Values Remain Constant after Brief Exercise- or Pharmacologic-Induced Reversible Myocardial Ischemia

Using a new precommercial high-sensitivity cardiac troponin T (hsTnT) assay, we evaluated whether hsTnT increases after reversible myocardial ischemia. In 195 patients undergoing nuclear stress testing (ST) using single-photon emission computed tomography (SPECT) for suspected ischemic heart disease, we measured hsTnT before and 18 min, 4 h, and 24 h after the stress test. Thirty patients were excluded before ST because of cardiac troponin T (cTnT) >30 ng/L (0.03 mug/L) as measured by the fourth-generation commercial test. Another 65 patients were excluded because of a combination of fixed and reversible perfusion defects (PDs) after SPECT. We studied 18 patients with reversible PDs, 41 patients with fixed PDs, and 41 patients without any PDs. Of these 100 patients, 61 received dynamic ST and 39 pharmacological ST. Median baseline hsTnT concentrations (25th, 75th percentile) were comparable in patients with reversible, fixed, and no PDs [5.57 (2.47, 12.60), 8.01 (4.55, 12.44), and 6.90 (4.63, 10.59) ng/L, respectively]. After ST, median hsTnT concentrations did not change in the reversible, fixed, or no PD groups from baseline to 18 min [-0.41 (-0.81, 0.01), 0.01 (-0.75, 0.79), and 0.36 (-0.42, 1.01) ng/L] or from baseline to 4 h [-0.56 (-1.82, 0.74), 0.24 (-0.60, 1.45), and 0.23 (-0.99, 1.15) ng/L]. Median baseline hsTnT concentrations tended to be higher in patients undergoing pharmacological vs dynamic ST; however, there were no significant increases in hsTnT concentrations after either type of ST. Elevation of cTnT is rather a consequence of irreversible myocyte death than reversible myocardial ischemia after exercise or pharmacologic myocardial ischemia.