Prevalence and clinical significance of an elevated cardiac troponin I in patients presenting to the Emergency Department without chest pain

BACKGROUND: Cardiac troponins are currently measured in patients presenting with chest pain. Little is known about routinely measured cardiac troponins in patients presenting without chest pain. The aim of this study was to determine the prevalence and clinical significance of an elevated cardiac troponin I (cTnI) in patients presenting to the Emergency Department without chest pain. METHODS: During a 6-month period, we routinely measured cTnI in all patients presenting to the internist, neurologist, or lung specialist for reasons other than chest pain. We followed patients with an elevated cTnI for 1 year and determined mortality and incidence of non-fatal myocardial infarction, percutaneous coronary intervention (PCI), and coronary artery bypass grafting (CABG). RESULTS: cTnI was elevated in 41 out of 1130 patients (3.6%). Patients with an elevated cTnI were older (78 vs. 62 years) and more often admitted to the hospital (95% vs. 78%) than those with a normal cTnI. Twenty-six patients (63%) with an elevated cTnI died within 1 year. Approximately 50% of these deaths were cardiac-related. Two patients (4.9%) suffered a non-fatal myocardial infarction, while no patient underwent PCI or CABG during follow-up. CONCLUSION: Routinely measured cTnI is seldom elevated in a general population of patients presenting to the Emergency Department without chest pain. Patients with an elevated cTnI are, on the average, 16 years older than those with a normal level. An elevated cTnI is clearly associated with an unfavorable outcome.     

Clinical utility of the exercise ECG in patients with diabetes and chest pain

OBJECTIVE: The purpose of this study was to determine the characteristics of exercise treadmill testing in diabetic patients presenting with chest pain. BACKGROUND: The diagnosis of coronary artery disease (CAD) in diabetic patients is confounded by different manifestations of coronary disease than are seen in the general population. Because of the association of diabetes with accelerated CAD, it is critical to assess the diagnostic utility of the standard exercise test in diabetic patients with chest pain. METHODS: This study was a retrospective analysis of standard exercise test results in 1,282 male patients without prior myocardial infarction who had undergone coronary angiography and were being evaluated for possible CAD at two Veterans' Administration institutions. RESULTS: In patients with diabetes, 38% had an abnormal exercise test result, and the prevalence of angiographic CAD was 69%; the sensitivity of the exercise test was 47% (95% confidence interval [CI], 41 to 58), and specificity was 81% (95% CI, 68 to 89). In patients without diabetes, 38% had an abnormal exercise test result, and the prevalence of angiographic CAD was 58%; the sensitivity of the exercise test was 52% (95% CI, 48 to 56), and specificity was 80% (95% CI, 76 to 83). The receiver operating characteristic curves were also similar in both diabetic and nondiabetic patients (0.67 and 0.68, respectively). CONCLUSION: These data demonstrate that the standard exercise test has similar diagnostic characteristics in diabetic as in nondiabetic patients.     

An external validation of the HEART pathway among Emergency Department patients with chest pain

The impact of an outpatient disposition strategy for patients with HEART score 0–3 (HEART pathway) on HEART score prognostic accuracy is unclear. Our objective is to perform an external validation the HEART score in the setting of recent implementation of the HEART pathway. We conducted an external validation study of the HEART pathway among patients presenting to our ED with chest pain 6 weeks after institutional implementation of a HEART pathway outpatient disposition pathway. We reviewed the charts of 625 consecutive patients with chest pain. Data abstracted included all elements of the HEART score to include history, electrocardiogram (ECG) read, patient age, patient risk factors, and troponin levels. We also reviewed each patient’s record for evidence of major adverse cardiac events (MACE) to include mortality, myocardial infarction, or coronary revascularization over 6 weeks following their initial ED visit. We double-abstracted 10% of the charts for quality assurance purposes. Of 625 charts, 449 patients met all criteria for study inclusion. Of these, 25 subjects (5.56%) experience 6-week MACE. No subject with a score of 3 or less has a MACE at 6 weeks (100% sensitivity, 38.7% specificity). The area under the receiver operator curve (AUROC) is 0.898 (95% confidence interval 0.847–0.950). Kappa coefficients for inter-rater reliability range from 0.62 for the history component of the HEART score to 1.0 for troponin. A low HEART score (0–3) maintains excellent sensitivity for predicting 6-week MACE in the setting of an outpatient disposition pathway for these patients.     

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 μg/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 μg/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 μg/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.     

Systolic blood pressure at Emergency Department presentation and 1-year mortality in acute chest pain patients

Background

High blood pressure at rest has been an established risk factor for cardiovascular disease. However the relationship between Systolic Blood Pressure (SBP) and 1-year-mortality among acute chest pain patients presenting to Emergency Department (ED); and effects of preexisting renal insufficiency, hemodynamic stress — as quantified by Brain Natriuretic Peptide (BNP) and chest pain duration, on this relationship is unknown.

Methods

Data was used from APACE (Advantageous Predictors of Acute Coronary Syndrome Evaluation), a prospective observational multicenter study of 1240 ED chest pain patients. SBP at presentation was categorized into quartiles: Q1 ≤ 127 mm Hg; Q2 128–142 mm Hg; Q3 143–160 mm Hg; Q4 ≥ 161 mm Hg.

