Myocardial Infarction Can Be Safely Excluded by High-sensitivity Troponin I Testing 3 Hours After Emergency Department Presentation.

BACKGROUND: The accuracy and speed by which acute myocardial infarction (AMI) is excluded are an important determinant of emergency department (ED) length of stay and resource utilization. While high-sensitivity troponin I (hsTnI) >99th percentile (upper reference level [URL]) represents a "rule-in" cutpoint, our purpose was to evaluate the ability of the Beckman Coulter hsTnI assay, using various level-of-quantification (LoQ) cutpoints, to rule out AMI within 3 hours of ED presentation in suspected acute coronary syndrome (ACS) patients. METHODS: This multicenter evaluation enrolled adults with >5 minutes of ACS symptoms and an electrocardiogram obtained per standard care. Exclusions were ST-segment elevation or chronic hemodialysis. After informed consent was obtained, blood samples were collected in heparin at ED admission (baseline), ≥1 to 3, ≥3 to 6, and ≥6 to 9 hours postadmission. Samples were processed and stored at -20°C within 1 hour and were tested at three independent clinical laboratories on an immunoassay system (DxI 800, Beckman Coulter). Analytic cutpoints were the URL of 17.9 ng/L and two LoQ cutpoints, defined as the 10 and 20% coefficient of variation (5.6 and 2.3 ng/L, respectively). A criterion standard MI diagnosis was adjudicated by an independent endpoint committee, blinded to hsTnI, and using the universal definition of MI. RESULTS: Of 1,049 patients meeting the entry criteria, and with baseline and 1- to 3-hour hsTnI results, 117 (11.2%) had an adjudicated final diagnosis of AMI. AMI patients were typically older, with more cardiovascular risk factors. Median (IQR) presentation time was 4 (1.6-16.0) hours after symptom onset, although AMI patients presented ~0.5 hour earlier than non-AMI. Enrollment and first blood draw occurred at a mean of ~1 hour after arrival. To evaluate the assay's rule-out performance, patients with any hsTnI > URL were considered high risk and were excluded. The remaining population (n = 829) was divided into four LoQ relative categories: both hsTnI < LoQ (Lo-Lo cohort); first hsTnI < LoQ and 2nd > LoQ (Lo-Hi cohort); first > LoQ and second < LoQ (Hi-Lo cohort); or both > LoQ (Hi-Hi cohort). In patients with any hsTnI result <20% CV LoQ (Groups 1-3), n = 231 (23.9% ruled out), AMI negative predictive value (NPV) was 100% (95% confidence interval [CI] = 98.9% to 100%). In patients with any hsTnI below the 10% LoQ, n = 611 (58% rule out), AMI NPV was 100% (95% CI = 99.5% to 100%). Of the Hi-Hi cohort (i.e., no hsTnI below the 10% LoQ, but both < URL), there were four AMI patients, NPV was 98.2% (95% CI = 95.4% to 99.3%), and sensitivity was 96.6. CONCLUSIONS: Patients presenting >3 hours after the onset of suspected ACS symptoms, with at least two Beckman Coulter Access hsTnI < URL and at least one of which is below either the 10 or the 20% LoQ, had a 100% NPV for AMI. Two hsTnI values 1 to 3 hours apart with both < URL, but also >LoQ had inadequate sensitivity and NPV.

Residents' performance in the interpretation of on-call "triple-rule-out" CT studies in patients with acute chest pain.

RATIONALE AND OBJECTIVES: To evaluate the performance of radiology residents in the interpretation of on-call, emergency "triple-rule-out" (TRO) computed tomographic (CT) studies in patients with acute chest pain. MATERIALS AND METHODS: The study was institutional review board-approved and Health Insurance Portability and Accountability Act compliant. Data from 617 on-call TRO studies were analyzed. Dedicated software enables subspecialty attendings to grade discrepancies in interpretation between preliminary trainee reports and their final interpretation as "unlikely to be significant" (minor discrepancies) or "likely to be significant" for patient management (major discrepancies). The frequency of minor, major and all discrepancies in resident's TRO interpretations was compared to 609 emergent non-electrocardiography (ECG)-synchronized chest CT studies using Pearson χ(2) test. RESULTS: Minor discrepancies occurred more often in the TRO group (9.1% vs. 3.9%, P < .001), but there was no difference in the frequency of major discrepancies (2.1% vs. 2.8%, P = .55). Minor discrepancies in the TRO group most commonly resulted from missed extrathoracic findings with missed liver lesions being the most frequent. Major discrepancies mostly encompassed cardiac and extracardiac vascular findings but did not result in unnecessary interventions, significant immediate changes in management, or adverse patient outcomes. CONCLUSIONS: On-call resident interpretation of TRO CT studies in patients with acute chest pain is congruent with final subspecialty attending interpretation in the overwhelming majority of cases. The rate of discrepancies likely to affect patient management in this domain is not different from emergent non-ECG-synchronized chest CT.

