Low-gradient aortic stenosis Clavel, Marie-Annick; Magne, Julien; Pibarot, Philippe
European heart journal,
09/2016, Letnik:
37, Številka:
34
Journal Article
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An important proportion of patients with aortic stenosis (AS) have a 'low-gradient' AS, i.e. a small aortic valve area (AVA <1.0 cm(2)) consistent with severe AS but a low mean transvalvular gradient ...(<40 mmHg) consistent with non-severe AS. The management of this subset of patients is particularly challenging because the AVA-gradient discrepancy raises uncertainty about the actual stenosis severity and thus about the indication for aortic valve replacement (AVR) if the patient has symptoms and/or left ventricular (LV) systolic dysfunction. The most frequent cause of low-gradient (LG) AS is the presence of a low LV outflow state, which may occur with reduced left ventricular ejection fraction (LVEF), i.e. classical low-flow, low-gradient (LF-LG), or preserved LVEF, i.e. paradoxical LF-LG. Furthermore, a substantial proportion of patients with AS may have a normal-flow, low-gradient (NF-LG) AS: i.e. a small AVA-low-gradient combination but with a normal flow. One of the most important clinical challenges in these three categories of patients with LG AS (classical LF-LG, paradoxical LF-LG, and NF-LG) is to differentiate a true-severe AS that generally benefits from AVR vs. a pseudo-severe AS that should be managed conservatively. A low-dose dobutamine stress echocardiography may be used for this purpose in patients with classical LF-LG AS, whereas aortic valve calcium scoring by multi-detector computed tomography is the preferred modality in those with paradoxical LF-LG or NF-LG AS. Although patients with LF-LG severe AS have worse outcomes than those with high-gradient AS following AVR, they nonetheless display an important survival benefit with this intervention. Some studies suggest that transcatheter AVR may be superior to surgical AVR in patients with LF-LG AS.
Abstract Up to 40% of patients with aortic stenosis (AS) harbor discordant Doppler-echocardiographic findings, the most common of which is the presence of a small aortic valve area (≤1.0 cm2 ) ...suggesting severe AS, but a low gradient (<40 mm Hg) suggesting nonsevere AS. The purpose of this paper is to present the role of multimodality imaging in the diagnostic and therapeutic management of this challenging entity referred to as low-gradient AS . Doppler-echocardiography is critical to determine the subtype of low-gradient AS: that is, classical low-flow, paradoxical low-flow, or normal-flow. Patients with low-flow, low-gradient AS generally have a worse prognosis compared with patients with high-gradient or with normal-flow, low-gradient AS. Patients with low-gradient AS and evidence of severe AS benefit from aortic valve replacement (AVR). However, confirmation of the presence of severe AS is particularly challenging in these patients and requires a multimodality imaging approach including low-dose dobutamine stress echocardiography and aortic valve calcium scoring by multidetector computed tomography. Transcatheter AVR using a transfemoral approach may be superior to surgical AVR in patients with low-flow, low-gradient AS. Further studies are needed to confirm the best valve replacement procedure and prosthetic valve for each category of low-gradient AS and to identify patients with low-gradient AS in whom AVR is likely to be futile.
Mitral regurgitation is the most common valve disease worldwide but whether the community-wide prevalence, poor patient outcomes, and low rates of surgical treatment justify costly development of new ...therapeutic interventions remains uncertain. Therefore, we did an observational cohort study to assess the clinical characteristics, outcomes, and degree of undertreatment of mitral regurgitation in a community setting.
We used data from Mayo Clinic electronic health records and the Rochester Epidemiology Project to identify all cases of moderate or severe isolated single-valvular mitral regurgitation (with no other severe left-sided valvular disease or previous mitral surgery) diagnosed during a 10-year period in the community setting in Olmsted County (MN, USA). We assessed clinical characteristics, mortality, heart failure incidence, and results of cardiac surgery post-diagnosis.
Between Jan 1, 2000, and Dec 31, 2010, 1294 community residents (median age at diagnosis 77 years IQR 66–84) were diagnosed with moderate or severe mitral regurgitation by Doppler echocardiography (prevalence 0·46% 95% CI 0·42–0·49 overall; 0·59% 0·54–0·64 in adults). Left-ventricular ejection fraction below 50% was frequent (recorded in 538 42% patients), and these patients had a slightly lower regurgitant volume than those with an ejection fraction of 50% or higher (mean 39 mL SD 16 vs 45 mL 21, p<0·0001). Post-diagnosis mortality was mainly cardiovascular in nature (in 420 51% of 824 patients for whom the cause of death was available) and higher than expected for residents of the county for age or sex (risk ratio RR 2·23 95% CI 2·06–2·41, p<0·0001). This excess mortality affected all subsets of patients, whether they had a left-ventricular ejection fraction lower than 50% (RR 3·17 95% CI 2·84–3·53, p<0·0001) or of 50% or higher (1·71 1·53 −1·91, p<0·0001) and with primary mitral regurgitation (RR 1·73 95% CI 1·53–1·96, p<0·0001) or secondary mitral regurgitation (2·72 2·48–3·01, p<0·0001). Even patients with a low comorbidity burden combined with favourable characteristics such as left-ventricular ejection fraction of 50% or higher (RR 1·28 95% CI 1·10–1·50, p<0·0017) or primary mitral regurgitation (1·29 1·09–1·52, p=0·0030) incurred excess mortality. Heart failure was frequent (mean 64% SE 1 at 5 years postdiagnosis), even in patients with left-ventricular ejection fraction of 50% or higher (49% 2 at 5 years postdiagnosis) or in those with primary mitral regurgitation (48% 2). Mitral surgery was ultimately done in only 198 (15%) of 1294 patients, of which the predominant type of surgery was valve repair (in 149 75% patients). Mitral surgery was done in 28 (5%) of 538 patients with left-ventricular ejection fraction below 50% and in 170 (22%) of 756 patients with ejection fraction of 50% or higher, and in 34 (5%) of 723 with secondary mitral regurgitation versus 164 (29%) of 571 with primary regurgitation. All other types of cardiac surgery combined were performed in only 3% more patients (237 18% patients) than the number who underwent mitral surgery.
