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"Development of the European Network in Orphan Cardiovascular Diseases"
„Rozszerzenie Europejskiej Sieci Współpracy ds Sierocych Chorób Kardiologicznych”
Title: Assessment of Left Ventricular Function in Aortic Stenosis
using Cardiac Magnetic Resonance
Author: Podolec Jakub MD, PhD
Affiliation: Interventional Cardiology Department, Cardiology Institute, Collegium
Medicum, Jagiellonian University at the John Paul II Hospital, Krakow, Poland
Date: 11.04.2014
Introduction
Calcific Aortic Stenosis (CAS) is the most common valve disease in North America and
Europe. According to the 2003 Euro Heart Survey on Valvular Heart Disease, aortic stenosis
represented 33.9% of valvular diseases, of which 81.9% were due to degenerative-calcific
etiology [1]. In 2006, Nkomo et al, found a 2.5% prevalence of aortic stenosis in the general
population, with prevalence increasing with age to 13.3% in those 75 years of age and older
[2]
Literature review
Calcific Aortic Stenosis (CAS) is defined as progressive narrowing of the aortic valve leading
to subsequent increased afterload which triggers the development of left ventricular
hypertrophy. The severity of both valve narrowing and ventricular hypertrophy determine
how quickly patients with CAS develop symptoms, the adverse effects, and the need for
surgical intervention [3-5] However, it was established by Dweck et al, that severity of
stenosis does not correlate with the degree left ventricle (LV) adaptation and hypertrophy [6]
As such, valve narrowing and ventricular hypertrophy should be viewed as two related but
different pathomechanisms contributing to the CAS clinical picture [3].
According to Dweck et al. the degree of left ventricular hypertrophy does not correlate with
the severity of stenosis [6]. It has also been found that LV ejection fraction is not an accurate
indicator of LV function. Therefore, other techniques must be employed to assess LV
function in patients with LV hypertrophy in CAS [7]. Cardiac magnetic resonance to visualize
abnormalities of left ventricular structure and function are an emerging tool in clinical
cardiology. CMR imaging with late gadolinium enhancement localized to the LV has been
found to be associated with worse LV function [8,9]. Dweck et al. have demonstrated the use
John Paul II Hospital in Kraków
Jagiellonian University, Institute of Cardiology
80 Prądnicka Str., 31-202 Kraków;
tel. +48 (12) 614 33 99; 614 34 88; fax. +48 (12) 614 34 88
e-mail: [email protected]
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of CMR imaging with late gadolinium enhancement allows noninvasive visualization of
midwall fibrosis in patients with CAS. They observed that 38% of patients with moderate to
severe CAS had a midwall pattern of myocardial fibrosis [8] This finding was associated with
an 8-fold increase in mortality suggesting this CMR technique could serve as prognostic
indicator for risk stratification and to potentially detect LV decompensation before the onset
of heart failure.
Late gadolinium enhancement is limited to detection of only regional differences in
myocardial fibrosis and is unable to detect diffuse interstitial fibrosis of the myocardium
which is the predominant pattern of fibrosis is CAS [10]. Techniques to overcome this using
T1 mapping are currently being studied.
Other CMR techniques are also being developed to measure LV function in CAS. These
include measurement of left ventricle muscle mass index (LVMi) using CMR which is
reflected in abnormal global longitudinal strain which has been found to be proportional to
extent of hypertrophy. This may allow in the future the use of LVMi to stratify high risk
patients irrespective LV ejection fraction [11]. Recently Keshavarz-Motamed et al. introduced
a new index of LV hemodynamic load, which can be measured by CMR, referred to as N-SW
(normalized stroke work), which measures the energy required to eject 1ml of blood through
the valvulo-arterial load. This may soon provide effective new measure for risk stratification
of patients with CAS superior to current indices [12]. While the above studies are promising,
more studies are needed to assess the role of CMR in the assessment of LV function in
patients with CAS.
Conclusions
With the rising prevalence of CAS, the development of new methods for proper risk
stratification are essential to reducing morbidity and mortality in these patients. While the
assessment of the severity of stenosis is well established, the assessment of LV function
requires further evaluation. Cardiac Magnetic Resonance seems to be a potential tool that may
allow for the accurate assessment of left ventricular function in patients CAS.
References
1.
Iung, B. et al. A prospective survey of patients with valvular heart disease in Europe:
The Euro Heart Survey on valvular heart disease. Eur. Heart J. 24, 1231–1243 (2003).
2.
Nkomo, V. T. et al. Burden of valvular heart diseases: a population-based study.
Lancet 368, 1005–11 (2006).
3.
Dweck, M. R., Boon, N. A. & Newby, D. E. Calcific aortic stenosis: A disease of the
valve and the myocardium. J. Am. Coll. Cardiol. 60, 1854–1863 (2012).
4.
Cioffi, G. et al. Prognostic effect of inappropriately high left ventricular mass in
asymptomatic severe aortic stenosis. Heart 97, 301–307 (2011).
John Paul II Hospital in Kraków
Jagiellonian University, Institute of Cardiology
80 Prądnicka Str., 31-202 Kraków;
tel. +48 (12) 614 33 99; 614 34 88; fax. +48 (12) 614 34 88
e-mail: [email protected]
www.crcd.eu
5.
Pellikka, P. A. et al. Outcome of 622 adults with asymptomatic, hemodynamically
significant aortic stenosis during prolonged follow-up. Circulation 111, 3290–3295
(2005).
6.
Dweck, M. R. et al. Left ventricular remodeling and hypertrophy in patients with aortic
stenosis: insights from cardiovascular magnetic resonance. J. Cardiovasc. Magn.
Reson. 14, 50 (2012).
7.
Ozkan, A., Kapadia, S., Tuzcu, M. & Marwick, T. H. Assessment of left ventricular
function in aortic stenosis. Nat. Rev. Cardiol. 8, 494–501 (2011).
9.
Wallby, L. T lymphocyte infiltration in non-rheumatic aortic stenosis: a comparative
descriptive study between tricuspid and bicuspid aortic valves. Heart 88, 348–351
(2002).
8.
Dweck, M. R. et al. Midwall fibrosis is an independent predictor of mortality in
patients with aortic stenosis. J. Am. Coll. Cardiol. 58, 1271–9 (2011).
9.
Nassenstein, K. et al. Prevalence, pattern, and functional impact of late gadolinium
enhancement in left ventricular hypertrophy due to aortic valve stenosis. Rofo 181,
472–6 (2009).
10.
Dweck, M. R. et al. Assessment of valvular calcification and inflammation by positron
emission tomography in patients with aortic stenosis. Circulation 125, 76–86 (2012).
11.
Dinh, W. et al. Reduced global longitudinal strain in association to increased left
ventricular mass in patients with aortic valve stenosis and normal ejection fraction: a
hybrid study combining echocardiography and magnetic resonance imaging.
Cardiovasc. Ultrasound 8, 29 (2010).
12.
Keshavarz-Motamed, Z. et al. Non-invasive determination of left ventricular workload
in patients with aortic stenosis using magnetic resonance imaging and Doppler
echocardiography. PLoS One 9, e86793 (2014).
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www.crcd.eu
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John Paul II Hospital in Kraków
Jagiellonian University, Institute of Cardiology
80 Prądnicka Str., 31-202 Kraków;
tel. +48 (12) 614 33 99; 614 34 88; fax. +48 (12) 614 34 88
e-mail: [email protected]
www.crcd.eu