Increased ventricular ectopy precedes Torsades de Pointes in patients with prolonged QT.

OBJECTIVE: Torsades de Pointes (TdP) is a potentially lethal ventricular tachydysrhythmia. Prolonged heartrate corrected QT interval (QTc) predicts TdP; however, with poor specificity. We performed this study to identify other predictors of TdP among patients with prolonged QTc. METHODS: We performed a retrospective case control study with 2:1 matching at an urban academic hospital. We searched our hospital electrocardiogram (ECG) database for tracings with heartrate ≤ 60, QTc ≥ 500, and QRS < 120, followed by a natural language search for electronic records with "Torsades," "polymorphic VT," or similar to identify TdP cases from 2005 to 19. We identified controls from a similar ECG database search matching for QTc, heartrate, age, and sex. We compared cardiologic and historical factors, medications, laboratory values, and ECG measurements including ectopy using univariate statistics. For those cases with saved telemetry strips that included preceding beats or TdP onset, we compared ectopy and TdP onset characteristics between the ECG and telemetry strips using mixed linear modeling. RESULTS: Seventy-five cases including 50 with telemetry strips and 150 controls were included. Historical, pharmacologic, laboratory, and cardiologic testing results were similar between cases and controls. The proportion of telemetry tracings with premature ventricular contractions (PVC's) preceding TdP was 0.78 compared to 0.16 for case ECG's (difference 0.62(95%CI 0.44-0.75)) and 0.10 for control ECGs (difference 0.68(95%CI 0.56-0.80)). Average telemetry heartrate was 72 and QTc 549 immediately preceding TdP, similar to the ECG values. CONCLUSIONS: Clinical factors don't differentiate patients with long QTc who develop TdP, however, an increase in PVC's in patients with prolonged QTc may usefully predict imminent TdP.

Atrial Fibrillation Occurring During Acute Hospitalization: A Scientific Statement From the American Heart Association.

Acute atrial fibrillation is defined as atrial fibrillation detected in the setting of acute care or acute illness; atrial fibrillation may be detected or managed for the first time during acute hospitalization for another condition. Atrial fibrillation after cardiothoracic surgery is a distinct type of acute atrial fibrillation. Acute atrial fibrillation is associated with high risk of long-term atrial fibrillation recurrence, warranting clinical attention during acute hospitalization and over long-term follow-up. A framework of substrates and triggers can be useful for evaluating and managing acute atrial fibrillation. Acute management requires a multipronged approach with interdisciplinary care collaboration, tailoring treatments to the patient's underlying substrate and acute condition. Key components of acute management include identification and treatment of triggers, selection and implementation of rate/rhythm control, and management of anticoagulation. Acute rate or rhythm control strategy should be individualized with consideration of the patient's capacity to tolerate rapid rates or atrioventricular dyssynchrony, and the patient's ability to tolerate the risk of the therapeutic strategy. Given the high risks of atrial fibrillation recurrence in patients with acute atrial fibrillation, clinical follow-up and heart rhythm monitoring are warranted. Long-term management is guided by patient substrate, with implications for intensity of heart rhythm monitoring, anticoagulation, and considerations for rhythm management strategies. Overall management of acute atrial fibrillation addresses substrates and triggers. The 3As of acute management are acute triggers, atrial fibrillation rate/rhythm management, and anticoagulation. The 2As and 2Ms of long-term management include monitoring of heart rhythm and modification of lifestyle and risk factors, in addition to considerations for atrial fibrillation rate/rhythm management and anticoagulation. Several gaps in knowledge related to acute atrial fibrillation exist and warrant future research.

Electrocardiographic measures of repolarization heterogeneity are not predictive for Torsades de Pointes among undifferentiated patients with prolonged QTc: A case control study.

