January 7, 2019

30-Day Outcomes in Syncope vs Near-Syncope

Background: Syncope, defined as a transient loss of consciousness with spontaneous and complete recovery to pre-event status, is a common emergency department (ED) presentation. Near-syncope is frequently seen as well. Unlike syncope, near-syncope has a more nebulous definition often thought of as the feeling of oncoming syncope without a complete loss of consciousness. Regardless of definition, many providers consider syncope and near-syncope as two ends of a spectrum of disease with near-syncope being not as dangerous and syncope being more dangerous. The literature on this, however, is inconsistent with a 2009 study stating that near-syncope was a “low-risk” factor (Sun 2009) and a 2015 study showing the opposite (Thiruganasambandamoorthy 2015). Additional high-quality data in this area is needed to further elucidate the risk of near-syncope presentations in the ED.

Article: Bastani A et al. Comparison of 30-Day Serious Adverse Clinical Events for Elderly Patients Presenting to the Emergency Department with Near-Syncope Versus Syncope. Ann Emerg Med 2018. PMID: 30529112

Clinical Question: What is the incidence of death or serious clinical events during the 30 days following an ED presentation for syncope or near-syncope?

Population: Patients > 60 years of age presenting to 11 geographically distributed academic and community EDs in the US

Primary Outcome: All-cause mortality or serious clinical event at 30-days

Serious Clinical Event (Based on the 2017 ACC/AHA/Heart Rhythm Society Guidelines): Cardiac arrhythmias (ventricular fibrillation, ventricular tachycardia [>30 seconds or symptomatic], sick sinus disease with altered mental status, sinus pause >3 seconds, Mobitz type II atrioventricular block, complete heart block, symptomatic supraventricular tachycardia, symptomatic bradycardia, and pacemaker and implantable cardioverter/defibrillator malfunction), myocardial infarction, cardiac intervention (pacemaker or defibrillator placement, or coronary artery revascularization), new diagnosis of structural heart disease (eg, critical aortic stenosis), stroke, pulmonary embolism, aortic dissection, subarachnoid hemorrhage, cardiopulmonary resuscitation (CPR), internal hemorrhage or anemia, and recurrent fall or syncope resulting in major injury

Design: Multicenter, prospective, observational, cohort study

Excluded: Any patient with a presumptive cause of syncope/near-syncope of seizure, stroke/TIA or hypoglycemia, intoxicated patients (drugs or alcohol) and hospice and do-not-resuscitate patients, patients requiring medical or electrical intervention to restore consciousness.

Primary Results:

  • 6930 subjects determined to meet inclusion/exclusion criteria
    • 53.2% (n = 3686) patients agreed to participate
    • 97.2% (n = 3581) of patients who agreed to participate were included in the final analysis (105 patients lost to follow up or withdrew consent)
      • 1380 patients (39%) had near syncope
      • 2201 patients (61%) had syncope
  • Subjects mean age = 72.8 years
  • 48.4% (n = 1733) of patients were women
  • At baseline, near-syncope patients were more likely than syncope patients to have CHF, CAD, a prior dysrhythmia and dyspnea on presentation

Critical Findings:

    • Overall 30-day serious outcome rate: 18.4%
    • Death or Serious Outcome Event at 30 days (primary outcome)
      • Syncope: 18.2%
      • Near-syncope: 18.7%
      • No statistically significant difference
    • Multivariate logistic regression analysis: OR 0.94 (95% CI 0.78 – 1.14) – No significant difference
    • Clinical Predictors of Serious Outcomes

Strengths:

  • Asks a clinically important question around which there is clinical equipoise
  • Largest prospective study of syncope and near-syncope in the elderly to date
  • Multicenter study increasing external validity
  • Prospective study design reduces risk of recall bias on initial assessment in ED
  • Follow up was excellent (97.2%)
  • Study staff obtained outside hospital records if the patient had a visit to a facility different from the index ED visit
  • Focuses on > 60 year old age group which is likely more present in clinicians’ minds
  • Used a validated data extraction tool to collect information during index visit and at 30-day follow-up
  • High inter-rater reliability of ECG interpretation (K = 0.8)

