Release of cardiac troponin I after temporally graded acute coronary ischaemia with electrocardiographic ST depression

Early kinetics of cardiac troponin in suspected acute myocardial infarction

INTRODUCTION AND OBJECTIVES

Release kinetics of high-sensitivity cardiac troponin (hs-cTn) T and I in patients with acute myocardial infarction (AMI) are incompletely understood. We aimed to assess whether hs-cTnT/I release in early AMI is near linear.

METHODS

In a prospective diagnostic multicenter study the acute release of hs-cTnT and hs-cTnI within 1 and 2hours from presentation to the emergency department was quantified using 3 hs-cTnT/I assays in patients with suspected AMI. The primary endpoint was correlation between hs-cTn changes from presentation to 1 hour vs changes from presentation to 2hours, among all AMI patients and different prespecified subgroups. The final diagnosis was adjudicated by 2 independent cardiologists, based on serial hs-cTnT from the serial study blood samples and additional locally measured hs-cTn values.

RESULTS

Among 2437 patients with complete hs-cTnT data, AMI was the adjudicated diagnosis in 376 patients (15%). For hs-cTnT, the correlation coefficient between 0- to 1-hour change and 0- to 2 hour change was 0.931 (95%CI, 0.916-0.944), P <.001. Similar findings were obtained with hs-cTnI (Architect) with correlation coefficients between 0- to 1-hour change and 0- to 2 hour change of 0.969 and hs-cTnI (Centaur) of 0.934 (P <.001 for both). Findings were consistent among type 1 and type 2 AMI and in the subgroup of patients presenting very early after chest pain onset.

CONCLUSIONS

Patients presenting with early AMI showed a near linear release of hs-cTnT and hs-cTnI. This near linearity provides the pathophysiological basis for rapid diagnostic algorithms using 0- to 1-hour changes as surrogates for 0- to 2 hour or 0- to 3 hour changes. Registered at ClinicalTrials.gov (Identifier: NCT00470587).

Detecting Acute Myocardial Infarction by Diffusion-Weighted versus T2-Weighted Imaging and Myocardial Necrosis Markers

We used a porcine model of acute myocardial infarction to study the signal evolution of ischemic myocardium on diffusion-weighted magnetic resonance images (DWI). Eight Chinese miniature pigs underwent percutaneous left anterior descending or left circumflex coronary artery occlusion for 90 minutes followed by reperfusion, which induced acute myocardial infarction. We used DWI preprocedurally and hourly for 4 hours postprocedurally. We acquired turbo inversion recovery magnitude T2-weighted images (TIRM T2WI) and late gadolinium enhancement images from the DWI slices. We measured the serum myocardial necrosis markers myoglobin, creatine kinase-MB isoenzyme, and cardiac troponin I at the same time points as the magnetic resonance scanning. We used histochemical staining to confirm injury. All images were analyzed qualitatively. Contrast-to-noise ratio (the contrast between infarcted and healthy myocardium) and relative signal index were used in quantitative image analysis. We found that DWI identified myocardial signal abnormity early (<4 hr) after acute myocardial infarction and identified the infarct-related high signal more often than did TIRM T2WI: 7 of 8 pigs (87.5%) versus 3 of 8 (37.5%) (P=0.046). Quantitative image analysis yielded a significant difference in contrast-to-noise ratio and relative signal index between infarcted and normal myocardium on DWI. However, within 4 hours after infarction, the serologic myocardial injury markers were not significantly positive. We conclude that DWI can be used to detect myocardial signal abnormalities early after acute myocardial infarction-identifying the infarction earlier than TIRM T2WI and widely used clinical serologic biomarkers.

Release kinetics of early ischaemic biomarkers in a clinical model of acute myocardial infarction

Objective

To determine the release kinetics of different biomarkers with potential as novel early ischaemic biomarkers in patients with acute coronary syndrome (ACS); it is difficult to establish the detailed release kinetics in patients with acute myocardial infarction (AMI).