INTRODUCTION: Torsades de Pointes (TdP) is a potentially lethal polymorphic ventricular tachydysrhythmia associated with and caused by prolonged myocardial repolarization. However, prediction of TdP is challenging. We sought to determine if electrocardiographic myocardial repolarization heterogeneity is necessary and predictive of TdP. METHODS: We performed a case control study of TdP at a large urban hospital. We identified cases based on a hospital center electrocardiogram (ECG) database search for tracings from 1/2005 to 6/2019 with heart rate corrected QT (QTc) > 500, QRS < 120, and heart rate (HR) < 60, and a subsequent natural language search of electronic health records for the terms: TdP, polymorphic ventricular tachycardia, sudden cardiac death, and relevant variants. Controls were drawn in a 2:1 ratio to cases from a similar pool of ECGs, and matching for QTc, heart rate, sex, and age. We abstracted historical, laboratory, and ECG data using detailed written instructions and an electronic database. We included a second blinded data abstractor to test data abstraction and manual ECG measurement reliability. We used General Electric (GE) QT Guard software for automated repolarization measurements. We compared groups using unpaired statistics. RESULTS: We included 75 cases and 150 controls. The number of current QTc prolonging medications and serum electrolytes were substantially the same between the two groups. We found no significant difference in measures of QT or T wave repolarization heterogeneity. CONCLUSION: Electrocardiographic repolarization heterogeneity is not greater in otherwise unselected patients with QTc prolongation who suffer TdP and does not appear predictive of TdP. However, previous observations suggest specific repolarization characteristics may be useful for defined patient subgroups at risk for TdP.

Diagnostic and prognostic test assessment in emergency medicine: likelihood and diagnostic odds ratios.

Emergency physicians use diagnostic and prognostic tests on a daily basis to assess for life-threatening illness and to inform clinical decisions. Current and new tests must be scientifically evaluated for their diagnostic utility. We discuss the evaluation of diagnostic and prognostic tests using the Bayesian likelihood ratio (LR) and logistic regression diagnostic odds ratio (OR) frameworks. These approaches can be applied to a single test in isolation using univariate techniques, or to a group of tests as commonly applied in clinical practice using multivariate methods. We compare and contrast the relative benefits and challenges of the LR and OR approaches, and assess their interchangeability. The concepts of diagnostic multivariate testing also underlie the framework of clinical decision rules which have gained acceptance in emergency medicine. Clinical decision rules can be viewed as a subanalysis within the joint LR framework. Ultimately, a variety of approaches may be acceptable and even complementary to assess a diagnostic test, each with its own merits and limitations.

Carotid Ultrasound in Assessing Fluid Responsiveness in Patients with Hypotension and Suspected Sepsis.

PURPOSE: We sought to assess whether ultrasound (US) measurements of carotid flow time (CFTc) and carotid blood flow (CBF) predict fluid responsiveness in patients with suspected sepsis. METHODS: This was a prospective observational study of hypotensive (systolic blood pressure < 90) patients "at risk" for sepsis receiving intravenous fluids (IVF) in the emergency department. US measurements of CFTc and CBF were performed at time zero and upon completion of IVF. All US measurements were repeated after a passive leg raise (PLR) maneuver. Fluid responsiveness was defined as normalization of blood pressure without persistent hypotension or need for vasopressors. RESULTS: A convenience sample of 69 patients was enrolled. The mean age was 65; 49% were female. Fluid responders comprised 52% of the cohort. CFTc values increased significantly with both PLR (P = 0.047) and IVF administration (P = 0.003), but CBF values did not (P = 0.924 and P = 0.064 respectively). Neither absolute CFTc or CBF measures, nor changes in these values with PLR or IVF bolus, predicted fluid responsiveness, mortality, or the need for intensive care unit admission. CONCLUSION: In patients with suspected sepsis, a fluid challenge resulted in a significant change in CFTc, but not CBF. Neither absolute measurement nor delta measurements with fluid challenge predicted clinical outcomes.

Confidence at 100%: Characteristics of Likelihood Ratio Confidence Intervals in the Emergency Medicine Diagnostics Literature.

