Rhabdomyolysis, Methamphetamine, Amphetamine and MDMA Use: Associated Factors and Risks.

OBJECTIVE: Rhabdomyolysis is associated with methamphetamine, amphetamine, and methylenedioxymethamphetamine (MA) use. The aim of this study was to determine the frequency, severity, and risk factors of rhabdomyolysis associated with MA use. Methods: We reviewed patients with an MA-positive toxicology screen with and without diagnosed rhabdomyolysis based on initial creatine kinase (CK) concentration over a period of 6 years. Demographics, vital signs, disposition, diagnoses, and laboratory results were recorded. Results: There were 7,319 patients with an MA-positive toxicology screen, of whom 957 (13%) were screened for rhabdomyolysis and included in the study. The majority were male, White, and middle-aged and smoked tobacco. Psychiatric (34%), neurological (15%), and trauma (13%) were the most common discharge diagnostic groups. The majority (55%) were admitted, and 8% were discharged to an inpatient psychiatric facility. Concomitant substance use included ethanol (10%) and cocaine (8%), and 190 (20%) had rhabdomyolysis with median (interquartile range) CK of 2,610 (1,530-6,212) U/L and range 1,020 to 98,172 U/L. There was significant difference in renal function between the rhabdomyolysis and non-rhabdomyolysis patients. Other differences included gender and troponin I concentration. A higher proportion of patients screening positive for both MA and cocaine use experienced rhabdomyolysis. Multiple logistic regression analysis revealed elevated troponin I, blood urea nitrogen, and/or creatinine concentration and male gender to be significant factors associated with rhabdomyolysis. Conclusions: The frequency of rhabdomyolysis in patients screening positive for MA was 20%. Factors associated with rhabdomyolysis in MA-positive patients included elevated troponin, blood urea nitrogen, creatinine concentration, and male gender. Clinicians caring for patients who screen positive for MA should also consider concomitant rhabdomyolysis, especially if renal/cardiac laboratory tests are abnormal and even if there is no history of injury, agitation, or physical restraint.

Methamphetamine use and heart failure: Prevalence, risk factors, and predictors.

OBJECTIVES: To compare methamphetamine users who develop heart failure to those who do not and determine predictors. METHODS: Patients presenting over a two-year period testing positive for methamphetamine on their toxicology screen were included. Demographics, vital signs, echocardiography and labs were compared between patients with normal versus abnormal B-type natriuretic peptide (BNP). RESULTS: 4407 were positive for methamphetamine, 714 were screened for heart failure, and 450 (63%) had abnormal BNP. The prevalence of abnormal BNP in methamphetamine-positive patients was 10.2% versus 6.7% for those who were negative or not tested. For methamphetamine-positive patients, there was a tendency for higher age and male gender with abnormal BNP. A higher proportion of Whites and former smokers had abnormal BNP and higher heart and respiratory rates. Echocardiography revealed disparate proportions for normal left ventricular ejection fraction (LVEF) and severe dysfunction (LVEF <30%), LV diastolic function, biventricular dimensions, and pulmonary arterial pressures between subgroups. For methamphetamine-positive patients with abnormal BNP, creatinine was significantly higher, but not Troponin I. Logistic regression analysis revealed predictors of abnormal BNP and LVEF <30% in methamphetamine-positive patients, which included age, race, smoking history, elevated creatinine, and respiratory rate. CONCLUSION: Methamphetamine-positive patients have a significantly higher prevalence of heart failure than the general emergency department population who are methamphetamine-negative or not tested. The methamphetamine-positive subgroup who develop heart failure tend to be male, older, White, former smokers, and have higher creatinine, heart and respiratory rates. This subgroup also has greater biventricular dysfunction, dimensions, and higher pulmonary arterial pressures.

Methamphetamine Use and Emergency Department Utilization: 20 Years Later.

