Assessment of the multiple-biomarker approach for diagnosis of myocardial infarction in patients presenting with symptoms suggestive of acute coronary syndrome.

BACKGROUND: Cardiac troponin is the preferred biomarker for detecting acute myocardial injury and infarction (MI). We studied whether multiple biomarkers of numerous pathophysiological pathways would increase the diagnostic accuracy for detecting MI. METHODS: Seven biomarkers [myeloperoxidase, soluble CD40 ligand, placental growth factor, matrix metalloproteinase 9 (MMP-9), high-sensitivity C-reactive protein (hsCRP), cardiac troponin I (cTnI), N-terminal pro-B-type natriuretic peptide] and estimated glomerular filtration rate were measured in 457 patients presenting on admission with symptoms suggestive of acute coronary syndrome. Twenty-five patients (5.4%) received MI diagnoses. Clinical sensitivities and specificities were evaluated from 99th-percentile reference values. Forward and backward stepwise logistic regression modeling techniques were used to identify biomarkers that were independently predictive of MI. RESULTS: Biomarker sensitivities ranged from 20% to 96%, and specificities ranged from 19% to 89%. MMP-9 had the highest sensitivity, but its specificity was 19%. cTnI demonstrated a sensitivity of 72% (95% CI, 51%-88%) and a specificity of 89% (95% CI, 85%-92%). In multivariate models, cTnI (P < 0.001) and either hsCRP (P = 0.009) or MMP-9 (P = 0.03) were independently predictive of MI. Addition of hsCRP or MMP-9 increased the specificity to 95% (95% CI, 92%-97%) or 91% (95% CI, 88%-94%), respectively, but reduced the sensitivity to 56% (95% CI, 35%-76%) and 68% (95% CI, 47%-85%) relative to cTnI alone. CONCLUSIONS: Our findings indicate that the most clinically accurate biomarker for the early diagnosis of MI is the use of cTnI alone, rather than a multiple-biomarker approach, when an analytically robust cardiac troponin assay based on the 99th percentile is used.

Decreased patient charges following implementation of point-of-care cardiac troponin monitoring in acute coronary syndrome patients in a community hospital cardiology unit.

BACKGROUND: The need to rapidly evaluate patients presenting to emergency departments and cardiology services for ruling in and ruling out acute myocardial infarction (AMI) is widely recognized as a clinical challenge. We determined the impact of incorporating point-of-care (POC) cardiac troponin I (cTnI) testing into a cardiology service regarding assay turn around time (TAT), patient length of stay (LOS), financial matrixes and patient outcomes compared to central laboratory cTnI testing. METHODS: Patients presenting with symptoms suggestive of acute coronary syndrome (ACS) were enrolled pre-POC (PreCS, n=271) and post-POC (PostCS, n=274). POC cTnI determinations were performed at the bedside on the Dade Behring Stratus CS by nursing staff. Routine cTnI determinations were performed in the central laboratory (Dade Behring Dimension) by laboratory staff. Data were collected and analyzed on each patient per hospital stay by review of electronic medical and financial records. In addition, risk stratification outcomes for all cause death were determined at 30 days and 1 y following baseline sampling based on the 99th percentile cutoff concentrations of <0.1 microg/l for both assays. RESULTS: There was a decrease in time from blood draw to result to healthcare provider (PreCS mean 76 min; PostCS mean 19.5 min; p<0.001) as well as a decrease trend in charge per patient admission (4281 dollars savings) following implementation of POC testing. Total charges per patient admission decreased by 25% PostCS vs. PreCS (17,163 dollars vs. 12,882 dollars); a composite of lower charges for: boarding (-21%), other departments (-58%), pharmacy (-28%), labs (-22%), non-cardiac procedures (-28%), cardiac procedures (-14%). The mean LOS also decreased 8% (p=0.05) from PreCS (2.36 days) to PostCS (2.19 days). cTnI reagents charges to the laboratory were higher for the POC assay, 10.54 dollars, vs. the central lab assay, 3.83 dollars. One year survival was greater in the <0.1 microg/l patients (PreCS 96.2%, PostCS 97.2%) compared to the >0.1 microg/l patients (PreCS 77.7%, PostCS 75.5%); both p<0.001. Kaplan-Meier survival curves showed early separation by 30 days in each group. CONCLUSIONS: Our study demonstrates the cost effectiveness and clinical effectiveness of implementation of POC whole blood, cTnI testing for assisting clinicians with diagnostic and risk assessment of ACS patients.

Point-of-care i-STAT cardiac troponin I for assessment of patients with symptoms suggestive of acute coronary syndrome.

BACKGROUND: Few studies have investigated the role of cardiac troponin point-of-care (POC) testing for predicting adverse outcomes in acute coronary syndrome (ACS) patients. We investigated the use of a POC cTnI assay in ACS patients. METHODS: We studied consecutive patients (n = 367) presenting with symptoms suggestive of ACS who were admitted through the emergency department. We measured plasma cTnI with the i-STAT assay. Patients were risk-stratified based on cTnI concentrations defined by the predetermined 99th percentile reference limit for plasma (0.04 microg/L). Patients were followed for 60 days. We computed survival and event curves with the Kaplan-Meier method and compared risk stratification groups with the log-rank test. RESULTS: Acute myocardial infarction (MI) was diagnosed in 8.1% of patients. Odds ratios and 95% confidence intervals for all-cause death (ACD), MI or ACD, MI or cardiac death, and cardiac death at 60 days were all statistically significant after adjustment for age, diabetes, hypertension, and history of renal failure as follows: 2.54 (1.24-5.20), P = 0.009; 2.76 (1.37-5.58), P = 0.003; 5.98 (1.65-21.7), P = 0.008; and 2.54 (1.24-5.20), P = 0.009. Kaplan-Meier curves showed early separation between patients with increased vs. reference concentrations before 30 days for ACD, MI or ACD, and MI or cardiac death. CONCLUSION: The i-STAT POC cTnI assay can be added to the list of assays for risk stratification.