How can hypertrophic cardiomyopathy be diagnosed?
The diagnosis can be made in adults by a maximal end-diastolic wall-thickness ≥15 mm anywhere in the left ventricle on imaging (echo or cardiac MRI) with no other cause e.g. explained by loading conditions. In the setting of a positive family history or genetic test, the left ventricular hypertrophy can be more limited (13-14mm). Similar to adults, in children the diagnosis requires an increased left ventricular wall thickness of more than two standard deviations from the predicted mean (z-score >2).
What phenotype do we have here?
This is an asymmetric hypertrophic phenotype maybe even mass-like.
What is the role of cardiac magnetic resonance (CMR) in the assessment of left ventricular hypertrophy?
Clarification of the diagnosis in the setting of inconclusive echocardiography; evaluation regarding alternative diagnoses (e.g. storage disease, infiltrative disease, athlete's heart etc.); assessment of the extent of myocardial fibrosis; clarification of findings in the setting of left ventricular outflow obstruction.
What is the clinical significance of late gadolinium enhancement?
If present and extensive (e.g. >15% of the LV mass, as proposed by some studies) it is associated with an increased risk for ventricular tachyarrhythmias and sudden cardiac death.
Heart rate: 62 bpm
Image quality: mild to moderate respiratory artifacts, otherwise no limitations
Morphology and functional analysis (endo-volume - including papillary muscles):
LV-EDVI: 93 mL/m²
LV-ESVI: 35 mL/m²
LV-SVI: 58 mL/m²
LV-EF: 63%
cardiac output: 6.4 L/min
cardiac index: 3.7 L/min/m²
LV-ED wall mas index (without papillary muscles): 70 g/cm
septum thickness: 20 mm
inferior wall thickness: 7 mm
Findings:
asymmetric mass-like thickening of the basal septum
visually normal atrial size
systolic anterior motion of the mitral valve
diastolic jet in the left ventricular outflow tract
no intracavitary thrombi, no ventricular aneurysm
no pericardial effusion
Myocardial tissue properties
fan-shaped, patchy late gadolinium enhancement at the right ventricular insertion points
T1 mapping native: mildly elevated, movement artifacts in the lateral segments
extracellular volume (ECV): elevated (>32%) in the basal anteroseptal and inferoseptal segments
T2 mapping: mildly elevated (~57 ms) in the midventricular inferoseptal segment with normal values in the remote myocardium ( 52 ms)
*Normal reference ranges based on local data:
-
native T1: 940-1060 ms; ECV: <32%; T2: 44-56 ms
QFlow (aortic annulus):
regurgitant fraction: ~12%
peak velocity: ~142 cm/s
peak pressure gradient <10 mmHg
Impression:
asymmetric hypertrophic cardiomyopathy almost mass-like phenotype
preserved systolic function
mild aortic valve insufficiency
Exam courtesy: Tobias Jahn & Sven Winzler (radiographers)