Comparison of Clinical and Echocardiographic Features of Asymptomatic Patients With Stenotic Bicuspid Versus Tricuspid Aortic Valves

Evolving Concept of Aortic Valve Replacement in Asymptomatic Patients With Severe Aortic Stenosis

BACKGROUND

Surgical treatment of asymptomatic severe aortic stenosis (AS) has been gaining attention ever since the results of the Early Surgery Versus Conventional Treatment in Very Severe Aortic Stenosis (RECOVERY) and Aortic Valve replacement versus conservative treatment in Asymptomatic seveRe aortic stenosis (AVATAR) trials showed survival benefits with early surgical aortic valve replacement (SAVR). This study analyzed the long-term clinical and echocardiographic outcomes of SAVR in asymptomatic severe AS.

METHODS

Between 2002 and 2020, 272 patients with asymptomatic severe AS and a left ventricular ejection fraction ≥50% underwent SAVR with or without concomitant aortic surgery and met the study criteria. The median follow-up was 8.5 years (interquartile range, 6-12.8 years), for a total of 2584 patient-years. The time course of the left ventricular mass index (LVMI) and the average E/E' (ratio of the Doppler-derived E wave to the tissue Doppler-derived E' wave) were assessed using 594 postoperative echocardiograms. The association of preoperative LVMI and average E/E' with survival was assessed using Cox proportional hazards.

RESULTS

There was no operative mortality. On longitudinal analyses, LVMI improved in patients who presented with moderate or severe preoperative left ventricular hypertrophy (LVH). However, after the early decline in average E/E', there was a late increase to greater than upper limit normal, particularly in patients with a preoperative average E/E'≥14. Postoperative survival was 100%, 94%, 84%, and 76% at 1, 5, 10, and 15 years, respectively, comparable to age- and sex-matched expected survival on the basis of the US general population. On adjusted Cox survival analysis, only moderate to severe LVH was associated with a survival penalty (hazard ratio], 2.32; 95% CI, 1.02-5.27; P = .045).

CONCLUSIONS

In asymptomatic patients with AS, SAVR restores survival and improves LVH, but patients with diastolic dysfunction are left with persistent dysfunction. Presentation with moderate or severe LVH at the time of surgery translated to a survival penalty. This observational study supports early SAVR in this population before development of LVH, although further investigation is needed.

The Prevalence of Coronary Artery Disease in Bicuspid Aortic Valve Patients: An Overview of the Literature

The prevalence of coronary artery disease (CAD) in bicuspid aortic valve (BAV) patients is a debatable topic. Several studies have indicated that BAV patients have a lower prevalence of CAD compared with patients with a tricuspid aortic valve (TAV), but the effects of age and gender have not always been considered. This systematic review provides an overview of articles which report on CAD in BAV and TAV patients. Searches were executed in April 2021 and January 2022 according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) guidelines in three online databases: Medline, Embase, and Scopus. Screening and data extraction was done by two investigators separately. Primary and secondary outcomes were compared between BAV and TAV patients; a fixed effects model was used for correcting on confounders. Literature search yielded 1,529 articles with 44 being eligible for inclusion. BAV patients were younger (56.4 ± 8.3 years) than TAV patients (64 ± 10.3 years, p < 0.001). All CAD risk factors and CAD were more prevalent in TAV patients. No significant difference remained after correcting for age and gender as confounders. BAV patients have a lower prevalence of CAD and CAD risk factors compared with TAV patients. However, when the age differences between both groups are considered in the analyses, a similar prevalence of both CAD and CAD risk factors is found.

Association of aortic distensibility and left ventricular function in patients with stenotic bicuspid aortic valve and preserved ejection fraction: a CMR study

