High-sensitivity cardiac troponin T in young, healthy adults undergoing non-cardiac surgery.

BACKGROUND: It is unclear if isolated postoperative cardiac-troponin elevation, often referred to as myocardial injury, represents a pathological event, as control studies in otherwise healthy adults are lacking. METHODS: In this single-centre prospective observational cohort study, serial high-sensitivity cardiac troponin T (hscTnT) plasma concentrations were obtained from young, healthy adults undergoing elective orthopaedic surgery at three time points: before operation, 2-6 h, and 18-30 h after surgery. End points were hscTnT increases after surgery: ≥20% (exceeding analytical variability), ≥50% (exceeding short-term biological variability), and ≥85% (exceeding long-term biological variability). The secondary end point was myocardial injury, defined as new postoperative hscTnT elevation >99th % upper reference limit (URL) (women >10 ng litre-1; men >15 ng litre-1). RESULTS: Amongst the study population (n=95), no hscTnT increase ≥20% was detected in 68 patients (73%). A hscTnT increase between 20% and 49% was observed in 17 patients (18%), 50-84% in seven patients (7%), and ≥85% in three patients (3%). Twenty patients (21%) had an absolute ΔhscTnT between 0 and 2 ng litre-1, 12 patients (13%) between 2 and 4 ng litre-1, three patients between 4 and 6 ng litre-1, and one patient (1%) between 6 and 8 ng litre-1. Myocardial injury (new hscTnT elevation >99th%) was diagnosed in one patient (1%). The median hscTnT concentrations did not increase after operation, and were 4 (3.9-5, inter-quartile range) ng litre-1 at baseline, 4 (3.9-5) ng litre-1 at 2-6 h after surgery, and 4 (3.9-5) ng litre-1 on postoperative day 1. CONCLUSIONS: One in four young adult patients without known cardiovascular disease developed a postoperative hscTnT increase, but without exceeding the 99th% URL and without evidence of myocardial ischaemia. These results may have important ramifications for the concept of postoperative myocardial injury, as they suggest that, in some patients, postoperative cardiac-troponin increases may be the result of a normal physiological process in the surgical setting. CLINICAL TRIAL REGISTRATION: NCT 02394288.

High sensitivity cardiac troponin T in patients with immunoglobulin light chain amyloidosis.

OBJECTIVES: To define whether the high sensitivity cardiac troponin T (hs-cTnT) assay in patients with immunoglobulin light chain amyloidosis (AL) improves risk prediction. BACKGROUND: Cardiac involvement is the major cause of death in patients with AL amyloidosis. Risk stratification is facilitated by cardiac biomarkers such as cardiac troponin T (cTnT) and N-terminal pro B-type natriuretic peptide (NT-proBNP). METHODS: Stored serum from patients with newly diagnosed AL was used to measure hs-cTnT, cTnT, and NT-proBNP. Survival modelling was performed. RESULTS: The direct numeric result from hs-cTnT measurement cannot merely be substituted for a cTnT measurement in the Mayo AL staging system. The performance of the receiver operator curve derived an hs-cTnT cut-point of 54 ng/L which improves on the value of 35 ng/L validated with the prior iteration of the assay. An alternate staging option using hs-cTnT alone-using the two thresholds 14 ng/L and 54 ng/L-performs as well as either the original Mayo AL staging system or other systems incorporating hs-cTnT. On multivariate analysis, an hs-cTnT alone staging system was independent of period of diagnosis, type of therapy, and NT-proBNP value, the last of which dropped out of the model. Alternate models were explored, but none performed better than the original system or the new hs-cTnT system. Thus, hs-cTnT can be used alone for the staging of disease prognosis. CONCLUSIONS: A survival model based on hs-cTnT improves the prognostic staging of patients with AL amyloidosis, relegating NT-proBNP to a measure of cardiac response.

Fatty acids and TxA(2) generation, in the absence of platelet-COX-1 activity.

