Friday, April 24, 2015

Cardiac arrest, defibrillated, diffuse ST depression and ST Elevation in aVR. Why?

A middle-aged male had a V Fib arrest.  He had not complained of any premonitory symptoms (which is very common).   He had a history of CAD with CABG.  Here was his initial ED ECG:
There is atrial fibrillation with a rapid ventricular response.  There is profound ST depression especially in I, II, V2-V6.
ST depression is common BOTH after resuscitation from cardiac arrest and during atrial fib with RVR.

The patient was cardioverted.  Here is the post cardioversion ECG:
ST depression, with ST elevation in aVR persists.

Does this patient have ACS?  Should he necessarily go to the cath lab?

Again, it is common to have an ECG that shows apparent subendocardial ischemia after resuscitation from cardiac arrest, after defibrillation, and after cardioversion.

One must wait a short time (perhaps 15 minutes?), and repeat the ECG, to see if the apparent ischemia persists.

This was done.  A third ECG was done about 25 minutes after the first:
This shows resolution of all apparent ischemia.

The patient thus did not need immediate angiography.

An echocardiogram showed:

Left ventricular hypertrophy concentric .
The estimated left ventricular ejection fraction is 58 %
Aortic stenosis, mild, 9.0 mmHg mean gradient. 1.50 cm^2 valve area.

Troponins were minimally elevated, consistent with type 2 MI from low flow state of cardiac arrest and high demand state of atrial fib with RVR.

The patient underwent angiography later (the next day) and there was no culprit lesion.  He did not have ACS.

He recovered and had an ICD implanted.

Learning Points:

1. Ventricular fibrillation is not only caused by acute coronary syndrome.   There are many other etiologies, including scarring from previous MI, medications, drugs, LVH, and channelopathies.  We found that 38% of out of hospital ventricular fibrillation was due to STEMI.  The remainder were due to other etiologies, (including NonSTEMI ACS).  But approximately 50% were due to non-ACS etiologies.

2. ST depression (with reciprocal ST elevation in lead aVR) is common shortly after BOTH resuscitation from ventricular fibrillation AND after cardioversion from atrial fibrillation.

3.  One should wait a short time (15 minutes?) to record another 12-lead ECG to ascertain whether there is ongoing ischemia and probable ACS, or whether the ST depression is transient only.

4. Not all patients with ventricular fibrillation necessarily need emergent angiography.  Much depends on the post resuscitation ECG and its evolution shortly after defibrillation.


Reference:

Scott NL. Mulder M. Bart B. Smith SW.  Correlation of STEMI in Resuscitated Non-traumatic out-of-hospital Cardiopulmonary Arrest patients with Initial Rhythm and Cardiac Catheterization Findings (Abstract 580). Academic Emergency Medicine 17(s1):S194; May 2010