Cardiac Imaging for Assessing Low-Gradient Severe Aortic Stenosis

Proposal criteria of paradoxical low-flow low-gradient aortic stenosis for predicting prognosis in patients undergoing transcatheter aortic valve implantation

BACKGROUND

Paradoxical low-flow, low-gradient (PLF-LG) aortic stenosis (AS) is associated with poor prognosis in patients undergoing transcatheter aortic valve implantation (TAVI). This study aimed to verify the conventional criteria of PLF-LG AS (left ventricular ejection fraction [LVEF] > 50%, mean aortic valve pressure gradient [AVPG] < 40 mm Hg and stroke volume index [SVI] < 35 ml/m² by measuring Doppler method) compatible for predicting prognosis in patients undergoing TAVI.

MATERIALS AND METHODS

A total of 128 consecutive patients who underwent TAVI for AS with LVEF > 50% were enrolled. The primary endpoint was the hospital readmission due to heart failure (HRHF) and the secondary endpoint was all-cause mortality after hospital discharge. The patients were classified by both the conventional criteria of PLF-LG AS and the proposal criteria of PLF-LG AS if mean aortic valve pressure gradient (AVPG) < 40 mmHg and SVI by measuring Simpson's method < cut off value based on the ROC curve for predicting HRHF.

RESULTS

According to the conventional criteria, only 6 patients were diagnosed with PLF-LG AS. However, according to the proposal criteria, 16 patients were diagnosed with PLF-LG AS. Fourteen patients developed HRHF during the follow-up period after TAVI. Based on the ROC curves, SVI by measuring Simpson's method (cut off value = 25 ml/m²) had higher sensitivity and specificity for predicting HRHF (AUC = 0.74, p = 0.0013) than SVI by measuring Doppler method (AUC = 0.63, p = 0.045). The multivariate analysis revealed that PLF-LG AS defined by the proposal criteria (HR: 5.25; 95% CI: 1.60-17.16; p = 0.0073) but not by the conventional criteria was independently associated with HRHF. PLF-LG AS defined by the conventional criteria and the proposal criteria were not associated with all-cause mortality in the univariate analysis.

CONCLUSIONS

Our results demonstrated that new criteria of PLF-LG AS defined as SVI < 25 ml/m² measured by Simpson's method could predict HRHF in patients with severe AS who underwent TAVI.

Moderate gradient severe aortic stenosis: diagnosis, prognosis and therapy

Aortic stenosis (AS) is defined as severe in the presence of: mean gradient ≥40 mmHg, peak aortic velocity ≥4 m/s, and aortic valve area (AVA) ≤1 cm² (or an indexed AVA ≤0.6 cm²/m²). However, up to 40% of patients have a discrepancy between gradient and AVA, i.e. AVA ≤1 cm² (indicating severe AS) and a moderate gradient: >20 and <40 mmHg (typical of moderate stenosis). This condition is called ‘low-gradient AS’ and includes very heterogeneous clinical entities, with different pathophysiological mechanisms. The diagnostic tools needed to discriminate the different low-gradient AS phenotypes include colour-Doppler echocardiography, dobutamine stress echocardiography, computed tomography scan for the definition of the calcium score, and recently magnetic resonance imaging. The prognostic impact of low-gradient AS is heterogeneous. Classical low-flow low-gradient AS [reduced left ventricular ejection fraction (LVEF)] has the worst prognosis, followed by paradoxical low-flow low-gradient AS (preserved LVEF). Conversely, normal-flow low-gradient AS is associated with a better prognosis. The indications of the guidelines recommend surgical or percutaneous treatment, depending on the risk and comorbidities of the individual patient, both for patients with classic low-flow low-gradient AS and for those with paradoxical low-flow low-gradient AS.

Should We Quantify Valvular Calcifications on Cardiac CT in Patients with Infective Endocarditis?

BACKGROUND

Evaluate the impact of valvular calcifications measured on cardiac computed tomography (CCT) in patients with infective endocarditis (IE).

METHODS

Seventy patients with native IE (36 aortic IE, 31 mitral IE, 3 bivalvular IE) were included and explored with CCT between January 2016 and April 2018. Mitral and aortic valvular calcium score (VCS) were measured on unenhanced calcium scoring images, and correlated with clinical, surgical data, and 1-year death rate.

