Atrial Fibrillation, You’re a Heart Breaker, Dream Maker, Love Taker:

But At Least There is Low Risk for Thromboembolic Events With Speedy Conversion to Sinus Rhythm…

This post reviews the article from Weigner, Marilyn et al. “Risk for Clinical Thromboembolism Associated with Conversion to Sinus Rhythm in Patients with Atrial Fibrillation Lasting Less Than 48 Hours,” from the Annals of Internal Medicine in 1997 as part of the ongoing 52 article series.

Main Points:

  1. This article reveals only a 0.8% risk of clinical thromboembolic event for patients who were clinically estimated to be in atrial fibrillation for less than 48 hours.
  1. This trial data supports the recommendation for early cardioversion, either pharmacologic or through electric cardioversion, in patients with recent onset of symptoms without the need for prior diagnostic imaging to evaluate for clot burden.

Background:

Atrial fibrillation is a common arrhythmia and responsible for over 250,000 hospital admissions annually. Patients often feel the effects of depressed cardiac output from the loss of atrial systole and seek medical attention in hopes of improved quality of life. Patients may describe a range of symptoms including palpitations, dyspnea, dizziness, angina and fatigue. Studies have demonstrated that patients with atrial fibrillation for more than two days may have a greater than five percent risk of clinical thromboembolism and often require weeks of anticoagulation or screening with transesophageal echocardiography prior to cardioversion. This study sought to answer the question of whether or not patients who experienced only a short duration of symptoms were low risk for thromboembolic disease.

Details:

This was a prospective study of consecutive patients at two academic medical centers, Beth Israel Deaconess Medical Center in Boston, MA and the John Dempsey Hospital and University of Connecticut Health Center in Farmington, CT. 1822 adult patients with a diagnosis of atrial fibrillation were screened and 375 patients who were clinically estimated to have symptoms for less than 48 hours were enrolled. Those patients whose duration of symptoms were unclear or had already initiated long term anticoagulation with warfarin were excluded. Patients with a previous history of thromboembolic events were not excluded, but one patient who had an acute thromboembolism was not enrolled in the trial. Clinical and transthoracic echocardiography data and outcomes were collected from review of the medical records. Clinical embolic events were considered if they occurred during the index hospitalization or within one month after conversion to sinus rhythm. Conditions that may have predisposed patients to atrial fibrillation included: previous history of atrial fibrillation (181 patients, 48.3%), hypertension (156, 41.7%), coronary artery disease (114, 30.4%), infection (25, 6.7%), history of thromboembolism (23, 6.1%), excessive alcohol use (22, 5.9%), rheumatic heart disease (7, 1.9%). Patients were noted to have left atrial dimensions of 4.2 +/- 0.7cm (normal ≤ 4.0cm) and a left atrial length of 5.7 +/- 0.7cm (normal ≤ 5.2cm) based on transthoracic echocardiogram data. 218 out of 280 patients who had echocardiograms performed were noted to have at least some evidence of mitral valve regurgitation with 61 patients noted to have either moderate or severe regurgitation.

Patients converted back to a normal sinus rhythm either spontaneously or through pharmacologic or electric cardioversion methods. Conversion was considered spontaneous if it occurred without the use of medications or electricity or in the setting of use of ventricular rate-controlling agents (digoxin, beta-blockers, and calcium channel blockers).

Three patients (0.8%, 95% CI 0.2-2.4) were noted to have a clinically significant thromboembolism and surprisingly all converted spontaneously. The cases included a left parietal embolic stroked in an 86 year old female with history of hypertension; a right proximal brachial artery embolus in an 83 year old female with coronary artery disease; and a transient ischemic attack in an 89 year old female with a recent diagnosis of pneumonia.

This study was a consecutive series that relied on both real time data gathering as well as retrospective chart review.

Level of Evidence:

This study was graded a level II based on the ACEP Clinical Policy Grading Scheme for prognostic questions and had only minimal methodological flaws.

Surprises:

The three patients in this trial were identified as having increased risk for thromboembolism based of the Stroke Prevention and Atrial Fibrillation Study I and II, however, how best to achieve post conversion anticoagulation in the era of direct oral anticoagulants remains a hot topic for further study and debate.