Limitations:

  • Primary endpoint composite of numerous outcomes. Not all of these outcomes are equivalent (ie death is much worse than symptomatic SVT)
  • This study only looked at older adults (all patients > 60, mean age > 72). The results should not be applied to younger patient groups
  • Near-syncope is a nebulous diagnosis without a clear definition. Many patients may have been misclassified or missed with this diagnosis
  • Follow-up conducted by telephone at 30 days and information may be subject to recall bias
  • No inter-rater reliability in the syncope vs near-syncope designation could introduce measurement bias
  • Unclear if research assistance for data gathering were available 24 hours a day
  • Large number of eligible patients  (46.8%) did not participate in study which may introduce a selection bias
  • Any testing beyond history, physical and ECG was at discretion of treating physician. Unclear what diagnoses or care was rendered at time of presentation and how this would have affected outcomes

Discussion:

  • Although the primary outcome was a composite, the majority of the pieces in that outcome were clinically important and patient centered
  • There’s no information on what workup or care was provided to patients in either the syncope or near-syncope group. This may bias the outcomes if syncope patients routinely had in-depth assessments and diagnostics and interventions were provided that would change outcomes
  • While 30-day outcomes is a relatively short-term measure, a more immediate outcome (ie 72 hours, 1 week) may be more relevant to emergency clinicians. What we want to know is “will this patient suffer an adverse outcome before they are able to follow up with their provider and have additional investigations and interventions performed?”
  • An overall 18% serious outcome rate at 30 days is, obviously significant but it’s unclear what to do with this information. These numbers may convince clinicians to admit all patients with syncope or near-syncope but there’s no evidence that this would benefit the patient. First, it’s unclear if the serious outcome that was experienced by the patient was the cause of the initial presentation. Additionally, there’s no evidence that admission or additional testing would find pathology upon which intervention could be rendered. In fact, there’s ample data showing that admissions for syncope when no cause is found in the ED are extremely low yield (Mendu 2009)

Authors Conclusions:

“Near-syncope confers risk to patients similar to that of syncope for the composite outcome of 30-day death or serious clinical event.”

Our Conclusions: In older adults (> 60 years of age), near-syncope appears to portend an equal risk of death or serious clinical event at 30 days when compared to syncope. These two entities should be considered as one when decisions are made in terms of evaluation in the ED.

Potential to Impact Current Practice: This data along with the work of Thirugnasambandamoorthy in 2015 has the potential to change the paradigm for many emergency clinicians who provide a different weight to syncope and near-syncope. This data should not be applied to patients < 60 as this group was not studied

Bottom Line: Near-syncope and syncope aren’t so different in terms of outcomes in older patients and should be considered equivalent presentations in terms of evaluation.

References:

  1. Sun BC et al. Predictors of 30-day serious events in older patients with syncope. Ann Emerg Med. 2009;54:769-778. PMID: 19766355
  2. Thiruganasambandamoorthy V et al. Outcomes in presyncope patients: a prospective cohort study. Ann Emerg Med. 2015;65:268-276. PMID: 25182542
  3. Mendu ML et al. Yield of diagnostic tests in evaluating syncopal episodes in older patients. Arch Intern Med 2009; 169(14): 1299-1305. PMID: 19636031

Post Peer Reviewed By: Salim R. Rezaie, MD (Twitter: @srrezaie)

Cite this article as: Anand Swaminathan, "30-Day Outcomes in Syncope vs Near-Syncope", REBEL EM blog, January 7, 2019. Available at: https://rebelem.com/30-day-outcomes-in-syncope-vs-near-syncope/.
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Anand Swaminathan

Clinical Assistant Professor of Emergency Medicine at St. Joe's Regional Medical Center (Paterson, NJ)
REBEL EM Associate Editor and Author
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