To determine the relationship between aortic distensibility and left ventricular (LV) remodeling, myocardial strain and blood biomarkers in patients with stenotic bicuspid aortic valve (BAV) and preserved ejection fraction (EF) by cardiovascular magnetic resonance (CMR). 43 stenotic BAV patients were prospectively selected for 3.0 T CMR. Patients were divided into LV remodeling group (LV mass/volume ≥ 1.15, n = 21) and non-remodeling group (LV mass/volume < 1.15, n = 22). Clinical characteristics, biochemical data including cardiac troponin T(cTNT), N-terminal pro-B type natriuretic peptide (NT-proBNP) and creatine kinase isoenzyme (CK-MB) were noted. Distensibility of middle ascending aorta (mid-AA) and proximal descending aorta, LV structural and functional parameters, global and regional myocardial strain were measured. Compared to non-remodeling group, LV remodeling group had significantly decreased LV global strain (radial: 26.04 ± 8.70% vs. 32.92 ± 7.81%, P = 0.009; circumferential: - 17.20 ± 3.38% vs. - 19.65 ± 2.34%, P = 0.008; longitudinal: - 9.13 ± 2.34% vs. - 11.63 ± 1.99%, P < 0.001) and decreased mid-AA distensibility (1.22 ± 0.24 10-3 mm/Hg vs 1.60 ± 0.41 10-3 mm/Hg, P = 0.001). In addition, mid-AA distensibility was independently associated with LV remodeling (β =  - 0.282, P = 0.003), and it was also significantly correlated with LV global strain (radial: r = 0.392, P = 0.009; circumferential: r =  - 0.348, P = 0.022; longitudinal: r =  - 0.333, P = 0.029), cTNT (r =  - 0.333, P = 0.029) and NT-proBNP (r =  - 0.440, P = 0.003). In this cohort with stenotic BAV and preserved EF, mid-AA distensibility is found significantly associated with LV remolding, which encouraging to better understand mechanism of ventricular vascular coupling.

The mechanistic pathways of oxidative stress in aortic stenosis and clinical implications

Despite the elucidation of the pathways behind the development of aortic stenosis (AS), there remains no effective medical treatment to slow or reverse its progress. Instead, the gold standard of care in severe or symptomatic AS is replacement of the aortic valve. Oxidative stress is implicated, both directly as well as indirectly, in lipid infiltration, inflammation and fibro-calcification, all of which are key processes underlying the pathophysiology of degenerative AS. This culminates in the breakdown of the extracellular matrix, differentiation of the valvular interstitial cells into an osteogenic phenotype, and finally, calcium deposition as well as thickening of the aortic valve. Oxidative stress is thus a promising and potential therapeutic target for the treatment of AS. Several studies focusing on the mitigation of oxidative stress in the context of AS have shown some success in animal and in vitro models, however similar benefits have yet to be seen in clinical trials. Statin therapy, once thought to be the key to the treatment of AS, has yielded disappointing results, however newer lipid lowering therapies may hold some promise. Other potential therapies, such as manipulation of microRNAs, blockade of the renin-angiotensin-aldosterone system and the use of dipeptidylpeptidase-4 inhibitors will also be reviewed.

Left ventricular remodelling in bicuspid aortic valve disease

AIMS

Characterization of left ventricular (LV) geometric pattern and LV mass could provide an important insight into the pathophysiological adaptations of the LV to pressure and/or volume overload in patients with bicuspid aortic valve (BAV) and significant (≥moderate) aortic valve (AV) disease. This study aimed to characterize LV remodelling and its prognostic impact in patients with BAV according to the predominant type of valvular dysfunction.

METHODS AND RESULTS

In this international, multicentre BAV registry, 1345 patients [51.0 (37.0-63.0) years, 71% male] with significant AV disease were identified. Patients were classified as having isolated aortic stenosis (AS) (n = 669), isolated aortic regurgitation (AR) (n = 499) or mixed aortic valve disease (MAVD) (n = 177). LV hypertrophy was defined as a LV mass index >115 g/m2 in males and >95 g/m2 in females. LV geometric pattern was classified as (i) normal geometry: no LV hypertrophy, relative wall thickness (RWT) ≤0.42, (ii) concentric remodelling: no LV hypertrophy, RWT >0.42, (iii) concentric hypertrophy: LV hypertrophy, RWT >0.42, and (iv) eccentric hypertrophy: LV hypertrophy, RWT ≤0.42. Patients were followed-up for the endpoints of event-free survival (defined as a composite of AV repair/replacement and all-cause mortality) and all-cause mortality. Type of AV dysfunction was related to significant variations in LV remodelling. Higher LV mass index, i.e. LV hypertrophy, was independently associated with the composite endpoint for patients with isolated AS [hazard ratio (HR) 1.08 per 25 g/m2, 95% confidence interval (CI) 1.00-1.17, P = 0.046] and AR (HR 1.19 per 25 g/m2, 95% CI 1.11-1.29, P < 0.001), but not for those with MAVD. The presence of concentric remodelling, concentric hypertrophy and eccentric hypertrophy were independently related to the composite endpoint in patients with isolated AS (HR 1.54, 95% CI 1.06-2.23, P = 0.024; HR 1.68, 95% CI 1.17-2.42, P = 0.005; HR 1.59, 95% CI 1.03-2.45, P = 0.038, respectively), while concentric hypertrophy and eccentric hypertrophy were independently associated with the combined endpoint for those with isolated AR (HR 2.49, 95% CI 1.35-4.60, P = 0.004 and HR 3.05, 95% CI 1.71-5.45, P < 0.001, respectively). There was no independent association observed between LV remodelling and the combined endpoint for patients with MAVD.

