Giuseppe Galati1, Ornella Leone1, Ferdinando Pasquale1, Iacopo Olivotto1, Elena Biagini1, Francesco Grigioni1, Emanuele Pilato1, Massimiliano Lorenzini1, Barbara Corti1, Alberto Foà1, Valentina Agostini1, Franco Cecchi1, Claudio Rapezzi2. 1. From the Units of Cardiology (G.G., F.P., E.B., F.G., M.L., A.F., C.R.), Pathology (O.L., B.C., V.A.), Cardiac Surgery (E.P.), Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum-University of Bologna, S.Orsola-Malpighi University Hospital, Italy; and Referral Center for Cardiomyopathies, Cardiothoraco-vascular Department, Careggi University Hospital, Florence, Italy (I.O., F.C.). 2. From the Units of Cardiology (G.G., F.P., E.B., F.G., M.L., A.F., C.R.), Pathology (O.L., B.C., V.A.), Cardiac Surgery (E.P.), Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum-University of Bologna, S.Orsola-Malpighi University Hospital, Italy; and Referral Center for Cardiomyopathies, Cardiothoraco-vascular Department, Careggi University Hospital, Florence, Italy (I.O., F.C.). claudio.rapezzi@unibo.it.
Abstract
BACKGROUND: Although noninvasively detected myocardial fibrosis (MF) has clinical implications in hypertrophic cardiomyopathy, the extent, type, and distribution of ventricular MF have never been extensively pathologically characterized. We assessed the overall amount, apex-to-base, circumferential, epicardial-endocardial distribution, pattern, and type of MF in 30 transplanted hearts of end-stage, hypertrophic cardiomyopathy. METHODS AND RESULTS: Visual and morphometric histological analyses at basal, midventricular, and apical levels were performed. Overall MF ranged from 23.1% to 55.9% (mean=37.3±8.4%). Prevalent types of MF were as follows: replacement in 53.3%, interstitial-perimyocyte in 13.3%, and mixed in 33.3%. Considering left ventricular base-to-apex distribution, MF was 31.9%, 43%, and 46.2% at basal, midventricular, and apical level, respectively (P<0.001). Circumferential distributions (mean percentage of MF within the section) were as follows: anterior 11.9%, anterolateral 15.8%, inferolateral 7.0%, inferior 24.3%, anteroseptal 11%, midseptal 10.7%, and posteroseptal 11.4%; circumferential distributions for anterior and inferior right ventricular walls were 3.4% and 4.5%, respectively. Epicardial-endocardial distributions were as follows: trabecular 26.1% and subendocardial 20.2%, midwall 33.4%, and subepicardial 20.3%. Main patterns identified were as follows: midwall in 33.3% of the hearts, transmural in 23.3%, midwall-subepicardial in 23.3%, and midwall-subendocardial in 20%. CONCLUSIONS: In end-stage, hypertrophic cardiomyopathy patients undergoing transplantation, more than one-third of the left ventricular myocardium was replaced by fibrosis, mainly of replacement type. MF preferentially involved the left ventricular apex and the midwall. Inferior and anterior walls and septum were maximally involved, whereas inferolateral and right ventricular were usually spared. These observations reflect the complex pathophysiology of hypertrophic cardiomyopathy and may provide clues for the timely recognition of disease progression by imaging techniques capable of quantifying MF.
BACKGROUND: Although noninvasively detected myocardial fibrosis (MF) has clinical implications in hypertrophic cardiomyopathy, the extent, type, and distribution of ventricular MF have never been extensively pathologically characterized. We assessed the overall amount, apex-to-base, circumferential, epicardial-endocardial distribution, pattern, and type of MF in 30 transplanted hearts of end-stage, hypertrophic cardiomyopathy. METHODS AND RESULTS: Visual and morphometric histological analyses at basal, midventricular, and apical levels were performed. Overall MF ranged from 23.1% to 55.9% (mean=37.3±8.4%). Prevalent types of MF were as follows: replacement in 53.3%, interstitial-perimyocyte in 13.3%, and mixed in 33.3%. Considering left ventricular base-to-apex distribution, MF was 31.9%, 43%, and 46.2% at basal, midventricular, and apical level, respectively (P<0.001). Circumferential distributions (mean percentage of MF within the section) were as follows: anterior 11.9%, anterolateral 15.8%, inferolateral 7.0%, inferior 24.3%, anteroseptal 11%, midseptal 10.7%, and posteroseptal 11.4%; circumferential distributions for anterior and inferior right ventricular walls were 3.4% and 4.5%, respectively. Epicardial-endocardial distributions were as follows: trabecular 26.1% and subendocardial 20.2%, midwall 33.4%, and subepicardial 20.3%. Main patterns identified were as follows: midwall in 33.3% of the hearts, transmural in 23.3%, midwall-subepicardial in 23.3%, and midwall-subendocardial in 20%. CONCLUSIONS: In end-stage, hypertrophic cardiomyopathypatients undergoing transplantation, more than one-third of the left ventricular myocardium was replaced by fibrosis, mainly of replacement type. MF preferentially involved the left ventricular apex and the midwall. Inferior and anterior walls and septum were maximally involved, whereas inferolateral and right ventricular were usually spared. These observations reflect the complex pathophysiology of hypertrophic cardiomyopathy and may provide clues for the timely recognition of disease progression by imaging techniques capable of quantifying MF.
Authors: Julie K Shade; Mark J Cartoski; Plamen Nikolov; Adityo Prakosa; Ashish Doshi; Edem Binka; Laura Olivieri; Patrick M Boyle; Philip J Spevak; Natalia A Trayanova Journal: Heart Rhythm Date: 2019-10-04 Impact factor: 6.343