Diagnosing Acute Heart Failure in the Emergency Department: A Systematic Review and Meta-analysis

Background

The chief complaint of “dyspnea” represents a very large cohort of patient who present to the emergency department. While acute heart failure (AHF) is a very common diagnosis in the setting of dyspnea, the diagnosis remains challenging when the emergency physician is presented with the undifferentiated dyspneic patient. Interestingly, emergency physicians have varied approaches to the work up and diagnosis of these patients and it is not clear as to which diagnostic element is most crucial in confirming the diagnosis of AHF. Spoiler: Ultrasound proves to be quite useful.

Diagnosing Acute Heart Failure in the Emergency Department: A Systematic Review and Meta-analysis‌

 

Clinical Question

What are the operating characteristics of the diagnostic elements available to the emergency physician for diagnosing acute heart failure?

Methods & Study Design

  • Design
    • This is a systematic review evaluating index test operating characteristics in diagnosing AHF. A medical literature search was performed using PubMed and EMBASE, evaluating peer-reviewed published papers from 1965 through 2015
    • Individual systematic reviews for each index test were conducted by two separate physicians and thereafter reconciled to obtain a comprehensive set of studies on the topic. These were then screened against the inclusion/exclusion criteria for final inclusion into the meta-analysis
    • The reference standard used was a final diagnosis of AHF based on review of clinical data by independent reviewers who were blinded to the study’s primary index test
  • Population
    • All studies included involved patients presenting to the emergency department (ED) with the chief complaint of “dyspnea.”
  • Outcomes
    • Pooled sensitivities, specificities and likelihood ratios (LRs) of index tests for diagnosing acute heart failure in patients presenting to the ED with dyspnea
    • They specifically looked at the following index tests in evaluation of AHF: history and physical exam, ECG, chest x-ray, BNP and NT-ProBNP, lung ultrasound (US), and bedside echocardiography
  • Excluded
    • Patients presenting to urgent care with dyspnea
    • Patients with chronic, compensated heart failure
    • Studies focusing on prognosis or therapeutics and not the diagnosis of AHF
    • Studies with ultrasound images that were not obtained and interpreted by emergency physicians

Results

    • History and Physical: S3 most specific finding for AHF (+LR 4)
    • ECG: Found to be insensitive and unspecific for diagnosing or ruling out AHF
    • CXR: Pulmonary edema was the most specific finding (LR + 4.8). All other imaging findings were insensitive for ruling out heart failure
    • BNP and NT-Pro-BNP: Quite sensitive for ruling out AHF at a threshold of 100/300pg/dL
    • Lung Ultrasound:
      • Presence of >3 B-lines in >2 lung fields is very specific for the presence of AHF
      • Lack of this also sensitive for ruling out acute heart failure
      • High inter-rater reliability
    • Bedside Echo
      • ED provider evaluation of systolic function had high inter-rater reliability with the ultimate ejection fraction assessed by cardiologists on formal echo
      • Restricted Mitral Inflow very specific for ruling in diastolic AHF in patients with preserved systolic function

Strengths & Limitations

  • Strengths
    • Very thorough analysis of the operating characteristics of a plethora of diagnostic elements and sub-elements available to the emergency physician in diagnosing AHF
    • Authors didn’t exclude comorbidities, etiology of AHF or if there was an underlying arrhythmia which increased the generalizability of their results
    • All data was screened and evaluated by two separate physicians
  • Limitations
    • The reference standard was a final diagnosis of AHF made by physicians in retrospective fashion which weakens this as a “gold standard.”
    • The authors did not specifically evaluate or reconcile whether the heart failure was left or right sided
    • Each of the tests or test characteristics were assessed in isolation to determine the likelihood of heart failure. The likelihood of AHF when considering multiple index tests was not assessed
    • As in all large meta-analyses, some spectrum bias may exist as inclusion/exclusion criteria varied among included studies. However, ome of this heterogeneity is likely countered by the pooled analysis and is unlikely to drastically change the calculated LRs

Author's Conclusions

"Bedside lung US and echocardiography appear to the most useful tests for affirming the presence of AHF while natriuretic peptides are valuable in excluding the diagnosis."

