Integration of 3D Imaging Data in the Assessment of Aortic Stenosis

Quantification of Significant Aortic Stenosis by Echocardiography versus Four-Dimensional Cardiac Computed Tomography: A Multi-Modality Imaging Study

Transthoracic echocardiography (TTE) grading of aortic stenosis (AS) is challenging when parameters are discrepant, and four-dimensional cardiac computed tomography (4D-CCT) is increasingly utilized for transcatheter intervention workup. We compared TTE and 4D-CCT measures contributing to AS quantification. AS patients (n = 80, age 86 ± 10 years, 71% men) referred for transcatheter replacement in 2014−2017 were retrospectively studied, 20 each with high-gradient AS (HG-AS), classical and paradoxical low-flow low-gradient AS (CLFLG-AS and PLFLG-AS), and normal-flow low-gradient AS (NFLG-AS). Correlation and Bland−Altman analyses were performed between TTE and 4D-CCT parameters. There were moderate-to-high TTE versus 4D-CCT correlations for left ventricular volumes, function, mass, and outflow tract dimensions (r = 0.51−0.88), though values were mostly significantly higher by 4D-CCT (p < 0.001). Compared with 4D-CCT planimetry of aortic valve area (AVA), TTE estimates had modest correlation (r = 0.37−0.43) but were significantly lower (by 0.15−0.32 cm2). The 4D-CCT estimate of LVSVi lead to significant reclassification of AS subtype defined by TTE. In conclusion, 4D-CCT quantified values were higher than TTE for the left ventricle and AVA, and the AS subtype was reclassified based on LVSVi by 4D-CCT, warranting further research to establish its clinical implications and optimal thresholds in severe AS management.

Association between multimodality measures of aortic stenosis severity and quality-of-life improvement outcomes after transcatheter aortic valve replacement

AIMS

Up to 40% of patients with aortic stenosis (AS) present with discordant grading of AS severity based on common transthoracic echocardiography (TTE) measures. Our aim was to evaluate the utility of TTE and multi-detector computed tomography (MDCT) measures in predicting symptomatic improvement in patients with AS undergoing transcatheter aortic valve replacement (TAVR).

METHODS AND RESULTS

A retrospective review of 201 TAVR patients from January 2017 to November 2018 was performed. Pre- and post-intervention quality-of-life was measured using the Kansas City Cardiomyopathy Questionnaire (KCCQ-12). Pre-intervention measures including dimensionless index (DI), stroke volume index (SVI), mean transaortic gradient, peak transaortic velocity, indexed aortic valve area (AVA), aortic valve calcium score, and AVA based on hybrid MDCT-Doppler calculations were obtained and correlated with change in KCCQ-12 at 30-day follow-up. Among the 201 patients studied, median KCCQ-12 improved from 54.2 pre-intervention to 85.9 post-intervention. In multivariable analysis, patients with a mean gradient >40 mmHg experienced significantly greater improvement in KCCQ-12 at follow-up than those with mean gradient ≤40 mmHg (28.1 vs. 16.4, P = 0.015). Patients with MDCT-Doppler-calculated AVA of ≤1.2 cm2 had greater improvements in KCCQ-12 scores than those with computed tomography-measured AVA of >1.2 cm2 (23.4 vs. 14.1, P = 0.049) on univariate but not multivariable analysis. No association was detected between DI, SVI, peak velocity, calcium score, or AVA index and change in KCCQ-12.

CONCLUSION

Mean transaortic gradient is predictive of improvement in quality-of-life after TAVR. This measure of AS severity may warrant greater relative consideration when selecting the appropriateness of patients for TAVR.

TAVR outcome after reclassification of aortic valve stenosis by using a hybrid continuity equation that combines computed tomography and echocardiography data

BACKGROUND

In the continuity equation, assumption of a round-shaped left ventricular outflow tract (LVOT) leads to underestimation of the true aortic valve area in two-dimensional echocardiography. The current study evaluated whether inclusion of the LVOT area, as measured by computed tomography (CT), reclassifies the degree of aortic stenosis (AS) and assessed the impact on patient outcome after transcatheter aortic valve replacement (TAVR).

