Thanks to Barnie for presenting the case of a middle-aged woman who was admitted with acute onset of SOB, found to have submassive PE.

Clinical Pearls:

• Risk stratification tools are helpful in estimating the pre-test probability of PE.  The best and most validated is Wells criteria.
  • YEARS items is a newer tool that was studied in an RCT in the Netherlands and found to lower the number of CTPA scans ordered by 14% without a significant impact on rates of missed PE diagnoses.
• For patients at low risk of PE according to Wells, PERC is useful in ED or outpatient setting to rule out PE without ordering a d-dimer (see graphic below).
• Age-adjusted d-dimer is age x 10 for patients older than 50 years.  This accounts for the increase in d-dimer baseline related to aging.  ADJUST-PE trial showed that age-adjusted d-dimer leads to higher specificity without subsequent VTE.
  • Studies have shown an 11.6% reduction in CTPA scans with the use of this correction factor without an appreciable increase in missed diagnoses of PE.
• Think of PE in three broad categories:
  • Massive PE = hemodynamically unstable ⇒ anticoagulation + thrombolysis
  • Submassive PE = hemodynamically stable + RV strain ⇒ anticoagulation + thrombolysis
  • Low risk PE = hemodynamically stable, no RV strain ⇒ anticoagulation.  Use the PESI score to determine if your patient can be treated outpatient.
• Remember that the most common EKG finding in PE is normal sinus rhythm!  The most common abnormal  EKG finding is sinus tachycardia.  S1Q3T3 pattern is only seen in 10% of patients with PE.

Diagnosis:

Suggested algorithm for diagnostic work up of suspected PE:

Remember that the scoring tools above are only there to add to your clinical judgment, not replace it!

Recent study in the Lancet looked at the utility of a different diagnostic algorithm, using the three most predictive items on Wells together with d-dimer.  Compared to Wells, this diagnostic tool led to a 14% reduction in unnecessary CTPA!

Treatment:

• Remember that clot burden does not factor into the treatment categories of PE.  Low clot burden in a patient with baseline cardiopulmonary disease can still lead to hemodynamic compromise and would be considered massive PE.
• Submassive PE treatment is an area of much debate.  A famous trial (PEITHO trial) in 2014 randomized 1006 patients to receive heparin + placebo vs heparin + tenecteplase (European version), and found a >50% reduction in combined death and cardiovascular collapse at 7 days but a > four-fold increase in risk of major bleed including intracranial hemorrhage.  Subsequent meta-analyses (and this one) found that the risk of major bleeding was highest in people >65 years of age.  So treatment decisions here are tricky and require consulting multiple services!

Signs of RV strain: 

• EKG findings:
  • S1Q3T3: this is a sign of cor pulmonale and can be seen in a number of conditions in addition to PE
    • Bronchospasm (really bad asthma)
    • ARDS
    • Pneumothorax
• Echo findings:
  • Elevated RVSP
  • Septal bowing
  • McConnell’s sign (regional wall motion abnormality sparing the RV apex)
    • Not sensitive but helpful in distinguishing RV strain due to chronic pulmonary HTN from RV strain due to acute PE
  • Increased RV size
  • Decreased RV function
  • Tricuspid regurgitation
• Labs
  • Elevated troponin
  • Elevated BNP