Methods

We analysed the release kinetics of soluble fms-like tyrosine kinase (sFlt-1), ischaemia modified albumin (IMA), and heart-type fatty acid binding protein (hFABP) in patients with hypertrophic obstructive cardiomyopathy who were undergoing transcoronary ablation of septal hypertrophy (TASH), a procedure mimicking AMI. Consecutive patients (n=21) undergoing TASH were included. Blood samples were collected before TASH and 15, 30, 45, 60, 75, 90, and 105 min and 2, 4, 8, and 24 h after TASH. sFlt-1 and hFABP were quantified in serum, and IMA was quantified in plasma using immunoassays.

Results

sFLT-1 and hFABP increased significantly 15 min after induction of AMI vs baseline as follows: sFlt-1, 3657.5 ng/L (IQR 2302.3–4475.0) vs 76.0 ng/L (IQR 71.2–88.8) (p<0.001); hFABP, 9.0 ng/mL (IQR 7.0–15.4) vs 4.6 ng/mL (IQR 3.4–7.1) (p<0.001). sFlt-1 demonstrated a continuous decrease after the 15th min. hFABP showed a continuous increase until the 8th hour with a decline afterwards. The IMA concentrations increased significantly 30 min after induction of AMI vs baseline, with values of 26.0 U/mL (IQR 21.8–38.6) vs 15.6 U/mL (IQR 10.1–24.7) (p=0.02), and then decreased after 75 min.

Conclusions

sFlt-1 and hFABP increased very early after induction of myocardial ischaemia, showing different release kinetics. The additional information provided by these findings is helpful for developing their potential combined use with cardiac troponins in patients with suspected AMI.

Procedural safety and predictors of acute outcome of intracoronary administration of progenitor cells in 775 consecutive procedures performed for acute myocardial infarction or chronic heart failure

BACKGROUND

Cell-based therapies are a promising option in patients with acute myocardial infarction or chronic heart failure (CHF). However, administration of cells requires intracoronary or intracardiac instrumentation, which is potentially associated with periprocedural risks. Therefore, we analyzed periprocedural complications and 30-day outcome in 775 consecutive procedures of intracoronary administration of progenitor cells using the stop-flow technique.

METHODS AND RESULTS

Indications for cell administration were acute myocardial infarction (n=126) and CHF of ischemic (n=562) or nonischemic (n=87) etiology. Vessel injury was observed in a total of 9 procedures (1.2%) and could be promptly managed by additional progenitor cell injection (PCI) in all but 1 case. No procedural deaths were observed. A periprocedural increase in troponin T was observed in 3.2% of the CHF procedures, in which no concomitant PCI was performed and troponin levels were not elevated before the procedure. Independent significant predictors of troponin T increase were higher New York Heart Association (NYHA) class (NYHA I versus NYHA IV; P=0.01; NYHA I versus III; P=0.19; NYHA I versus II; P=0.55), concomitant revascularization (P<0.01), presence of elevated troponin T before the procedure (P<0.01), and peripheral occlusive disease (P=0.04). At 30 days, there were 4 deaths (0.5%), 1 stroke (0.13%), 8 acute myocardial infarctions (1%), and 5 hospitalizations for exacerbation of heart failure (0.64%).

CONCLUSIONS

Intracoronary infusion of progenitor cells can be performed with adequate safety in patients with acute myocardial infarction or CHF, because the safety profile was similar to what is usually expected from a coronary angiogram in the present cohort.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00962364, NCT00284713, and NCT00289822.

Release Kinetics of Cardiac Biomarkers in Patients Undergoing Transcoronary Ablation of Septal Hypertrophy

BACKGROUND

The release kinetics of cardiac troponin T measured with conventional vs high-sensitivity cardiac troponin T (hs-cTnT) assays in patients with acute myocardial infarction (AMI) is difficult to establish.

