W. Drake

Duke University Medical Center, Durham, North Carolina, United States

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Publications (13)33.5 Total impact

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    ABSTRACT: Study Objectives: Currently many patients undergo ED-based stress testing to rule out acute coronary syndrome. These tests are dependent on imaging modalities that have limited availability. Our previous work demonstrated that myocardial ischemia does not significantly change N-terminal pro-B Type natriuretic peptide (proBNP) levels at 2 hours following stress tests. We hypothesized that delayed stress-delta ProBNP levels (difference between levels 4 hours after stress testing and baseline) would be higher in patients with myocardial ischemia on stress testing. Methods: Design: Prospective Case-Control Study. Study setting: ED-based observation unit in an urban academic medical center. Participants: Adult patients who were scheduled for exercise stress echocardiography as part of usual care were eligible and approached by trained research staff. Patients with acute myocardial infarction or heart failure were excluded. Clinical data was collected after informed consent. Plasma samples were obtained at baseline (pre-stress test) and 4 hours post-test and frozen for batch processing. All stress tests were interpreted as part of usual care by board-certified cardiologists blinded to stress-delta proBNP values. Stress test outcome data were compared to the clinical record for quality assurance by the principal investigator. Indeterminate studies were reviewed in conjunction with the clinical data from the medical record and adjudicated by one investigator who is a board-certified cardiologist. ProBNP concentrations (Roche Diagnostics) were measured by an investigator blinded to stress test outcomes. Cases were defined as those with stress-induced worsening of regional wall motion activity versus controls with normal stress test results. Nonparametric statistics (Wilcoxon test) were used due to skew. Absolute and relative (%) stress-delta proBNP levels were calculated and compared between groups after controlling for log-transformed baseline levels. Results: We enrolled 171 patients. The median age of participants was 51 (IQR 44, 59) years, 45.6% were men and 40.4% were African-American. Fifteen patients (8.8%) had myocardial ischemia on stress testing. The median baseline, 4-hour, and absolute and relative stress-delta proBNP values are shown in Table 1. Patients with myocardial ischemia had significantly higher 4-hour, absolute and relative stress delta proBNP levels. After adjusting for log-transformed baseline proBNP, there was a statistically significant difference in log-transformed 4-hour proBNP between patients with positive and negative stress test (p=0.0084). Conclusion: Delayed stress-delta proBNP values are significantly higher among patients with myocardial ischemia on stress testing even after accounting for baseline values. Further study on the clinical value of such a testing paradigm appears warranted.
    No preview · Conference Paper · Oct 2015
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    ABSTRACT: Study Objectives: Acute coronary blood flow insufficiency causes a spectrum of myocardial dysfunction that includes myocardial ischemia and myocardial necrosis. Currently, myocardial ischemia is distinguished by the lack of measurable cardiac troponin release. We hypothesized that a newer generation troponin assay with a lower detection level limit might be able to detect myocardial ischemia-induced troponin level changes (stress-delta levels) 4 hours after stress testing. Methods: We prospectively enrolled adult patients who were scheduled for exercise stress echocardiography as part of usual care in an ED-based observation unit at an urban academic hospital into a case-control study. Patients with acute myocardial infarction or heart failure were excluded by usual care protocols. After informed consent, trained research staff collected clinical data and plasma samples at baseline (pre-stress test) and 4 hours post-test. High sensitivity troponin T concentrations (Roche Diagnostics) were measured on these samples by an investigator blinded to clinical data and stress test results. Stress tests were interpreted as per usual care by board-certified cardiologists blinded to stress-delta troponin values. The principal investigator audited stress test outcome data for quality assurance. A board-certified cardiologist investigator adjudicated indeterminate stress test results after reviewing the clinical record. Cases were defined as those with stress-induced worsening of regional wall motion activity whereas controls were patients with normal stress test imaging results. Absolute (4-hour levels minus baseline levels) and relative (%) stress-delta troponin T levels were calculated and compared between groups using nonparametric Wilcoxon test. Additionally, log-transformed 4-hour troponin T levels were compared using linear regression while controlling for log-transformed baseline levels. Results: A total of 169 patients were enrolled with 15 patients (8.8%) having myocardial ischemia on stress testing. The median age was 52 (IQR 44, 59) years, 45.6% were men and 40.2% were African-American. The median baseline, 4-hour, and absolute and relative stress-delta troponin T values are shown in Table 1. There were no significant differences in absolute or relative 4-hour stress-delta troponin T levels or in log-transformed 4-hour levels after adjusting for log-transformed baseline levels (p=0.25). Conclusion: Myocardial ischemia is a distinct entity from myocardial infarction, distinguished by the lack of detectable troponin T release. Future studies should focus on developing better methods for identifying myocardial ischemia.
    No preview · Conference Paper · Oct 2015