METHODS AND RESULTS

Four hundred and twenty-two patients with indexed aortic valve area index (AVAi) of <0.6 cm² /m² , assessed by using the classical continuity equation (mean age: 81.5 ± 6.1 years, 51% female, mean left ventricular ejection fraction: 53.2 ± 13.6%), underwent TAVR and were included. After inclusion of the CT measured LVOT area into the continuity equation, the hybrid AVAi led to a reclassification of 30% (n = 128) of patients from severe to moderate AS. Multivariate predictors for reclassification were male sex, lower mean aortic gradient, and lower annulus/LVOT ratio (all p < .01). Reclassified patients had significantly higher sST2 at baseline and higher NT-proBNP values at baseline and 6 months follow-up compared to non-reclassified patients. Acute kidney injury was experienced more frequently after TAVR by reclassified patients, but no significant mortality difference occurred during 2 years of follow-up.

CONCLUSION

The hybrid AVAi reclassifies a significant portion of low-gradient severe AS patients into moderate AS. Reclassified patients showed increased fibrosis and heart failure markers at baseline compared to non-reclassified patients. But reclassification had no significant impact on mortality up to 2 years after TAVR. Routine assessment of hybrid AVAi seems not to improve further risk stratification of TAVR patients.

Multimodality imaging derived energy loss index and outcome after transcatheter aortic valve replacement

Aims 

To assess whether the combination of transthoracic echocardiography (TTE) and multidetector computed tomography (MDCT) data affects the grading of aortic stenosis (AS) severity under consideration of the energy loss index (ELI) in patients undergoing transcatheter aortic valve replacement (TAVR).

Methods and results 

Multimodality imaging was performed in 197 patients with symptomatic severe AS undergoing TAVR at the University Hospital Zurich, Switzerland. Fusion aortic valve area index (fusion AVAi) assessed by integrating MDCT derived planimetric left ventricular outflow tract area into the continuity equation was significantly larger as compared to conventional AVAi (0.41 ± 0.1 vs. 0.51 ± 0.1 cm2/m2; P &lt; 0.01). A total of 62 patients (31.4%) were reclassified from severe to moderate AS with fusion AVAi being &gt;0.6 cm2/m2. ELI was obtained for conventional AVAi and fusion AVAi based on sinotubular junction area determined by TTE (ELILTL 0.47 ± 0.1 cm2/m2; fusion ELILTL 0.60 ± 0.1 cm2/m2) and MDCT (ELIMDCT 0.48 ± 0.1 cm2/m2; fusion ELIMDCT 0.61 ± 0.05 cm2/m2). When ELI was calculated with fusion AVAi the effective orifice area was &gt;0.6 cm2/m2 in 85 patients (43.1%). Survival rate 3 years after TAVR was higher in patients reclassified to moderate AS according to multimodality imaging derived ELI (78.8% vs. 67%; P = 0.01).

Conclusion 

Multimodality imaging derived ELI reclassifies AS severity in 43% undergoing TAVR and predicts mid-term outcome.

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.

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

Aortic valve area is one of the main criteria used by echocardiography to determine the degree of valvular aortic stenosis, and it is calculated using the continuity equation which assumes that the flow volume of blood is equal at two points, the aortic valve area and the left ventricular outflow tract (LVOT). The main fallacy of this equation is the assumption that the LVOT area which is used to calculate the flow volume at the LVOT level is circular, where it is often an ellipse and sometimes irregular. The aim of this review is to explain the physiology of the continuity equation, the different sources of errors, the added benefits of using three-dimensional imaging modalities to measure LVOT area, the latest recommendations related to valvular aortic stenosis, and to introduce future perspectives. A literature review of studies comparing aortic valve area and LVOT area, after using three-dimensional data, has shown underestimation of both measurements when using the continuity equation. This has more impact on patients with discordant echocardiographic measurements when aortic valve area is disproportionate to haemodynamic measurements in assessing the degree of aortic stenosis. Although fusion imaging modalities of LVOT area can help in certain group of patients to address the issue of aortic valve area underestimation, further research on introducing a correction factor to the conventional continuity equation might be more rewarding, saving patients additional tests and potential radiation, with no clear evidence of cost-effectiveness.