BACKGROUND: Methamphetamine (MAP) users present to the emergency department (ED) for myriad reasons, including trauma, chest pain, and psychosis. The purpose of this study is to determine how their prevalence, demographics, and resource utilization have changed. METHODS: Retrospective review of MAP patients over 3 months in 2016. Demographics, mode of arrival, presenting complaints, disposition, and concomitant cocaine/ethanol use were compared to a 1996 study at the same ED. RESULTS: 638 MAP-positive patients, 3,013 toxicology screens, and 20,203 ED visits represented an increase in prevalence compared to 1996: 461 MAP-positive patients, 3,102 screens, and 32,156 visits. MAP patients were older compared to the past. Mode of arrival was most frequently by ambulance but at a lower proportion than 1996, as was the proportion of MAP patients with positive cocaine toxicology screens and ethanol coingestion. Admission rate was lower compared to the past, as was discharge to jail. The proportion of MAP patients presenting with blunt trauma was lower compared to the past and higher for chest pain. CONCLUSION: A significant increase in the prevalence of MAP-positive patients was found. Differences in presenting complaints and resource utilization may reflect the shifting demographics of MAP users, as highlighted by an older patient population relative to the past.

Acute Medical Diagnoses Are Common in "Found Down" Adult Patients Presenting to the Emergency Department as Trauma.

BACKGROUND: Patients often present to the emergency department (ED) as "found down," with limited history to suggest a primary traumatic or medical etiology. OBJECTIVE: The study objective was to describe the characteristics of "found down" adult patients presenting to the ED as trauma, specifically the incidence of acute medical diagnoses and major trauma. METHODS: Using an institutional trauma registry, we reviewed trauma activations with the cause of injury "found down" between January 2008 and December 2012. We excluded patients with cardiac arrest, transfers from other hospitals, and patients with a more than likely (>50%) traumatic or medical etiology on initial ED presentation. Inclusion and exclusion criteria were reviewed by two independent abstractors. We abstracted demographic, clinical, injury severity, and outcomes variables. Major trauma was defined as Injury Severity Score ≥ 16. RESULTS: There were 659 patients identified with the cause of injury "found down." A total of 207 (31%) patients met inclusion criteria; median age was 67 years (interquartile range 50-82 years), and 110 (53%) were male. Among the included patients, 137 (66%, 95% confidence interval [Cl] 59-73%) had a discharge diagnosis of an acute medical condition, 14 (7%, 95% Cl 4-11%) with major trauma alone, 21 (10%, 95% Cl 6-15) with both an acute medical condition and major trauma, and 35 (17%, 95% Cl 12-23%) with minor trauma. The most common acute medical diagnoses were toxicological (56 patients, 35%; 95% Cl 28-43%) and infectious (32 patients, 20%; 95% Cl 14-27%). CONCLUSION: Acute medical diagnoses were common in undifferentiated ED patients "found down" in an institutional trauma registry. Clinicians should maintain a broad differential diagnosis in the workup of the undifferentiated "found down" patient.

Characteristics of the pediatric patients treated by the Pediatric Emergency Care Applied Research Network's affiliated EMS agencies.