  • No preview · Article · Mar 2014 · Wilderness and Environmental Medicine

  • No preview · Article · Oct 2013 · Annals of Emergency Medicine

  • No preview · Article · Oct 2013 · Annals of Emergency Medicine
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    ABSTRACT: The Thrombolysis in Myocardial Infarction (TIMI) score is a validated tool for risk stratification of acute coronary syndrome. We hypothesized that the TIMI risk score would be able to risk stratify patients in observation unit for acute coronary syndrome. Study design: Retrospective cohort study of consecutive adult patients placed in an urban academic hospital emergency department observation unit with an average annual census of 65,000 between 2004 and 2007. Exclusion criteria included elevated initial cardiac biomarkers, ST segment changes on ECG, unstable vital signs, or unstable arrhythmias. A composite of significant coronary artery disease (CAD) indicators, including diagnosis of myocardial infarction, percutaneous coronary intervention, coronary artery bypass surgery, or death within 30 days and 1 year, were abstracted via chart review and financial record query. The entire cohort was stratified by TIMI risk scores (0-7) and composite event rates with 95% confidence interval were calculated. In total 2228 patients were analyzed. Average age was 54.5 years, 42.0% were male. The overall median TIMI risk score was 1. Eighty (3.6%) patients had 30-day and 119 (5.3%) had 1-year CAD indicators. There was a trend toward increasing rate of composite CAD indicators at 30 days and 1 year with increasing TIMI score, ranging from a 1.2% event rate at 30 days and 1.9% at 1 year for TIMI score of 0 and 12.5% at 30 days and 21.4% at 1 year for TIMI ≥4. In an observation unit cohort, the TIMI risk score is able to risk stratify patients into low-, moderate-, and high-risk groups.
    Full-text · Article · Sep 2013 · Critical pathways in cardiology
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    ABSTRACT: BACKGROUND: Determining which patients presenting to the Emergency Department (ED) require further work-up for acute coronary syndrome (ACS) can be difficult. The utility of routine observation for cardiac testing in low-risk young adult patients has been questioned. STUDY OBJECTIVES: We investigated the rate of positive findings yielded by routine cardiac observation unit work-up in patients aged 40 years or younger. METHODS: This was a retrospective observational cohort study of patients aged 18-40 years who were evaluated for ACS in an ED-based observation unit. Data were collected by trained abstractors from electronic medical records. RESULTS: A total of 362 patients met inclusion criteria. Of those, 239 received stress testing, yielding five positive and nine indeterminate results. One other patient had acute troponin elevation while under observation. The positive stress test patients and troponin-elevated patient underwent cardiac angiography. Only one positive stress test patient showed significant coronary stenosis and received coronary interventions. In follow-up data, one patient had an adverse cardiac outcome within 1 year of index visit, but no coronary interventions. Thus, only 3 patients had adverse cardiac events, with only one patient warranting intervention discovered by observation unit stress testing and a second via serial cardiac markers. CONCLUSION: Routine observation of symptomatic young adults for ACS had low yield. Observation identified one patient with acute cardiac marker elevation and further stress testing identified only one patient with intervenable ACS, despite a high false-positive rate. This suggests that observation and stress testing should not be routinely performed in this demographic absent other high-risk features.
    Full-text · Article · Sep 2012 · Journal of Emergency Medicine
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    ABSTRACT: There are unique challenges to enrolling patients in emergency department (ED) clinical research studies, including the time-sensitive nature of emergency conditions, the acute care environment, and the lack of an established relationship with patients. Prolonged ED wait times have been associated with a variety of adverse effects on patient care. The objective of this study was to assess the effect of ED wait times on patient participation in ED clinical research. The hypothesis was that increased ED wait times would be associated with reduced ED clinical research consent rates. This was a retrospective cohort study of all patients eligible for two diagnostic clinical research studies from January 1, 2008, through December 31, 2008, in an urban academic ED. Sex, age, race, study eligibility, and research consent decisions were recorded by trained study personnel. The wait times to registration and to be seen by a physician were obtained from administrative databases and compared between consenters and nonconsenters. An analysis of association between patient wait times for the outcome of consent to participate was performed using a multivariate logistic regression model. A total of 903 patients were eligible for enrollment and were asked for consent. Overall, 589 eligible patients (65%) gave consent to research participation. The consent rates did not change when patients were stratified by the highest and lowest quartile wait times for both time from arrival to registration (68% vs. 65%, p = 0.35) and time to be seen by a physician (65% vs. 66%, p = 0.58). After adjusting for patient demographics (age, race, and sex) and study, there was still no relationship between wait times and consent (p > 0.4 for both wait times). Furthermore, median time from arrival to registration did not differ between those who consented to participate (15 minutes; interquartile range [IQR] = 9 to 36 minutes) versus those who did not (15.5 minutes; IQR = 10 to 39 minutes; p = 0.80; odds ratio [OR] = 1.00, 95% confidence interval [CI] = 0.99 to 1.01). Similarly, there was no difference in the median time to be seen by a physician between those who consented (25 minutes; IQR = 15 to 55 minutes) versus those who did not (25 minutes; IQR = 15 to 56 minutes; p = 0.70; OR = 1.00, 95% CI = 0.99 to 1.01). Regardless of wait times, nearly two-thirds of eligible patients were willing to consent to diagnostic research studies in the ED. These findings suggest that effective enrollment in clinical research is possible in the ED, despite challenges with prolonged wait times.
    Full-text · Article · Apr 2012 · Academic Emergency Medicine

