Wednesday, December 7, 2011

Found an ECG zebra... maybe.

Quick one today.

I wasn't sure about putting the case up, partly because there isn't a tidy follow-up and definite diagnosis yet. Also because I just talked about ECGs and PE, and this is material that is done better by Stephen Smith, or at Dr. S. Venkatesan's blog. Nonetheless.

I get ECGs tossed at me all day, checking for STEMI. A number of these are on folks under he age of 40, and I admit that my guard goes down a bit when I see the age. Nothing's impossible, but... Probably not on my shift.

So the tech comes up to me, hands me the 12-lead, and says "He passed out."

Huh. This looks different.

So, when you are looking at the ECG for cardiac causes of syncope, 4 entities you cnned to consider are long-QT syndrome, WPW, Brugada, and hypertrophic cardiomyopathy. Residents are good at describing the ECG appearance of the first 3, but are a little hazy on HCM.

Well, it looks a lot like the ECG above! I'll briefly review the manifestations of HCM on the ECG, boiling down a few of the references. Speaking of which, you may do as well to stop reading this post, and just download the great article by Kelly, Mattu, and Brady. You can download it here (pdf).

A few essential facts about HCM and the ECG:

  • Most ECGs in patients with HCM will be abnormal.
  • The ECG may be abnormal even if the echocardiogram (often taken to be the diagnostic standard) is normal.
  • Signs of LVH are typical, including the high R-waves, and the concomitant ST-T wave depressions laterally.
  • Q waves are often found in the inferior and lateral leads, erroneously suggesting old MI.

These Q waves are different from infarct-related Q's, however. The are deep and narrow, and have been described as "stiletto-like." Here's an example from the Kelly paper:

Unlike ischemic Q's, the HCM variety are generally under "one small box" in width, but may be fairly deep. Deep has been defined as 1/3 or 1/4 the height of the succeeding R wave (which my guy had), or at least 3 mm in depth in at least 2 leads (ditto).

So, did he have HCM? Hard to say at this point. The patient had an echo done, and was brought in for monitoring. The echo was limited, and no "obvious" abnormalities of chamber hypertrophy or outflow obstruction were found. If I hear more about his course, I'll share it.


  1. One point for other readers unfamiliar with the changes in HCM, is this ECG looks a bit like Early Repolarization. That is, except for the inferiolateral Q-waves present, which aren't a common finding in early repol.

    Great ECG!

  2. Yeah, it's a great ECG - but I need closure!