An Uncommon Type of Hypertrophic Cardiomyopathy

Case presentation

A 35-year-old African American male who was being worked up for exertion-related dizziness presents to the ER after a witnessed cardiac arrest. In the ER he is found to be in pulseless ventricular tachycardia and is defibrillated back to a normal rhythm. He is intubated for post-cardiac arrest encephalopathy and transferred to the ICU.

Hypertrophic Cardiomyopathy ( HC ) is an autosomal dominant disease caused by mutations in one of 9 genes encoding sarcomeric proteins. Asymmetric basal septal hypertrophy is the most common type with outflow tract obstruction seen in most patients. Apical Cardiomyopathy on the other hand is uncommon and rare in the US population. However, it is 15-20 % of all hypertrophic cardiomyopathies in Japan where it was first recognized. 

Diagnostic criteria for Yamaguchi Cardiomyopathy

1. Asymmetric LV hypertrophy but predominantly at the apex 
2. LV wall thickness of 15 mm or above at end-diastole 
3. Apical to posterior wall thickness ratio of 1.5 or above. 

Unique features 

1.   Negative T waves in precordial leads
2.   Spade like LV cavity ( best to look at end-diastole) 
3.   Outflow obstruction is not typically observed. 
4.   Generally a reasonable prognosis

Echo points 

1. A close look at the apex in 4C and PSLA view. 
2. Contrast may be needed to better visualize the spade shape of the LV cavity LV and LVOT gradient are not common in this type of hypertrophic cardiomyopathy (nonobstructive) 
3. You may need to consider TOE or CMR if TTE views are poor (See reference below)