  • No preview · Article · Oct 2011 · Annals of Emergency Medicine
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    ABSTRACT: Early recognition of left ventricular hypertrophy is important because antihypertensive treatment decreases morbidity and mortality. The ideal screening method for left ventricular hypertrophy in hypertensive emergency department (ED) patients has not been identified. Our objective was to determine the diagnostic accuracies of electrocardiogram (ECG) and N-terminal Pro-B-type natriuretic peptide (pro-BNP) for left ventricular hypertrophy individually and in combination in hypertensive ED patients. Prospective diagnostic study in an academic urban tertiary care hospital ED with annual census of 65,000 visits. Inclusion criteria are as follows: adult ED patients with systolic blood pressure greater than or equal to 160 mm Hg or diastolic blood pressure greater than or equal to 100 mm Hg on 2 or more measurements taken 60 minutes apart. Exclusion criteria are as follows: patients with heart failure, renal insufficiency/failure, acute myocardial infarction, or without recent or scheduled echocardiograms. All patients received echocardiograms and had pro-BNP levels measured using a RAMP point-of-care device (Response Biomedical, Vancouver, BC, Canada). We calculated diagnostic test characteristics with 95% confidence intervals (CIs). A total of 49 patients were enrolled. The average age was 57.9 years, 26.5% were male, and 63.3% were African American. Thirty-two patients (65%) had left ventricular hypertrophy by echocardiogram. Twenty-one (43%) had ECG evidence of left ventricular hypertrophy. Median pro-BNP level was 268 pg/mL. The combination of the 2 tests provided the greatest specificity (94%; 95% CI, 69%-99.7%) and positive predictive value (94%; 95% CI, (68%-99.7%). The combination of ECG and pro-BNP is a promising screening algorithm for identification of hypertensive ED patients with left ventricular hypertrophy.
    Full-text · Article · Dec 2010 · The American journal of emergency medicine

  • No preview · Article · Sep 2009 · Annals of Emergency Medicine
  • A. Chandra · D. Freeman · G. Mani · W. Drake · A. Limkakeng

    No preview · Article · Sep 2009 · Annals of Emergency Medicine

  • No preview · Article · Oct 2008 · Annals of Emergency Medicine