METHODS

We analyzed the release kinetics of cTnT measured by fourth generation and high-sensitivity assays, creatine kinase-MB (CK-MB), and myoglobin in patients with hypertrophic obstructive cardiomyopathy undergoing transcoronary ablation of septal hypertrophy (TASH), a model of AMI. Consecutive patients (n = 21) undergoing TASH were included. Serum and EDTA-plasma samples were collected before and at 15, 30, 45, 60, 75, 90, and 105 min, and 2, 4, 8, and 24 h after TASH.

RESULTS

cTnT concentrations measured by the hs assay were significantly increased at 15 min [21.4 ng/L, interquartile range (IQR) 13.3–39.7 ng/L vs 11.3 ng/L, IQR 6.0–18.8 ng/L at baseline; P = 0.031]. In comparison, cTnT concentrations measured by the conventional fourth generation assay increased significantly at 60 min (30.0 ng/L, IQR 20.0–30.0 ng/L vs &lt;10.0 ng/L, IQR &lt;10.0–10.0 ng/L; P &lt; 0.01), CK-MB at 90 min (8.4 μg/L, IQR 6.9–14.4 μg/L vs 0.9 μg/L, IQR 0.4–1.1 μg/L; P &lt; 0.01), and myoglobin at 30 min (188.0 μg/L, IQR 154.0–233.0 μg/L vs 38.0 μg/L, IQR 28.0–56.0; P &lt; 0.01).

CONCLUSIONS

cTnT concentrations measured by the hs assay were significantly increased after TASH at all of the time points, with a doubling at 15 min after induction of AMI, confirming earlier evidence of myocardial injury compared to the fourth generation cTnT assay and CK-MB and myoglobin.

Elevated baseline hs-cTnT levels predict exercise-induced myocardial ischemia in patients with peripheral arterial disease

INTRODUCTION

Due to the systemic nature of atherosclerosis, the prevalence of coronary artery disease (CAD) is high in patients with peripheral arterial disease (PAD). A biochemical assay for assessing cardiac risk might improve clinical evaluation of PAD patients. The aim of this study was to investigate whether a new high-sensitivity cardiac Troponin T (hs-cTnT) assay can predict exercise-induced myocardial ischemia in PAD patients without clinical signs of CAD.

METHODS

Sixty-eight ambulatory patients with Fontaine stage II PAD underwent treadmill stress testing to maximum walking distance. Myocardial ischemia was assessed using a 2-lead Holter ECG and ST-segment depression of ≥ 0.2 mV was considered significant. Hs-cTnT was measured from serum samples taken at baseline as well as 5, 10 and 30 min after exercise.

RESULTS

Hs-cTnT baseline levels were significantly higher (19.3 ng/L (5.0; 20.2 ng/L) vs. 6.6 ng/L (4.4; 9.4 ng/L); p=0.037) and increase of serum levels 5 min after cessation of exercise was more pronounced (1.09 ng/L (0.23; 1.80 ng/L) vs. 0.22 ng/L (-0.1; 0.65 ng/L), p=0.032) in ECG positive patients compared to individuals with normal ECG. Logistic regression analysis identified the baseline hs-cTnT serum level as an independent risk factor for developing significant exercise-induced ST-segment depression (odds ratio 1.2 per 1-unit increase, p=0.015).

CONCLUSIONS

In patients with PAD, exercise-induced myocardial ischemia is associated with elevated baseline levels and a significant early increase of hs-cTnT serum levels.

Cardiac troponin I release after transcatheter atrial septal defect closure correlated with the ratio of the occluder size to body surface area

BACKGROUND

Cardiac troponin I (cTnI) is a very specific and sensitive marker of myocardial injury. The degree of myocardial injury associated with transcatheter atrial septal defect (ASD) closure in children is unknown.

METHODS

In a longitudinal study on children with ASD, cTnI serum concentrations were measured after transcatheter ASD closure. Implantation success, complications, and latest patient follow-up were described.