BACKGROUND AND AIMS: Omega-3 fatty acids suppress Thromboxane A(2) (TxA(2)) generation via mechanisms independent to that of aspirin therapy. We sought to evaluate whether baseline omega-3 fatty acid levels influence arachidonic acid proven platelet-cyclooxygenase-1 (COX-1) independent TxA(2) generation (TxA(2) generation despite adequate aspirin use). METHODS AND RESULTS: Subjects with acute myocardial infarction, stable CVD or at high risk for CVD, on adequate aspirin therapy were included in this study. Adequate aspirin action was defined as complete inhibition of platelet-COX-1 activity as assessed by <10% change in light transmission aggregometry to ≥1 mmol/L arachidonic acid. TxA(2) production was measured via liquid chromatography-tandem mass spectrometry for the stable TxA(2) metabolite 11-dehydro-thromboxane B2 (UTxB2) in urine. The relationship between baseline fatty acids, demographics and UTxB(2) were evaluated. Baseline omega-3 fatty acid levels were not associated with UTxB(2) concentration. However, smoking was associated with UTxB(2) in this study. CONCLUSION: Baseline omega-3 fatty acid levels do not influence TxA(2) generation in patients with or at high risk for CVD receiving adequate aspirin therapy. The association of smoking and TxA(2) generation, in the absence of platelet COX-1 activity, among aspirin treated patients warrants further study.

Cardiac troponin T before and after kidney transplantation: determinants and implications for posttransplant survival.

Pretransplant cardiac troponin T(cTnT(pre) ) is a significant predictor of survival postkidney transplantation. We assessed correlates of cTnT levels pre- and posttransplantation and their relationship with recipient survival. A total of 1206 adult recipients of kidney grafts between 2000 and 2010 were included. Pretransplant cTnT was elevated (≥0.01 ng/mL) in 56.4%. Higher cTnT(pre) was associated with increased risk of posttransplant death/cardiac events independent of cardiovascular risk factors. Elevated cTnT(pre) declined rapidly posttransplant and was normal in 75% of recipients at 3 weeks and 88.6% at 1 year. Elevated posttransplant cTnT was associated with reduced patient survival (cTnT(3wks) : HR = 5.575, CI 3.207-9.692, p < 0.0001; cTnT(1year) : 3.664, 2.129-6.305, p < 0.0001) independent of age, diabetes, pretransplant dialysis, heart disease and allograft function. Negative/positive predictive values for high cTnT(3wks) were 91.4%/50% respectively. Normalization of cTnT posttransplant was associated with reduced risk. Variables related to elevated cTnT posttransplant included pretransplant diabetes, older age, time on dialysis, high cTnT(pre) and lower graft function. Patients with delayed graft function and those with GFR < 30 mL/min at 3 weeks were more likely to have an elevated cTnT(3wks) and remained at high risk. When allografts restore sufficient kidney function cTnT normalizes and patient survival improves. Lack of normalization of cTnT posttransplant identifies a group of individuals with high risk of death/cardiac events.

Multicenter analytical evaluation of a high-sensitivity troponin T assay.

BACKGROUND: High-sensitivity cardiac troponin assays are being introduced clinically for earlier diagnosis of acute myocardial infarction (AMI). We evaluated the analytical performance of a high-sensitivity cardiac troponin T assay (hscTnT, Roche Diagnostics) in a multicenter, international trial. METHODS: Three US and 5 European sites evaluated hscTnT on the Modular® Analytics E170, cobas® 6000, Elecsys 2010, and cobas® e 411. Precision, accuracy, reportable range, an inter-laboratory comparison trial, and the 99th percentile of a reference population were assessed. RESULTS: Total imprecision (CVs) were 4.6-36.8% between 3.4 and 10.3 ng/L hscTnT. Assay linearity was up to 10,000 ng/L and the limit of blank and detection were 3 and 5 ng/L, respectively. The 99th percentile reference limit was 14.2 ng/L (n=533). No significant differences between specimen types, assay incubation time, or reagent lots existed. A substantial positive bias (76%) exists between the 4th generation and hscTnT assays at the low end of the measuring range (<50 ng/L). hscTnT serum pool concentrations were within 2SD limits of the mean of means in the comparison trial, indicating comparable results across multiple platforms and laboratories. CONCLUSION: The Roche hscTnT assay conforms to guideline precision requirements and will likely identify additional patients with myocardial injury suspicious for AMI.

Patient survival after kidney transplantation: relationship to pretransplant cardiac troponin T levels.