OBJECTIVE: To describe pediatric patients transported by the Pediatric Emergency Care Applied Research Network's (PECARN's) affiliated emergency medical service (EMS) agencies and the process of submitting and aggregating data from diverse agencies. METHODS: We conducted a retrospective analysis of electronic patient care data from PECARN's partner EMS agencies. Data were collected on all EMS runs for patients less than 19 years old treated between 2004 and 2006. We conducted analyses only for variables with usable data submitted by a majority of participating agencies. The investigators aggregated data between study sites by recoding it into categories and then summarized it using descriptive statistics. RESULTS: Sixteen EMS agencies agreed to participate. Fourteen agencies (88%) across 11 states were able to submit patient data. Two of these agencies were helicopter agencies (HEMS). Mean time to data submission was 378 days (SD 175). For the 12 ground EMS agencies that submitted data, there were 514,880 transports, with a mean patient age of 9.6 years (SD 6.4); 53% were male, and 48% were treated by advanced life support (ALS) providers. Twenty-two variables were aggregated and analyzed, but not all agencies were able to submit all analyzed variables and for most variables there were missing data. Based on the available data, median response time was 6 minutes (IQR: 4-9), scene time 15 minutes (IQR: 11-21), and transport time 9 minutes (IQR: 6-13). The most common chief complaints were traumatic injury (28%), general illness (10%), and respiratory distress (9%). Vascular access was obtained for 14% of patients, 3% received asthma medication, <1% pain medication, <1% assisted ventilation, <1% seizure medication, <1% an advanced airway, and <1% CPR. Respiratory rate, pulse, systolic blood pressure, and GCS were categorized by age and the majority of children were in the normal range except for systolic blood pressure in those under one year old. CONCLUSIONS: Despite advances in data definitions and increased use of electronic databases nationally, data aggregation across EMS agencies was challenging, in part due to variable data collection methods and missing data. In our sample, only a small proportion of pediatric EMS patients required prehospital medications or interventions.

Value of high-sensitivity C-reactive protein in low risk chest pain observation unit patients.

OBJECTIVE: High-sensitivity C-reactive protein (hs-CRP) rises with cardiac injury/ischemia. We evaluated its efficacy in aiding in the identification of an acute coronary syndrome (ACS) in patients (pts) admitted to the chest pain unit (CPU) for possible ACS. METHODS: Retrospective study of all patients admitted to the CPU with chest pain who underwent hs-CRP testing as part of their CPU evaluation from January 2004 to October 2008. Patients were low risk for ACS (compatible symptoms, nondiagnostic initial ECG, and negative cTnI). ACS was diagnosed by positive functional study, cardiac catheterization, or cardiac event during 30-day follow-up. Positive hs-CRP was defined based on local laboratory levels (>1.0 mg/l or >3.0 mg/l), and population-based and prior study values >2.0 mg/l. Chi-square analysis was performed, and odds ratios (OR) are presented. Multivariate analysis was done to determine whether hs-CRP was independently associated with the diagnosis of ACS. Cardiac risk factors, demographics, and diagnosis of ACS were included in the model. Medians with IQR are presented for continuous data. Ninety-five percent confidence intervals are presented where applicable. RESULTS: A total of 958 patients had hs-CRP testing as part of their CPEU evaluation. Excluded from the analysis were 39 patients lost to follow-up. The final cohort comprised 478 (52%) women and 441 (48%) men with a median age of 56 (IQR 48-64). ACS was diagnosed in 128 (13.4%). The median cohort hs-CRP value was 2.2 mg/l (IQR 0.7, 5.8) and 2.3 mg/l (IQR 0.6, 5.9) in those with and without ACS, respectively. In the multivariate analysis hs-CRP was not independently associated with the diagnosis of ACS (0.99; 95% CI 0.98 - 1.01). CONCLUSION: In large patient cohort managed in a single-center CPU, measurement of hs-CRP did not enhance the diagnostic accuracy for ACS. Routine hs-CRP as a diagnostic tool should not be recommended in the CPU setting.

Relationship of myocardial ischemia and injury to coronary artery disease in patients with supraventricular tachycardia.

Increase of serum troponin I and ST-segment depression are objective markers of myocardial ischemia/injury. Abnormalities of the 2 indicators have been associated with supraventricular tachycardia (SVT) but their relevance for diagnosing acute coronary syndrome and the presence of coronary artery disease (CAD) in this setting have not been clarified. Therefore, we sought to evaluate the frequency of CAD based on increased troponin I and ST-segment depression during SVT. During a 5-year period, 104 patients were admitted with a diagnosis of SVT, 80 of whom had troponin I testing, and 70 of these patients could be assessed for ST-segment changes. Thirty-seven patients (48%) had increased troponin I (mean 1.54 +/- 2.7 ng/dl, normal or=1.0 mm. There were no significant differences in baseline characteristics and clinical presentation of patients with and without troponin I increase or ST-segment depression. There was no difference in the diagnosis of CAD by noninvasive or invasive testing in patients with and without increased troponin I. More patients with than without ST-segment depression had evidence of CAD (22% vs none, p = 0.01), but after adjusting for covariates, ST-segment depression was not a significant predictor of CAD. In conclusion, increased troponin I and ST-segment depression are not significant markers of acute coronary syndrome in patients with SVT.