RESULTS

We inserted 73 Amplatzer septal occluders in 73 patients. Of these, we excluded two patients in whom the device embolized to the right ventricle the day after deployment. The median age was 4.5 years (range, 1.1-18.0) with 20 boys and 51 girls (male:female ratio, 1:2.6). The mean ASD size was 17 ± 7 mm, and device size ranged from 7 mm to 38 mm. The Amplatzer size/body surface area ratio was validated by demonstrating positive correlation with cTnI elevation. In children who had a successful attempt, 30 samples had a cTnI value higher than 1.0 μg/L l at 6 hours after procedure. Six patients had a significant release of cTnI greater than normal limits (mean level of 1.51 ± 0.26 μg/L).

CONCLUSION

In our study, transcatheter ASD closure induced minor myocardial lesion, the extent of which depended on the ratio of the occluder size to body surface area (p<0.05) but not on the patient's weight or preprocedural left ventricular ejection fraction.

Detection of acute changes in circulating troponin in the setting of transient stress test-induced myocardial ischaemia using an ultrasensitive assay: results from TIMI 35

AIMS

To determine whether an ultrasensitive assay can permit quantification of changes in circulating cardiac troponin (Tn) in the setting of stress test-induced myocardial ischaemia.

METHODS AND RESULTS

Blood samples were obtained before, immediately after, and 2 and 4 h after stress testing with nuclear perfusion imaging in 120 patients. Troponin was measured using commercial assays as well as with a novel, ultrasensitive cardiac TnI assay with a limit of detection of 0.2 pg/mL. Using the ultrasensitive assay, TnI was detectable in all patients before stress testing (median 4.4 pg/mL, interquartile range 3.1-8.6 pg/mL). By 4 h, troponin levels were unchanged in patients without ischaemia, whereas circulating levels had increased by a median of 1.4 pg/mL (24% increase) in patients with mild ischaemia (P = 0.002) and by 2.1 pg/mL (40% increase) in patients with moderate-to-severe ischaemia (P = 0.0006). In contrast, changes in troponin levels across patients in different ischaemic categories were indistinguishable using commercial troponin assays. When added to clinical factors, a >1.3 pg/mL increase in TnI using the ultrasensitive assay was an independent predictor of ischaemia (odds ratio 3.54, P = 0.007).

CONCLUSION

Transient stress test-induced myocardial ischaemia is associated with a quantifiable increase in circulating troponin that is detectable with a novel, ultrasensitive TnI assay.

Safety and efficacy of consecutive cycles of granulocyte-colony stimulating factor, and an intracoronary CD133+ cell infusion in patients with chronic refractory ischemic heart disease: the G-CSF in angina patients with IHD to stimulate neovascularization (GAIN I) trial

BACKGROUND

Preclinical studies suggest granulocyte-colony stimulating factor (G-CSF) holds promise for treating ischemic heart disease; however; its clinical safety and efficacy in this setting remain unclear. We elected to evaluate the safety and efficacy of G-CSF administration in patients with refractory "no-option" ischemic heart disease.

METHODS

Twenty patients (18 males, 2 females, mean age 62.4 years) were enrolled and underwent baseline cardiac ischemia assessment (CA) (angina questionnaire, exercise stress test [EST], technetium Tc 99m sestamibi and dobutamine-stress echocardiographic imaging). Patients then received open-label G-CSF commencing at 10 microg/kg SC for 5 days, with an EST on days 4 and 6 (to facilitate myocardial cytokine generation and stem cell trafficking). After 3 months, CA and the same regimen of G-CSF+ESTs were repeated but, in addition, leukapheresis and a randomized double-blinded intracoronary infusion of CD133+ or unselected cells were performed. Final CA occurred 3 months thereafter.

RESULTS

There were no deaths, but only 16 patients were permitted to complete the study. Eight events fulfilled prespecified "adverse event" criteria, including 4 troponin I-positive events and 2 episodes of thrombocytopenia. Also, frequent minor troponin I-positive events (troponin I<0.9 microg/L) were observed, which did not meet adverse event criteria. The administration of consecutive cycles of G-CSF resulted in stepwise improvements in anginal frequency, EST performance, and Duke treadmill scores (all P<.005). However, from baseline to final follow-up, technetium Tc 99m sestamibi and dobutamine-stress echocardiographic results were unchanged.

