Research: Prehospital Thrombolysis

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Also a topic within The EKG Club

Emerg Med J. 2010 Aug 3. [Epub ahead of print]
Paramedic decision making: prehospital thrombolysis and beyond.
Smith AM, Hardy PJ, Sandler DA, Cooke J.


Background Mortality from acute myocardial infarction is influenced by the speed at which reperfusion therapy is delivered. In the UK, prehospital thrombolysis (PHT), administered by paramedics, has been developed to improve call to needle (CTN) times. Recently, it has been shown in randomised trials that mortality can be further reduced by primary percutaneous coronary intervention (PPCI). This project was developed to assess current ST-elevation myocardial infarction practice in a district general hospital and to prepare paramedics for PPCI. Methods Data were collected prospectively over a 12-month period for all patients who received thrombolysis for a presumed myocardial infarct. The primary outcome measures for each case were who delivered the thrombolysis, either the paramedic crew or the hospital, and if the patient did not receive PHT the reason why not. Secondary outcome measures included the CTN time. Results 153 patients received thrombolysis over the time period (99 men, 54 women, mean age 66+/-15 years). Of this group, 55 patients received PHT (35.9%) with a median CTN time of 36 min (inter-quartile range (IQR) 30-42 min). The commonest reason for exclusion from receiving PHT was that the patient's history did not fit the eligibility criteria (25% of cases). Conclusions Paramedics are able to deliver PHT promptly and safely. With the focus now on PPCI, it is anticipated that not only will paramedics be able to select patients for delivery to a heart attack centre for PPCI, they will be selecting many more patients for this treatment than have up to now received PHT.

So, what do you think?  Are you ready to start administering clot busters?  Here is another abstract that concludes that the early identification of STEMI improves patient outcomes.

Am J Cardiol. 2009 Apr 1;103(7):907-12. Epub 2009 Feb 7.
Effect of prehospital triage on revascularization times, left ventricular function, and survival in patients with ST-elevation myocardial infarction.
Sivagangabalan G, Ong AT, Narayan A, Sadick N, Hansen PS, Nelson GC, Flynn M, Ross DL, Boyages SC, Kovoor P.

Shorter reperfusion times lead to better outcomes in patients with ST-elevation myocardial infarction (STEMI). We assessed the efficacy of prehospital triage with bypass of community hospitals and early activation of the cardiac catheterization team on revascularization times, left ventricular (LV) ejection fraction, and survival. Patients with STEMI (624) were divided into 3 groups determined by site of triage: ambulance field triage (163), interventional center emergency department (202), and 3 community hospital emergency departments (259). Compared with community hospital and interventional center triages, ambulance field triage resulted in a significant median decrease in door-to-balloon times of 68 and 27 minutes, respectively (p <0.001). LV ejection fraction was highest in the field triage group (52 +/- 13%) compared with the interventional center (49 +/- 12%) and community hospital (48 +/- 12%, p = 0.017) groups. Thirty-day mortality was lowest in the ambulance field group (3%) compared with the interventional facility (11%) and community hospital (4%, p = 0.007) groups. There was a significant difference in long-term survival with up to 30-month follow-up among the 3 triage groups (p = 0.041). With time-dependent Cox regression modeling the difference in survival was significant only during the first week after STEMI (p = 0.020). Every extra minute of symptom onset to reperfusion time was associated with a relative risk of long-term mortality of 1.003 (95% confidence interval 1.000 to 1.006, p = 0.027). In conclusion, field triage of patient with STEMI decreased revascularization times, which preserved LV function, and improved early survival.
And another advocating statement from 2007:

J Emerg Med. 2008 May;34(4):405-16. Epub 2007 Dec 27.
The role of fibrinolytics in the prehospital treatment of ST-elevation myocardial infarction (STEMI).
Sayah AJ, Roe MT.

The efficacy of fibrinolytics in the treatment of ST-elevation myocardial infarction is directly related to the time of administration, with the first 2 h after symptom onset seen as a critical period for greatest improvement in cardiovascular parameters and mortality. The American College of Cardiology/American Heart Association recommends a medical contact to treatment time of 30 min for fibrinolysis in patients with ST-elevation myocardial infarction. In selected patients, reperfusion goals may be expedited with prehospital administration of fibrinolytics. In clinical trials, prehospital fibrinolysis markedly reduced the time from symptom onset to treatment, allowed earlier ST-segment resolution, and reduced short- and long-term mortality compared with in-hospital treatment. Prehospital fibrinolysis has become more feasible with the introduction of prehospital 12-lead electrocardiography, improved skills of emergency medical services personnel, improved communication with the Emergency Department, and the advent of bolus fibrinolysis. Rapid and accurate administration of a fibrinolytic is vital for the success of prehospital fibrinolysis.

Okay, that one is a bit old.  Lets open the discussion on this topic.  Let me know what you think.  Provide some better research, and I will tell you now... there is some out there.  I'd also like to hear from anyone out there that has been a part of a thrombolysis trial.

Thanks for your participation,

Adam Thompson, EMT-P

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