Frequency of non-ST-segment elevation injury patterns on prehospital electrocardiograms.

INTRODUCTION: Prehospital electrocardiograms (ECGs) have been recommended to facilitate early diagnosis of ST-segment elevation myocardial infarction (STEMI). However, prehospital ECGs can also be used to triage patients with non-ST-segment elevation acute coronary syndromes, who comprise a majority of patients with ischemic events presenting by ambulance to overcrowded emergency departments. OBJECTIVE: We assessed the frequency of non-ST-segment elevation injury patterns on prehospital ECGs in patients with a chief complaint of chest pain evaluated by the emergency medical services (EMS) system. METHODS: We analyzed prehospital ECGs of patients with the chief complaint of chest pain during a nine-month period. The ECGs were divided into three categories: injury pattern; no injury pattern; and technically uninterpretable. Injury pattern criteria were as follows: 1) regional ST depression >or=1.0 mm; 2) regional T-wave inversion (TWI) >or=3 mm; 3) left bundle branch block (LBBB); and 4) regional ST-segment elevation >or=1.0 mm. Descriptive statistics with 95% confidence intervals (CIs) are presented. RESULTS: Prehospital ECGs were obtained for 322 of 340 chest pain patients: 72% were men; the average age was 60 years (range 18-96 years). Seventy-seven ECGs (24%, 95% CI 19.3-28.9%) met the criteria for injury pattern, 230 (71%) did not show injury, and 15 (5%) were uninterpretable. Of the 77 ECGs that exhibited an injury pattern, 39 (51%) showed ST depression, seven (9%) TWI, seven (9%) LBBB, and 24 (31%) ST-segment elevation. Thus, non-ST-segment elevation injury patterns (ST depression/TWI/LBBB) accounted for 53 (17%, 95% CI 12.6-20.9) of the total 322 prehospital ECGs. CONCLUSION: Our findings demonstrate a relatively high frequency (17%) of non-ST-segment elevation injury patterns on prehospital ECGs of patients who summon EMS because of chest pain. These results suggest the potential of prehospital ECGs to facilitate early triage in these high-risk chest pain patients who present to overcrowded emergency departments.

Frequency of acute coronary syndrome in patients with normal electrocardiogram performed during presence or absence of chest pain.

OBJECTIVES: The authors hypothesized that patients with active chest pain at the time of a normal electrocardiogram (ECG) have a lower frequency of acute coronary syndrome (ACS) than patients being evaluated for chest pain but with no active chest pain at the time of a normal ECG. The study objective was to describe the association between chest pain in patients with a normal ECG and the diagnosis of ACS. METHODS: This was a prospective observational study of emergency department (ED) patients with a chief complaint of chest pain and an initial normal ECG admitted to the hospital for chest pain evaluation over a 1-year period. Two groups were identified: patients with chest pain during the ECG and patients without chest pain during the ECG. Normal ECG criteria were as follow: 1) normal sinus rhythm with heart rate of 55-105 beats/min, 2) normal QRS interval and ST segment, and 3) normal T-wave morphology or T-wave flattening. "Normal" excludes pathologic Q waves, left ventricular hypertrophy, nonspecific ST-T wave abnormalities, any ST depression, and discrepancies in the axis between the T wave and the QRS. Patients' initial ED ECGs were interpreted as normal or abnormal by two emergency physicians (EPs); differences in interpretation were resolved by a cardiologist. ACS was defined as follows: 1) elevation and characteristic evolution of troponin I level, 2) coronary angiography demonstrating >70% stenosis in a major coronary artery, or 3) positive noninvasive cardiac stress test. Chi-square analysis was performed and odds ratios (ORs) are presented. RESULTS: A total of 1,741 patients were admitted with cardiopulmonary symptoms; 387 met study criteria. The study group comprised 199 males (51%) and 188 females (49%), mean age was 56 years (range, 25-90 years), and 106 (27%) had known coronary artery disease (CAD). A total of 261 (67%) patients experienced chest pain during ECG; 126 (33%) patients experienced no chest pain during ECG. There was no difference between the two groups in age, sex, cardiac risk factors, or known CAD. The frequency of ACS for the total study group was 17% (67/387). There was no difference in prevalence of ACS based on the presence or absence of chest pain (16% or 42/261 vs. 20% or 25/126; OR = 0.77, 95% confidence interval = 0.45 to 1.33, p = 0.4). CONCLUSIONS: Contrary to our hypothesis concerning patients who presented to the ED with a chief complaint of chest pain, our study demonstrated no difference in the frequency of acute coronary syndrome between patients with chest pain at the time of acquisition of a normal electrocardiogram and those without chest pain during acquisition of a normal electrocardiogram.

