Non Sustained VT: Making a Lasting Impression!

Putting on the Pressure

A 60 yo male presents to EMS with several hours of chest pressure and diaphoresis. A 12 lead ECG is obtained following a 10 beat run of non sustained ventricular tachycardia. Despite the EMT's excitement at "firing up the paddles," the paramedic administers 324 mg of aspirin and prepares for transport to the nearest facility capable of percutaneous coronary intervention. Your partner informs you that the monitor discerns the presence of a paced rhythm. The patient has no previous medical history.


12 LEAD ECG:

12 LEAD ECG Analysis:

A sinus rhythm is present and the rate is regular. Diffuse and concerning ST segment changes appear in this tracing. First, pathologic ST segment elevation occurs in leads V2, V3 and V4. Q waves also appear throughout the tracing. The monitor misinterprets the ischemic Q wave as a pacer spike. The QRS is narrow, so an interventricular conduction delay is less likely responsible for the "false pacer" call. Reciprocal changes appear in lead aVF. There is minimal J point depression in lead III and V6. The baseline is also irregular.


12 Lead ECG Interpretation: 

Sinus rhythm, anterior wall ST segment myocardial infarction.

Comments:

• It is difficult to discern the location of the anatomic lesion based upon this ECG. The large ST segment elevation in the precordial leads suggests involvement of the LAD. The findings of lateral wall ischemia could implicate the circumflex as well. 
• The run of VT was likely due to ventricular irritability. Remember that the most devastating complications of anterior wall ischemia are lethal dysrhythmia and cardiogenuc pulmonary edema 
• Pathologic Q waves generally follow a few rules: (1) larger than a third of the corresponding R wave or (2) measure in excess of 0.03 seconds. Q waves that accompany poor R wave progression are more likely to indicate ischemia. 

Hey, my heart just stopped- can you downgrade the ambulance?

The EMS community is all a-twitter with the results of the trial published in the latest issue of JAMA- Internal Medicine.

Sanghavi, et al (2014) published an observational study of over 32,000 cases of out of hospital cardiac arrest. The study examined relevant outcomes such as survival to hospital discharge and neurological outcome. Not surprisingly, patients treated by BLS crews experienced a higher rate of overall survival AND better neurologic functioning. Sanghavi's study affirms the results of the landmark Ontario Prehospital Advanced Life Support (OPALS) study in which the introduction of advanced life support services failed to demonstrate improvement in survival rates from out of hospital cardiac arrest.

So, what are the take home points of this study? Are we to heed calls to mothball ALS ambulances? Do paramedics make any difference at all? What's the value of ALS in cardiac arrest?

First of all, this study is consistent with decades of resuscitation research. Interventions associated with survival from cardiac arrest have remained relatively constant: high quality, minimally interrupted compressions, early defibrillation, hypothermia, and possibly percutaneous coronary intervention. The reflexive, historical practice of intubating every arrest simply to "secure" an airway has no basis in evidence. Its not that the presence of a paramedic is harmful. Rather, the routine addition of advanced life support interventions to a prehospital resuscitation event continually fails to confer additional benefit. The value of a paramedic rests with his/her ability to orchestrate resuscitative efforts and prioritize those things most likely to achieve ROSC. Survival has inched ever higher in the wake of high performance and bystander CPR initiatives- the EMS community should take notice and embrace a "BLS centric" approach to the problem of out of hospital cardiac arrest.

Practice patterns shouldn't change on the basis of one study- that's why we'll follow this discussion up  by highlighting recent articles focusing on the role of epinephrine and advanced airways in cardiac arrest management.

PubMed abstract

Outcomes After Out-of-Hospital Cardiac Arrest Treated by Basic vs Advanced Life Support.

Sanghavi P1, Jena AB2, Newhouse JP3, Zaslavsky AM4.

Author information

Abstract

IMPORTANCE:

Most out-of-hospital cardiac arrests receiving emergency medical services in the United States are treated by ambulance service providers trained in advanced life support (ALS), but supporting evidence for the use of ALS over basic life support (BLS) is limited.

OBJECTIVE:

To compare the effects of BLS and ALS on outcomes after out-of-hospital cardiac arrest.

DESIGN, SETTING, AND PARTICIPANTS:

Observational cohort study of a nationally representative sample of traditional Medicare beneficiaries from nonrural counties who experienced out-of-hospital cardiac arrest between January 1, 2009, and October 2, 2011, and for whom ALS or BLSambulance services were billed to Medicare (31 292 ALS cases and 1643 BLS cases). Propensity score methods were used to compare the effects of ALS and BLS on patient survival, neurological performance, and medical spending after cardiac arrest.

MAIN OUTCOMES AND MEASURES:

Survival to hospital discharge, to 30 days, and to 90 days; neurological performance; and incremental medical spending per additional survivor to 1 year.

RESULTS:

Survival to hospital discharge was greater among patients receiving BLS (13.1% vs 9.2% for ALS; 4.0 [95% CI, 2.3-5.7] percentage point difference), as was survival to 90 days (8.0% vs 5.4% for ALS; 2.6 [95% CI, 1.2-4.0] percentage point difference). Basic life support was associated with better neurological functioning among hospitalized patients (21.8% vs 44.8% with poor neurological functioning for ALS; 23.0 [95% CI, 18.6-27.4] percentage point difference). Incremental medical spending per additional survivor to 1 year for BLS relative to ALS was $154 333.

CONCLUSIONS AND RELEVANCE:

Patients with out-of-hospital cardiac arrest who received BLS had higher survival at hospital discharge and at 90 days compared with those who received ALS and were less likely to experience poor neurological functioning.