The mystery of defining aortic valve area: what have we learnt from three-dimensional imaging modalities?

Volume-outcome relationship in balloon aortic valvuloplasty: results of a consecutive, patient-level data analysis from a Japanese nationwide multicentre registry (J-SHD)

OBJECTIVE

Transcatheter balloon aortic valvuloplasty (BAV) remains an important alternative treatment for severe, symptomatic aortic stenosis. With increasing numbers of BAVs being performed, the need for large-scale volume-outcome relationship assessments has become evident. Here, we aimed to explain such relationships by analysing consecutive, patient-level BAV data recorded in a prospective Japanese nationwide multicentre registry.

DESIGN

Prospective study.

SETTING

Data of 1920 BAVs performed in 200 Japanese hospitals from January 2015 to December 2019.

PARTICIPANTS

The mean patient age was 85 years, and 36.9% of procedures involved male patients.

METHODS

The efficacy of BAV was assessed by reducing the mean transaortic valve gradient after the procedure. We also assessed in-hospital complication rates, including in-hospital death, bleeding, urgent surgery, distal embolism, vessel rupture and contrast-induced nephropathy. Based on the distribution of case volume (median 20, IQR 10-46), we divided the patients into high-volume (≥20) and low-volume (<20) groups. In-hospital complication risk was assessed with adjustment by logistic regression modelling.

RESULTS

Indications for BAV included palliative/destination (44.2%), bridge to transcatheter aortic valve replacement (34.5%), bridge to surgical aortic valve replacement (7.4%) and salvage (9.7%). Reduction of the mean transaortic valve gradient was similar between the high-volume and low-volume groups (20 mm Hg vs 20 mm Hg, p=0.12). The proportion of in-hospital complications during BAV was 4.2%, and the incidence of complications showed no difference between the high-volume and low-volume groups (4.2% vs 4.1%, p=1.00). Rather than hospital volume, salvage procedure was an independent predictor of in-hospital complications (OR, 4.04; 95% CI, 2.03 to 8.06; p<0.001).

CONCLUSION

The current study demonstrated that procedural outcomes of BAV were largely independent of its institutional volume.

Normative values of the aortic valve area and Doppler measurements using two-dimensional transthoracic echocardiography: results from the Multicentre World Alliance of Societies of Echocardiography Study

AIMS

Aortic valve area (AVA) used for echocardiographic assessment of aortic stenosis (AS) has been traditionally interpreted independently of sex, age and race. As differences in normal values might impact clinical decision-making, we aimed to establish sex-, age- and race-specific normative values for AVA and Doppler parameters using data from the World Alliance Societies of Echocardiography (WASE) Study.

METHODS AND RESULTS

Two-dimensional transthoracic echocardiographic studies were obtained from 1903 healthy adult subjects (48% women). Measurements of the left ventricular outflow tract (LVOT) diameter and Doppler parameters, including AV and LVOT velocity time integrals (VTIs), AV mean pressure gradient, peak velocity, were obtained according to ASE/EACVI guidelines. AVA was calculated using the continuity equation. Compared with men, women had smaller LVOT diameters and AVA values, and higher AV peak velocities and mean gradients (all P < 0.05). LVOT and AV VTI were significantly higher in women (P < 0.05), and both parameters increased with age in both sexes. AVA differences persisted after indexing to body surface area. According to the current diagnostic criteria, 13.5% of women would have been considered to have mild AS and 1.4% moderate AS. LVOT diameter and AVA were lower in older subjects, both men and women, and were lower in Asians, compared with whites and blacks.

CONCLUSION

WASE data provide clinically relevant information about significant differences in normal AVA and Doppler parameters according to sex, age, and race. The implementation of this information into clinical practice should involve development of specific normative values for each ethnic group using standardized methodology.

Implementation of a CT-derived correction factor to refine the measurement of aortic valve area and stroke volume using Doppler echocardiography improves grading of severity and prediction of prognosis in patients with severe aortic stenosis

AIMS

To assess rates of reclassification of severity and associated 5-year survival in patients with severe aortic stenosis (AS) and preserved left ventricular ejection fraction (LVEF) after application of a CT-derived correction factor (CF) to refine the measurement of aortic valve area (AVA) and stroke volume index (SVi) using Doppler echocardiography.