Modified continuity equation using left ventricular outflow tract three-dimensional imaging for aortic valve area estimation

PURPOSE

Aortic valve area (AVA) is usually estimated by the continuity equation (CE) in which the left ventricular outflow tract (LVOT) area is calculated assuming a circular shape. This study aimed to compare measurements of LVOT area using standard 2D transthoracic echocardiography (2DTTE), 3D transesophageal echocardiography (3DTEE), and multidetector computed tomography (MDCT) and assess their relative impact on AVA estimated by the CE.

METHODS AND RESULTS

We prospectively enrolled 60 patients with severe aortic stenosis (AS) referred for transcatheter aortic valve replacement (TAVR) who systematically underwent 2DTTE, 3DTEE, and MDCT. Mean LVOT areas obtained by 2DTTE (3.28±0.66 cm² ) and 3DTEE (3.95±0.90 cm² ) were significantly underestimated when compared to the mean MDCT LVOT area (4.31±0.99 cm² ). LVOT was rather elliptical than round, with a mean eccentricity index of 1.47 (ratio of maximum to minimum LVOT diameters) assessed by MDCT. Mean TTE AVA estimated by the CE was 0.62±0.20 cm² . Substitution of 2DTTE LVOT area by 3DTEE LVOT area in the CE resulted in AVA of 0.74±0.24 cm² , while using MDCT LVOT area held an AVA of 0.80±0.24 cm² . MDCT-derived AVA was similar to MDCT planimetric AVA and allowed 24% of patients to be reclassified from severe to moderate AS.

CONCLUSIONS

2DTTE and 3DTEE underestimate LVOT area when compared to MDCT with significant impact on AVA estimation. Assessment through MDCT fusion AVA may be of incremental value in patients with discrepant severity criteria for AS.

Advanced imaging in valvular heart disease

Although echocardiography remains the mainstay imaging technique for the evaluation of patients with valvular heart disease (VHD), innovations in noninvasive imaging in the past few years have provided new insights into the pathophysiology and quantification of VHD, early detection of left ventricular (LV) dysfunction, and advanced prognostic assessment. The severity grading of valve dysfunction has been refined with the use of Doppler echocardiography, cardiac magnetic resonance (CMR), and CT imaging. LV ejection fraction remains an important criterion when deciding whether patients should be referred for surgery. However, echocardiographic strain imaging can now detect impaired LV systolic function before LV ejection fraction reduces, thus provoking the debate on whether patients with severe VHD should be referred for surgery at an earlier stage (before symptom onset). Impaired LV strain correlates with the amount of myocardial fibrosis detected with CMR techniques. Furthermore, accumulating data show that the extent of fibrosis associated with severe VHD has important prognostic implications. The present Review focuses on using these novel imaging modalities to assess pathophysiology, early LV dysfunction, and prognosis of major VHDs, including aortic stenosis, mitral regurgitation, and aortic regurgitation.

Pathophysiology and management of multivalvular disease

Multivalvular disease (MVD) is common among patients with valvular disease, and has a complex pathophysiology dependent on the specific combination of valve lesions. Diagnosis is challenging because several echocardiographic methods commonly used for the assessment of stenosis or regurgitation have been validated only in patients with single-valve disease. Decisions about the timing and type of treatment should be made by a multidisciplinary heart valve team, on a case-by-case basis. Several factors should be considered, including the severity and consequences of the MVD, the patient's life expectancy and comorbidities, the surgical risk associated with combined valve procedures, the long-term risk of morbidity and mortality associated with multiple valve prostheses, and the likelihood and risk of reoperation. The introduction of transcatheter valve therapies into clinical practice has provided new treatment options for patients with MVD, and decision-making algorithms on how to combine surgical and percutaneous treatment options are evolving rapidly. In this Review, we discuss the pathophysiology, diagnosis, and treatment of MVD, focusing on the combinations of valve pathologies that are most often encountered in clinical practice.

Synergistic Utility of Brain Natriuretic Peptide and Left Ventricular Strain in Patients With Significant Aortic Stenosis

BACKGROUND

In aortic stenosis (AS), symptoms and left ventricular (LV) dysfunction represent a later disease state, and objective parameters that identify incipient LV dysfunction are needed. We sought to determine prognostic utility of brain natriuretic peptide (BNP) and left ventricular global longitudinal strain (LV-GLS) in patients with aortic valve area <1.3 cm(2).