CONCLUSIONS

Granulocyte-colony stimulating factor administration was associated with improvement in a range of subjective outcomes. However, adverse events were common, and objective measures of cardiac perfusion/ischemia were unchanged.

Attenuating the defibrillation dosage decreases postresuscitation myocardial dysfunction in a swine model of pediatric ventricular fibrillation

OBJECTIVE

The optimal biphasic defibrillation dose for children is unknown. Postresuscitation myocardial dysfunction is common and may be worsened by higher defibrillation doses. Adult-dose automated external defibrillators are commonly available; pediatric doses can be delivered by attenuating the adult defibrillation dose through a pediatric pads/cable system. The objective was to investigate whether unattenuated (adult) dose biphasic defibrillation results in greater postresuscitation myocardial dysfunction and damage than attenuated (pediatric) defibrillation.

DESIGN

Laboratory animal experiment.

SETTING

University animal laboratory.

SUBJECTS

Domestic swine weighing 19 +/- 3.6 kg.

INTERVENTIONS

Fifty-two piglets were randomized to receive biphasic defibrillation using either adult-dose shocks of 200, 300, and 360 J or pediatric-dose shocks of approximately 50, 75, and 85 J after 7 mins of untreated ventricular fibrillation. Contrast left ventriculograms were obtained at baseline and then at 1, 2, 3, and 4 hrs postresuscitation. Postresuscitation left ventricular ejection fraction and cardiac troponins were evaluated.

MEASUREMENTS AND MAIN RESULTS

By design, piglets in the adult-dose group received shocks with more energy (261 +/- 65 J vs. 72 +/- 12 J, p < .001) and higher peak current (37 +/- 8 A vs. 13 +/- 2 A, p < .001) at the largest defibrillation dose needed. In both groups, left ventricular ejection fraction was reduced significantly at 1, 2, and 4 hrs from baseline and improved during the 4 hrs postresuscitation. The decrease in left ventricular ejection fraction from baseline was greater after adult-dose defibrillation. Plasma cardiac troponin levels were elevated 4 hrs postresuscitation in 11 of 19 adult-dose piglets vs. four of 20 pediatric-dose piglets (p = .02).

CONCLUSIONS

Unattenuated adult-dose defibrillation results in a greater frequency of myocardial damage and worse postresuscitation myocardial function than pediatric doses in a swine model of prolonged out-of-hospital pediatric ventricular fibrillation cardiac arrest. These data support the use of pediatric attenuating electrodes with adult biphasic automated external defibrillators to defibrillate children.

Cardiopulmonary complications of ERCP in older patients

BACKGROUND

Biochemical markers of ERCP-related myocardial injury have not previously been investigated.

OBJECTIVE

To evaluate ERCP-related cardiac troponin I (cTnI) release, myocardial ischemia, hemodynamic changes, and arterial hypoxemia in a series of consecutive patients according to age and to determine their relationship to preexisting cardiovascular risk factors (RF) and the development of post-ERCP pancreatitis.

DESIGN

Prospective cohort study.

SETTING

Tertiary teaching hospital, Canberra, Australia.

PATIENTS

Data were collected on 130 consecutive ERCPs performed on 100 unselected patients (aged 18-93 years) by one endoscopist. Patients were divided into two groups: 65 years of age and older (group 1, n = 53; 27 women) and less than 65 years of age (group 2, n = 47; 33 women).

INTERVENTIONS

ERCP.

MAIN OUTCOME MEASUREMENTS

Cardiovascular RFs were identified, and electrocardiogram (ECG), cTnI, creatine kinase (CK), amylase, and lipase were measured before and 24 hours after ERCP. Oxygen saturation (SpO(2)), heart rate (HR), blood pressure (BP), and ECG were monitored continuously during each procedure.