Relevant articles:

Mookadam, M. Shamoun FE. Mookadam, F. “Novel Anticoagulants in Atrial Fibrillation: A Primer for the Primary Physician.” J Am Board Fam Med, 2015, 28(4):510-22

Source Articles:

Weigner, M. Caulfield, T. Danias, P. et al. “Risk for Clinical Thromboembolism Associated with Conversion to Sinus Rhythm in Patients with Atrial Fibrillation Lasting Less Than 48 Hours.” Annals of Internal Medicine, 1997, (126):615-20.

Faculty Reviewer: Dr. Siket

Spare the Tube, Save a Life

This is part of a recurring series examining landmark articles in Emergency Medicine, in the style of ALiEM’s 52 Articles.

Discussing:

Brochard, L. Mancebo, J. Wtsocki, M. et al. “Noninvasive Ventilation for Acute Exacerbations of Chronic Obstructive Pulmonary Disease.” NEJM 1995, 333(13):817-22.

Main Points:

  1. In this randomized prospective multicenter trial of 85 patients admitted to ICUs throughout Europe with COPD exacerbations, noninvasive ventilation reduced the need for endotracheal intubation, length of stay and in-hospital mortality rate.
  1. 31 of the 42 patients in the standard arm required intubation, compared to 11 of 43 patients in the noninvasive arm (p<0.001). These results were consistent among the five centers studied. The mortality rate and length of stay was similar in the two groups in whom endotracheal intubation was required, suggesting that the benefits observed in noninvasive ventilation resulted from lower rates of intubation.
Figure 1. Mask used to deliver noninvasive ventilation

Figure 1. Mask used to deliver noninvasive ventilation

Background:

COPD exacerbations often manifest as acute hypercapnic ventilatory failure and endotracheal intubation can be a life-saving procedure. This intervention, however, is not without associated risks both during the time of the procedure as well as later in the course of the patient’s care. This patient population is at risk for hemodynamic compromise during intubation and may be difficult to manage on the ventilator due to a multitude of concerns including air trapping and tachypnea. The risk for ventilator associated pneumonia and other complications secondary to being intubated for prolonged periods of time are also worth considering.

Brochard and his colleagues investigated the use of noninvasive ventilation in COPD exacerbations in hopes of reducing mortality through the reduction of intubation. Thiswas a multicenter prospective randomized study that recruited patients in five European ICUs. The primary and secondary outcomes were patient-centered and this article from 1995 has clearly framed the manner in which we manage the sick COPD patient today. The medications used and manner in which noninvasive ventilation is employed has evolved since the publication and a comprehensive review of management was published in 2010 by the American Academy of Family Physicians. ACEP also has published clinical guidelines on use of noninvasive ventilation in 2010.

Details:

This prospective multicenter study enrolled 85 out of 275 patients admitted to the ICU with COPD or a high probability of the disease based on careful history, physical examination and chest x-ray. Patients were selected if they had a respiratory acidosis and elevated bicarbonate level. Additional criteria included dyspnea for less than two weeks and at least two of the following: respiratory rate >30 BPM, partial pressure of arterial O2 <45 mm Hg, arterial pH <7.35 after the patient was breathing room air for at least 10 minutes. The exclusion criteria included: respiratory rate <12 BPM, need for immediate intubation-defined by strict criteria in the paper, already intubated, use of sedative drugs in the past 12 hours, CNS disorder, cardiac arrest in the past five days, cardiogenic pulmonary edema, neuromuscular or skeletal disorder, upper airway obstruction or asthma, clear cause of decompensation requiring treatment, or facial deformity. Patients were either assigned to the standard arm which included treatment with: maximum of 5LPM O2 by nasal prongs with goal O2 saturation >90%, medications such as subcutaneous heparin, antibiotic agents and bronchodilators (subcutaneous terbutaline, aerosolized or intravenous albuterol, corticosteroids or intravenous aminophylline), correction of electrolytes. The noninvasive arm received the same medications with the addition of periods of noninvasive ventilation. The same apparatus was used at all five sites to deliver pressure support of 20 cm H20 with an expiratory pressure that was atmospheric. Patients underwent noninvasive ventilation for at least six hours a day with overall duration determined by clinical criteria and arterial blood gal levels.