Assessing cardiovascular (CV) risk pretransplant is imprecise. We sought to determine whether cardiac troponin T (cTnT) relates to patient survival posttransplant. The study includes 603 adults, recipients of kidney transplants. In addition to cTnT dobutamine stress echography and coronary angiography were done in 45% and 19% of the candidates respectively. During 28.4 +/- 12.9 months 5.6% of patients died or had a major cardiac event. cTnT levels were elevated (>0.01 ng/ml) in 56.2% of patients. Elevated cTnT related to reduced event-free survival (hazard ratio (HR) = 1.81, CI 1.33-2.45, p < 0.0001) whether those events occurred during the first year or beyond. This relationship was statistically independent of all other variables tested, including older age, reduced left ventricular ejection fraction (EF) and delayed graft function. cTnT levels allowed better definition of risk in patients with other CV risk factors. Thus, event-free survival was excellent in older individuals, patients with diabetes, low EF and those with preexisting heart disease if their cTnT levels were normal. However, elevated cTnT together with another CV risk factor(s) identified patient with very poor survival posttransplant. Pretransplant cTnT levels are strong and independent predictors of posttransplant survival. These results suggest that cTnT is quite helpful in CV risk stratification of kidney transplant recipients.

Perioperative red blood cell transfusion and outcome in stable patients after elective major vascular surgery.

OBJECTIVES: Definitive evidence that red blood cell transfusion improves outcome after vascular surgery is lacking. The aims of the study were to determine, among stable consecutive patients who underwent elective major vascular surgery, (1) the association between postoperative transfusion and 30-day death, myocardial infarction, and both, and (2) and if this association differs according to the presence of postoperative anaemia (haemoglobin value less than 9.0 g/dL within 7 days after surgery). METHODS: A retrospective observational study was conducted on 359 patients prospectively screened according to the ACC/AHA guidelines for preoperative risk in non-cardiac surgery. Main outcome was 30-day death; secondary outcomes 30-day myocardial infarction, and composite of 30-day myocardial infarction or death. RESULTS: Of the patients included, 95 (26.5%) received at least one unit of red blood cells. Patients who received transfusion had a significantly increased hazard of 30-day death (hazard ratio [HR] 11.72, 95% confidence interval [CI] 3.92-35.10; p<0.0001), myocardial infarction (HR 3.3, 95% CI 1.7-6.1; p=0.0003), and both (HR 4.0 95% CI 2.2-7.3; p<0.0001). Such associations held even after adjusting for baseline characteristics, surgical risk, bleeding, and propensity to receive transfusion. There was a significant interaction between transfusion and postoperative anaemia (p=0.012). In patients without anaemia, transfusion was associated with higher risk of 30-day death (HR 19.20, 95% CI 3.99-92.45; p=0.007), myocardial infarction (HR 5.05, 95% CI 2.23-11.44; p=0.0001), and both. Conversely, in patients with anaemia this association was not significant. CONCLUSIONS: In patients who underwent elective major vascular surgery, perioperative transfusion was associated with a significantly increased risk of 30-day events which was more attributable to patients with lesser degree of anaemia. Our data caution against the use of liberal transfusion in stable vascular surgery patients.

Survival of patients on the kidney transplant wait list: relationship to cardiac troponin T.

Patients waiting for a kidney transplant have high mortality despite careful preselection. Herein, we assessed whether cardiac troponin T (cTnT) can help stratify risk in patients selected for kidney transplantation. cTnT levels were measured in all kidney transplant candidates but the results were not used for patient selection. Among 644 patients placed on the kidney waiting list from 9/2004 to 12/2006, 61% had elevated cTnT levels (>0.01 ng/mL). Higher levels related to diabetes, longer time on dialysis, history of cardiovascular disease and low serum albumin. High cTnT also related to cardiac anomalies, including left ventricular hypertrophy (LVH), wall motion abnormalities and stress-inducible ischemia by dobutamine echo (DSE). However, 54% of patients without these cardiac findings had elevated cTnT. Increasing cTnT levels were associated with reduced survival (HR = 1.729, CI (1.25-2.39), p = 0.01) independently of low serum albumin (0.449 (0.24-0.83), p = 0.011) and history of stroke (3.368 (1.47-7.73), p = 0.0004). The results of the DSE and/or coronary angiography did not relate significantly to survival. However, high cTnT identified patients with abnormal echo findings and poor survival. Wait listed patients with normal cTnT have excellent survival irrespective of other factors. In contrast, high cTnT levels are strongly predictive of poor survival in the kidney transplant waiting list.

A new simplified immediate prognostic risk score for patients with acute myocardial infarction.

