Characteristics of late gadolinium enhancement in hypertrophic cardiomyopathy and its relationship with perfusion abnormalities: a cardiovascular magnetic resonance imaging study

hypertrophic cardiomyopathy (HCM) is characterized by hypertrophy of the left ventricle (LV) and can be accompanied by the development of fibrosis and microvascular abnormalities and thereby a reduced myocardial perfusion (1,2). Fibrosis can lead to reduced myocardial perfusion, and vice versa. Little is known about the interplay between hypertrophy, cardiac fibrosis and perfusion in HCM.

to define the relationship between Late Gadolinium Enhancement (LGE) patterns and areas with perfusion abnormalities and hypertrophy in HCM patients using cardiovascular magnetic resonance imaging (CMR).

we retrospectively assessed fibrosis (LGE) and myocardial perfusion by first-pass perfusion imaging during stress in HCM patients who underwent CMR. LGE was quantitatively assessed using Circle (cvi42) and perfusion analysis was performed visually. LGE was defined as a signal intensity 5 standard deviations (SD) above the reference point (normal myocardium). The global LGE value for each patient was obtained, as well as the regional LGE values of each segment (figure 2, panel A). LGE was expressed as grams or as a percentage of the entire LV mass.

62 HCM patients were included, of which 17 (27.4%) exhibited no LGE or perfusion abnormalities (figure 1). Among the remaining patients, three groups were identified: 23 (37.1%) showed LGE without perfusion abnormalities, 3 (4.8%) showed isolated perfusion abnormalities without LGE, and 19 exhibited both (30.6%). Patients with LGE (n=38) were included for further analysis. The average age was 61.7±11.9 years and 31.6% were genotype positive. Average LGE amount did not differ between patients with (12.0±6.4 gram; 8.9±5.4%) and without perfusion abnormalities (10.0±9.5 gram; 7.1±5.7%) (p-value=0.463 for gram and 0.339 for %). Segments 2,15,3 and 8 exhibited the highest LGE percentage (figure 2, panel B). The average maximum wall thickness (MWT) was 19.4 mm±6.3 and was mostly present in AHA segments 3, 2 and 9 (figure 2, panel C). The average LGE amount of the MWT segments (15.2±17.7%) was higher than the average LGE amount in other segments (8.0±11.3%) (p=0.019). Perfusion abnormalities occurred most frequently in segments 14,9,8 and 13 respectively (figure 2, panel D). 55.6% of the MWT segments exhibited perfusion abnormalities. Segments with perfusion abnormalities had an average LGE amount of 11.9±10.1%, whereas segments without abnormal perfusion had an average LGE amount of 8.3±10.1% (p=0.056).

LGE is common in HCM patients and occurs mostly in the hypertrophied segments. The amount of LGE does not differ between patients with and without perfusion abnormalities. However, on a segmental level, segments with perfusion deficits tend to have a higher amount of LGE. Moreover, LGE can occur in the absence of perfusion abnormalities, suggesting it is fibrosis that precedes ischemia and not the other way around.

Flowchart of included HCM patients.