CONCLUSIONS

LV hypertrophy or remodelling were independently associated with the composite endpoint of AV repair/replacement and all-cause mortality for patients with isolated AS and isolated AR, although not for patients with MAVD.

Prognostic Implications of Bicuspid and Tricuspid Aortic Valve Phenotype on Progression of Moderate Aortic Stenosis and Ascending Aorta Dilatation

Studies on the impact of aortic valve anatomy (bicuspid aortic valve [BAV] or tricuspid aortic valve [TAV]) on the progression of moderate aortic stenosis (AS) and ascending aorta (AA) dilatation and its prognostic implications are limited. From 1991 to 2016, 288 asymptomatic patients with moderate AS detected during index echocardiography with at least 1 year of echocardiographic follow-up were retrospectively studied. Baseline clinical and echocardiographic characteristics were compared between patients with BAV (n = 80) and patients with TAV (n = 208). Co-primary outcomes were 1-year hemodynamic and anatomic progression of AS and AA dilatation. Secondary end points were the incidence of AA rapid progressors, all-cause mortality, aortic valve replacement, and congestive heart failure. Determinants of AS progression, AA diameters, AA dilatation, and prognostic outcomes were evaluated. Similar 1-year progression of the aortic valve peak velocity, V_max (9 ± 18 vs 9 ± 23 cm/s), mean gradient (1.5 ± 2.3 vs 1.3 ± 3.2 mm Hg), and aortic valve area (AVA) (-0.04 ± 0.09 vs -0.05 ± 0.10 cm²) were noted for BAV and TAV groups, respectively. One-year progressions of AA were similar at Valsalva (0.11 ± 0.88 vs 0.14 ± 1.10 mm) and tubular levels (0.12 ± 0.68 vs 0.30 ± 1.51 mm) in BAV and TAV groups, respectively. A trend toward increased rapid AA progression in patients with BAV (31.3%) was observed compared with patients with TAV (14.8%, p = 0.099). BAV was associated with progression of V_max (β = 0.17, p = 0.036), the dimensionless index (β = -0.17, p = 0.008), and AVA (β = -0.14, p = 0.048), but not mean gradient after adjusting for age, baseline severity indexes, gender, hypertension, diabetes, and body surface area. Although BAV was a determinant of larger baseline AA diameter, there was no significant association between BAV and AA rapid progressors. Adjusted Kaplan-Meier curves demonstrated no differences in congestive heart failure, aortic valve replacement, or mortality between valve morphology. In conclusion, there was a similar 1-year disease progression in terms of AVA, V_max, mean gradient, and AA diameters between patients with BAV and patients with TAV. BAV was associated with a significant increase in V_max, dimensionless index, and AVA after adjusting for important confounders. Close and prolonged follow-up is warranted in both groups of patients.

Biological knowledge-slanted random forest approach for the classification of calcified aortic valve stenosis

Background

Calcific aortic valve stenosis (CAVS) is a fatal disease and there is no pharmacological treatment to prevent the progression of CAVS. This study aims to identify genes potentially implicated with CAVS in patients with congenital bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) in comparison with patients having normal valves, using a knowledge-slanted random forest (RF).

Results

This study implemented a knowledge-slanted random forest (RF) using information extracted from a protein-protein interactions network to rank genes in order to modify their selection probability to draw the candidate split-variables. A total of 15,191 genes were assessed in 19 valves with CAVS (BAV, n = 10; TAV, n = 9) and 8 normal valves. The performance of the model was evaluated using accuracy, sensitivity, and specificity to discriminate cases with CAVS. A comparison with conventional RF was also performed. The performance of this proposed approach reported improved accuracy in comparison with conventional RF to classify cases separately with BAV and TAV (Slanted RF: 59.3% versus 40.7%). When patients with BAV and TAV were grouped against patients with normal valves, the addition of prior biological information was not relevant with an accuracy of 92.6%.

Conclusion

The knowledge-slanted RF approach reflected prior biological knowledge, leading to better precision in distinguishing between cases with BAV, TAV, and normal valves. The results of this study suggest that the integration of biological knowledge can be useful during difficult classification tasks.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13040-021-00269-4.