Our Conclusions

This is one of the most thorough studies available to assess the likelihood that a patient presenting to the emergency department has acute heart failure based on an index test. There are many old standby diagnostic modalities available to emergency physicians including the history, physical exam, and chest x-ray. Unfortunately, these diagnostic elements are relatively non-specific in establishing that a patient’s acute symptoms are likely or unlikely due to heart failure. BNP and NT Pro BNP are quite useful in ruling out heart failure however these tests take time to result. Ultrasound is rapidly becoming a fundamental tool in every emergency physicians tool belt and should be utilized alongside the primary patient assessment in determining the likelihood that a patient has heart failure. The presence or absence of B lines (>3 in at least 2 fields) is quite specific for ruling in heart failure and the absence is nearly as sensitive as a normal BNP or NT Pro BNP, too. And in the event of systolic heart failure, echo is a great modality to rapidly assess a patient’s pump function; our interpretation is consistent with the formal result obtained by cardiologists [2].

Caution must nevertheless be maintained when evaluating these results. The LRs found in these studies were calculated independently of other findings and in reality, the emergency physician takes multiple factors from the history, physical exam, and other diagnostic modalities, to ultimately come to a definitive diagnosis. Essentially, the short answer is that no single test should be taken as definitive in diagnosis of AHF (or any diagnosis for that matter) and the emergency physician should follow a bayesian approach using pre- and post- test probabilities from their fund of knowledge to rule in and rule out cannot miss diagnoses. Lastly, with regards to this study, physicians should be wary about interpreting these results in the context of renal failure primarily but also superimposed pneumonia or underlying concern for pulmonary embolism as these patients were excluded in a number of papers included in this meta-analysis.

The Bottom Line

Bedside ultrasound to evaluate for the presence or absence of pulmonary edema should be an integral part of the emergency physicians approach to evaluating patients to the emergency department with undifferentiated dyspnea.

Authors

This post was written by Matt Correia, MD PGY-2 at UCSD. It was edited by Michael Macias, MD.

References

    1. Martindale JL, e. (2017). Diagnosing Acute Heart Failure in the Emergency Department: A Systematic Review and Meta-analysis. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 14 August 2017, from https://www.ncbi.nlm.nih.gov/pubmed/26910112
    2. Moore CL, e. (2017). Determination of left ventricular function by emergency physician echocardiography of hypotensive patients. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 14 August 2017, from https://www.ncbi.nlm.nih.gov/pubmed/11874773

Case # 2: A Needle In the Haystack

A 40 year old male presented with 3 days of progressive dyspnea on exertion. He notes he was in a normal state of health prior to this and played basketball daily without issue but now he can no longer walk across the room without becoming winded. He has no chest pain, a normal chest x-ray and an ECG demonstrating sinus tachycardia

Vitals: HR 109 BP 110/72 RR 22 O2 96

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Answer and Learning Point

Answer

There is evidence of severe aortic regurgitation and aortic root dilation (~6 cm) on this parasternal long axis view. In a patient without any previous cardiac history with new aortic regurgitation this is concerning for acute aortic dissection. Cardiac surgery was consulted immediately and the patient was taken straight to CT scan for confirmation of type A aortic dissection. The patient was in the OR within 1 hour and had an excellent outcome.

Learning Point

Aortic dissection is quite uncommon (~5-30 per 1 million people per year) and is often seen in patients with chronic uncontrolled hypertension or other diseases such as bicuspid aortic valve, Marfan Syndrome or Ehlers-Danlos Syndrome. Unfortunately all the "classic" indicators of dissection are actually not that common [1].  Traditionally we are taught that patients with acute aortic dissection will arrive hypertensive, while in actuality up to 1 in 4 patients with Stanford Type A dissection will have a presenting systolic blood pressure below 100 mmHg. Additionally, it is taught that a dissection presents as a “ripping or tearing” pain going to the back.  Looking at the data, while over 90% of patients felt that it was the worst pain they had ever experienced, only 50% of subjects described their pain as ripping or tearing (62% described pain as sharp), only 35% had any posterior chest pain, and only 85.4% of patients described the onset of their pain as ‘acute.’ [1]

The varied presentation of this disease makes aortic dissection difficult to diagnose, and the clinician should have a high index of suspicion for this life-threatening disease process.  This is where ultrasound comes in. Anyone who has a concerning chest pain story, pain above and below the diaphragm, chest pain + a neurological symptom, or signs and symptoms of acute heart failure without any previous cardiac history, should have a bedside ultrasound performed.  While ultrasound cannot rule out aortic dissection, it can rapidly identify complications of dissection and expedite care in these patients whom time is of the essence.

The Approach

Perform standard abdominal aorta ultrasound evaluating for aneurysm or intimal flap. Be sure to evaluate from proximal aorta, in the epigastric region, distally to the iliac vessels. A normal aorta caliber is < 3 cm.