METHODS AND RESULTS

Five-hundred and thirty-one patients between January 2007 and December 2008 with aortic valve area <1.3 cm(2) (86% with aortic valve area ≤1.1 cm(2)) and left ventricular ejection fraction ≥50% who had BNP drawn ≤90 days from initial echo were included. Society of Thoracic Surgeons (STS) score and mortality were recorded. Mean STS score, glomerular filtration rate, and median BNP were 11±5, 73±35 mL/min per 1.73 m , and 141 (60-313) pg/mL, respectively; 78% were in New York Heart Association class ≥II. Mean LV-stroke volume index (LV-SVI) and LV-GLS were 39±10 mL/m(2) and -13.9±3%. At 4.7±2 years, 405 patients (76%) underwent aortic valve replacement; 161 died (30%). On multivariable survival analysis, age (hazard ratio [HR] 1.46), New York Heart Association class (HR 1.27), coronary artery disease (HR 1.72), decreasing glomerular filtration rate (HR 1.15), increasing BNP (HR 1.16), worsening LV-GLS (HR 1.13) and aortic valve replacement (time dependent) (HR 0.34) predicted survival (all P<0.01). For mortality, the c-statistic incrementally increased as follows (all P<0.01): STS score (0.60 [0.58-0.64]), STS score+BNP (0.67 [0.62-0.70]), and STS score+BNP+LV-GLS (0.74 [0.68-0.78]).

CONCLUSIONS

In normal LVEF patients with significant aortic stenosis, BNP and LV-GLS provide incremental (additive not duplicative) prognostic information over established predictors, suggesting that both play a synergistic role in defining outcomes.

Low gradient severe aortic stenosis with preserved ejection fraction: reclassification of severity by fusion of Doppler and computed tomographic data

AIMS

Low gradient severe aortic stenosis (AS) with preserved left ventricular ejection fraction (LVEF) may be attributed to aortic valve area index (AVAi) underestimation due to the assumption of a circular shape of the left ventricular outflow tract (LVOT) with 2-dimensional echocardiography. The current study evaluated whether fusing Doppler and multidetector computed tomography (MDCT) data to calculate AVAi results in significant reclassification of inconsistently graded severe AS.

METHODS AND RESULTS

In total, 191 patients with AVAi < 0.6 cm²/m² and LVEF ≥ 50% (mean age 80 ± 7 years, 48% male) were included in the current analysis. Patients were classified according to flow (stroke volume index <35 or ≥35 mL/m²) and gradient (mean transaortic pressure gradient ≤40 or >40 mmHg) into four groups: normal flow-high gradient (n = 72), low flow-high gradient (n = 31), normal flow-low gradient (n = 46), and low flow-low gradient (n = 42). Left ventricular outflow tract area was measured by planimetry on MDCT and combined with Doppler haemodynamics on continuity equation to obtain the fusion AVAi. The group of patients with normal flow-low gradient had significantly larger AVAi and LVOT area index compared with the other groups. Although MDCT-derived LVOT area index was comparable among the four groups, the fusion AVAi was significantly larger in the normal flow-low gradient group. By using the fusion AVAi, 52% (n = 24) of patients with normal flow-low gradient and 12% (n = 5) of patients with low flow-low gradient would have been reclassified into moderate AS due to AVAi ≥ 0.6 cm²/m².

CONCLUSION

The fusion AVAi reclassifies 52% of normal flow-low gradient and 12% of low flow-low gradient severe AS into true moderate AS, by providing true cross-sectional LVOT area.

Recent developments in echocardiographic imaging

PURPOSE OF REVIEW

This review provides an outline of recent applications related to the use of ultrasonography in various catheter-based procedures for the repair of many valvular abnormalities.

RECENT FINDINGS

Percutaneous interventions are becoming a safe and effective therapeutic modality in the management of various valvular defects. The intrinsic ability of ultrasound to provide real-time accurate assessment of cardiac and valvular structural and functional abnormalities makes this modality distinctively useful in the execution of percutaneous valvular procedures and evaluation of their results.Clinical applications of myocardial deformation and cardiac mechanics have been investigated in an increasing number of clinical applications. Speckle tracking accurately measures myocardial deformation parameters and has been recently applied to the evaluation of mitral insufficiency mechanisms.

