End-stage hypertrophic cardiomyopathy explanted hearts exhibited significantly greater myocardial fibrosis compared to hypertrophic obstructive cardiomyopathy myectomy specimens (34.6% vs 10.3%; p<0.001).
Observational (n=57)
How do microvasculopathy and myocardial fibrosis compare between hypertrophic obstructive cardiomyopathy and end-stage hypertrophic cardiomyopathy?
Microvasculopathy is a consistent feature across phases of hypertrophic cardiomyopathy, whereas myocardial fibrosis progresses to a predominantly scar-like pattern in end-stage disease.
Absolute Event Rate: 34.6% vs 10.3%
p-value: p=<0.001
BACKGROUND: Although imaging techniques have demonstrated the existence of microvascular abnormalities in hypertrophic cardiomyopathy (HCM), a detailed histopathological assessment is lacking as well as a comparison between different phases of the disease. We aimed to compare microvasculopathy and myocardial fibrosis in hypertrophic obstructive cardiomyopathy (HOCM) versus end-stage (ES) HCM. METHODS: 27 myectomy specimens of HOCM patients and 30 ES-HCM explanted hearts were analyzed. Myocardial fibrosis was quantitatively determined with dedicated software and qualitatively classified as scar-like or interstitial. Intramural coronary arteries were evaluated separately according to lumen diameter: 100-500 μ versus <100 μ. Microvasculopathy assessment included the description of medial and intimal abnormalities and stenosis grading. The two subgroups were compared considering only the anterobasal septum of ES explanted hearts. RESULTS: Median value of fibrosis in the anterobasal septum of explanted hearts was 34.6% as opposed to 10.3% of myectomy specimens (p < 0.001). Scar-like fibrosis was widely found in ES hearts while interstitial fibrosis was distinctive of HOCM (p < 0.001). All slides showed 100-500 μ microvasculopathy without any differences between subgroups in terms of lumen narrowing, extent of the disease and type of parietal involvement. Among ES hearts these lesions were associated with scar-like fibrosis (p = 0.034). <100-μ microvasculopathy was also frequent with no differences between subgroups. CONCLUSIONS: Microvasculopathy is an intrinsic feature of HCM with similar characteristics across the natural phases of the disease. Conversely, myocardial fibrosis changes over time with ES hearts showing a three-fold greater amount, mainly scar-like. ES showed a closer association between microvasculopathy and replacement fibrosis.
Foà et al. (Thu,) conducted a observational in Hypertrophic cardiomyopathy (HOCM and ES-HCM) (n=57). End-stage hypertrophic cardiomyopathy (explanted hearts) vs. Hypertrophic obstructive cardiomyopathy (myectomy specimens) was evaluated on Median value of myocardial fibrosis in the anterobasal septum (p=<0.001). End-stage hypertrophic cardiomyopathy explanted hearts exhibited significantly greater myocardial fibrosis compared to hypertrophic obstructive cardiomyopathy myectomy specimens (34.6% vs 10.3%; p<0.001).