OBJECTIVE: We hypothesized that "perfect" 100% sample sensitivity or specificity (PSSS) is common in the emergency medicine (EM) literature. When results yield PSSS, calculating the likelihood ratio (LR) 95% confidence interval (CI) has been challenging. Consequently, we also hypothesized that studies with PSSS would be less likely to report the LR and associated CI, and those that did would use imperfect methods. METHODS: We searched PubMed or Scopus for all articles reporting diagnostic test results in the 20 top EM journals from 2011 to 2016 and randomly sampled 124 articles. Trained researchers coded the articles as having PSSS or not ("controls"). We separately sampled 100 articles with PSSS and compared them to 100 controls in terms of their reporting of diagnostic tests and associated CIs. RESULTS: Of the 124 articles, 19.4% (95% CI = 13% to 27.6%) feature a diagnostic test with PSSS. The LR is reported significantly less often in PSSS studies versus control studies: 18 of 100 articles (18% [95% CI = 11.3% to 27.2%]) versus 34 of 100 articles (34% [95% CI = 25% to 44.2%]), with an odds ratio (OR) of 0.43 (95% CI = 0.21 to 0.86). The LR 95% CI is also reported less often in PSSS versus control studies: five of 100 articles (5% [95% CI = 1.9% to 11.8%]) versus 27 of 100 articles (27% [95% CI = 18.8% to 37%]), with an OR of 0.11 (95% CI = 0.02 to 0.44). Five articles with perfect sample sensitivity reported their negative LR CI. The bootstrap method resulted in CIs that were 42.7% smaller on average (range = 16.6% to 63.6%). CONCLUSION: This analysis provides systematic evidence of diagnostic test reporting in the EM literature. Sample sensitivity or specificity of 100% is common. LRs and their associated 95% CIs are infrequently reported, particularly for PSSS samples. When the LR CI is reported in this scenario, it is overly wide. Improved reporting and methods can enhance the utility and confidence in diagnostic tests in EM.

Synchronized Chest Compressions for Pseudo-PEA: Proof of Concept and a Synching Algorithm.

Objective: The two objectives of this report are: first, to describe a comparison of chest compressions unsynchronized or synchronized to native cardiac activity in a porcine model of hypotension, and second, to develop an algorithm to provide synchronized chest compressions throughout a range of native heart rates likely to be encountered when treating PEA cardiac arrest. Methods: We adapted our previously developed signal-guided CPR system to provide compressions synchronized to native electrical activity in a porcine model of hypotension as a surrogate of PEA arrest. We describe the first comparison of unsynchronized to synchronized compressions in a single animal as a proof-of-concept. We developed an algorithm to provide optimal synchronized chest compressions regardless of intrinsic PEA heart rate while simultaneously maintaining the chest compression rate within a desired range. We tested the algorithm with computer simulations measuring the proportion of intrinsic and compression beats that were synchronized, and the compression rate and its standard deviation, as a function of intrinsic heart rate and heart rate jitter. Results: We demonstrate and compare unsynchronized versus synchronized chest compressions in a single porcine model with an intrinsic rhythm and hypotension. Synchronized, but not unsynchronized, chest compressions were associated with increased blood pressure and coronary perfusion pressure. Our synchronized chest compression algorithm is able to provide synchronized chest compressions to over 90% of intrinsic beats for most heart rates while maintaining an average compression rate between 90 and 140 compressions per minute with relatively low variability. Conclusions: Synchronized chest compression therapy for pulseless electrical rhythms is feasible. A high degree of synchronization can be maintained over a broad range of intrinsic heart rates while maintaining the compression rate within a satisfactory range. Further investigation to assess benefit for treatment of PEA is warranted.

Cardioplegia defibrillation of circulatory and metabolic phase ventricular fibrillation in a swine model.

INTRODUCTION: We previously found potassium cardioplegia followed by rapid calcium reversal (Kplegia) can achieve defibrillation in a swine model of electrical phase of ventricular fibrillation (VF) comparable to standard care. HYPOTHESIS: Exploring 3 possible potassium dose and timing protocols, we hypothesize Kplegia may benefit resuscitation of longer duration untreated VF. METHODS: Three separate blinded randomized placebo-controlled trials were performed with electrically-induced VF untreated for durations of 6, 9, and 12min in a swine model. Experimental groups received infusion of 1 or 2 boluses of intravenous (IV) potassium followed by a single calcium reversal bolus. Potassium was replaced by saline in the control groups. Outcomes included: amplitude spectrum area (AMSA) during VF, resulting rhythms, number of defibrillations, return of spontaneous circulation (ROSC), and hemodynamics for 1h post ROSC. Binomial and interval data outcomes were compared with exact statistics. Serial interval data were assessed with mixed regression models. RESULTS: Twelve, 12, and 8 animals were included at 6, 9, and 12min VF durations for a total of 32. ROSC was achieved in: 4/6 Kplegia and 3/6 control animals in the 6min protocol, (p=1.00), 4/6 Kplegia and 2/6 control animals in the 9min protocol,(p=0.57), and 0/5 Kplegia and 1/3 control animals in the 12min protocol,(p=0.38). Two of 8 Kplegia animals achieved ROSC with chemical defibrillation alone. CONCLUSIONS: The majority of animals achieved ROSC after up to 9min of untreated VF arrest using K plegia protocols. K plegia requires further optimization for both peripheral IV and intraosseous infusion, and to assess for superiority over standard care. Institutional Animal Care and Use Committee protocol #15127224.