In the community, isolated mitral regurgitation is common and is associated with excess mortality and frequent heart failure postdiagnosis in all patient subsets, even in those with normal left-ventricular ejection fraction and low comorbidity. Despite these poor outcomes, only a minority of affected patients undergo mitral (or any type of cardiac) surgery even in a community with all means of diagnosis and treatment readily available and accessible. This suggests that in a wider population there might be a substantial unmet need for treatment for this disorder.
Mayo Clinic Foundation.
The first-line evaluation of aortic stenosis severity is Doppler echocardiography. However, in up to 40% of patients, resting echocardiographic assessment of aortic stenosis severity is discordant, ...leading to clinical uncertainty. Interest has therefore grown in aortic valve calcium scoring by multidetector computed tomography (CT-AVC) as an alternative load independent assessment of aortic stenosis severity. This paper will briefly review the pathophysiology of aortic stenosis and the crucial role that calcification plays in driving progressive obstruction of the valve. Subsequently, it will describe published reports that have investigated CT-AVC, validating this parameter against histology, and establishing its diagnostic accuracy versus echocardiography as well as its powerful independent prognostic capability. Finally, this review seeks to provide a practical guide about how best to acquire and interpret CT-AVC with a close focus on potential pitfalls and how these might be best avoided as this technique becomes more widely adopted in to clinical practice.
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•Measurement of aortic valve calcification is useful in assessing aortic stenosis severity in patients for whom echocardiography is not conclusive.•Aortic valve calcification should be measured on noncontrast electrocardiogram-gated computer tomography scans (120 kV to 140 kV; 60% to 80% RR interval) with the use of the Agatston method.•Calcification of left ventricular outflow tract, aorta, mitral annulus, and coronary arteries should carefully be excluded from the measurement of aortic valve calcification.•An aortic valve calcification score higher than 1,300 AU in women or 2,000 AU in men should be considered severe.
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.
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Background In calcific aortic valve disease on tricuspid aortic valves (TAVs), men have higher aortic valve calcification and less fibrosis than women. However, little is known in bicuspid aortic ...valves (BAV). We thus aimed to investigate the impact of age, sex, and valve phenotype (TAVs versus BAVs) on fibro-calcific remodeling in calcific aortic valve disease. Methods and Results We included 2 cohorts: 411 patients who underwent multidetector computed tomography (37% women) for aortic valve calcification density assessment and 138 explanted aortic valves (histological cohort; 50% women). The cohorts were divided in younger (<60 years old) or older patients with BAV (≥60 years old), and TAV patients. In each group, women and men were matched. Women presented less aortic valve calcification density than men in each group of the multidetector computed tomography cohort (all
≤0.01). Moreover, in women, younger patients with BAV had the lowest aortic valve calcification density (both
=0.02). In multivariate analysis, aortic valve calcification density correlated with age (β estimate±standard error: 6.5±1.8;
=0.0004) and male sex (109.2±18.4;
<0.0001), and there was a trend with TAVs (41.5±23.0;
=0.07). Women presented a higher collagen content than men (77.8±10.8 versus 69.9±12.9%;
<0.001) in the entire cohort. In women, younger patients with BAV had denser connective tissue than TAV and older patients with BAV (both
≤0.05), while no difference was observed between men. Conclusions In calcific aortic valve disease, women had less calcification and more fibrotic remodeling than men, regardless of the phenotype of the valve or age of the patient. Moreover, younger women with BAVs had less valve calcification. Thus, mineralization/fibrosis of the aortic valve is likely to have sex/age-specific mechanisms and be influenced by the valve morphology.
The prevalence of calcific aortic stenosis (AS) and of cardiac amyloidosis (CA) increases with age, and their association is not uncommon in the elderly. The identification of CA is particularly ...challenging in patients with AS because these 2 conditions share several features. It is estimated that ≤15% of the AS population and ≤30% of the subset with low-flow, low-gradient pattern may have CA. In patients with AS, CA is associated with increased risk of heart failure, mortality, and treatment futility with aortic valve replacement. In case of suspicion of CA, it is thus crucial to confirm the diagnosis to guide therapeutic management of AS and eventually implement recently developed pharmacological treatment dedicated to transthyretin amyloidosis. Given the high surgical risk of patients with AS and concomitant CA, transcatheter aortic valve replacement may be preferred to surgery in these patients.
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