Differences in coronary artery disease by CT angiography between patients developing unstable angina pectoris vs. major adverse cardiac events.

OBJECTIVE: CT angiography (CTA) has prognostic value in patients. But it is unknown whether differences in atherosclerosis by CTA predict the development of unstable angina pectoris (UAP) vs. major adverse cardiac events (MACE). METHODS: We followed patients undergoing CTA as part of their acute chest pain work-up. Primary outcome was the development of UAP or MACE (cardiac death, myocardial infarction, revascularization) during a minimum follow-up of 12-months. CTAs were assessed for extent and composition of coronary plaque and stenosis. Ordinal regression with a 3-level outcome (no events, UAP, MACE) was applied. RESULTS: Among 315 patients, 22 developed UAP and 31 MACE. While UAP patients had higher atherosclerosis burden with respect to all assessed features compared to patients with no events (p ≤ 0.02), only mixed plaque extent was significantly different between UAP and MACE patients (p=0.02). The odds ratio was 4.55 for being in a higher disease-level comparing patients with low extent to those with no mixed plaque, and 3.02 comparing patients with high to those with low. These findings remained after adjustments for potential confounders. CONCLUSION: The extent of mixed coronary plaque is different between patients who develop UAP vs. MACE, supporting the hypothesis that it is a more culprit morphology.

Atherosclerotic plaque burden in cocaine users with acute chest pain: analysis by coronary computed tomography angiography.

Chest pain associated with cocaine use represents an increasing problem in the emergency department (ED). Cocaine use has been linked to the acute coronary syndrome (ACS) and acute myocardial infarction (AMI). We used coronary computed tomography angiography (cCTA) to evaluate the prevalence, severity and composition of atherosclerotic lesions in cocaine users. We studied 78 patients with non-occasional cocaine use (52 men, 44 ± 7 years, 23 under the acute influence) and acute chest pain but without ACS, who had undergone cCTA in the ED. Patients were matched one-to-one by gender, race, symptoms, and risk-factors with a control cohort (n = 78; 52 men, 45 ± 6 years) not using cocaine. Each coronary segment was evaluated for the presence and composition (calcified, non-calcified, partially calcified) of atherosclerotic plaque and for stenosis. The prevalence of coronary stenosis was not significantly different between patients with and without cocaine use (13% versus 5%, P > 0.05). However, cocaine users on average had significantly more atherosclerotic plaques (0.44 ± 0.88 versus 0.29 ± 0.83, P < 0.05) and a tendency towards more calcified (0.64 ± 1.23 versus 0.55 ± 1.22, P > 0.05) and non-calcified plaques (0.26 ± 0.63 versus 0.17 ± 0.57, P > 0.05), yet not reaching statistical significance. Furthermore, cocaine users had significantly more partially calcified plaques (0.41 ± 0.61 versus 0.17 ± 0.41, P < 0.05) and higher partially calcified plaque volume (59.7 ± 33.3 mm(3) versus 25.6 ± 12.6 mm(3), P < 0.05). Thus, cocaine users tend to have more pronounced coronary atherosclerosis compared to patients without cocaine use at the time of presentation with acute chest pain.

Incremental prognostic value of different components of coronary atherosclerotic plaque at cardiac CT angiography beyond coronary calcification in patients with acute chest pain.