BACKGROUND: Immediate risk stratification of patients with myocardial infarction in the emergency department (ED) at the time of initial presentation is important for their optimal emergency treatment. Current risk scores for predicting mortality following acute myocardial infarction (AMI) are potentially flawed, having been derived from clinical trials with highly selective patient enrollment and requiring data not readily available in the ED. These scores may not accurately represent the spectrum of patients in clinical practice and may lead to inappropriate decision making. METHODS: This study cohort included 1212 consecutive patients with AMI who were admitted to the Mayo Clinic coronary care unit between 1988 and 2000. A risk score model was developed for predicting 30 day mortality using parameters available at initial hospital presentation in the ED. The model was developed on patients from the first era (training set--before 1997) and validated on patients in the second era (validation set-during or after 1997). RESULTS: The risk score included age, sex, systolic blood pressure, admission serum creatinine, extent of ST segment depression, QRS duration, Killip class, and infarct location. The predictive ability of the model in the validation set was strong (c = 0.78). CONCLUSION: The Mayo risk score for 30 day mortality showed excellent predictive capacity in a population based cohort of patients with a wide range of risk profiles. The present results suggest that even amidst changing patient profiles, treatment, and disease definitions, the Mayo model is useful for 30 day risk assessment following AMI.

Increased cardiac troponin I on admission predicts in-hospital mortality in acute pulmonary embolism.

BACKGROUND: To investigate the frequency of cardiac troponin I (cTnI) increases in patients with pulmonary embolism (PE) and to assess the correlation between this finding, the clinical presentation, and outcomes. METHODS: Consecutive patients admitted to the coronary care unit with acute PE were prospectively enrolled between January 2000 and December 2001. cTnI was sequentially determined. Various cut off concentrations were analysed, but patients were categorised prospectively as having increased or no increased cTnI based on a cut off concentration of 0.6 ng/ml. The main outcome measure was in-hospital mortality. RESULTS: On admission, 14 of the 48 patients (29%) had cTnI concentrations greater than the receiver operating characteristic curve value used to diagnose acute myocardial infarction (> 0.6 ng/ml). Subsequently, six patients developed increases for an overall prevalence of 42% (20 of 42). The prevalence was higher when lower cut off concentrations were used: 73% (35 of 48) at the 99th centile and 60% (29 of 48) at the 10% coefficient of variability. Increased cTnI > 0.6 ng/ml was associated with a slower oxygen saturation (86 (7)% v 93 (4)%, p < 0.0001) and more frequent involvement of the main pulmonary arteries as assessed by spiral computed tomography (100% v 60%, p = 0.022). In-hospital mortality was 36% (5 of 14) of patients with increases > 0.6 ng/ml v 3% (1 of 42) of patients with lower concentrations (p = 0.008). Increased cTnI > 0.6 ng/ml on admission was the most powerful predictor of mortality (p = 0.046). CONCLUSIONS: In high risk patients with acute PE, cTnI was frequently detected on admission. It was the strongest independent predictor of mortality.

Cardiac troponin levels following monitored epileptic seizures.

Cardiac arrhythmia associated with myocardial injury is a proposed mechanism for sudden unexplained death in epilepsy. The authors measured serial cardiac troponin levels in 11 patients after monitored seizures. Using highly sensitive assays and criteria, no troponin elevations were seen, indicating that myocardial injury does not occur during uncomplicated seizures. An elevation in postictal troponin elevations should suggest the presence of cardiac injury secondary to neurocardiogenic mechanisms or primary cardiac factors, prompting further evaluation.

Evidence of cardiac ischemia during seizures in drug refractory epilepsy patients.

The authors investigated whether patients with drug refractory epilepsy have cardiovascular abnormalities that might be related to a high frequency of sudden death. Twenty-three subjects underwent comprehensive cardiovascular evaluations before and during video-EEG monitoring. ST-segment depression occurred in 40% and was associated with a higher maximum heart rate during seizures. These data suggest that cardiac ischemia may occur in these patients.

New standard for the diagnosis of acute myocardial infarction.

Recently, the European Society of Cardiology and the American College of Cardiology met to discuss the diagnosis of acute myocardial infarction (AMI). The consensus document published advocated several changes. First, it was suggested that the preferred marker for the diagnosis of cardiac injury was troponin. It also emphasized that elevations of this sensitive marker did not define the mechanism of cardiac injury. Thus, a clinical determination that the mechanism for the troponin elevation is ischemic is essential for the diagnosis of AMI. This change will require clinicians to reorient their thinking about the use of cardiac markers. They will need to be cognizant of the analytic difficulties that many of the assays manifest and the large number of elevations that can occur because of other forms of cardiac injury, which can now be detected by this new more sensitive strategy. The current article will review the thinking that underpins the recommendations of the European Society of Cardiology/American College of Cardiology Task Force in the hope that it will improve clinicians' ability to implement this new strategy in a more facile manner.