Wednesday, November 30, 2016

A Young Man with Recurrent Chest Pain and Dyspnea with Exertion

Case

This is a young man who has had chest pain and dyspnea with exertion for years.  He presented to the ED with these symptoms again.  On this occasion, the CP was associated with stress and accompanied by some SOB, 7/10 at it's worse and made worse with activity, with radiation up into the left side of his neck and face.

No h/o hypertension.

Here is the ECG:
Probable Diagnosis?
I was shown this ECG and gave my opinion, as below.


Here is an ED bedside echo, parasternal long axis:

Look at the small the end-systolic LV chamber size


Parasternal short axis:


Again, look at the end-systolic chamber size!

What is the Diagnosis?














The ECG shows profound LVH with secondary ST/T abnormalities.  There is deep ST depression and T-wave inversions that are discordant to (in the opposite direction of) large voltage R-waves.  These ST-T abnormalities do not represent ischemia, although they could certainly hide ischemia.  Instead, these repolarization (ST-T) abnormalities are entirely secondary to depolarization abnormalities (huge voltage).

The echo shows profound LVH.  Whether it is definitely concentric or assymetric (which is seen in HOCM with assymetric septal hypertrohy) is hard to tell for certain with these bedside echos.

Comment: In a young man with no history of hypertension, and with these typical symptoms of hypertrophic cardiomyopathy (HOCM), this is HOCM until proven otherwise.

Case continued

He refused hospital admission.  He was discharged with followup for a formal contrast ultrasound and cardiology clinic.

Comment: In someone like this who refuses to be admitted, it is wise to start a beta blocker.

Case continued

He returned about a week later with similar symptoms: Central CP and SOB that can last minutes or hours, but this time it lasted for less than an hour and was again worse with activity.  There was no nausea or diaphoresis.

Here is his ECG on this visit:
Slower sinus rate, but otherwise the same.

His serial troponin I (Abbott Architect contemporary troponin, 99% = 0.030 ng/mL):
0 hour: 0.034 ng/mL
3 hour: 0.024 ng/mL
6 hour: 0.011 ng/mL

Thus, he had symptoms compatible with myocardial infarction and a diagnostic fall of troponin with one level (the first) above the 99% cutoff.  This meets the definition of MI, but only if the troponin elevation is also thought to be due to ischemia.


A Formal stress echo was done:

Dynamic intraventricular gradient 15 mmHg at rest and increased to 26 mmHg post stress.
Normal estimated left ventricular ejection fraction at rest.
Normal estimated left ventricular ejection fraction improved with stress.
No wall motion abnormality at rest.
No wall motion abnormality with stress.
Left ventricular hypertrophy concentric .
Dynamic intraventricular gradient .
Hypertrophic cardiomyopathy .
Left ventricular hypertrophy concentric obstruction.

Comment: So he has HOCM and it is likely that stress induces some ischemia in this hypertrophic myocardium. Therefore, one would call this a type 2 myocardial infarction due to outflow obstruction in HOCM.

Case continued

He was started on metoprolol and discharged.

Comment: Explanation of outflow obstruction and use of beta blockade:  In obstructive HOCM, the end-systolic volume is very small due to the hypertrophic myocardium, and it thus obstructs aortic outflow at end systole.  This the source of the "gradient."  It is similar to mild aortic stenosis, but only at end systole.  Beta blockers: 1) diminish the contractility and thus result in a larger end-systolic volume and less outflow obstruction and 2) slow the heart rate, allowing for more time to fill, resulting in larger end-diastolic volume which also results in higher end-systolic volume.


Here are some other cases of HOCM:
Exertional Chest pain and Near Syncope in a Young Adolescent
In this case, the more typical large septal R-wave is present in V1, indicative of hypertrophy of the septum.

Here is a fascinating case in which dehydration leads to low end-systolic volume and shock in an HOCM patient.  Esmolol works to manage the patient:

History of Hypertrophic Cardiomyopathy (HOCM), with Tachycardia and High Lactate










2 comments:

  1. Thanks for these amazing posts. I have a question about the ECGs. In the 2nd ECG in lead III the QRS voltage is much smaller, there almost looks like STE and the T wave has changed from inverted to biphasic. I notice this is isolated to lead III and there are no other contiguous lead changes (or any leads for that matter) to confirm with so does that mean this is nonspecific changes? Or can this be the only clue of ischemia now in an ECG that is otherwise normally dominated by LVH and strain pattern?

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    Replies
    1. The axis is less towards III than towards II. So III does not get to "see" all that voltage. Similarly, the T-wave axis is perpendicular to III, with the initial phase towards (+) and the later phase away (-). A complex's axis determintes where the voltage is best seen.

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