RESULTS

VCS of patients with mitral IE and no peripheral embolism was higher than those with peripheral embolism (868 (25-1725) vs. 6 (0-95), p < 0.05). Patients with high calcified mitral IE (mitral VCS > 100; n = 15) had a lower rate of surgery (40.0% vs.78.9%; p = 0.03) and a higher 1-year-death risk (53.3% vs. 10.5%, p = 0.04; OR = 8.5 (2.75-16.40) than patients with low mitral VCS (n = 19). Patients with aortic IE and high aortic calcifications (aortic VCS > 100; n = 18) present more frequently atypical bacteria on blood cultures (33.3% vs. 4.8%; p = 0.03) than patients with low aortic VCS (n = 21).

CONCLUSION

The amount of valvular calcifications on CT was associated with embolism risk, rate of surgery and 1-year risk of death in patients with mitral IE, and germ's type in aortic IE raising the question of their systematic quantification in native IE.

Resting echocardiographic predictors for true-severe aortic stenosis in patients with low-gradient severe aortic stenosis: A dobutamine stress echocardiography study

OBJECTIVE

Dobutamine stress echocardiography (DSE) is not always feasible in patients with low-gradient severe aortic stenosis (LG-SAS), and there are limited data available on the resting echocardiographic predictors for true-severe aortic stenosis (TSAS). This study investigated resting echocardiographic predictors for TSAS.

METHODS

Clinical data of 106 LG-SAS patients who underwent DSE were retrospectively analyzed. LG-SAS was defined as an aortic valve area index (AVAi) < .6 cm² /m² , and a mean AV pressure gradient < 40 mm Hg. The velocity ratio (VR) was calculated as the peak left ventricular outflow tract velocity/peak AV velocity. TSAS was defined as a projected AVAi < .6 cm² /m² .

RESULTS

The mean age was 79.3 ± 7.3 years, and 45 (42.5%) were men. The resting AV data were as follows: AVAi, .50 ± .07 cm² /m² ; mean AV pressure gradient, 23.0 ± 7.4 mm Hg; and VR, .25 ± .05. The projected AVAi was .58 ± .09 cm² /m² , and TSAS was documented in 65 (61.3%) patients. In multivariate analysis, the independent predictors of TSAS were AVAi (p = 0.012) and VR (p = 0.004) with respective best cut-off values of .52 cm² /m² and .25 on receiver-operating characteristic curve analysis. According to incremental numbers of the predictors, correct classification percentages of TSAS significantly increased with the Cochran-Armitage trend test (16.2% in no predictors, 65.2% in one predictor, and 95.7 % in two predictors; p < 0.001).

CONCLUSIONS

Resting AVAi and VR were independent predictors of TSAS in LG-SAS patients. The true severity might be predictable using the combination of resting parameters.

Rational and design of the ROTAS study: a randomized study for the optimal treatment of symptomatic patients with low-gradient severe aortic valve stenosis and preserved left ventricular ejection fraction

AIMS

Fifteen to thirty percentage of patients with severe aortic stenosis (AS) have preserved left ventricular ejection fraction (LVEF) and a discordant AS pattern at Doppler echocardiography, which is characterized by a small (<1 cm2) aortic area and low mean aortic gradient (<40 mmHg). The 'Randomized study for the Optimal Treatment of symptomatic patients with low-gradient severe Aortic Stenosis and preserved left ventricular ejection fraction' (ROTAS trial) aims at demonstrating the superiority of aortic valve replacement vs. a 'watchful waiting strategy' in symptomatic patients with low-gradient (LS), severe AS, and preserved LVEF, stratified according to indexed stroke volume, in terms of all-cause mortality or cardiovascular-related hospitalization during follow-up (FU).

METHODS AND RESULTS

The ROTAS trial will be a multicentre randomized non-blinded study involving 16 reference centres. AS severity will be confirmed by a multimodality approach (rest and stress echocardiography, calcium scoring, and cardiac magnetic resonance imaging for optimally characterize the population), which could provide important inputs to improve the pathophysiological understanding of this complex disease. Well-characterized patients will be randomized according to the management strategy. The primary endpoint will be the occurrence of all-cause mortality or cardiac related-hospitalizations during 2-year FU. One hundred and eighty subjects per group will be included.

CONCLUSION

The management of patients with LS severe AS and preserved LVEF is largely debated. ROTAS trial will allow a comprehensive evaluation of this particular pattern of AS and will establish which is the most appropriate management of these patients.