In order to standardize care, the authors created major and minor criteria as objective markers for the need to perform endotracheal intubation. The major criteria included: respiratory arrest, respiratory failure with LOC or gasping for air, psychomotor agitation making nursing care impossible and requiring sedation, HR<50 BPM with loss of alertness, hemodynamic instability with SBP <70 mm Hg. There was a series of minor criteria also relating to vital sign instability, mental status changes or arterial pH <7.3. In both groups the presence of one major criterion was an indication for intubation. After the first hour of treatment the presence of two minor criteria was an indication for intubation.

Patients were evaluated at the one hour, three hour and 12 hour mark following the initiation of therapy. The primary outcome examined was the need for endotracheal intubation with secondary end points including length of stay, complications not present on admission (pneumonia, barotrauma, gastrointestinal hemorrhage, renal insufficiency, neurologic events and pulmonary embolism), duration of ventilatory assistance, and mortality rate during hospitalization. 31 of the 42 patients in the standard arm required intubation, compared to 11 of 43 patients in the noninvasive arm (p<0.001). Per the authors, these results were consistent among the five centers studied, however, examining table 2 sites one and two seemed to have high percentages of intubation, 100 and 83 percent respectively, compared to the others. This may be skewed by the overall low numbers studied. Patients who ultimately were intubated both in the standard and noninvasive arms had extended ventilation time with 17 +/- 21 days and 25 +/- 17 days respectively. Complications and events leading to death are shown in Table 4.

Level of Evidence:

This study was graded a level I based on the ACEP Clinical Policy Grading Scheme for therapeutic questions.

Surprises:

The use of pressure support of 20/0 is quite different from the manner in which many providers initiate noninvasive ventilation today. This may be secondary to the limitations of the technology at the time because the photograph in figure 1 (see above) displays a mask that appears different from what you find on modern machines.

Relevant articles:

Ahn, J. Pillow, T. “Focus On: Noninvasive Positive Pressure Ventilation in the Emergency Department.” 2010, http://www.acep.org/Clinical—Practice-Management/Focus-On–Noninvasive-Positive-Pressure-Ventilation-In-the-Emergency-Department/

Evensen, A. “Management of COPD Exacerbation.” Am Fam Physician 2010, 81(5): 607-13. http://www.aafp.org/afp/2010/0301/p607.html

Faculty Reviewer: Dr. Siket

Source Articles:

Brochard, L. Mancebo, J. Wtsocki, M. et al. “Noninvasive Ventilation for Acute Exacerbations of Chronic Obstructive Pulmonary Disease.” NEJM 1995, 333(13):817-22.

LBBB doesn’t have to block an MI diagnosis

What we are taking about:

Sgarbossa EM, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) Investigators. N Engl J Med. 1996 Feb 22;334(8):481-7.


Main Points:

In the presence of a left bundle branch block, suspect acute infarction when:

  1. ST-segment elevation ≥1 mm and concordant with QRS complex
  2. ST-segment depression ≥1 mm in lead V1, V2, or V3
  3. ST-segment elevation ≥5 mm and discordant with QRS complex

Background:

The presence of left bundle branch block on the electrocardiogram may conceal the changes of acute myocardial infarction, which can delay both its recognition and treatment. This study aimed to identify electrocardiographic criteria for the diagnosis of acute infarction in the presence of left bundle-branch block.


Methods:

This was a retrospective cohort study looking at electrocardiograms of North American patients enrolled in the GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) trial who presented with chest pain, had left bundle-branch block on baseline EKG, and acute myocardial infarction confirmed by enzyme studies (total of 131 patients). These EKGs were blindly compared with the electrocardiograms of control patients from the Duke Databank for Cardiovascular Disease who had chronic coronary artery disease and left bundle-branch block. The patients in the control group did not have acute chest pain at the time of the electrocardiographic recording.

Multivariate Analysis was used to determine independent predictors of acute myocardial infarction. These criteria were used to develop a scoring system to identify patients with acute myocardial infarction. Continue reading

Passed out…Peace out. Who can go home after syncope?