Obtain a parasternal long axis view:

Measure aortic root, this should be less than 4 cm. There are varying opinions on where the best place to take this measurement is, I suggest measuring the largest area you see as it is better to be on the conservative side.
Apply color doppler to evaluate for aortic regurgitation.
Assess global cardiac function. This is useful to see if a patient is compensated or decompensated as well as assist with fluid/pressor management if needed.
Evaluate for pericardial effusion. If there is evidence of effusion and concern for Type A aortic dissection, this suggests that there is communication with pericardial sac.
Evaluate descending thoracic aorta for intimal flap

References

  1. Hagan PG, Nienaber CA, Isselbacher EM, et al. The International Registry of Acute Aortic Dissection (IRAD): New Insights Into an Old Disease. JAMA. 2000;283(7):897-903. doi:10.1001/jama.283.7.897.
  2. Taylor RA, e. (2017). Point-of-care focused cardiac ultrasound for the assessment of thoracic aortic dimensions, dilation, and aneurysmal disease. - PubMed - NCBI Ncbi.nlm.nih.gov. Retrieved 22 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/?term=22288871
  3. C, K. (2017). Emergency department diagnosis of aortic dissection by bedside transabdominal ultrasound. - PubMed - NCBI Ncbi.nlm.nih.gov. Retrieved 22 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/19549013
  4. Lang R, Bierig M, Devereux R, et al. Recommendations for Chamber Quantification: A Report from the American Society of Echocardiography’s Guidelines and Standards Committee and the Chamber Quantification Writing Group, Developed in Conjunction with the European Association of Echocardiography, a Branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005; 18: 1440-63.
  5. Rubano E, e. (2017). Systematic review: emergency department bedside ultrasonography for diagnosing suspected abdominal aortic aneurysm. - PubMed - NCBI Ncbi.nlm.nih.gov. Retrieved 22 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/?term=23406071

Case # 1: The Acutely Winded Traveler

A 65 year old female presents with shortness of breath after a return flight from the Gold Coast of Australia to the United States.

Vitals: HR 107 BP 110/80 RR 22 O2 95

RV+Strain_Mead

Answer and Learning Point

Answer

There is right ventricular dysfunction demonstrated as septal bowing appreciated on this parasternal short axis view. This is concerning for a pulmonary embolism in the setting of the provided clinical context.

Learning Point

Echocardiography can be a useful adjunct to laboratory markers (i.e. BNP and troponin) and CTA for evaluation of right heart strain in normotensive patients presenting with concern for pulmonary embolism.  While there is building evidence that many patients presenting with pulmonary embolism are safe for discharge [1] , those patients that have evidence of right ventricular dysfunction are at higher risk for morbidity and mortality and may also be candidates for more advanced therapies, other than simple anticoagulation, such as catheter directed thrombolysis.  The most up-to-date evidence supports that emergency physicians can accurately perform echocardiography at the bedside to risk stratify patients presenting with concern for pulmonary embolism. In a recent study by Weekes et al, emergency physicians (EP) performed goal directed echocardiography to assess for right ventricular dysfunction. If any of the following criteria below were present, a patient was considered positive by goal directed echocardiography for right ventricular dysfunction:

This study found the EP goal-directed echocardiography sensitivity and specificity for right ventricular dysfunction to be 100% (CI 87% to 100%) and 99% (95% CI 94% to 100%), respectively [2]. Our patient ended up having a saddle embolus and underwent catheter directed thrombolysis and did well.

References

  1. Aujesky D, e. (2017). Outpatient versus inpatient treatment for patients with acute pulmonary embolism: an international, open-label, randomised, non-inferiority trial. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 8 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/21703676

  2. Weekes AJ, e. (2017). Diagnostic Accuracy of Right Ventricular Dysfunction Markers in Normotensive Emergency Department Patients With Acute Pulmonary Embolism. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 8 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/?term=26973178

FAST Ultrasound Examination as a Predictor of Outcomes After Resuscitative Thoracotomy

Background

The emergency resuscitative thoracotomy (RT), aka The ED Thoracotomy, is a procedure performed as a last-ditch effort during resuscitation of a patient in traumatic arrest or impending traumatic arrest. Unfortunately despite physicians’ best efforts, outcomes for this procedure are generally poor. The largest review of outcomes after RT performed in the emergency department found an overall survival of 7.4% (8.8% for penetrating injury, 1.4% for blunt injury), with good neurological outcomes present in 92.4% of surviving patients [2]. Furthermore, given the lack of high quality evidence on this procedure, there are no universal guidelines that exist to determine optimal candidates [3,4]. Point-of-care ultrasound has become a core adjunct in evaluation of the trauma patient, however there is minimal data evaluating its utility in determining which trauma patients may benefit from RT [5].

