Clinical and imaging description of the Maron subtypes of hypertrophic cardiomyopathy

Longitudinal strain analysis enables early detection of left ventricular (LV) contraction abnormalities in patients with preserved ejection fraction. Hypertrophic cardiomyopathy (HCM) is associated with low values of regional and global longitudinal myocardial deformations. In addition to contraction abnormalities, LV regional strain abnormalities are partially related to the degree of hypertrophy. This study sought to describe global longitudinal strain (GLS) in HCM patients as categorized using the Maron’s classification. Complete echocardiography examinations, including GLS analysis, were performed in consecutive HCM patients followed up in two French HCM-clinics. A total of 271 patients (mean age 49 ± 16yrs; 71 % male) were evaluated. In this population, the most frequently classified hypertrophy pattern was Type II (47 %), following the Maron’s classification. Type III was characterized by a higher degree of LV hypertrophy in terms of mass and maximal wall thickness, and was more frequently obstructive at rest, with lower GLS values (−15.3 ± 3.9 %, p = 0.016), higher E/E’ ratio (13.4 ± 6.7, p < 0.001), and a more frequently inadequate blood pressure response to exercise (30 %, p = 0.04) compared to other patterns. The variable that correlated best with GLS was LV mass index (r = 0.49, p < 0.01), while GLS did not significantly correlate with left ventricular outflow tract obstruction. This study demonstrated that the Type III HCM pattern presented with lower GLS, which was partially related to higher LV mass index, more elevated LV filling pressures, and a more frequently inadequate blood pressure response to exercise, in comparison with other patterns categorized using the Maron’s classification.