Results

60 deaths occurred during 1-year. One-year-mortality-rate showed lower Hazard Ratios for Q2, Q3 and Q4 vs Q1 (HR [95% CI]; 0.39 (0.19–0.78), 0.34 (0.17–0.70), 0.35 (0.17–0.72); p < 0.01 respectively). Cox model adjusted for various demographic and treatment variables showed that participants in Q3 and Q4 had better prognoses than Q1. Patients showed progressively better prognosis from Q2 through Q4 vs Q1 only in patients who presented to ED with for more than 12 h of chest pain duration. Patients with renal insufficiency had lower SBP at presentation than others (p = 0.001). There was no association between the outcome and interaction variable of SBP quartiles and BNP (p = 0.27).

Conclusion

Acute chest pain patients presenting to ED exhibit an inverse association between SBP at presentation and 1-year-mortality; a relationship which appears stronger in those who present with chest pain of greater than 12 h duration.     

Prognostic value of troponin T, myoglobin, and CK-MB mass in patients presenting with chest pain without acute myocardial infarction.

OBJECTIVE: To assess the prognostic value of minor myocardial damage in patients presenting with chest pain without myocardial infarction. DESIGN: The relative risk of suffering a cardiac event in the next six months was assessed in patients with minor myocardial damage assessed by the cardiac markers CK-MB, myoglobin, and troponin T. SETTING: Emergency department of a large university hospital. PATIENTS: In 128 consecutive patients with chest pain, acute myocardial infarction (by WHO criteria) was ruled out; of these, 39 had a rise and fall of one or more markers, indicating minor myocardial damage. The presence of a documented history of coronary artery disease was assessed on admission. RESULTS: 24 patients had a subsequent event (cardiac death, acute myocardial infarction, percutaneous transluminal coronary angioplasty, coronary artery bypass grafting) in the next six months. An abnormal troponin T predicted a subsequent event while abnormal CK-MB or myoglobin did not. The relative risk for troponin T was 2.8 (95% confidence interval: 1.0 to 7.9), for myoglobin 1.0 (0.3 to 3.2), and for CK-MB 0.9 (0.2 to 3.4). A documented history of coronary artery disease predicted subsequent events with a relative risk of 3.9 (1.3 to 11.3). CONCLUSIONS: Troponin T was the only marker that predicted future events, but a documented history of coronary artery disease was the best predictor in patients in whom an acute myocardial infarction had been ruled out.     

Potential impact of noncontrast computed tomography as gatekeeper for myocardial perfusion positron emission tomography in patients admitted to the chest pain unit

We investigated the ability of coronary artery calcium (CAC) to predict a normal adenosine stress rubidium-82 (Rb-82) myocardial perfusion positron emission tomography (PET) in patients admitted to the chest pain unit. Eighty-four consecutive patients (33 men; mean age 62 +/- 14.8 years) with low to intermediate likelihood of coronary artery disease were included. A single noncontrast computed tomogram under shallow breathing was obtained for attenuation correction and to assess the presence of CAC. This was followed by a rest and adenosine stress dynamic Rb-82 emission PET. Computed tomography and PET images were interpreted independently. There was a high prevalence of risk factors (80% hypertension, 30% diabetes, 38% hypercholesterolemia, 13% smoking); prior coronary revascularization and myocardial infarction were present in 21% and 15% of the patients, respectively. The absence of CAC was associated with a normal adenosine stress Rb-82 myocardial perfusion PET in 34 of 34 patients, yielding a negative predictive value of 100%. The presence of CAC (50 of 84) was associated with a higher incidence of myocardial perfusion defects (13 of 50), yielding a positive predictive value of 26%. Sensitivity was 100% (13 of 13) and specificity was 48% (34 of 71). In conclusion, the absence of CAC is predictive of a normal adenosine stress Rb-82 myocardial perfusion PET in patients admitted to the chest pain unit. If these results are confirmed, myocardial perfusion imaging probably can be safely avoided in chest pain patients with negative CAC with low to intermediate pretest likelihood of disease. This approach may decrease overall radiation exposure and hospital time and prove to be cost effective.     

Risk prediction in patients with chest pain: early assessment by the combination of troponin I results and electrocardiographic findings

OBJECTIVE: To evaluate the prognostic value of point of care troponin I (TnI) results in combination with findings from the admission electrocardiogram (ECG) in patients with chest pain. METHODS: Rapid measurements of TnI were performed in 191 consecutive patients with chest pain and a non-diagnostic ECG for myocardial infarction. RESULTS: Within 6 h from admission, maximum TnI elevations of > or = 0.07 microg/l and > or = 0.1 microg/l were noted in 59 and 39% of all patients, respectively. TnI elevations in the range of 0.07-0.09 microg/l were found in many patients with diagnoses other than acute coronary syndrome. By 6-month follow-up, cardiac death had occurred in 7.1 and 11% of patients with maximum TnI > or = 0.07 microg/l and > or = 0.1 microg/l, respectively and myocardial reinfarction was documented in 12 and 15%, respectively. ST-segment depression on the admission ECG was present in 16% of all patients and was the electrocardiographic abnormality with the highest risk (cardiac death 7.7%, myocardial reinfarction 15%). The combination of TnI > or = 0.1 microg/l and ST-segment depression or an abnormal admission ECG in general allowed the identification of patients at low, intermediate and high cardiac risk, 3 h after admission. CONCLUSION: A threshold of TnI > or = 0.1 microg/l corresponding to the 10% coefficient of variation is prognostically most suitable for prediction of cardiac events in patients with chest pain. The combination of TnI results and findings from the admission ECG improves prognostic assessment and allows early and reliable risk stratification in this patient population.     