RESULTS

New ECG changes (ischemia, arrhythmias) occurred in 24% of procedures in group 1 and in 9.3% in group 2 (p = 0.168), and episodic arterial hypoxemia (SpO(2) < 90%) in 16.2% (group 1) and 21.4% (group 2) (p = 0.596). A post-ERCP rise in cTnI levels was documented in 6 patients in the older group. Two of these patients died: one from acute myocardial infarction and one from undiagnosed ascending aortic aneurysm. A cTnI rise was not related to any comorbid conditions, total number of RFs, hemodynamic or ECG changes, or arterial desaturation. In patients with a new cTnI rise, the duration of ERCP was significantly longer (59.5 vs. 26.4 minutes, p = 0.026), being 30 minutes or longer in 5 of 6 patients. Post-ERCP pancreatitis was associated with desaturation (relative risk [RR] = 5.9; 95% confidence interval [CI] [1.2, 32.0], p = 0.027) and myocardial ischemia/injury (RR = 4.4; 95% CI [1.4, 7.8]; p = 0.009).

CONCLUSIONS

Although the majority of older patients tolerated ERCP well, in 8% of procedures, most of which were prolonged (>30 minutes), myocardial injury, as defined by the release of cTnI, occurred. Desaturation and myocardial ischemia/injury were associated with post-ERCP pancreatitis.

Release of cardiac biochemical markers after percutaneous myocardial laser or sham procedures

BACKGROUND

Percutaneous myocardial laser (PML) reduces symptoms in patients with intractable angina. PML leads to a certain loss of viable myocardium, we therefore assessed if troponin or cardiac markers release may explain the clinical effect, and furthermore assessed the markers release during percutaneous sham procedures.

METHODS

Eighty-two patients with chronic refractory angina were randomized to either percutaneous myocardial laser or a true sham procedure. Cardiac markers were assessed before the procedure, and (1/2), 2, 4, 6, and 10-12 h postprocedure.

RESULTS

Troponin I increased to median peak levels (range) of 4 (0.6-43) microg/L in the laser group vs. 1.5 (0.1-5.9) microg/L, p=0.001, and creatine kinase MB to 14 (6-357) microg/L vs. 11 (3-40) microg/L, p<0.05, within and between-group comparison, the rise of CK-MB occurred significantly earlier in the sham group, 3.8 vs. 2.5 h. A time-dependent between-group difference was only detected for troponin. 88% of sham and 100% of laser patients had marker levels above reference limits. There was no correlation between the number of laser/sham created channels, biomarker levels postprocedure, and changes in left ventricular ejection fraction or angina improvement during 12 months of follow-up.

CONCLUSIONS

The release of cardiac markers is not related to relief of angina after myocardial laser. The use of intracardiac catheters induces a considerable marker release, which is not caused by acute ischemia.

Acidosis, lactate, electrolytes, muscle enzymes, and other factors in the blood of Sus scrofa following repeated TASER exposures

Repeated exposure to electro-muscular incapacitating devices could result in repetitive, sustained muscle contraction, with little or no muscle recovery period. Therefore, rhabdomyolysis and other physiological responses, including acidosis, hyperkalaemia, and altered levels of muscle enzymes in the blood, would be likely to occur. Experiments were performed to investigate effects of repeated exposures of TASER International's Advanced TASER X26 on muscle contraction and resultant changes in blood factors in an anaesthetized swine model. A total of 10 animals were used. Six swine were exposed for 5 s, followed by a 5-s period of no exposure, repeatedly for 3 min. (In five of the animals, after a 1-h delay, a second 3-min exposure period was added.) The remaining four animals were used for an additional pilot study. All four limbs of each animal exhibited contraction even though the electrodes were positioned in areas at some distances from the limbs. The degree of muscle contraction generated during the second exposure period was significantly lower than that in the first exposure series. This finding was consistent with previous studies showing that prolonged activity in skeletal muscle will eventually result in a decline of force production. There were some similarities in blood sample changes in the current experiments with previous studies of muscular exercise. Thus problems concerning biological effects of repeated TASER exposures may be related, not directly to the "electric output" per se, but rather to the resulting contraction of muscles (and related interruption of respiration) and subsequent sequelae. Transient increases in hematocrit, potassium, and sodium were consistent with previous reports in the literature dealing with studies of muscle stimulation or exercise. It is doubtful that these short-term elevations would have any serious health consequences in a healthy individual. Blood pH was significantly decreased for 1h following exposure, but subsequently returned toward a normal level. Leg muscle contractions and decreases in respiration each appeared to contribute to the acidosis. Lactate was highly elevated, with a slow return (time course greater than 1 h) to baseline. Other investigators have reported profound metabolic acidosis during restraint-associated cardiac arrest. Since restraint often occurs immediately after TASER exposure, this issue should be considered in further development of deployment concepts. On the basis of the results of the current studies, the repeated use of electro-muscular incapacitating devices in a short period of time is, at least, feasible, with the caveat that some medical monitoring of subjects may be required (to observe factors such as lactate and acidosis).

