Small Vessel Disease: Another Component of the Hypertrophic Cardiomyopathy Phenotype Not Necessarily Associated with Fibrosis.

Monica De Gaspari,Annalisa Angelini,Stefania Rizzo,Cristina Basso,Stefania Elia,Martina Perazzolo Marra,Gaetano Thiene,Maria Bueno Marinas

doi:10.3390/jcm10040575

Monica De Gaspari, Annalisa Angelini + Show 6 more

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https://doi.org/10.3390/jcm10040575

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Abstract

Background: Hypertrophic cardiomyopathy (HCM) is characterized by myocardial disarray, small vessel disease (SVD), and fibrosis. The relationship between SVD and replacement-type fibrosis is still unclear. Methods: Histopathologic assessment of replacement-type fibrosis and SVD in HCM patients with either end-stage heart failure (HF) or sudden cardiac death (SCD). Chronic ischemic heart disease (IHD) patients served as controls. Results: Forty HCM hearts, 10 HF and 30 SCD, were studied. Replacement-type fibrosis was detected in all HF and in 57% of SCD cases. In SCD, replacement-type fibrosis was associated with older age, greater septal thickness, SVD prevalence, and score (all p < 0.05). Prevalence of SVD did not show significant differences among SCD, HF, and IHD (73%, 100% and 95%, respectively), while SVD score was higher in HF than IHD and SCD (2.4, 1.95, and 1.18, respectively) and in areas with replacement-type fibrosis vs. those without in HF (3.4 vs. 1.4) and SCD (1.4 vs. 0.8) (all p < 0.05). Conclusions: SVD is a frequent feature in HCM independent of the clinical presentation. A higher SVD score is observed in HCM-HF and in areas with replacement-type fibrosis. Although SVD is part of the HCM phenotype, further remodeling of the microcirculation might occur secondarily to fibrosis.

Highlights

Hypertrophic cardiomyopathy (HCM) is an inherited myocardial disease due to mutations of genes that mostly encode for sarcomeric proteins, with a heterogeneous clinical and prognostic spectrum [1]
The present study was undertaken to evaluate the relationship between small vessel disease (SVD) and replacement-type fibrosis in HCM patients presenting with either sudden cardiac death (SCD) or end-stage systolic
We previously demonstrated that fibrosis in HCM is most probably ischemic in origin and represents the ideal substrate for electrical instability and life-threatening ventricular arrhythmias [5], so that cardiac magnetic resonance (CMR) is considered for risk stratification in HCM patients [11]

Summary

Introduction

Hypertrophic cardiomyopathy (HCM) is an inherited myocardial disease due to mutations of genes that mostly encode for sarcomeric proteins, with a heterogeneous clinical and prognostic spectrum [1] It is characterized by either symmetric or asymmetric hypertrophy, involving predominantly the interventricular septum (IVS) which can cause left ventricular (LV) outflow tract obstruction [1,2]. Histological abnormalities affect the cardiac myocyte and the interstitial space, with hypertrophy, disarray, and both interstitial and replacement-type fibrosis, and the microcirculation, with thickening of the walls of the intramyocardial arterioles These myocardial features may represent the substrates of either ventricular arrhythmias at risk of sudden cardiac death (SCD) or evolution towards systolic dysfunction (so-called “end-stage” heart failure—HF) [3,4,5,6,7]. Replacement-type fibrosis was detected in all HF and in 57% of SCD cases

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