Thrombolysis of Pulmonary Embolism

EM-Critical Care Conference: August 2013

PULMONARY EMBOLISM

Summary by Dr. Eugene Kang

Diagnosis and EKG:

-Most common EKG finding: non-specific ST-T changes (at least for our boards)

-Other findings: sinus tachycardia, complete or incomplete RBBB, RAD, right atrial enlargement, dominant R in V1, atrial tachyarrhythmias

-Some likelihood ratios (see Kline paper in references):

-S1Q3T3, LR=4.9 (2.4-10.3)

-TWI in V1-4, LR=3.1 (1.4-6.9)

-Although certain EKG abnormalities (S1Q3T3, anterior+inferior TWI) can help in the diagnosis of pulmonary embolism, absence of these findings should not decrease suspicion

Consequences:

-Massive PE can obviously cause hemodynamic instability leading to death

-Smaller but clinically significant PE can lead to pulmonary hypertension, RV dysfunction and subsequently poor quality of life (decreased exercise tolerance and even dyspnea at rest)

Treatment: Who do we lyse?

AHA

-Massive: hemodynamic instability defined as SBP<90 (or 40 point drop from baseline) for >15 minutes

-YOU MUST LYSE (if no contraindications to thrombolytic therapy)

-Similar recommendations by European Society of Cardiology, American College of Chest Physicians

-Submassive: hemodynamically stable but with signs of RV strain (elevated troponin/BNP, echo findings of RV dysfunction)

-AHA says thrombolysis may be considered (level IIb/C)

-ESC/ACCP similarly says choose case-by-case (i.e. lyse younger patients who are less likely to bleed and also need their RV function intact)

ACEP

-Hemodynamically unstable patients: lyse (if benefits outweigh risks of bleeding)

-Level B recommendation

-Hemodynamically stable patients: insufficient evidence to lyse

-”Thrombolytics have demonstrated faster improvements in RV function and pulmonary perfusion, but these benefits have not translated to improvements in mortality.”

MOPETT (Moderate Pulmonary Embolism Treated with Thrombolysis):

-Symptomatic moderate defined as ≥2 signs/symptoms (7 total in inclusion criteria) in addition to:

-CTPA involvement of >70% involvement of thrombus in ≥2 lobar, or left or right main pulmonary arteries

-Ventilation/perfusion scan showing mismatch in ≥2 lobes

-SBP<95 excluded

-enoxaparin/heparin only vs enoxaparin/heparin + half dose tPA (10mg bolus then 40mg over 2 hours)

-primary end point: pulmonary HTN at 28 months

-rates in treatment group=16%, control group=57%

-combined end point: pulmonary HTN at 28 months + recurrent PE

-treatment group=16%, control group=63%

-no patients in either group bled

-Conclusion: results suggest that half-dose thrombolysis is safe/effective in the treatment of moderate PE, with a significant immediate reduction in pulmonary artery pressure that was maintained at 28 months.

-Still, the measured outcome is of questionable significance as opposed to actual measurements of quality-of-life.

-Perhaps consider in younger in whom potential improvement in exercise tolerance in remaining lifetime may be more relevant than in older, immobile patients.

*At the American College of Cardiology Scientific Assembly this year, Jeff Kline presented the TOPCO study that assessed patient-oriented outcomes. Please see the reference below.

References:

Kline J et al. 12-Lead ECG Findings of Pulmonary Hypertension Occur More Frequently in ED Patients With Pulmonary Embolism Than in Patients Without Pulmonary Embolism. Annals of Emergency Medicine. 2010; 55(4): 331-335
Sharifi M et al. Moderate Pulmonary Embolism Treated with Thrombolysis. The American Journal of Cardiology. 2013; 11(2): 273-277.
Jaff MR. Management of massive and submassive pulmonary embolism, iliofemoral deep vein thrombosis, and chronic thromboembolic pulmonary hypertension: a scientific statement from the American Heart Association. Circulation. 2011; 123(16):1788-830
Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department with Suspected Pulmonary Embolism. Annals of Emergency Medicine. 2011; 57: 628-652.
Kline J et al. Randomized Trial of Tenecteplase Placebo with Low Molecular Weight Heparin For Acute Submassive Pulmonary Embolism: Assessment of Patient-Oriented Cardiopulmonary Outcomes at Three Months. Journal of the American College of Cardiology. 2013: 61(10)