Discussing: Quinn et al. Annals of Emergency Medicine. Prospective Validation of the San Francisco Syncope Rule to Predict Patients With Serious Outcomes

Main Points:
1. This 2006 prospective cohort trial aimed to validate a clinical rule to help risk stratify patients presenting to the ER with syncope in relation to short term outcomes. The rule was validated to have a sensitivity of 98% in preventing serious outcomes after syncope within 30 days.

2. The San Francisco Syncope rule is positive if the patient has a chief complaint of “shortness of breath”, a medical history of CHF, a presenting SBP <90mm Hg, a hematocrit <30%, or an abnormal ECG result (any non-sinus rhythm or new changes).

Background:

Approximately 25% of the general population will have an episode of syncope in their lifetime. Patients with syncope account for 1-2% of all Emergency Department visits and hospital admissions. Patients admitted for syncope, however, have been shown to receive little to no further diagnostic care, nor do they often receive a firm diagnosis concerning the cause of their syncope. Given this, the authors’ purpose was to validate the decision rule in a prospective cohort of consecutive ED patients by determining whether it can predict short-term serious outcomes.

Syncope was defined as “transient loss of consciousness with return to baseline neurologic function,” and patients presenting with acute syncope or pre-syncope were screened for the study. When a clinician had finished working up the selected patient, a short Web-based questionnaire was completed to evaluate for aspects of the history, ECG, vitals or lab results that pertain to the decision rule. In this trial, the decision rule was 98% sensitive and 56% specific to predict a serious outcome within 30 days. If applied in the study cohort, this clinical rule may have decreased syncope admissions by 24%.

Continue reading

‘Let’s talk about N-STEMI, Let’s talk about Cath, baby, Let’s talk about all the good things and the bad things that may be…’

This is part of a recurring series examining landmark articles in Emergency Medicine, in the style of ALiEM’s 52 Articles.

Discussing: Mehta et al., NEJM 2005. Routine vs. Selective Invasive Strategies in Patients With Acute Coronary Syndromes. A Collaborative Meta-analysis of Randomized Trials PMID: 15956636

Main Points:

  1. This 2005 meta-analysis was devised to answer one of medicine’s most stubborn (but important) questions: Is an ‘early invasive’ strategy for Unstable Angina (UA) and Non-ST-Elevation Myocardial Ischemia (NSTEMI) associated with improved outcomes compared to medical therapy alone?
  2. Yes and no! High-risk patients with positive biomarkers and evidence of ongoing ischemia seem to gain long-term benefit from immediate coronary angiography and revascularization. This benefit appears to outweigh the increased hazard associated with a routine invasive strategy.
  3. Patients with negative biomarkers and lower risk don’t appear to gain long-term benefit from invasive strategy and therefore the increased hazard of a routine invasive strategy is not justified in this group. Patients with negative biomarkers do just as well with medical therapy alone.

 

Background:

 

Acute Coronary Syndrome (ACS) comprises a spectrum of illness. Presenting signs, symptoms and clinical findings (elevated troponin, EKG changes) are thought to correlate with the degree and the acuity of ischemia. In theory, patients with more severe illness are thought to benefit from more aggressive therapies – i.e. invasive revascularization – while patients with less severe illness have been thought to derive equal benefit medical therapy alone. To an extent, these suppositions have been proven true: There are clear mortality benefits to emergent PCI for patients with STEMI. However, optimal treatment for patients presenting with unstable angina or NSTEMI remains controversial. Importantly, the goal of revascularization in STEMI is different then in NSTEMI/UA. For STEMI, PCI is intended to restore perfusion by eliminating an occlusive thrombus. In NSTEMI, thrombi typically are not occlusive – thus the focus of PCI is to improve long-term outcomes.

 

The purpose of this study was to determine whether a routine invasive strategy vs. a selective invasive strategy was more effective in the treatment of ACS. The authors devised a meta-analysis of randomized trials to answer this question. Continue reading

Clinical Image of the Week: Case 1

This is a case I saw in the ED. This case has been deliberately altered to protect the identity of the patient:

28 y/o patient presents to the ED after sustaining blunt trauma to the chest. An EKG is ordered as part of her workup:

Case 1 Upon further questioning, the patient endorses periods of palpitations over the past couple of months where her “heart was racing”. She denies chest pain, shortness of breath, dizziness, or syncope with these episodes.  What’s the diagnosis?

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