A High-yield Fall Risk and Adverse Events Screening Questions From the Stopping Elderly Accidents, Death, and Injuries (STEADI) Guideline for Older Emergency Department Fall Patients.

OBJECTIVES: The objectives were to examine whether responses to the Stopping Elderly Accidents, Death, and Injuries (STEADI) questions responses predicted adverse events after an older adult emergency department (ED) fall visits and to identify factors associated with such recurrent fall. METHODS: We conducted a prospective study at two urban, teaching hospitals. We included patients aged ≥ 65 years who presented to the ED for an accidental fall. Data were gathered for fall-relevant comorbidities, high-risk medications for falls, and the responses to 12 questions from the STEADI guideline recommendation. Our outcomes were the number of 6-month adverse events that were defined as mortality, ED revisit, subsequent hospitalization, recurrent falls, and a composite outcome. RESULTS: There were 548 (86.3%) patients who completed follow-up and 243 (44.3%) patients experienced an adverse event after a fall within 6 months. In multivariate analysis, seven questions from the STEADI guideline predicted various outcomes. The question "Had previous fall" predicted recurrent falls (odds ratio [OR] = 2.45, 95% confidence interval [CI] = 1.52 to 3.97), the question "Feels unsteady when walking sometimes" (OR = 2.34, 95% CI = 1.44 to 3.81), and "Lost some feeling in their feet" predicted recurrent falls. In addition to recurrent falls risk, the supplemental questions "Use or have been advised to use a cane or walker," "Take medication that sometimes makes them feel light-headed or more tired than usual," "Take medication to help sleep or improve mood," and "Have to rush to a toilet" predicted other outcomes. CONCLUSION: A STEADI score of ≥4 did not predict adverse outcomes although seven individual questions from the STEADI guidelines were associated with increased adverse outcomes within 6 months. These may be organized into three categories (previous falls, physical activity, and high-risk medications) and may assist emergency physicians to evaluate and refer high-risk fall patients for a comprehensive falls evaluation.

Is myocardial repolarization duration associated with repolarization heterogeneity?

BACKGROUND: Dispersion of repolarization is theorized as one mechanism by which myocardial repolarization prolongation causes lethal torsades de pointes, (TdP). Our primary purpose was to determine whether prolongation of myocardial repolarization as measured by the heart rate-corrected J-to-T peak interval (JTpkc), is associated with repolarization heterogeneity as measured by transmural dispersion, defined as the median duration from the peak to the end of the T wave (TpTe). METHODS: A retrospective cohort study was performed at a single urban tertiary ED from July 2011-September 2012. Inclusion criteria included all consecutive ED patients with ECG based on QTc and QRS intervals. Automated measurements of all intervals were performed. The association of JTpkc with the dependent variable TpTe was assessed after adjustment for QRS and RR interval durations with a multiple linear regression model. A secondary analysis included a similar adjusted assessment of the association of JTpkc with QT dispersion, QTd. Finally, we constructed two multiple regression models to assess the association of clinical causative factors of TdP with TpTe and JTpkc. RESULTS: Eight hundred seventy-four cases were included: 186 with QTc <500 ms, 118 with QTc ≥500 and QRS ≥120 ms, and 570 with QTc ≥500 and QRS <120 ms. The coefficient for association of JTpkc with TpTe was -0.10 (95%CI -0.15 to -0.05), and for JTpkc with QTd was 0.03 (95% CI -0.01 to 0.06). Clinical causative TdP factors were associated more with JTpkc than TpTe. CONCLUSION: Repolarization duration as measured by JTpkc is not positively associated with dispersion of repolarization as measured by TpTe or QTd. Dispersion of repolarization may not be a critical mechanistic link between QTc prolongation and TdP.

