The Relationship between Cardiac Magnetic Resonance-Assessed Replacement and Interstitial Fibrosis and Ventricular Arrhythmias in Hypertrophic Cardiomyopathy

Aleksandra Karabinowska-Małocha,Piotr Podolec,Maciej Krupiński,Paweł Banyś,Aleksandra Budkiewicz,Sylwia Wiśniowska-Śmiałek,Małgorzata Urbańczyk-Zawadzka,Magdalena Kostkiewicz,Łukasz Żydzik,Małgorzata Mielnik,Jacek Łach,Paweł Rubiś,Ewa Dziewięcka,Katarzyna Holcman

doi:10.3390/jpm12020294

Abstract

Non-sustained ventricular tachycardia (nsVT) creates the electrical basis for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). We aimed to evaluate the relationship between interstitial fibrosis on cardiac magnetic resonance (CMR) and nsVT in HCM. A total of 50 HCM patients underwent CMR with a 3 T scanner to determine the presence of replacement fibrosis expressed by late gadolinium enhancement (LGE), and interstitial fibrosis expressed by native T₁, post-contrast T₁, and extracellular volume (ECV). The incidence of nsVT was assessed by Holter monitoring. We detected nsVT in 14 (28%) out of 50 HCM patients. Replacement fibrosis expressed by LGE was present in 37 (74%) patients and only showed a trend towards a differentiation between the groups with and without nsVT (p = 0.07). However, the extent of LGE was clearly higher in the nsVT group (3.8 ± 4.9% vs. 7.94 ± 4.5%, p = 0.002) and was an independent predictor of nsVT in a multivariable regression analysis (OR 1.2; 95%CI 1.02–1.4; p = 0.02). No relationship was observed between interstitial fibrosis and nsVT. To conclude, it was found that it is not the mere presence but the actual extent of LGE that determines the occurrence of nsVT in HCM patients; the role of interstitial fibrosis remains unclear.

Highlights

Hypertrophic cardiomyopathy (HCM) is a common genetic myocardial disease with a prevalence of approximately 1:500, caused by mutations in sarcomeric genes [1,2,3]
Approximately one-fifth of patients develop moderate-to-severe symptoms of chest pain, early fatigue, palpitations, syncope, etc., that result in five major pathologies: diastolic dysfunction (DD), left ventricle (LV) outflow tract obstruction (LVOTO), an imbalance between the myocardial oxygen supply and demand, end-stage heart failure (HF), and arrhythmias, including atrial fibrillation and non-sustained ventricular tachycardia that may lead to sudden cardiac death (SCD) [6,7,8]
We report lower values of late gadolinium enhancement (LGE) extent, as it was almost 8% in the non-sustained ventricular tachycardia (nsVT)-positive group in comparison to 3.8% in the nsVT-negative group; the difference is statistically sound and clearly indicates that more fibrotic LV is more prone to ventricular arrhythmias

Summary

Introduction

Hypertrophic cardiomyopathy (HCM) is a common genetic myocardial disease with a prevalence of approximately 1:500, caused by mutations in sarcomeric genes [1,2,3]. Approximately one-fifth of patients develop moderate-to-severe symptoms of chest pain, early fatigue, palpitations, syncope, etc., that result in five major pathologies: diastolic dysfunction (DD), LV outflow tract obstruction (LVOTO), an imbalance between the myocardial oxygen supply and demand, end-stage heart failure (HF), and arrhythmias, including atrial fibrillation and non-sustained ventricular tachycardia (nsVT) that may lead to sudden cardiac death (SCD) [6,7,8]. Replacement fibrosis develops as a consequence of the death of local myocytes (necrosis, apoptosis), whereas interstitial fibrosis is caused by systemic processes, such as hypertension, inflammation, or genetic mutations. Both local and diffuse fibrosis coexist in HCM, as well as in many other cardiomyopathies

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