METHODS AND RESULTS

We enrolled 1450 patients with severe AS and preserved LVEF from a French registry. Multiplication of echocardiographic LV outflow tract diameter by a CT-derived CF of 1.13 to calculate the AVA and SVi using the continuity equation resulted in reclassification of 39% of patients from severe to moderate AS (AVA > 1 cm²) and 77% from low flow (LF, SVi < 35 ml/m²) to normal flow (NF, SVi ≥ 35 ml/m²). After application of the CF, 5-year survival with conservative management was 50 ± 4% for severe AS compared to 62 ± 4% for moderate AS (p < 0.001). A strategy of medical management followed by intervention for severe AS was associated with higher risk of mortality over 5-year follow-up after adjustment for covariates and application of the CF (HR 1.35 [1.10-1.55], p = 0.015). Five-year survival was also poorer in patients remaining in the LF group after application of the CF, even after valve intervention (72%, 66% and 47% for NF to NF, LF to NF and LF to LF, respectively). After adjustment for covariates (including intervention), risk of mortality was higher in LF to LF patients compared to NF to NF (HR 1.78 [1.25-2.56]), but similar for NF to NF and LF to NF (HR 1.20 [0.90-1.60]).

CONCLUSION

Refined accuracy of echocardiographic LV outflow tract diameter measurement using a CF of 1.13 before derivation of AVA and SVi in patients with severe AS and preserved LVEF allows improved grading of severity, and prediction of prognosis. We recommend implementation of the CF during routine echocardiography when using the continuity equation for Doppler haemodynamic measurements.

Compression Stockings Improve Cardiac Output and Cerebral Blood Flow during Tilt Testing in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) Patients: A Randomized Crossover Trial

Background and Objectives: Orthostatic intolerance (OI) is a clinical condition in which symptoms worsen upon assuming and maintaining upright posture and are ameliorated by recumbency. OI has a high prevalence in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Limited data are available to guide the treatment of OI in ME/CFS patients. We and others have previously described patient-reported subjective improvement in symptoms using compression stockings. We hypothesized that these subjective reports would be accompanied by objective hemodynamic improvements. Materials and Methods: We performed a randomized crossover trial in 16 ME/CFS patients. Each underwent two 15-min head-up tilt table tests, one with and one without wearing knee-high compression stockings that provided 20–25 mm Hg compression. The order of the tests was randomized. We measured heart rate and blood pressure as well as cardiac output and cerebral blood flow (CBF) using extracranial Doppler of the internal carotid and vertebral arteries. Results: There were no differences in supine measurements between the 2 baseline measurements. There were no differences in heart rate and blood pressure at either end-tilt testing period. Compared to the test with the stockings off, the mean percentage reduction in cardiac output during the test with compression stockings on was lower, 15 (4)% versus 27 (6)% (p < 0.0001), as was the mean percentage CBF reduction, 14 (4)% versus 25 (5)% (p < 0.0001). Conclusion: In ME/CFS patients with orthostatic intolerance symptoms, cardiac output and CBF are significantly reduced during a tilt test. These abnormalities were present without demonstrable heart rate and blood pressure changes and were ameliorated by the use of compression stockings.

Discrepancy of Aortic Valve Area Measurements by Doppler vs. Biplane Stroke Volume Measurements and Utility of Combining the Different Areas in Aortic Valve Stenosis - The Asian Valve Registry

BACKGROUND

The aortic valve area index (AVAI) in aortic stenosis (AS) is measured by echocardiography with a continuity equation using the stroke volume index by Doppler (SVI_Doppler) or biplane Simpson (SVI_Biplane) method. AVAI_Dopplerand AVAI_Biplaneoften show discrepancy due to differences between SVI_Dopplerand SVI_Biplane. The degree of discrepancy and utility of combined AVAIs have not been investigated in a large population of AS patients, and the characteristics of subjects with larger discrepancies are unknown.Methods and Results:We studied 820 patients with significant AS (AVA_Doppler<1.5 cm²) enrolled in the Asian Valve Registry, a prospective multicenter registry at 12 Asian centers. All-cause death and aortic valve replacement were defined as events. SVI_Dopplerwas significantly larger than SVI_Biplane(49±11 vs. 39±11 mL/m², P<0.01) and AVAI_Dopplerwas larger than AVAI_Biplane(0.51±0.15 vs. 0.41±0.14 cm²/m², P<0.01). An increase in (AVAI_Doppler- AVAI_Biplane) correlated with shorter height, lower weight, older age, smaller left ventricular (LV) diameter and increased velocity of ejection flow at the LV outflow tract. Severe AS by AVAI_Doppleror AVAI_Biplaneenabled prediction of events, and combining these AVAIs improved the predictive value of each.

CONCLUSIONS

Discrepancy in AVAI by Doppler vs. biplane method was significantly more pronounced with increased LV outflow tract flow velocity, shorter height, lower weight, older age and smaller LV cavity dimensions. Combining the AVAIs enabled mutual and incremental value in predicting events.