Diagnostic value of serial measurement of cardiac markers in patients with chest pain: limited value of adding myoglobin to troponin I for exclusion of myocardial infarction

BACKGROUND

Despite improved laboratory assays for cardiac markers and a revised standard for definition of myocardial infarction (AMI), early detection of coronary ischemia in unselected patients with chest pain remains a difficult challenge.

METHODS

Rapid measurements of troponin I (TnI), creatine kinase MB (CK-MB), and myoglobin were performed in 197 consecutive patients with chest pain and a nondiagnostic electrocardiogram for AMI. The early diagnostic performances of these markers and different multimarker strategies were evaluated and compared. Diagnosis of AMI was based on European Society of Cardiology/American College of Cardiology criteria.

RESULTS

At a given specificity of 95%, TnI yielded the highest sensitivity of all markers at all time points. A TnI cutoff corresponding to the 10% coefficient of variation (0.1 microg/L) demonstrated a cumulative sensitivity of 93% with a corresponding specificity of 81% at 2 hours. The sensitivity was considerably higher compared to CK-MB and myoglobin, even considering patients with a short delay until admission. Using the 99th percentile of TnI results as a cutoff (0.07 microg/L) produced a cumulative sensitivity of 98% at 2 hours, but its usefulness was limited due to low specificities. Multimarker strategies including TnI and/or myoglobin did not provide a superior overall diagnostic performance compared to TnI using the 0.1 microg/L cutoff.

CONCLUSION

A TnI cutoff corresponding to the 10% coefficient of variation was most appropriate for early diagnosis of AMI. A lower TnI cutoff may be useful for very early exclusion of AMI. CK-MB and in particular myoglobin did not offer additional diagnostic value.

Temporal pattern of cardiac troponin I after thoracotomy and lung surgery

BACKGROUND

Several studies have shown that patients with perioperative myocardial infarction (MI) are at higher risk for subsequent cardiac events and the identification of these patients is important. However, the diagnosis of perioperative MI can be difficult in many cases. The cardiac troponins are biomarkers with high cardiospecificity, and the aim of this study was to assess cTnI and cTnT among other cardiac biomarkers after thoracotomy and lung surgery.

METHODS

24 consecutive patients were included in the final analysis. Venous blood samples were drawn prior to the procedure, 1-3, 4-6, 16-18 and 30-32 h after surgery. Thoracotomy was performed as a standard posterolateral incision on the left or right side under general anesthesia.

RESULTS

Both cTnI and cTnT were completely unaffected by the thoracotomy and the lung surgery. Furthermore, no single value of the troponins was above the 99th percentile at any time. In contrast, CK-MB was elevated in nearly half the patients, although the mean values complied well with the reference limit. CK and myoglobin were both considerably elevated and did not discriminate between acute myocardial infarction and release of the markers due to extracardiac injury.

CONCLUSIONS

Only the troponins were unaffected by extracardiac surgery and were, thus, reliable markers of myocardial injury in patients who underwent thoracotomy and lung surgery. If the troponins are unavailable, CK-MB mass combined with the CK-MB/CK percentage should be preferred.