SUMMARY

Recent developments in echocardiography are promoting this modality from its traditional role of diagnostic technique into one suitable for aiding in the execution of complex catheter-based procedures and for accurate monitoring of therapeutic response in many clinical settings.

Multidimensional MDCT angiography in the context of transcatheter aortic valve implantation

OBJECTIVE

Transcatheter aortic valve implantation has emerged as a viable treatment alternative for patients with severe aortic stenosis who are not surgical candidates. Multidimensional (3D and 4D) MDCT angiography plays a critical role in the safety, success, and outcome of an institutional transcatheter aortic valve implantation program.

CONCLUSION

Given the increasing therapeutic role of this innovative technique, an understanding of essential imaging concepts in its context is critical for appropriate image acquisition and interpretation.

Interactions between inflammatory activation and endothelial dysfunction selectively modulate valve disease progression in patients with bicuspid aortic valve

OBJECTIVES

Bicuspid aortic valve (BAV) is associated with increased risk of valvular degeneration and ascending aortic aneurysm formation and rupture. We sought to evaluate the roles of endothelial dysfunction and inflammatory activation in modulating these processes.

METHODS

We performed a case-control study of patients with BAV together with a multivariate analysis within the BAV group to identify factors associated with: development of significant valvular disease; dilatation of the ascending aorta; differential valve relative to aortic disease. Endothelial function of patients and controls was evaluated via flow-mediated dilatation (FMD) and plasma concentrations of asymmetric dimethylarginine (ADMA). Correlations with inflammatory markers and endothelial progenitor cell counts were also examined. Morphological and physiological assessment of the valve and ascending aorta was performed with transthoracic echocardiography and MRI.

RESULTS

Patients with BAV (n=43) and controls (n=25) were matched for age and gender. FMD was significantly lower in patients than controls (7.85±3.48% vs 11.58±3.98%, p=0.001), and these differences were age-independent. Within the BAV cohort, multivariate correlates of peak aortic valve velocity were plasma concentrations of ADMA and myeloperoxidase (MPO) (both p<0.01), while increasing age was an independent correlate of ascending aortic diameter (p<0.05). Furthermore, both low FMD and inflammatory activation were multivariate correlates of selectivity for valvular disease.

CONCLUSIONS

BAV is associated with endothelial dysfunction. The extent of inflammatory activation (specifically MPO release) and that of endothelial dysfunction impact primarily on integrity of the valve rather than aortic structure.

An insight into transcatheter aortic valve implantation-a perspective from multidetector-computed tomography

Transcatheter aortic valve implantation (TAVI) has now become an acceptable alternative to surgical aortic valve replacement for patients with severe aortic stenosis at high risk. The early enthusiasm for this technology has not diminished but rather has developed at an unprecedented rate over the last decade. Alongside the developments in implantation technique, transcatheter design, and postprocedural care, cardiac imaging modalities have also had to concurrently evolve to meet the perpetual demand for lower peri- and postprocedural complication rates. Although transthoracic and transesophageal echocardiography remain vital in patient's selection and periprocedural guidance, there is now emerging evidence that indicates that multidetector-computed tomography (MDCT) may also have an equally important role to play. The aim of the current review is to examine the modern role of MDCT in assessing patients with aortic stenosis being considered for TAVI.

Low gradient "severe" aortic stenosis with preserved left ventricular ejection fraction

In developed nations, aortic stenosis (AS) is the most common valvular heart disease presentation, and its prevalence is increasing due to aging populations. Accurate diagnosis of the disease process and determination of its severity are essential in clinical decision-making. Although current guidelines recommend measuring transvalvular gradients, maximal velocity, and aortic valve area in determining the disease severity, inconsistent grading of disease severity remains a common problem in clinical practice. Recent studies suggest that patients with paradoxical low-flow and/or low-gradient, severe AS are at a more advanced stage of the disease process and have a poorer prognosis. This mode of presentation may lead to an undervaluation of symptoms and inappropriate delay of AVR. Therefore, this challenging clinical situation should be carefully assessed in particular in symptomatic patients and clinical decisions should be tailored individually.