Venous ultrasound testing for suspected thrombosis: incidence of significant non-thrombotic findings.

Duplex ultrasound (US) is used to "rule out" deep venous thrombosis (DVT), but can also diagnose other causes of leg pain or swelling in Emergency Department (ED) patients. Recent literature suggests that US imaging is unnecessary among patients with low or moderate clinical probability of DVT with a normal D-dimer. We attempted to determine the incidence of clinically important incidental findings detected using venous US imaging in patients with suspected lower extremity DVT. We conducted a retrospective chart review of all ultrasounds performed by the non-invasive vascular laboratory on ED patients > 18 years old. Results were classified: normal, DVT, or incidental finding. The latter were classified as clinically significant major findings if the diagnosis led to immediate and specific treatment to prevent morbidity, or clinically significant minor findings. A total of 484 US studies were reviewed; 179 were excluded (arterial studies, penetrating trauma, upper extremity US). Findings among 305 studies were: 238 (78%) normal, 28 (9%) DVT, and 39 (12%) incidental findings. Among 39 incidental findings, 10 were clinically significant major findings and 29 clinically significant minor findings. Clinically significant major findings included: pseudoaneurysm, arterial occlusive disease, vascular graft complication, compartment syndrome, and tumor. Among 38 abnormal US studies that required immediate treatment, DVT comprised 74% (95% confidence interval 59%-85%) and important major incidental findings 26% (95% confidence interval 14%-41%). Among ED patients who underwent US to evaluate leg pain and swelling, 26% of positive studies showed clinically important findings other than DVT. Further research is needed to determine if D-dimer plus a clinical probability tool will include or exclude the patients with clinically significant major findings.

Reporting patterns for "lapses of consciousness" by California emergency physicians.

Physician reporting of lapses of consciousness (LOC) to the Department of Motor Vehicles is a controversial topic in medicine. The objective of this study was to describe current LOC reporting practices by emergency physicians (EPs) in a state with mandatory reporting requirements (California). A questionnaire describing 14 different clinical scenarios involving LOC was distributed to a diverse sample of California EPs. Clinical scenarios included new seizure, hypoglycemia, atrial fibrillation/rapid heart rate, cerebrovascular accident, micturation syncope, vasovagal syncope, hepatic encephalopathy, alcohol intoxication, closed head injury, hyperosmolar coma, methamphetamine psychosis, dementia, hyperventilation syndrome, and hypercalcemia. Emergency physicians were asked how often they would report these LOC-related conditions to the state. Simple summary statistics were calculated. The response rate was 207/340 (61%) of the forms distributed. The average number of years in Emergency Medicine practice among respondents was 12 (range 1-35), and 57% were Emergency Medicine trained. Of the 14 scenarios, only one (new-onset seizure) was reported frequently by EPs (89% reported "nearly always" or "most of the time"). The remaining 13 scenarios were rarely reported (mean of 86% for "occasionally" or "never"). Although reporting of LOC, from any cause, is mandatory in California, only new-onset seizures are frequently reported by California EPs.