Three-dimensional versus two-dimensional transthoracic echocardiography for left ventricular outflow tract measurements in severe aortic stenosis. A cross-sectional study using computer tomography and Haegar sizers as reference

Objectives. In grading of aortic stenosis, two-dimensional transthoracic echocardiography (2D TTE) routinely results in underestimation of the left ventricular outflow tract (LVOT) area, and hence the aortic valve area (AVA). We investigated whether three-dimensional (3D) TTE measurements of the LVOT would be more accurate. We evaluated the feasibility, agreement and inter-observer variability of 3D TTE LVOT measurements with computed tomography (CT) and Haegar sizers as reference. Design. Sixty-one patients with severe aortic stenosis were examined with 2D and 3D TTE. 41 had CT and 13 also had perioperative Haegar sizing. Pearson's correlation and Bland-Altman plots were used to compare methods. Inter-observer variability was tested for 2D and 3D TTE. Trial registration: Current research information system in Norway (CRISTIN). Id: 555249. Results. Feasibility was 67% with 3D TTE and 100% with 2D TTE and CT. Mean LVOT area for 2D, 3D, CT and Haegar sizers were 3.7 ± 0.6 cm2, 4.0 ± 0.9 cm2, 5.2 ± 0.8 cm2 and 4.4 ± 1.0 cm2 respectively. Bias and limits of agreements for 2D TTE was 1.5 ± 1.3 cm2, compared with CT and 0.4 ± 1.5 cm2 with Haegar sizers. Corresponding results for 3D TTE were 1.2 ± 1.6 cm2 and 0.2 ± 1.8 cm2. Intraclass correlation coefficients for LVOT area were 0.62 for 3D and 0.86 for 2D. Conclusions. 2D TTE showed better feasibility and inter-observer variability in measurements of LVOT than 3D TTE. Both echocardiographic methods underestimated LVOT area compared to CT and Haegar sizers. These observations suggest that 2D TTE is still preferable to 3D TTE in the assessment of aortic stenosis.

Mid-term effect of balloon aortic valvuloplasty on mitral regurgitation in aortic stenosis

Background

Balloon aortic valvuloplasty (BAV) offers an alternative to conventional aortic valve replacement in elderly and frail patients with severe aortic stenosis (AS) for whom there are no other effective options. We aimed to investigate the mid-term effect of BAV on mitral regurgitation (MR) in patients with severe AS.

Methods

Our analysis was based on the data from 83 patients with severe AS (mean age, 86 ± 5 years; female, 68) treated using BAV. Echocardiography was performed before the procedure and at 1 and 3 months after. MR was quantified by measuring the MR jet area, with more-than-moderate MR being clinically significant.

Results

Forty patients were classified in this group (MR group). Significant reduction of MR was observed in the MR group at 1 month and 3 months after procedure, with no improvement in patients in the non-MR group. At 3 months, 15 of the 40 patients in the MR group still had significant MR, with the change at 1 month in the left ventricular end-systolic dimension (OR: 1.36; 95% CI: 1.05–1.76; P = 0.022) and MR jet area (OR: 1.95; 95% CI: 1.16–3.29; P = 0.012) being predictive of persisting significant MR at 3 months after BAV. The prevalence of New York Heart Association functional class III or IV decreased at 1 and 3 months after BAV in both groups.

Conclusions

BAV provides a useful therapeutic strategy for elderly patients with severe AS who are not candidates for surgical or transcatheter aortic valve replacement, especially in those with significant MR.

Direct Planimetry of Left Ventricular Outflow Tract Area by Simultaneous Biplane Imaging: Challenging the Need for a Circular Assumption of the Left Ventricular Outflow Tract in the Assessment of Aortic Stenosis

BACKGROUND

Evaluation of aortic stenosis (AS) requires calculation of aortic valve area (AVA), which relies on the assumption of a circular-shaped left ventricular outflow tract (LVOT). However, the LVOT is often elliptical, and the circular assumption underestimates the true LVOT area (LVOTA). Biplane imaging using transthoracic echocardiography allows direct planimetry of LVOTA. The aim of this study was to assess the feasibility of obtaining LVOTA using this technique and its impact on the discordance between AVA and gradient criteria in AS grading.

METHODS

We prospectively studied 134 patients (median age, 80 years; interquartile range, 73-87 years; 39% women) with AS, including 82 (61%) with severe AS and 52 (39%) with mild or moderate AS. LVOTA was traced using direct planimetry (LVOTA_biplane) and compared with LVOTA calculated using the circular assumption (LVOTA_circ). In a subset of patients who underwent cardiac computed tomography, direct planimetry of LVOTA was used as a reference standard.

RESULTS

LVOTA_biplane was significantly larger than LVOTA_circ (4.20 cm² [interquartile range, 3.66-4.90 cm²] vs 3.73 cm² [interquartile range, 3.14-4.15 cm²], P < .001). Among 30 patients who underwent cardiac computed tomography, LVOTA_biplane had better agreement with LVOTA by direct planimetry than LVOTA_circ (mean bias, -0.45 ± 0.63 vs -1.02 ± 0.63 cm²; P < .0001). Of 82 patients with severe AS (AVA ≤ 1 cm² using LVOTA_circ), 40 (49%) had discordant mean gradient (<40 mm Hg). By using LVOTA_biplane, patients with discordant AVA and mean gradient decreased from 49% to 27% (P = .004), and 29% of patients with severe AS were reclassified with moderate AS, with the highest percentage of reclassification in the group with low-gradient AS with preserved left ventricular ejection fraction.