PURPOSE: To systematically evaluate the incremental predictive value of cardiac computed tomographic (CT) angiography beyond the assessment of coronary artery calcium (CAC) in patients who present with acute chest pain but without evidence of acute coronary syndrome (ACS). MATERIALS AND METHODS: The human research committee approved this study and waived the need for individual written informed consent. The study was HIPAA compliant. A total of 458 patients (36% male; mean age, 55 years ± 11) with acute chest pain at low to intermediate risk for coronary artery disease underwent coronary calcification assessment with cardiac CT angiography. All patients who did not experience ACS at index hospitalization were followed for instances of a major adverse cardiac event (MACE), such as a myocardial infarct, revascularization, cardiac death, or angina requiring hospitalization. CAC score and cardiac CT angiography were used to derive the presence and extent of atherosclerotic plaque (calcified, noncalcified, or mixed), and obstructive lesions (>50% luminal narrowing) were related to outcomes by using univariate and adjusted Cox proportional hazards models. RESULTS: Of the 458 patients, 70 (15%) experienced MACE (median follow-up, 13 months). Patients with no plaque at cardiac CT angiography remained free of events during the follow-up period, while 11 (5%) of 215 patients with no CAC had MACE. The extent of plaque was the strongest predictor of MACE independent of traditional risk factors (hazard ratio [HR], 151.77 for four or more segments containing plaque as compared with those containing no plaque; P < .001). Patients with mixed plaque were more likely to experience MACE (HR, 86.96; P = .002) than those with exclusively noncalcified plaque (HR, 58.06; P = .005) or exclusively calcified plaque (HR, 32.94; P = .02). CONCLUSION: The strong prognostic value of cardiac CT angiography is incremental to its known diagnostic value in patients with acute chest pain without ACS and is independent of traditional risk factors and CAC.

Coronary atherosclerosis in African American and white patients with acute chest pain: characterization with coronary CT angiography.

PURPOSE: To use coronary computed tomographic (CT) angiography to compare the prevalence, extent, and composition of coronary atherosclerotic lesions in African American and white patients with acute chest pain. MATERIALS AND METHODS: The institutional review board waived the requirement for informed consent for this retrospective, HIPAA-compliant matched-cohort study. The authors analyzed the CT angiographic data of 301 patients (150 consecutive African American patients; 151 white control patients; mean age, 55 years ± 11 [standard deviation]; 33% male) with acute chest pain. Each coronary artery segment was evaluated for presence of atherosclerotic plaque, plaque composition (calcified, noncalcified, or mixed), and stenosis. In addition, the noncalcified plaque volume was quantified by using a threshold-based automated algorithm. The presence and extent of atherosclerotic plaque were compared between the groups by using univariate and multivariate regression analyses. RESULTS: While there was no significant difference between the African American and white patients with respect to presence of any plaque (118 [79%] of 150 vs 112 [74%] of 151 patients, respectively; P = .36) or presence of stenosis (26 [17%] vs 37 [24%] patients, respectively; P = .13), the African American patients had a significantly higher prevalence (96 [64%] vs 62 [41%] patients, respectively; P < .001) and volume (median volume, 2.2 vs 1.4 mL, respectively; P < .001) of noncalcified plaque, independent of diabetes and other cardiovascular risk factors (odds ratio, 2.45; 95% confidence interval: 1.52, 4.04). In contrast, the African American patients had a lower prevalence of calcified plaque (39 [26%] vs 68 [45%] white patients, P = .001). CONCLUSION: Study results suggest that atherosclerotic plaque burden and composition, as measured by using coronary CT angiography, differ between African American and white patients, with relatively more noncalcified disease in African Americans and more calcified disease in white individuals. Further research is warranted to determine whether CT plaque characterization can improve cardiac risk prediction in African Americans.

Cardiac CT in the assessment of acute chest pain in the emergency department.

OBJECTIVE: The purpose of this article is to describe the current role of ECG-synchronized CT in the evaluation of patients with acute chest pain (triple rule-out) in the emergency department. We discuss clinical contexts of the chest pain algorithm, technical improvements that have enabled CT to attain its current role for this application, scan protocols and radiation considerations, the evidence base regarding diagnostic and prognostic performance, and initial data on the cost-effectiveness of this promising emerging test. CONCLUSION: Currently available evidence suggests that CT-based approaches with modern scan technology are safe, accurate, and potentially cost-saving, although large-scale clinical trials are needed to ascertain the precise role of CT in the evaluation of acute chest pain.