Evaluation of patients with methamphetamine- and cocaine-related chest pain in a chest pain observation unit.

OBJECTIVE: Risk of acute coronary events in patients with methamphetamine and cocaine intoxication has been described. Little is known about the need for additional evaluation in these patients who do not have evidence of myocardial infarction after the initial emergency department evaluation. We herein describe our experience with these patients in a chest pain unit (CPU) and the rate of cardiac-related chest pain in this group. METHODS: Retrospective analysis of patients evaluated in our CPU from January 1, 2000 to December 16, 2004 with a history of chest pain. Patients who had a positive urine toxicologic screen for methamphetamine or cocaine were included. No patients had ECG or cardiac injury marker evidence of myocardial infarction or ischemia during the initial emergency department evaluation. A diagnosis of cardiac-related chest pain was based upon positive diagnostic testing (exercise stress testing, nuclear perfusion imaging, stress echocardiography, or coronary artery stenosis >70%). RESULTS: During the study period, 4568 patients were evaluated in the CPU. A total of 1690 (37%) of patients admitted to the CPU underwent urine toxicologic testing. The result of urine toxicologic test was positive for cocaine or methamphetamine in 224 (5%). In the 2871 patients who underwent diagnostic testing for coronary artery disease (CAD), 401 (14%) were found to have positive results. There was no difference in the prevalence of CAD between those with positive result for toxicology screens (26/156, 17%) and those without (375/2715, 13%, RR 1.2, 95% CI 0.8-1.7). CONCLUSION: These findings suggest a relatively high rate of CAD in patients with methamphetamine and cocaine use evaluated in a CPU.

Electrocardiogram differentiation of benign early repolarization versus acute myocardial infarction by emergency physicians and cardiologists.

OBJECTIVES: ST-segment elevation (STE) related to benign early repolarization (BER), a common normal variant, can be difficult to distinguish from acute myocardial infarction (AMI). The authors compared the electrocardiogram (ECG) interpretations of these two entities by emergency physicians (EPs) and cardiologists. METHODS: Twenty-five cases (13 BER, 12 AMI) of patients presenting to the emergency department with chest pain were identified. Criteria for BER required four of the following: 1) widespread STE (precordial greater than limb leads), 2) J-point elevation, 3) concavity of initial up-sloping portion of ST segment, 4) notching or irregular contour of J point, and 5) prominent, concordant T waves. Additional BER criteria were 1) stable ECG pattern, 2) negative cardiac injury markers, and 3) normal cardiac stress test or angiography. AMI criteria were 1) regional STE, 2) positive cardiac injury markers, and 3) identification of culprit coronary artery by angiography in less than eight hours of presentation. The 25 ECGs were distributed to 12 EPs and 12 cardiologists (four in academic medicine, four in community practice, and four in community academics [health maintenance organization] in each physician group). The physicians were informed of the patients' age, gender, and race, and they then interpreted the ECGs as BER or AMI. Undercalls (AMI misdiagnosed as BER) and overcalls (BER misdiagnosed as AMI) were calculated for each physician group. RESULTS: Cardiologists correctly interpreted 90% of ECGs, and EPs correctly interpreted 81% of ECGs. The proportion of undercalls (missed AMI/total AMI) was 2.8% for cardiologists (95% confidence interval [CI] = 0.09% to 5.5%) compared with 9.7% for EPs (95% CI = 4.8% to 14.6%) (p = 0.02). The proportion of overcalls (missed BER/total BER) was 17.3% for cardiologists (95% CI = 11.4% to 23.3%) versus 27.6% for EPs (95% CI = 20.6% to 34.6%) (p = 0.03). The mean number of years in practice was 19.8 for cardiologists (95% CI = 19 to 20.5) and 11 years for EPs (95% CI = 10.5 to 12.0) (p < 0.001). CONCLUSIONS: Although correct interpretation was high in both groups, cardiologists, who had significantly more years of practice, had fewer misinterpretations than EPs in distinguishing BER from AMI electrocardiographically.

