The Significance of Interstitial Fibrosis on Left Ventricular Function in Hypertensive versus Hypertrophic Cardiomyopathy

Abstract

Extracellular volume (ECV) has been validated as a surrogate measure of interstitial fibrosis, that is increased in both hypertension-induced left ventricular hypertrophy (H-LVH) and hypertrophic cardiomyopathy (HCM). We aimed to explore the correlation between ECV and left ventricular cardiac function. Eighty-one patients with HCM, 44 with H-LVH and 35 controls were prospectively enrolled. Even among patients with normal diastolic function, patients in HCM group had increased- ECV. In terms of diastolic dysfunction (DD), a similar increase in ECV was associated with a larger percentage of patients with severe or moderate-to-severe DD in HCM group. In addition, there was a compensatory increase in the left ventricular ejection fraction (LVEF) in HCM, but no hyperdynamic LVEF was observed in H-LVH. ECV was negatively correlated with LVEF in the late gadolinium enhancement (+) (LGE+) subgroups in the H-LVH group, while no significant linear correlation was observed in HCM group. The increased ECV in HCM patients with normal diastolic function warrants further exploration of the prognostic value of ECV assessments in the early stages of HCM. The associations between ECV and left ventricular functional parameters differed and taking both LGE and ECV into account might be reasonable way to differentiate between the two disorders.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

Fibrotic Distribution and Extent. (a) Examples illustrating myocardial T1 values and LGE characteristics in cases of abnormalities in H-LVH and HCM patients. Higher global native T1 values (yellow in cardiomyopathies, green in controls) and lower post-contrast T1 values (blue-purple in cardiomyopathies, light blue in controls) were seen in patients with H-LVH and HCM than in controls. Note the reddish colour on the native T1 and the blue-purple dots on the post-T1 images diffusively distributed in H-LVH patients (hollow arrows) compared to the much denser but concentrated foci in HCM patients; in HCM patients, the dense concentrated foci enabled the hyperenhancement that is visibly present with the conventional LGE technique (blue arrows). The same ECV (28%) was calculated for the H-LVH and HCM groups, which was higher than that of the control group (23%). (b–c) Presence and percentage of LGE. LGE was present in 84% of the patients with HCM and the interquartile range of the scar size was 2.2–15.1%. Conversely, only 34% of the H-LVH patients were LGE-positive, and the scar size ranged from 0–0.9%. ECV = extracellular volume; HCM = hypertrophic cardiomyopathy; H-LVH = hypertension-induced left ventricular hypertrophy; LGE = late gadolinium enhancement.

Figure 2

Relationship between ECV and Cardiac Function. (a) The relationship between ECV and the LV mass/volume ratio. With the same range of ECVs (p = 0.6 for the H-LVH group vs. the HCM group), the LV mass/volume ratio was mildly impaired in H-LVH patients (1.19–1.66 compared with 0.65–0.97 in controls, p < 0.001), but it was markedly impaired in HCM patients (1.33–2.30, p < 0.001 compared with H-LVH or controls). (b) Relationship between ECV and LVEF. A hyperdynamic LVEF was observed in HCM patients but was not observed in patients with H-LVH for correspondingly similar ranges of ECV (p = 0.004 for the HCM group vs. the control group and p = 0.7 for the H-LVH group vs. the control group). ECV: extracellular volume; H-LVH: hypertension-induced left ventricular hypertrophy; HCM: hypertrophic cardiomyopathy; LV: left ventricle; LVEF: left ventricular ejection fraction.

Figure 3

Relationship between LVEF and ECV in LGE (+) and LGE (−) subgroups. (a) LVEF in the LGE (+) or LGE (−) subgroups. (b) Relationship between LVEF and LGE size in patients with LGE (+) manifestations. (c) ECV in the LGE (+) or LGE (−) subgroups. (d) Relationship between ECV and LVEF in patients with LGE (+). ECV: extracellular volume; LVEF: left ventricular ejection fraction; HCM: hypertrophic cardiomyopathy; H-LVH: hypertension-induced left ventricular hypertrophy; LGE: late gadolinium enhancement.