FAST Ultrasound Examination as a Predictor of Outcomes After Resuscitative Thoracotomy: A Prospective Evaluation

Clinical Question

Can the Focused Assessment Using Sonography for Trauma (FAST) predict survival after a RT in patients presenting to the emergency department in traumatic cardiac arrest?

Methods & Study Design

  • Population
    • All penetrating trauma patients with absent vital signs and blunt trauma patients with a loss of vital signs en route or in the resuscitation bay that underwent RT.
  • Intervention
    • A FAST exam was performed just prior to RT to assess for the presence or absence of a pericardial effusion and cardiac motion.
  • Outcomes
    • Survival to Discharge or Organ Donation
  • Design
    • Prospective, observational study performed at a single academic level-1 trauma center
  • Excluded
    • Patients who were taken directly to the OR for an emergent or urgent thoracotomy were excluded.
    • Patients who did not have a FAST exam performed prior to RT were excluded from analysis

Results

    • 223 patients underwent RT, 187 underwent analysis (36 had no FAST performed)
      • Primary Outcome
        • Survival: 3.2%
        • Organ Donation: 1.6%

Strengths & Limitations

  • Strengths
    • First large, prospective observation study on emergency RT
    • Sensitivity analysis performed to include patients who had inadequate views obtained
  • Limitations
    • Study performed at a high-volume, single academic level-1 trauma center with which may skew generalizability
    • Residents who had formal training in the FAST exam performed all ultrasound scans. Many emergency medicine physicians are not credentialed in ultrasound or FAST examination

Author's Conclusions

"In summary, for the patients that arrived to hospital and underwent a FAST examination, all survivors and organ donors had visible cardiac motion. If no cardiac motion or pericardial effusion was seen, the survival was zero. Ultrasound was, therefore, able to effectively identify those patients who had the potential to survive the RT and discriminate them from those who did not. Utilizing ultrasound would have resulted in the avoidance of a significant proportion of thoracotomies which were ultimately found to be futile.”

Our Conclusions

This is a well done study examining the utility of the FAST exam in identifying which patients will potentially benefit from emergency RT. One may look at the primary outcomes of this study and think that the very low overall survival rate (3.2%) does not jive with previously reported studies. However, it is important to note that during the study period, 21 patients who had a penetrating cardiac injury and went straight to the OR for thoracotomy, were excluded. All of these patients survived. If we were to incorporate this number into the the final analysis, survival would be ~13% which fits better with previous data. But that isn’t the point of this study. The big question that I feel is appropriately answered is which patient population can we safely avoid undertaking an emergency RT, knowing it is futile. While resource utilization for a procedure of this magnitude may be less burdensome at an academic level-1 trauma center, performing a RT in an emergency department where this is rare occurrence requires a much larger undertaking by the staff. The new data from this study, demonstrates that patients who did not have cardiac motion or a pericardial effusion on initial FAST had a zero survival rate. This is practice changing, especially for providers who rarely perform this procedure. If an experienced trauma team performing this procedure had zero survival rate in patients with no cardiac motion or pericardial effusion, it is safe to say that a provider with less experience will not perform better. Furthermore, having real time data to share with the entire resuscitation team during a traumatic arrest can provide closure to the team and a sense that performing any further heroic procedures is futile.

The Bottom Line

The FAST exam is a critical adjunct in traumatic patients and should be applied to all cases of traumatic arrest in order to determine the utility of performing an emergency RT.

References

    1. Inaba K, e. (2017). FAST ultrasound examination as a predictor of outcomes after resuscitative thoracotomy: a prospective evaluation. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/26258320
    2. Rhee PM, e. (2017). Survival after emergency department thoracotomy: review of published data from the past 25 years. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/10703853
    3. Seamon MJ, e. (2017). An evidence-based approach to patient selection for emergency department thoracotomy: A practice management guideline from the Eastern Association ... - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/26091330
    4. Burlew CC, e. (2017). Western Trauma Association critical decisions in trauma: resuscitative thoracotomy. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/23188227
    5. Moore EE, e. (2017). Defining the limits of resuscitative emergency department thoracotomy: a contemporary Western Trauma Association perspective. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 4 July 2017, from https://www.ncbi.nlm.nih.gov/pubmed/21307731
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