Figure 1.
Qualitative and quantitative assessments of myocardial fibrosis in endomyocardial biopsy and LGE-CMR in the HCM patients.
(A–C) Typical histology from endomyocardial biopsy. Upper panels; no pathological fibrosis (A), increased interstitial fibrosis (B), and severe myocardial scarring (C). Slides were stained with Azan dye. Interstitial fibrosis was defined as increased interstitial collagen without evidence of cardiomyocyte loss [9], [22]. Lower panels: areas of fibrosis visualized by ImageJ software. Fibrosis volume fraction determined by digital planimetry was 2% (A), 15% (B) and 45% (C), respectively. Myocardial scarring was defined as increased interstitial collagen with evidence of cardiomyocyte loss [9], [22]. The presence of islands of surviving cardiomyocyte among fibrotic tissues was considers as evidence of cardiomyocyte loss [23]. (D) Islands of surviving cardiomyocyte (arrows) among fibrotic tissues observed with high magnification of Image C. (E and F) Defining and quantifying LGE. Representative HCM patients with no LGE (E) and with positive LGE (F). Areas of LGE (traced by yellow lines) were quantified by manual planimetry and presented as percentage of left ventricular areas (traced by blue lines). Total of 6 short axes views were analyzed in each HCM patient. The LGE volume fraction was 0% in Case D, and 16% in Case E. Scale bars represent 200 µm. CMR = cardiac magnetic resonance imaging, HCM = hypertrophic cardiomyopathy, LGE = late gadolinium enhancement.
Table 1.
Characteristics of the 21 patients with HCM.
Figure 2.
Representative patterns of LGE in the HCM patients.
(A) No LGE. (B) Patchy midwall LGE in the anterior wall. (C) Linear midwall LGE in anteroseptal and lateral wall. (D) Extensive midwall and subendocardial LGE in the diffuse left ventricle.
Table 2.
Histological characteristics of fibrosis in biopsy specimens in the 21 patients with HCM.
Table 3.
Characteristics of LGE-CMR in the 21 patients with HCM.
Table 4.
Diagnostic values of LGE for detecting microscopic myocardial scarring or interstitial fibrosis in biopsied specimens in the HCM patients (N = 21).
Table 5.
Diagnostic values of LGE for detecting microscopic myocardial scarring or interstitial fibrosis in biopsied specimens in the HCM patients with preserved systolic function (N = 16).
Figure 3.
Relationships between the microscopic fibrosis fraction and the LGE fraction in the HCM patients.
(A) A fair correlation was found between the LGE fraction and the total fibrosis fraction in biopsied specimens (N = 21). (B) To examine whether the LGE fraction correlated with the microscopic collagen fraction in HCM with preserved LV systolic function, 5 end-stage HCM patients were excluded from analyses. In the remaining 16 HCM patients, a correlation between the LGE fraction in the whole heart and the microscopic collagen fraction in biopsied specimens was observed (r = 0.62, p = 0.011). Abbreviations as in Figure 1.
Table 6.
Predictors of the collagen fraction in biopsied specimens (unadjusted and multivariate-adjusted regression analyses).
Figure 4.
Concordant and discordant appearance of fibrosis in LGE-CMR and endomyocardial biopsy in the HCM patients.
(A) Myocardial scarring was observed both in CMR and endomyocardial biopsy. (B) LGE was present in CMR, but there was no evidence of microscopic myocardial scarring. Scale bars represent 200 µm. Abbreviations as in Figure 1.