Assessing the need for functional diagnostic testing in low-risk women with chest pain.

OBJECTIVE: The objective of this study was to assess the need for functional diagnostic testing to identify coronary artery disease (CAD) in women presenting with chest pain and deemed at low risk in a chest pain evaluation unit (CPEU) setting. METHODS: Low-risk women evaluated in a CPEU were defined as having < or =1 intermediate determinant of CAD (hypertension, tobacco use, or hypercholesterolemia) or < or =2 minor determinants (age, obesity, sedentary lifestyle, or family history of CAD). Patients were followed for 30 days for the occurrence of CAD, defined as a positive stress imaging study, significant CAD on angiography, myocardial revascularization, myocardial infarction (MI), or cardiac death. RESULTS: Of 1355 consecutive women evaluated, 527 (39%) were classified as low risk. The rate of CAD in the low-risk group was 1.3% of which there were no coronary events. CONCLUSION: Women admitted to a CPEU and identified as low risk are at very low risk for CAD.

Use of additional electrocardiograph leads in low-risk patients undergoing exercise treadmill testing.

BACKGROUND: Studies have shown that the addition of right precordial and left posterior leads to the standard 12-lead electrocardiogram (ECG) can significantly improve the sensitivity of exercise treadmill testing (ETT) for the diagnosis of myocardial ischemia. OBJECTIVE: The objective of this study was to determine the value of adding 2 rightsided (RV3, RV4) and 2 left posterior (V8, V9) auxiliary leads to enhance detection of myocardial ischemia in patients with chest pain identified as low risk. METHODS: The authors conducted a prospective study of all patients undergoing ETT as part of their management in a chest pain evaluation unit (CPEU) at a tertiary medical center from November 1999 to November 2001. Patients were considered low risk for acute coronary syndrome based on the clinical presentation to the CPEU, absence of ischemia on resting ECG, and negative initial cardiac markers. Diagnosis of coronary artery disease (CAD) was based on confirmatory testing, which included coronary angiography, myocardial stress scintigraphy, exercise echocardiography, or 30-day follow-up period. RESULTS: The study cohort comprised 705 patients who underwent 16-lead ETT. Of these, 70 (10%) had positive ETT and CAD was confirmed by further evaluation in 26. ECG changes positive for ischemia were demonstrated on the standard 12-lead exercise ECG in 68 patients. An additional 2 patients had positive ECG alterations only in the 4 auxiliary leads on the 16-lead ECG. There was no significant difference in the sensitivity or positive predictive value between the 12- and 16-lead exercise ECG. CONCLUSION: Electrocardiographic changes in auxiliary leads did not change the diagnostic use of the ETT and therefore may provide only a minimal contribution to the assessment of the low-risk CPEU population.

Exercise testing in chest pain units: rationale, implementation, and results.

Chest pain units are now established centers for assessment of low-risk patients presenting to the emergency department with symptoms suggestive of acute coronary syndrome. Accelerated diagnostic protocols, of which treadmill testing is a key component, have been developed within these units for efficient evaluation of these patients. Studies of the last decade have established the utility of early exercise testing,which has been safe, accurate, and cost-effective in this setting. Specific diagnostic protocols vary, but most require 6 to 12 hours of observation by serial electrocardiography and cardiac injury markers to exclude infarction and high-risk unstable angina before proceeding to exercise testing. However, in the chest pain unit at UC Davis Medical Center,the approach includes "immediate" treadmill testing without a traditional process to rule out myocardial infarction. Extensive experience has validated this approach in a large, heterogeneous population. The optimal strategy for evaluating low-risk patients presenting to the emergency department with chest pain will continue to evolve based on current research and the development of new methods.