Paradoxical Low-gradient Aortic Stenosis Research Articles

Role of Exercise Testing and Speckle Tracking Echocardiography in Paradoxical Severe Aortic Stenosis.

IntroductionThe clinical behavior and prognosis of patients with asymptomatic paradoxical low-gradient aortic stenosis (PLGAS) still remain controversial. Some authors consider PLGAS as an echocardiographically poorly quantified moderate AS (MAS). We aimed to investigate the clinical behavior of PLGAS by comparing it with that of asymptomatic high-gradient aortic stenosis (HG-AS) and MAS using transthoracic echocardiography (TTE) with speckle tracking imaging (STI) and cardiopulmonary exercise testing (CPET). The hypothesis of our study is, unlike that described by other authors, to demonstrate the existence of clinical and echocardiographic differences between PLGAS and MAS.MethodsA cohort of 113 patients was included and categorized into three groups according to AS type: MAS (n=63), HG-AS (n=29), and PLGAS (n=21). Patients’ clinical data were obtained. Patients underwent 2D TTE with STI and CPET.ResultsThere were no significant differences in the clinical variables between the three AS groups. In the multivariate multinomial logistic regression analysis, with PLGAS being the reference category, the most powerful variable for establishing a difference with HG-AS was the left ventricular mass (LVM) indexed by body-surface area (odds ratio [OR]=1.04, confidence interval (CI)=1.01-1.06, p<0.05). The MAS group showed less abnormal CPET (OR=0.198, CI=0.06-0.69, p<0.05), and higher left ventricle global longitudinal strain rate (GLSR) (OR=0.003, CI=0.00-0.35, p<0.05) than the PLGAS group.ConclusionsTTE with STI and CPET established the clear differences between patients with asymptomatic PLGAS and those with asymptomatic MAS, as well as the similarities between patients with PLGAS and those with HG-AS. Our data identify PLGAS as a completely different entity from MAS.

Structural and Functional Correlates of Gradient-Area Patterns in Severe Aortic Stenosis and Normal Ejection Fraction

ObjectivesThe authors sought to characterize the functional and structural myocardial phenotypes of patients with moderate-to-severe aortic stenosis (AS) and to determine whether severe paradoxical low-gradient AS (LG-AS) is specifically associated with left ventricular (LV) remodeling and fibrosis. BackgroundRecently, it was suggested that severe paradoxical LG-AS is a more advanced form of AS, with greater reduction of longitudinal deformation, adverse LV remodeling, and more interstitial fibrosis. MethodsThe study population includes 147 patients with moderate-to-severe AS and a normal LV ejection fraction, and 75 normal control subjects. They prospectively underwent 2-dimensional speckle-tracking echocardiography and cardiac magnetic resonance to evaluate myocardial deformation, LV remodeling, and age- and sex-adjusted extravascular volume fraction (ECV, %). Among AS patients, 18 had moderate AS, 74 had severe high-gradient AS (HG-AS), and 55 had severe paradoxical LG-AS. ResultsReduced longitudinal and circumferential deformation was observed in 21% and 6% of the AS patients, respectively. Multivariate analyses identified increased ECV (ß = 1.99; p = 0.001) and the absence of normal LV geometry (ß = −1.37; p = 0.007) and as independent predictors of reduced longitudinal deformation. Increased ECV was an independent predictor of reduced circumferential deformation (ß = 2.19; p = 0.001). Over a median follow-up of 29 months, reduced longitudinal deformation (hazard ratio: 0.82; p = 0.023) and higher transvalvular gradients (hazard ratio: 1.05; p < 0.001) increased the risk of death or need for aortic valve replacement. LV hypertrophy was more frequently observed among patients with severe HG-AS (65%) than among the other AS patients (14%; p < 0.001). On average, ECV was within normal limits and did not differ among gradient-area subgroups. When present, increased ECV was associated with reduced longitudinal deformation. ConclusionsThis study’s data show that patients with severe paradoxical LG-AS less frequently display reduced longitudinal deformation, LV hypertrophy, or myocardial fibrosis than patients with HG-AS. Also, interstitial fibrosis only occurs when reduced longitudinal deformation and severe HG-AS are present together. Finally, this study suggests that reduced longitudinal deformation and higher transvalvular gradients adversely affect patients’ outcomes.

What Is New in Low Gradient Aortic Stenosis: Surgery, TAVR, or Medical Therapy?

A significant proportion of patients with aortic stenosis (AS) have discordance in severity by mean gradient/peak velocity and aortic valve area. Low gradient aortic stenosis (LG-AS) is defined when the aortic valve area is < 1cm2 consistent with severe AS and mean aortic gradient is < 40mmHg consistent with non-severe AS. LG-AS represents a diagnostic and therapeutic challenge. To summarize the different categories, diagnosis, management, and prognosis of LG-AS. LG-AS is classified as classical (ejection fraction (EF) < 50%, indexed stroke volume (SVi) < 35ml/m2), paradoxical (EF > 50%, SVi < 35ml/m2), pseudo-severe (moderate AS with reduced EF), or normal flow low gradient AS. Recent findings emphasize the importance of low-dose dobutamine stress echocardiography and CT calcium score in the assessment of aortic valve. In addition, flow reserve (increase in SV > 50%) can be evaluated during dobutamine stress echocardiography and helps predict perioperative prognosis. Patients with LG-AS have better survival with aortic valve replacement (AVR) compared to medical therapy, irrespective of presence or absence of flow reserve. Some recent studies suggest that transcatheter aortic valve replacement (TAVR) may be superior to surgical AVR for patients with a lack of contractile flow reserve or those with paradoxical LG-AS, but further investigation is needed to clarify optimal treatment. The role of TAVR in patients with moderate AS and reduced EF is also under investigation.

