Value of a single troponin T at the time of presentation as compared to serial CK-MB determinations in patients with suspected myocardial ischemia

Cardiac troponin-T and CK-MB (mass) levels in cardiac and non cardiac disease

Serum cardiac troponin T (cTnT) and CKMB (mass) were analysed in three groups of patients. The first group (n=32) were patients with acute coronary syndromes including myocardial infarction. The second group (n=35)were patients with hypertension. The third group (n=24) were patients who had succumbed to non cardiac diseases. In all 3 groups, cardiac troponin T was elevated when compared with controls (p<0.001). However, CKMB elevation was not significant in all groups. CKMB levels correlated well with troponin T levels only when CKMB was greater than 50 ng/ml (r=1.00). Small elevations of troponin T identifies minimal cardiac necrosis and patients can benefit from early invasive therapy.

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.

Can We Exclude the Diagnosis of Non-ST Segment Myocardial Infarction on the Basis of a Single Troponin I and a Symptom Duration ≥8 Hours?

Background. The use of a single troponin measurement to exclude the diagnosis of non-ST segment myocardial infarction (NSTEMI) in patients that present with ischemic symptom duration ≥8 hours is sometimes used in the Emergency Department. Study Objective. To describe the characteristics of patients with initial nondiagnostic troponin values who develop a positive troponin while in the Emergency Department and to evaluate whether NSTEMI can be excluded using symptom duration ≥8 hours and initial troponin I. Methods. Retrospective chart review of patients evaluated for NSTEMI in the Emergency Department. Results. 4,510 patients had at least two troponin I values obtained during the two-year study period. 115 (2.5%) of these patients had an initially nondiagnostic (<0.6 ng/mL) and subsequent positive (≥0.6 ng/mL) troponin I result. Twenty-five (22%) of the 115 had duration of symptoms ≥8 hours. Of these 25 patients, 18 had an intermediate first troponin value (i.e., >0.06 ng/mL, but <0.6 ng/mL). Only two of the remaining seven patients had a final primary diagnosis of NSTEMI. Conclusion. The use of a negative initial troponin I together with a symptom onset of ≥8 hours defines a population with a very low incidence of a hospital diagnosis of NSTEMI.

Automated heart-type fatty acid-binding protein assay for the early diagnosis of acute myocardial infarction

We compared an automated quantitative heart-type fatty acid-binding protein (H-FABP) assay with other cardiac-marker assays to examine its usefulness as an early diagnostic marker of acute myocardial infarction (AMI). Serum samples for cardiac troponin T (cTnT), creatine kinase-MB isozyme (CK-MB), myoglobin, and H-FABP were obtained from 64 patients with AMI and 53 patients with other conditions (control group). H-FABP was measured by using 2 immunoassays, the H-FABP enzyme-linked immunosorbent assay (ELISA; Biocheck, Foster City, CA) and the H-FABP latex turbidimetric immunoassay (LTIA; HBI, Anyang, Korea). Sensitivities of assays for cTnT, CK-MB, myoglobin, H-FABP (by ELISA), H-FABP (by LTIA), and electrocardiogram (ECG) for the diagnosis of AMI at hospital admission were 39.1%, 59.4%, 64.1%, 68.7%, 70.3%, and 54.7%, respectively. Specificities of cTnT, CK-MB, myoglobin, H-FABP (by ELISA), H-FABP (by LTIA), and ECG were 98.1%, 71.7%, 81.1%, 77.4%, 90.6%, and 92.5%, respectively. The automated H-FABP (by LTIA) is superior to cTnT, CK-MB, myoglobin, and H-FABP (by ELISA) tests for the diagnosis of AMI in patients admitted within 4 hours from the onset of chest pain.

Diagnosis of acute myocardial infarction: CK-MB versus cTn-T in Indian patients

The comparative diagnostic efficacy of two cardiac markers: CK-MB and cTn-T, has scarcely been investigated in Indian patients of acute myocardial infarction. The present study was conducted for the same objective. The present study comprised of 59 patients. Males were 44 (75%) and females were 15 (25 %). The age of patients ranged from 32-84 years with mean age of 62.8 yrs. The mean age of males and females were 60 and 63 yrs respectively. All patients presented with history of chest pain with a 12 leads ECG proven MI (ST Elevation, discordant T-waves). CK-MB was estimated in peripheral blood samples at 0,24,48 and 72 hours by an autoanalyzer. Following 12 hours of admission bed side Troponin-T test was done employing cTn-T marker kit. Initially (0 hr), in 50% patients CK-MB was elevated. By end of 24 hours all the patients were CKMB positive and peak level was attained at 24 hrs. Then it tended to decline over next 48 hrs. There were no false positive or negative results. The cTn-T test was positive only in 22 % of ECG positive infarctions. However, the cTn-T positive cases were always accompanied by a higher CK-MB levels. A significantly lower cTn-T positive cases in Indian patients can only be attributed to some difference in amino acid sequence of Indian cTn-T and occidental cTn-T. A larger study from other Indian cardiac centers can either substantiate or contradict our results.