Standardized imaging for aortic annular sizing: implications for transcatheter valve selection

The safety and efficacy of transcatheter aortic valve replacement procedures are directly related to proper imaging. This report revisits the existing noninvasive and invasive approaches that have concurrently evolved to meet the demands for optimal selection and guidance of patients undergoing transcatheter aortic valve replacement. The authors summarize the published evidence and discuss the strengths and pitfalls of echocardiographic, computed tomographic, and calibrated aortic balloon valvuloplasty techniques in sizing the aortic valve annulus. Specific proposals for 3-dimensional tomographic reconstructions of complex 3-dimensional aortic root anatomy are provided for reducing intermodality variability in annular sizing. Finally, on the basis of the sizing approaches discussed in this review, the authors provide practical recommendations for balloon-expandable and self-expandable prostheses selection. Strategic use of echocardiographic, multislice computed tomographic, and angiographic data may provide complementary information for determining the anatomical suitability, efficacy, and safety of the procedure.

Incremental prognostic value of cardiac computed tomography angiography in asymptomatic aortic stenosis: significance of aortic valve calcium score

BACKGROUND

Cardiac computed tomography angiography (CCTA) provides the simultaneous evaluation of the aortic valve, myocardium, and coronary arteries. In particular, aortic valve calcium score (AVCS) can be accurately measured on the same scanning sequence used to measure coronary artery calcification, with no additional cost or radiation exposure. We sought to evaluate the prognostic value of CCTA measures, including AVCS, in asymptomatic aortic stenosis (AS).

METHODS AND RESULTS

Sixty-four initially asymptomatic patients with AS with a normal ejection fraction were prospectively enrolled and followed for median 29 (IQR=18-50) months. During follow-up, 27 (42%) patients experienced cardiac events, including five cardiac deaths, eleven aortic valve replacements. Multivariate Cox proportional hazards analysis identified three CCTA measures as significant predictors of cardiac events: aortic valve area (per 0.1cm(2) decrease; hazard ratio [HR]: 1.19, 95% confidence interval [CI]: 1.05-1.34); multi-vessel obstructive coronary artery disease (HR: 2.84, 95% CI: 1.10-7.32); and AVCS (per 100; HR: 1.09, 95% CI: 1.04-1.15). Kaplan-Meier analysis showed that patients with AVCS greater than or equal to the median value of 723 had significantly worse outcomes than those with AVCS less than 723 (p<0.0001). The C-statistic value for cardiac events substantially increased when these CCTA measures were added to clinical characteristics plus echocardiographic peak transaortic velocity (0.913 vs. 0.702, p<0.001).

CONCLUSIONS

In patients with asymptomatic AS, CCTA measures of valve area, coronary stenosis, and calcification severity provide independent and incremental prognostic value after accounting for the echocardiographic severity of stenosis.

Dynamic characterization of aortic annulus geometry and morphology with multimodality imaging: predictive value for aortic regurgitation after transcatheter aortic valve replacement

BACKGROUND

Patients undergoing transcatheter aortic valve replacement (TAVR), as compared with those undergoing surgical aortic valve replacement (AVR), have higher postprocedural aortic regurgitation (AR), associated with higher mortality. We hypothesized that reduced annular deformation is associated with higher postprocedural AR and sought to assess incremental value of assessment of aortic annular deformation in prediction of post-TAVR AR.

METHODS

We included 87 patients with high-risk severe aortic stenosis (AS) (81 ± 10 years, 54% men) who underwent preprocedural echocardiography and contrast-enhanced (4-dimensional) multidetector computed tomography (MDCT) of the aortic root, followed by TAVR (n = 55) or surgical AVR (n = 32). On MDCT, minimal/maximal annular circumference, circumferential deformation (maximum-minimum over cardiac cycle), and eccentricity (largest/smallest diameter during systole) were calculated. Degree of commissural/annular calcification was graded semiquantitatively (scale 1-3). Oversizing/undersizing of the prosthesis during TAVR was assessed.