CONCLUSIONS

Direct planimetry using biplane imaging avoids the inherent underestimation of LVOTA using the circular assumption. LVOTA obtained by biplane planimetry can lead to better concordance between AVA and mean gradient and classification of AS severity.

Aortic Valvular Disease in Elderly Subjects with Heterozygous Familial Hypercholesterolemia: Impact of Lipid-Lowering Therapy

Hypercholesterolemia and statins are risk factors for aortic stenosis (AS) and vascular calcification, respectively. Whether heterozygous subjects with familial hypercholesterolemia (HeFH) treated with statins are at risk of AS is unknown. We study the prevalence of AS, aortic valve calcification (AoVC), and aortic sclerosis (ASc) in elderly subjects with HeFH in a prolonged statin treatment. Case-control study, cases were adults ≥65 years of age with a genetic diagnosis of HeFH, LDLc >220 mg/dl, and statin treatment ≥5 years. Controls were relatives of HeFH patients, with LDLc <190 mg/dl. Participants underwent a cardiac ultrasound for aortic valve analysis. We studied 205 subjects, 112 HeFH and 93 controls, with mean age 71.8(6.5) years and 70.0(7.3) years, respectively. HeHF, with respect to controls, presented greater gradients of aortic transvalvular pressure, 7.4(7.3) mmHg versus 5.0(2.8) mmHg, and maximum aortic velocity, 1.7(0.7) m/s versus 1.5(0.4) m/s, and lower aortic valve opening area, 2.0(0.7) cm² versus 2.4(0.6) cm² (all p < 0.05). AoVC and ASc were also more prevalent in HeFH (p < 0.05 between groups). Moderate/severe AS prevalence was higher among HeFH: 7.1% versus 1.1% (age- and sex-adjusted odds ratio (OR) 8.33, p = 0.03). Independent risk factors for aortic valve disease in HeFH were age and LDLc before treatment. The number of years under statin treatment was not associated with any aortic valve measurement. Subjects ≥65 years with HeFH in prolonged statin treatment show more aortic valvular disease and higher frequency of AS than controls. Life-long elevated LDLc exposure, rather than time of exposure to statins, explains this higher risk.

Insights into the mechanism of paradoxical low-flow, low-pressure gradient severe aortic stenosis: association with reduced O2 consumption by the whole body

The mechanism of reduced stroke volume index (SVi) in paradoxical low-flow, low-pressure gradient (PLFLPG) aortic stenosis (AS) remains unclarified. Guyton et al. ( 21 ) demonstrated that SVi is determined by whole body O₂ consumption (V̇o₂) in many subjects, including patients with heart disease. We hypothesized that reduced SVi in PLFLPG AS is associated with reduced V̇o₂ by the whole body. This study investigated the relationship between V̇o₂, SVi, and AS severity in patients with AS to examine the association between reduced V̇o₂ and PLFLPG AS. In 59 patients (24 men and 35 women, mean age: 78 ± 7 yr old) with severe AS, SVi, AS severity, and type were evaluated by echocardiography, and V̇o₂ was measured by the fraction of O₂ in expired gases. SVi and V̇o₂ were significantly decreased in 20 patients with PLFLPG AS compared with 39 patients with non-PLFLPG AS (30 ± 4 vs. 41 ± 7 ml/m² and 2.4 ± 0.5 vs. 3.0 ± 0.5 ml·min^-1·kg^-1, respectively, P < 0.01). The SVi-to-V̇o₂ ratio was not different between the two groups (13.1 ± 2.6 vs. 13.6 ± 2.1, not significant). SVi was independently correlated with V̇o₂ ( r = 0.74, P < 0.01) but not with the aortic valve area index. Categorized PLFLPG AS was also significantly associated with reduced V̇o₂ ( P < 0.001). PLFLPG AS is associated with reduced V̇o₂ by the whole body, which may offer insights into the mechanism of PLFLPG AS. NEW & NOTEWORTHY Paradoxical low-flow, low-pressure gradient severe aortic stenosis (PLFLPG AS) is an important and problematic subtype, and its central pathophysiology with reduced stroke volume is yet to be clarified. We hypothesized and subsequently clarified that reduced stroke volume in PLFLPG AS is associated with reduced O₂ consumption by the whole body. This study suggests important insights into the mechanism of PLFLPG AS and may further promote studies to investigate further mechanisms and novel treatment.