Implication of different cardiac troponin I levels for clinical outcomes and prognosis of acute chest pain patients

OBJECTIVES: We compared outcomes in patients with non-ST-segment elevation acute coronary syndromes (ACS) according to the degree of cardiac troponin I (cTnI) elevation. BACKGROUND: Controlled trials of high-risk patients have found that troponin elevations identify an even higher risk subset. It is unclear whether outcomes are similar among a lower risk, heterogeneous patient group. Also, few studies have reported outcomes other than myocardial infarction (MI) or death, based on the peak troponin value. METHODS: Consecutively, admitted patients without ST-segment elevation on the initial electrocardiogram underwent serial marker sampling using creatine kinase (CK), CK-MB fraction, and cTnI. Patients were grouped according to peak cTnI: negative = no detectable cTnI; low = peak greater than the lower limit of detectability but less than the optimal diagnostic value; intermediate = peak greater than or equal to the optimal diagnostic value but less than the manufacturer's suggested upper reference limit (URL); and high = peak greater than or equal to the URL. Thirty-day outcomes included cardiac death, MI based on CK-MB, revascularization, significant disease, and a reversible defect on stress testing. Six-month mortality was also determined. Negative evaluations for ischemia included nonsignificant disease, no reversible stress defect, and negative rest perfusion imaging. RESULTS: Of the 4,123 patients admitted, 893 (22%) had detectable cTnI values. Cardiac events and positive test results at 30 days and 6-month mortality increased significantly with increasing cTnI values. Negative evaluations for ischemia were significantly and inversely related to peak cTnI values. Although adverse events were significantly more common in patients with a low cTnI value than in those with negative cTnI, negative evaluations for ischemia were frequent. CONCLUSIONS: Increased cTnI values are associated with worse outcomes. Although low cTnI values are associated with adverse events, they do not have the same implication as higher cTnI values, and nonischemic evaluations are frequent.     

The causes of musculoskeletal chest pain in patients admitted to hospital with suspected myocardial infarction

BACKGROUND: We wished to investigate the causes and characteristics of musculoskeletal chest pain leading to acute medical admission. METHODS: We studied patients admitted to Queen Elizabeth Hospital, Gateshead, over a 10-week period. Patients with chest pain for which no acute cardiorespiratory cause was evident were identified and only included if they were tender on anteroposterior chest compression, thoracic spine rotation or firm sternal pressure. A detailed clinical history, anxiety and depression scale and a focussed physical examination were done to define the nature of musculoskeletal disease and their therapeutic requirements. RESULTS: Fifty patients satisfying the inclusion criteria were admitted in the 10-week period and comprised 54% females with a mean age of 57 years (S.D.=13.48). Chest pain lasted for 1 h or less in 24 patients and was mostly anterior. Three distinct groups of patients were identified. Twelve patients had evidence of inflammatory joint disease, thirteen had fibromyalgia and half had regional syndromes with pain arising from the shoulder, neck, thoracic spine or sternocostal areas. Visual analogue scores were highest in fibromyalgia for pain, and highest in inflammatory arthritis for impaired mobility. Anxiety and depression scores were highest in fibromyalgia and lowest among patients with regional syndromes. CONCLUSIONS: Musculoskeletal causes for acute chest pain are common and varied. Most patients have an identifiable cause of pain, but accurate diagnosis is needed to select the most appropriate intervention. Anxiety and depression are frequent, with much self-reported pain and dysfunction. However, all patients in this study had a disorder that was amenable to treatment and diagnosis. Management needs to be actively pursued in all patients.     

The utility of four biochemical markers in the triage of chest pain patients

Four biochemical markers, creatine kinase (CK)-MB isoenzyme, myoglobin, myosin light chains and troponin I, were studied in 1,338 patients presenting to the emergency department with chest pain suggestive of coronary artery disease (CAD). One hundred and eighty-seven patients had an acute myocardial infarction (MI). At least one of the four markers was over the threshold on the first sample in 78% of MI patients, as compared to only 40% with an elevated CK-MB. After 4 h, 88% had at least one marker elevated. None of the 69 patients with atypical chest pain, no history of CAD, no markers over threshold on the first sample and a normal electrocardiogram had an acute MI or unstable angina. If we had discharged this group, we would have saved USD 264,000, estimating a cost of USD 2,000 per day. Using four biochemical markers improved the early diagnosis of CAD and may help identify groups suitable for early discharge.