Hypokalemia in women and methadone therapy are the strongest non-cardiologic factors associated with QT prolongation in an emergency department setting.

BACKGROUND: Our primary objective was to determine the adjusted quantitative associations of clinical predictors with QT prolongation, a defining cause of Torsades de Pointes (TdP). METHODS: A retrospective cohort study was performed on consecutive emergency department patients identified by ECG acquisition date, and heart rate corrected QT (QTc) and QRS durations. QTc was modeled as a function of clinical predictors with multiple linear regression. RESULTS: 1010 patients were included. The strongest predictors of QTc and their coefficients were: antidysrhythmic (26.1ms, 95% CI 15.6-36.6) and methadone (43.6ms, 95% CI 28.1-59.2) therapies, and genetic long QT syndrome diagnosis (32.6ms, 95% CI -4.7-70.0). The association of QTc with serum potassium was approximated by a two piecewise linear function that differed by sex. For potassium below 3.9mmol/L, QTc increased by 43.0ms (95% CI 26.2-59.7) and 29.5ms (95% CI 19.1-40.0) for every 1mmol/L decrease in potassium in women and men, respectively. TdP occurred in only 4/686 (0.6%) of patients with QTc≥500 and QRS<120, but mortality during the visit including hospitalization was 8.0%. CONCLUSIONS: QTc duration is highly sensitive to hypokalemia, particularly in women. Methadone prolongs QTc remarkably compared to other non-cardiologic medicines. QTc>500 with normal QRS often signifies profound illness and substantial mortality risk, though not necessarily imminent TdP.

Estimating negative likelihood ratio confidence when test sensitivity is 100%: A bootstrapping approach.

Objectives Assessing high-sensitivity tests for mortal illness is crucial in emergency and critical care medicine. Estimating the 95% confidence interval (CI) of the likelihood ratio (LR) can be challenging when sample sensitivity is 100%. We aimed to develop, compare, and automate a bootstrapping method to estimate the negative LR CI when sample sensitivity is 100%. Methods The lowest population sensitivity that is most likely to yield sample sensitivity 100% is located using the binomial distribution. Random binomial samples generated using this population sensitivity are then used in the LR bootstrap. A free R program, "bootLR," automates the process. Extensive simulations were performed to determine how often the LR bootstrap and comparator method 95% CIs cover the true population negative LR value. Finally, the 95% CI was compared for theoretical sample sizes and sensitivities approaching and including 100% using: (1) a technique of individual extremes, (2) SAS software based on the technique of Gart and Nam, (3) the Score CI (as implemented in the StatXact, SAS, and R PropCI package), and (4) the bootstrapping technique. Results The bootstrapping approach demonstrates appropriate coverage of the nominal 95% CI over a spectrum of populations and sample sizes. Considering a study of sample size 200 with 100 patients with disease, and specificity 60%, the lowest population sensitivity with median sample sensitivity 100% is 99.31%. When all 100 patients with disease test positive, the negative LR 95% CIs are: individual extremes technique (0,0.073), StatXact (0,0.064), SAS Score method (0,0.057), R PropCI (0,0.062), and bootstrap (0,0.048). Similar trends were observed for other sample sizes. Conclusions When study samples demonstrate 100% sensitivity, available methods may yield inappropriately wide negative LR CIs. An alternative bootstrapping approach and accompanying free open-source R package were developed to yield realistic estimates easily. This methodology and implementation are applicable to other binomial proportions with homogeneous responses.

Concordance of Brain and Core Temperature in Comatose Patients After Cardiac Arrest.

Comatose patients after cardiac arrest should receive active targeted temperature management (TTM), with a goal core temperature of 32-36°C for at least 24 hours. Small variations in brain temperature may confer or mitigate a substantial degree of neuroprotection, which may be lost at temperatures near 37°C. The purpose of this study was to define the relationship between brain and core temperature after cardiac arrest through direct, simultaneous measurement of both. We placed intracranial monitors in a series of consecutive patients hospitalized for cardiac arrest at a single tertiary care facility within 12 hours of return of spontaneous circulation to guide postcardiac arrest care. We compared the absolute difference between brain and core (esophageal or rectal) temperature measurements every hour for the duration of intracranial monitoring and tested for a lag between brain and core temperature using the average square difference method. Overall, 11 patients underwent simultaneous brain and core temperature monitoring for a total of 906 hours of data (Median 95; IQR: 15-118 hours per subject). On average, brain temperature was 0.34C° (95% confidence interval [CI] 0.31-0.37) higher than core temperature. In 7% of observations, brain temperature exceeded the measured core temperature ≥1°C. Brain temperature lagged behind core temperature by 0.45 hours (95% CI = -0.27-1.27 hours). Brain temperature averages 0.34°C higher than core temperature after cardiac arrest, and is more than 1°C higher than core temperature 7% of the time. This phenomenon must be considered when carrying out TTM to a goal core temperature of <36°C.

