Yasuo Amano MD, Presenter: Nothing to Disclose

Mitsunobu Kitamura, Abstract Co-Author: Nothing to Disclose

Morimasa Takayama, Abstract Co-Author: Nothing to Disclose

Masaki Tachi MD, PhD, Abstract Co-Author: Nothing to Disclose

Yasuhiro Kobayashi, Abstract Co-Author: Nothing to Disclose

Shinichiro Kumita MD, Abstract Co-Author: Nothing to Disclose

To classify asymmetrical septal hypertrophic cardiomyopathy (ASH), the most common type of hypertrophic cardiomyopathy (HCM), using cardiac MRI and to evaluate the relation between the MRI classification and risk factors of ASH.

Eighty-five patients with ASH, in which basal septal / posterior wall thicknesses > 1.3, underwent cine and delayed-enhancement (DE) MRI. Apical and midventricular obstruction HCM were excluded. ASH was classified by cine MRI at end-diastole, and the relation between the MRI classification and risk factors (i.e., family history of HCM, ventricular tachyarrhythmias, syncope, myocardial DE%, atrial fibrillation) was evaluated.

Using MRI, ASH was classified to classical (55%), inferoseptal (19%), sigmoid (11%), anteroseptal (8%), and reverse-curve (7%) subtypes. Myocardial mass was related to atrial fibrillation and myocardial DE% (P< 0.01). Family history of HCM was related to ventricular tachyarrhythmias (P< 0.01), while patients’ age was inversely related to myocardial DE% (P < 0.01). Classical subtype showed various MRI findings. Inferoseptal subtype included fewer cases with the risk factors. Sigmoid subtype was seen in the elderly with few risk factors. Anteroseptal subtype had the family history of HCM more frequently (P< 0.01). Reverse-curve subtype was characterized by younger age, thicker septal myocardium, and lower ejection fraction (P< 0.05).

Cardiac MRI classified ASH to 5 subtypes and estimated the myocardial mass and DE%. Anteroseptal and reverse-curve subtypes might be high-risk ones, while sigmoid subtype might be a low-risk one. The MRI classification of ASH may contribute to its risk stratification.

Cardiac MRI was able to classify asymmetrical septal hypertrophic cardiomyopathy to 5 subtypes, which might extract low- and high-risk subtypes.

Amano, Y, Kitamura, M, Takayama, M, Tachi, M, Kobayashi, Y, Kumita, S, MRI Classification of Asymmetrical Septal Hypertrophic Cardiomyopathy and Its Relation with Risk Factors.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11001364.html