Modified Thrombolysis in Myocardial Infarction (TIMI) risk score to risk stratify patients in the emergency department with possible acute coronary syndrome

OBJECTIVE

To assess the prognostic utility of the Thrombolysis in Myocardial Infarction (TIMI) risk score in patients in the emergency department (ED) evaluated for possible acute coronary syndrome (ACS).

BACKGROUND

The ability of the TIMI risk score to risk stratify patients at initial presentation in the ED with chest pain of unclear etiology is uncertain.

METHODS

We investigated the prognostic utility of the TIMI risk score in 947 consecutive patients evaluated in the ED for possible ACS. A multivariate analysis was done to evaluate the independent predictive power of the individual components of the TIMI risk score to predict an adverse event at 30 days (all-cause death, myocardial infarction, and coronary revascularization).

RESULTS

There were 151 (16%) patients diagnosed with ACS. At 30 days there were 48 (5%) deaths, 84 (9%) myocardial infarctions, and 49 (5%) coronary revascularization procedures. The mean TIMI risk score was significantly higher in patients with an adverse event compared with those without (2.6 +/- 1.3 vs. 1.7 +/- 1.2, P < 0.0001). Four of the 7 TIMI risk factors (age > or = 65 years, ST segment deviation > or = 0.5 mm elevated troponin I, and coronary stenosis > or = 50%) were independently associated with adverse events. A simplified TIMI risk score was computed and was found to have similar prognostic ability as the 7 variable TIMI risk score.

CONCLUSION

A modified TIMI risk score may simplify risk stratification of ED patients with undifferentiated chest pain.

The diagnostic value of troponin T testing in the community setting

BACKGROUND

Many patients presenting with chest pain to their family physician are referred to the emergency room, in part, due to lack of accurate objective diagnostic tools. This study aimed to assess the diagnostic value of bedside troponin T kit testing in patients presenting with chest pain to their family physician.

DESIGN

Prospective, multi-center study.

METHODS

Consecutive subjects with chest pain were recruited from 44 community clinics in Jerusalem. Following clinical assessment by the family physician, qualitative troponin kit testing was performed. Patients with a negative clinical assessment and negative troponin kit were sent home and all others were referred to the emergency room. The final diagnosis at the time of hospital discharge was recorded and telephone follow up was performed after 60 days. Positive predictive value, negative predictive value, sensitivity and specificity of troponin kit for myocardial infarction diagnosis and of family physician for hospitalization, were assessed.

RESULTS

Of 392 patients enrolled, 349 (89%) were included in the final analysis. The prevalence of myocardial infarction was 1.7%. The positive and negative predictive values of the troponin kit for myocardial infarction diagnosis were 100% and 99.7%, respectively. The positive and negative predictive values of the family physician's assessment to predict hospitalization were 41.4% and 94.1%, respectively.

CONCLUSIONS

Troponin kit testing is an important tool to assist the family physician in the assessment of patients with chest pain in the community setting. Troponin kit testing may identify otherwise undiagnosed cases of myocardial infarctions, and reduce unnecessary referrals to the emergency room.

An Echocardiographic Left Ventricular Wall Area Index for Functional Detection of Myocardial Injury in Hemodynamically Unloaded Hearts

Functional assessment of the left ventricle is affected by loading conditions. Detection of rejection-mediated myocardial injury in a heterotopic heart transplant model is a challenge for the echocardiographer because the heart is in an unloaded state. We examined the relationship of a novel left ventricular (LV) wall area index (LVWAI) and serum cardiac troponin T (cTnT) levels. The LVWAI, based on prior methods of determining LV mass, was defined as the difference between epicardial and endocardial areas divided by the epicardial area. The biphasic morphometric response of LVWAI reflected changes in the cTnT levels and allowed echocardiographic detection of myocardial injury in hemodynamically unloaded hearts.