The Functional Significance of Paradoxical Low-Gradient Aortic Valve Stenosis: Hemodynamic Findings During Cardiopulmonary Exercise Testing

ObjectivesThe goal of this study was to determine the functional impact of paradoxical low-gradient aortic stenosis (PLGAS) and clarify whether the relevance of the valvular obstruction is related to baseline flow. BackgroundEstablishing the significance of PLGAS is particularly challenging. MethodsTwenty symptomatic patients (77 ± 6 years of age; 17 female subjects) with PLGAS (mean gradient 28 ± 6 mm Hg; aortic valve area 0.8 ± 0.1 cm2; ejection fraction 66 ± 7%) underwent cardiopulmonary exercise testing combined with right-heart catheterization and Doppler echocardiographic measurements. ResultsAortic valve area increased by 84 ± 23% (p < 0.001) and, in 70% of subjects, it reached values >1.0 cm2 at peak exercise. Stroke volume index and blood pressure increased by 83 ± 56% and 26 ± 16%, respectively (both p < 0.0001). Peak oxygen consumption inversely correlated with the rate of increase in pulmonary capillary wedge pressure (PCWP) (PCWP slope: R = –0.61; p = 0.004). In turn, the PCWP slope was determined by changes in the valvular and vascular load but not by the rest of the indices of aortic stenosis. The functional impact of PLGAS was also not related to baseline flow. Agreement between Doppler echocardiography and the Fick technique was good up to intermediate workload. ConclusionsIn symptomatic patients with PLGAS, the capacity to dynamically reduce vascular and valvular loads determines the effect of exercise on PCWP, which, in turn, conditions the functional status. A critically fixed valvular obstruction may not be the main mechanism of functional impairment in a large proportion of patients with PLGAS. Exercise echocardiography is suitable to study the dynamics of PLGAS.

Aortic valve stenosis: Survey on practice in the north of France

Aortic stenosis has become the most frequent type of valvular heart disease in Europe. Severe Aortic Stenosis (SAS) is defined as an aortic valve area b1 cm (or 0.6 cm/m), a mean transvalvular gradient N40 mmHg, a peak velocity N4 m/s, and permeability index b25% [1]. Some patients may have lower than expected transvalvular gradients (b40 mmHg) as a consequence of “low flow/low gradient SAS with depressed LVEF” or in the recently described “paradoxical low gradient aortic stenosis”. This survey was designed to explore practices on aortic valve stenosis, with particular interest for the management of patients with “nonclassical” aortic stenosis, for which guidelines were lacking in 2012. From June to November 2012, all graduated cardiologists of the region “Nord-Pas-de-Calais”were asked to answer a survey on SAS and received a questionnaire comprising 5 clinical scenarios of SAS. A choice of four different responses to each scenariowas proposed, i.e. surgical treatment, trans-aortic valve implantation, medical treatment with follow up or complementary explorations. An echocardiography specialist was defined as a cardiologist who performed more than 25 echocardiographies a week and an aortic stenosis specialist as a practitioner who diagnosed more than 40 aortic stenosis a year. Categorial variables were compared with the Chi-squared test of Pearson. A p-value≤ 0.05 was considered for statistical significance. Analysiswas conducted using Statistical Package for Social Sciences (SPSS, v17.0) software. 313 cardiologists were surveyed. The response rate was 29.7% (93/ 313) overall. Cardiologists' mean age was 42.6 ± 11.4 years old. 36 (38.7%) of them were echocardiography specialists and 30 (32.3%) were aortic stenosis specialists. 35 (37.6%) cardiologists worked in a teaching hospital, 32 (34.4%) in a general hospital, and 26 (26%) have a nonhospital activity.

Survey on practices: Severe aortic stenosis and new syndromes of paradoxical low gradient aortic stenosis

Survey on practices: Severe aortic stenosis and new syndromes of paradoxical low gradient aortic stenosis

Low Gradient Severe Aortic Stenosis With Preserved Ejection Fraction: Don’t Forget the Flow!

In Revista Espanola de Cardiologia, Gonzalez-Canovas et al. reported the results of a study that examined whether severe aortic stenosis (AS) with low-gradient and preserved ejection fraction is a real phenomenon or whether it corresponds to an error in measurement. As they appropriately emphasize in their introduction, most cardiologists now recognize that this mode of presentation is frequently encountered during echocardiographic examinations. Also, several studies have reported that this entity is a more advanced form of the disease and has a worse prognosis. In contrast, a recent prospective study suggested that prognosis in these cases is similar to moderate AS and that this subcategory of patients probably reflects an error in classification. To answer this question, Gonzalez-Canovas et al. examined 63 patients with paradoxical low-gradient AS and found that aortic valve area (AVA) measured by 3-dimensional (3D) aortic valve planimetry was congruent with that obtained by transthoracic echocardiography (TTE) using the continuity equation; the presence of severe AS was confirmed in 85% of patients. They hence concluded that paradoxical low-gradient severe AS is a real entity. These results are important and we would like to make a few observations so that these results may be interpreted in the right context.