RESULTS

Pre-AVR aortic valve area (0.6 ± 0.1 vs 0.6 ± 0.1 cm(2)), mean aortic valve gradient (46 ± 14 vs 45 ± 11 mm Hg), AR (1 ± 0.8 vs 0.9 ± 0.7), maximal annular circumference (8 ± 1 vs 7.9 ± 0.8 cm), annular deformation (0.3 ± 0.1 vs 0.3 ± 0.1 cm), eccentricity (1.2 ± 0.1 vs 1.2 ± 0.1), commissural (2.1 ± 0.6 vs 2 ± 0.7), and annular calcification scores (1.7 ± 0.8 vs 1.7 ± 0.8) were similar in TAVR and surgical AVR groups (P = not significant). A higher proportion of patients had ≥ mild AR in the TAVR than in the surgical AVR group (58% vs 34%; P < .03). In TAVR patients, reduced annular deformation (P = .01) predicted postprocedural AR, in addition to prosthesis undersizing (P = .03) and higher annular calcification (P = .03).

CONCLUSIONS

Residual post-TAVR AR is predicted by reduced aortic annular deformity, higher annular calcification, and prosthesis undersizing. Pre-TAVR 4-dimensional annular assessment aids in prediction of post-TAVR AR.

Invasive assessment of doubtful aortic stenosis by measuring simultaneous transaortic gradient with a pressure wire

Two-dimensional transthoracic echocardiography (2D-TTE) is the reference technique for evaluating aortic stenosis (AS) but may be unreliable in some cases. We aimed to assess whether the use of a pressure wire to measure simultaneous transaortic gradient and aortic valve area (AVA) could be helpful in patients in whom initial noninvasive evaluations were considered doubtful for AS. Fifty-seven patients (mean age 76 years; 39 men) underwent cardiac catheterization with single arterial access for assessment of AVA with the Gorlin and Gorlin formula. Transaortic pressure was obtained by 2 invasive methods: (1) conventional pullback method (PM) from the left ventricle toward the aorta and (2) simultaneous method (SM) with transaortic pressure simultaneously recorded with a 0.014-inch pressure wire introduced into the left ventricle and with a diagnostic catheter placed in the ascending aorta. Reasons for inaccurate assessment by 2D-TTE were low flow states (88%) and/or atrial fibrillation (79%). Agreement for severe AS defined by AVA <0.6 cm²/m² between SM and 2D-TTE and between SM and PM was fair, with kappa coefficients of 0.38 (95% confidence interval [CI] 0.14-0.75) and 0.36 (95% CI 0.22-0.7) respectively; agreement was poor between 2D-TTE and PM (kappa: 0.23; 95% CI 0.002-0.36). SM led to a reclassification of the severity of AS in 9 patients (15.8%) compared with 2D-TTE and in 11 patients (19.3%) compared with PM. In conclusion, invasive evaluation of doubtful AS by measuring simultaneous transaortic gradient using a pressure wire may provide an attractive method that can lead to a change in therapeutic strategy in a substantial proportion of patients.

Advanced 3-D analysis, client-server systems, and cloud computing-Integration of cardiovascular imaging data into clinical workflows of transcatheter aortic valve replacement

Degenerative aortic stenosis is highly prevalent in the aging populations of industrialized countries and is associated with poor prognosis. Surgical valve replacement has been the only established treatment with documented improvement of long-term outcome. However, many of the older patients with aortic stenosis (AS) are high-risk or ineligible for surgery. For these patients, transcatheter aortic valve replacement (TAVR) has emerged as a treatment alternative. The TAVR procedure is characterized by a lack of visualization of the operative field. Therefore, pre- and intra-procedural imaging is critical for patient selection, pre-procedural planning, and intra-operative decision-making. Incremental to conventional angiography and 2-D echocardiography, multidetector computed tomography (CT) has assumed an important role before TAVR. The analysis of 3-D CT data requires extensive post-processing during direct interaction with the dataset, using advance analysis software. Organization and storage of the data according to complex clinical workflows and sharing of image information have become a critical part of these novel treatment approaches. Optimally, the data are integrated into a comprehensive image data file accessible to multiple groups of practitioners across the hospital. This creates new challenges for data management requiring a complex IT infrastructure, spanning across multiple locations, but is increasingly achieved with client-server solutions and private cloud technology. This article describes the challenges and opportunities created by the increased amount of patient-specific imaging data in the context of TAVR.

