Imaging and Impact of Myocardial Fibrosis in Aortic Stenosis

Abstract

Aortic stenosis is characterized both by progressive valve narrowing and the left ventricular remodeling response that ensues. The only effective treatment is aortic valve replacement, which is usually recommended in patients with severe stenosis and evidence of left ventricular decompensation. At present, left ventricular decompensation is most frequently identified by the development of typical symptoms or a marked reduction in left ventricular ejection fraction <50%. However, there is growing interest in using the assessment of myocardial fibrosis as an earlier and more objective marker of left ventricular decompensation, particularly in asymptomatic patients, where guidelines currently rely on nonrandomized data and expert consensus. Myocardial fibrosis has major functional consequences, is the key pathological process driving left ventricular decompensation, and can be divided into 2 categories. Replacement fibrosis is irreversible and identified using late gadolinium enhancement on cardiac magnetic resonance, while diffuse fibrosis occurs earlier, is potentially reversible, and can be quantified with cardiac magnetic resonance T1 mapping techniques. There is a substantial body of observational data in this field, but there is now a need for randomized clinical trials of myocardial imaging in aortic stenosis to optimize patient management. This review will discuss the role that myocardial fibrosis plays in aortic stenosis, how it can be imaged, and how these approaches might be used to track myocardial health and improve the timing of aortic valve replacement.

IL‐11 in cardiac and renal fibrosis: Late to the party but a central player

“…In the conduction system, fibrosis causes bradyarrhythmia and heart block, a substantial cause of morbidity in the elderly (Csepe, Kalyanasundaram, Hansen, Zhao, & Fedorov, ; Kerola et al, ). Risk factors for cardiac fibrosis are diverse and include hypertension (Cuspidi, Ciulla, & Zanchetti, ), ischaemic heart disease (Hinderer & Schenke‐Layland, ), aortic stenosis (Bing et al, ; Katbeh et al, ), inherited cardiomyopathy (Gulati et al, ; Ho et al, ), diabetes (Russo & Frangogiannis, ), and ageing (Lu et al, ).…”

“…hypertension (Cuspidi, Ciulla, & Zanchetti, 2006), ischaemic heart disease (Hinderer & Schenke-Layland, 2019), aortic stenosis (Bing et al, 2019;Katbeh et al, 2018), inherited cardiomyopathy (Gulati et al, 2013;Ho et al, 2010), diabetes (Russo & Frangogiannis, 2016), and ageing (Lu et al, 2017).…”

Impact of diastolic dysfunction on long‐term mortality and quality of life after transcatheter aortic valve replacement

“…Given that historically this latency period has been characterized by a low incidence of clinical events, current ACC/AHA guidelines have recommended a conservative approach for most patients with asymptomatic severe AS . A potential pitfall of this strategy is continuous adverse LV remodeling with replacement fibrosis that may not be reversible with aortic valve replacement . In addition, many asymptomatic patients present with sudden death as their first manifestation of severe AS with an annual incidence of 1.5–2% .…”

“…In addition, many asymptomatic patients present with sudden death as their first manifestation of severe AS with an annual incidence of 1.5–2% . In this context, advanced cardiac imaging could be useful in detecting early left ventricular decompensation and guide optimal timing of aortic valve replacement prior to the onset of symptoms or irreversible heart damage . Although our study was conducted in symptomatic patients with severe AS undergoing TAVR, it adds to the ongoing debate on the optimal timing of AVR referral by providing prognostic information on the negative role of advanced and indeterminate DD and elevated NT‐pro BNP levels prior to valve replacement.…”

Role of advanced left ventricular imaging in adults with aortic stenosis

“…Unlike LGE, which is insensitive for the detection of diffuse interstitial fibrosis, T1 mapping techniques can provide overall assessments of the extracellular compartment. While providing a close surrogate assessment of myocardial fibrosis,42 these markers are also affected by other extracellular factors including oedema and capillary volume. The most studied methods are native T1, which does not require gadolinium contrast, and extracellular volume fraction (ECV%) 43.…”