Thrombolytics in the Treatment of STEMI

By Chelsea Mikolowsy, PGY4

In my final weeks of residency, I’m becoming overwhelmingly aware of the things that will scare me as an attending. This is especially true of the (admittedly few) areas of medicine that we get very little experience with at Einstein. TPA for STEMI is certainly not something I’ve ever considered giving, but outside of Einstein it is something I may be asked to do. Also it is important to note that some institutions are using TPA to attempt to withhold catheterization for COVID-19 patients. Also, unfortunately, it’s on the boards this post will seek to review the use of TPA as well as explore some literature on the topic. 

While it is certainly less common, there are still institutions that administer TPA for STEMI with some regularity, and it is therefore important to be familiar and comfortable with its use. Firstly, the goal in STEMI treatment is to administer within 30 minutes of ED arrival if PCI is deemed not an option. Below are its specific indications for use. 

Class I recommendations for thrombolytics: 

  • STEMI
  • symptoms <12 hours,
  • PCI >120 minutes from arrival

Class II recommendations: 

  • ongoing ischemia 12-24s after onset
  • large area of effected myocardium
  • hemodynamic instability

*As a reminder: Class I recommendations are strong and indicate that the intervention is useful and effective and should be performed or administered for most patients under most circumstances. Class II recommendations are weaker, denoting a lower degree of benefit in proportion to risk. 

Perhaps the one of the most important things to know, and likely have to often look up, are the contra-indications for TPA, as there are many and the risk is high. 

Contraindications:

  • ICH
  • known intracranial lesion (vascular or malignancy)
  • CVA<3 months
  • aortic dissection
  • active bleeding or diathesis
  • bp>185/ 110, oral ACs
  • intraspinal/ intracranial sx< 2 months
  • significant closed head trauma< 3 months

Relative contraindications:

  • Significant HTN on arrival (pressure > 180 mmHg)
  • Ischemic stroke >3 months
  • Dementia
  • Other intracranial pathology
  • Traumatic CPR >10 min
  • Major surgery ❤ weeks
  • Internal bleeding ❤ weeks
  • Non-compressible vascular punctures
  • Pregnancy
  • Active peptic ulcer disease

Once you’ve decided your patient needs TPA, its important that you have the dose in your back pocket…at least in ABEM general. You should also be sure to administer ASA, clopidogrel or ticagrelor, and heparin or lovenox as normal. 

Dose: 100 mg alteplase or tenecteplase administered in 15 mg bolus, 50 mg over 30 m, and 35 mg over 60 min

Reperfusion Rhythms

After TPA, thing really start to get outside the emergency medicine comfort zone. These are rhythms that are both expected and encouraging when occurring after administration of TPA, though they can be frightening to the ED physician who is unfamiliar with the aftereffects of reperfusion, as most are in the age of the cath lab. These are regular rhythms, of rates between 50 and 110, with 3 or more 3 PVCs, as well as fusion and capture beats, pictured below. They are a signal of successful thrombolysis and SHOULD NOT be intervened on with antiarrhythmics. 

Fusion Beats and Capture Beats

Fusion Beats

Fusion beats due to VT – the first of the narrower complexes is a fusion beat (the next two are capture beats)

Fusion Beats

Treatment Goals

So how do you know you’ve been successful when you cannot visualize reperfusion in the lab? Goals of treatment for thrombolysis in STEMI include:

  • cessation of chest pain 
  • reduction in ST elevations >70%
  • resolution of elevations within 60-90 minutes. 

Transfer of the patient to a STEMI -center should occur within 24 hours regardless, however, transfer sooner should be sought for failure to re-perfuse, meaning < 50% reduction in ST elevations after 2 hours and no reperfusion rhythm, or hemodynamic instability. 

Literature Review

Sadia et al, Safety of Thrombolytic therapy at emergency department vs coronary care unit: A comparative study of 100 patients at tertiary Cardiac care center. Journal of Cardiovascular Medicine and Cardiology. 2019.

This is a comparative cross-sectional study of 100 patients with confirmed STEMI in a military hospital in Pakistan between 2016 and 2017. Patients were followed who received TPA either in the ED or in the CCU. They found that TPA administration in the ED was comparatively safe and reduced door to needle times as compared to administration in the CCU. This was a small trial and is not very generalizable but it is in accordance with prior literature on the subject and is all the more reason we as emergency physicians must be comfortable with this intervention as it clearly lies within our scope of practice. 

References

Sadia et al, Safety of Thrombolytic therapy at emergency department vs coronary care unit: A comparative study of 100 patients at tertiary Cardiac care center. Journal of Cardiovascular Medicine and Cardiology. 2019.

O’Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: executive summary: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2013; 127:529.

Effectiveness of intravenous thrombolytic treatment in acute myocardial infarction. Gruppo Italiano per lo Studio della Streptochinasi nell’Infarto Miocardico (GISSI). Lancet 1986; 1:397.

Cohen, Jordan. Fibrinolytic Therapy for STEMI. Brown Emergency Medicine Blog. January 25, 2019

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