Transcatheter aortic valve repair, imaging, and electronic imaging health record

Degenerative aortic stenosis (AS) is a common valvular pathology in developed nations. Secondary to advanced age and often multiple co-morbidities, a significant percentage of patients are not considered surgical candidates. For these high-risk patients, transcatheter aortic valve replacement (TAVR) is a rapidly emerging less-invasive treatment alternative. Because of the lack of direct exposure and visualization of the operative field, pre-procedural planning and intra-procedural guidance relies on imaging. Large 3-dimensional data files are acquired, which are reconstructed on advanced workstations during review and interpretation. Optimally, the imaging data is organized into a comprehensive digital file as an integral part of the electronic health record (EHR) following the patient. This manuscript will discuss the role of image data management in the context of TAVR.

Comparison of Invasive and Noninvasive Assessment of Aortic Stenosis Severity in the Elderly

Background—

Aortic valve area (AVA) in aortic stenosis (AS) can be assessed noninvasively or invasively, typically with similar results. These techniques have not been validated in elderly patients, where common assumptions make them most prone to error. Accurate assessment of AVA is crucial to determine which patients are appropriate candidates for aortic valve replacement.

Methods and Results—

Fifty elderly patients (mean 86 years, 46% female) referred for cardiac catheterization to evaluate AS also underwent transthoracic echocardiography within 24 hours. To minimize assumptions all patients had 3-dimensional echocardiography (Echo-3D), and at catheterization using directly measured oxygen consumption (Cath-mVo 2 ) and thermodilution cardiac output (Cath-TD). Correlation between Cath-mVo 2 and Echo-3D AVA was poor ( r =0.41). Cath-TD AVA had a moderate correlation with Echo-3D AVA ( r =0.59). Cath-mVo 2 (AVA=0.69 cm 2 ) and Cath-TD (AVA=0.66 cm 2 ) underestimated AVA compared with Echo-3D (AVA=0.76 cm 2; P =0.08 for comparison with Cath-mVo 2 ; P =0.001 for Cath-TD). Compared with Echo-3D, the sensitivity and specificity for determining critical disease (AVA <0.8 cm 2 ) were 81% and 42% for Cath-mVo 2 , and 97% and 53% for Cath-TD. The only independent predictor of the difference between noninvasive and invasive AVA was stroke volume index ( P <0.01). Resistance, a less flow-dependent measure, showed a stronger correlation between Echo-3D and Cath-mVo 2 ( r =0.69), and Echo-3D and Cath-TD ( r =0.77).

Conclusions—

Standard techniques of AVA assessment for AS show poor correlation in elderly patients, with frequent misclassification of critical AS. Less flow-dependent measures, such as resistance, should be considered to ensure that only appropriate patients are treated with aortic valve replacement.

The Editors. Most Important Papers in Transcatheter Aortic Valve Replacement and Transcatheter Aortic-Valve Implantation

The following are highlights from the series, Circulation: Cardiovascular Interventions Topic Review . This series summarizes the most important manuscripts, as selected by the editors, which have published in the Circulation portfolio. The studies included in this article represent the most noteworthy research in the areas of transcatheter aortic valve replacement and transcatheter aortic-valve implantation.

Computed tomography in the evaluation for transcatheter aortic valve implantation (TAVI)

If left untreated, symptomatic, severe aortic stenosis (AS) is associated with a dismal prognosis. Open-heart surgical valve replacement is the treatment of choice and is associated with excellent short and long-term outcome. However, many older patients with multiple co-morbidities and anticipated increased surgical risk are excluded from surgical intervention. For these patients, transcatheter aortic valve implantation (TAVI) is emerging as a viable treatment alternative. Transcatheter valvular heart procedures are characterized by lack of exposure and visualization of the operative field, therefore relying on image guidance, both for patient selection and preparation and the implantation procedure itself. This article describes the role of multi-detector row computed tomography (MDCT) for detailed assessment of the aortic valve, aortic root, and iliac arteries in the context of TAVI.