Energy conserving chemical defibrillation of ventricular fibrillation: A randomized two phase controlled blinded trial.

OBJECTIVES: Potassium cardioplegia-induced transient asystole may conserve myocardial energy, foster chemical defribrillation, and improve VF arrest outcome. A trial of potassium infusion with or without calcium reversal was conducted to test for improvement in intra-arrest VF waveform and post-ROSC hemodynamics. METHODS: Eighteen swine were randomized to three treatment arms in two phases. VF was electrically induced and untreated for 4min. The animals then received 6min of mechanical CPR. Blinded investigators infused two study medicines peripherally during this interval. One group received 1.5mEq/kg KCl with CPR initiation followed 3min later by CaCl 10% infusion 0.12cm(3)/kg, the second group received 1.5mEq/kg KCl without CaCl, and the third group received placebo infusions. Ten minutes post VF initiation, defibrillation was performed, as appropriate, followed by ACLS for continued arrest or observation for 30min if ROSC. AMSA change from before to 5min post study drug infusion was compared with nonparametric statistics. MAP post ROSC was compared using mixed linear regression analysis. RESULTS: Average normalized AMSA change was -0.15, -0.63, and +0.27 in the KCl, KCl+CaCl, and placebo groups, respectively (p=0.01). Three KCl+CaCl animals developed on organized rhythm chemically without electrical defibrillation. One, 3, and 4 animals in the KCl, KCl+CaCl, and placebo groups, respectively, survived post ROSC. Post ROSC, MAP decreased 1.8mmHg (95% CI -1.4 to 5.1) min(-1) less in the KCl+CaCl group compared to placebo. CONCLUSIONS: Chemical defibrillation and ROSC are possible post potassium-induced asystole. Potassium followed by calcium reversal, but not potassium alone, led to ROSC and post-ROSC hemodynamics comparable to recommended therapy.

Differentiating Types of Wide-Complex Tachycardia to Determine Appropriate Treatment in the Emergency Department.

Wide-complex tachycardia is a rare disease entity among patients presenting to the emergency department. However, due to its potential life-threatening nature, emergency clinicians must know how to assess and manage this condition. Wide-complex tachycardia encompasses a range of cardiac dysrhythmias, some of which can be difficult to distinguish and may require specific treatment approaches. This review summarizes the etiology and pathophysiology of wide-complex tachycardia, describes the differential diagnosis, and presents an evidence-based approach to identification of the different types of tachycardias through the use of a thorough history and physical examination, vagal maneuvers, electrocardiography, and adenosine. The treatment options and disposition for patients with various wide-complex tachycardias are also discussed, with attention to special circumstances and select controversial/contemporary topics.

Aortic dissection associated with blunt chest trauma diagnosed by elevated D-dimer.

INTRODUCTION: Similar to spontaneous aortic dissection, traumatic aortic dissection is diagnosed with a careful history and physical exam, chest radiograph, and ultimately, dedicated aortic imaging. The diagnosis of spontaneous aortic dissection may be aided by using the serum D-dimer test. The use of D-dimer for diagnosing aortic injury in the setting of blunt trauma has not previously been reported. PRESENTATION OF CASE: We present a case of aortic dissection in a 61-year-old male diagnosed when the patient presented with chest pain after blunt chest trauma. DISCUSSION: The patient had no known history or risk factors for aortic disease. None of the classic findings were present by history, physical examination or chest radiograph and the diagnosis was made as the result of an elevated D-dimer. We discuss how the D-dimer test fortuitously led to the diagnosis in this case, and the implications. CONCLUSION: D-dimer could be helpful in diagnosing aortic injuries in low-risk chest trauma patients.