Presentation
History of atrial flutter and ventricular wall thickening with preserved LVEF noted on echocardiography.
Patient Data
Cine sequences demonstrate the characteristic "dumbbell" configuration of midventricular hypertrophic cardiomyopathy (HCM) with nearly circumferential mural thickening of the mid-cavity segments of the heart with relative sparing of the basal and apical segments. In particular, the mid-cavity inferoseptal, anterolateral, and inferolateral segments measured 15 mm, 20 mm, and 24 mm, respectively.
- EDVI = 51 ml/m2
- ESVI = 18 ml/m2
- SVI = 33 ml/m2
- LVEF = 65%
- LVMI = 45 g/m2
There are few scattered patchy areas of mid-wall enhancement, including along the basal anterior and anteroseptal segments as well as in the mid-cavity inferolateral segment, with the LGE representing ~4% of LV mass.
There is associated bi-atrial enlargement. Moderate pericardial and bilateral pleural effusions are also present.
Wall-motion is within normal limits. No apical aneurysmal dilatation. No SAM or LVOT obstruction.
Case Discussion
There are several phenotypes of HCM: asymmetric (septal), apical, symmetric, mass-like, midventricular, and noncontiguous. Most often, cases of midventricular HCM are reported in the context of midventricular obstruction with associated apical aneurysm formation. Echocardiogram in this case demonstrated no evidence of dynamic obstruction as a result of the mid-cavity thickening, and there was no apical aneurysm present.
The patient was diagnosed with midventricular HCM (nonobstructive subtype). Genetic testing demonstrated mutations in the MYPN and SCN5A genes. While these are not the most common genetic mutations found in HCM, the former is a known association 5 while the latter has been seen in at least one case of familial HCM 6.
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