Estimating the Haemodynamic Streamline Vena Contracta as the Effective Orifice Area Measured from Reconstructed Multislice Phase-contrast MR Images for Patients with Moderately Accelerated Aortic Stenosis

PURPOSE

In aortic stenosis (AS), the discrepancy between moderately accelerated flow and effective orifice area (EOA) continues to pose a challenge. We developed a method of measuring the vena contracta area as hemodynamic EOA using cardiac MRI focusing on AS patients with a moderately accelerated flow to solve the problem that AS severity can currently be determined only by echocardiography.

METHODS

We investigated 40 patients with a peak transvalvular velocity > 3.0 m/s on transthoracic echocardiography (TTE). The patients were divided into highly accelerated and moderately accelerated AS groups according to whether or not the peak transvalvular velocity was ≥ 4.0 m/s. From the multislice 2D cine phase-contrast MRI data, the cross-sectional area of the vena contracta of the reconstructed streamline in the Valsalva sinus was defined as MRI-EOAs. Patient symptoms and echocardiography data, including EOA (defined as TTE-EOA), were derived from the continuity equation using TTE.

RESULTS

All participants in the highly accelerated AS group (n = 19) showed a peak velocity ≥ 4.0 m/s in MRI. Eleven patients in the moderately accelerated AS group (n = 21) had a TTE-EOA < 1.00 cm². In the moderately accelerated AS group, MRI-EOAs demonstrated a strong correlation with TTE-EOAs (r = 0.76, P < 0.01). Meanwhile, in the highly accelerated AS group, MRI-EOAs demonstrated positivity but a moderate correlation with TTE-EOAs (r = 0.63, P = 0.004). MRI-EOAs were overestimated compared to TTE-EOAs. In terms of the moderately accelerated AS group, the best cut-off value for MRI-EOAs was < 1.23 cm², compatible with TTE-EOAs < 1.00 cm², with an excellent prediction of the New York Heart Association classification ≥ III (sensitivity 87.5%, specificity 76.9%).

CONCLUSION

MRI-EOAs may be an alternative to conventional echocardiography for patients with moderately accelerated AS, especially those with discordant echocardiographic parameters.

True-severe stenosis in paradoxical low-flow low-gradient aortic stenosis: outcomes after transcatheter aortic valve replacement

AIMS

The ESC/EACTS guidelines propose criteria that determine the likelihood of true-severe aortic stenosis (AS). We aimed to investigate the impact of the guideline-based criteria of the likelihood of true-severe AS in patients with low-flow low-gradient (LFLG) AS with preserved ejection fraction (pEF) on outcomes following transcatheter aortic valve replacement (TAVR).

METHODS AND RESULTS

In a prospective TAVR registry, LFLG-AS patients with pEF were retrospectively categorized into high (criteria ≥6) and intermediate (criteria <6) likelihood of true-severe AS. Haemodynamic, functional, and clinical outcomes were compared with high-gradient AS patients with pEF. Among 632 eligible patients, 202 fulfilled diagnostic criteria for LFLG-AS. Significant haemodynamic improvement after TAVR was observed in LFLG-AS patients, irrespective of the likelihood. Although >70% of LFLG-AS patients had functional improvement, impaired functional status [New York Heart Association (NYHA III/IV)] persisted more frequently at 1 year in LFLG-AS than in high-gradient AS patients (7.8%), irrespective of the likelihood (high: 17.4%, P = 0.006; intermediate: 21.1%, P < 0.001). All-cause death at 1 year occurred in 6.6% of high-gradient AS patients, 10.9% of LFLG-AS patients with high likelihood [hazard ratio (HR)adj 1.43, 95% confidence interval (CI) 0.68-3.02], and in 7.2% of those with intermediate likelihood (HRadj 0.92, 95% CI 0.39-2.18). Among the criteria, only the absence of aortic valve area ≤0.8 cm2 emerged as an independent predictor of treatment futility, a combined endpoint of all-cause death or NYHA III/IV at 1 year (OR 2.70, 95% CI 1.14-6.25).

CONCLUSION

Patients with LFLG-AS with pEF had comparable survival but worse functional status at 1 year than high-gradient AS with pEF, irrespective of the likelihood of true-severe AS.

CLINICAL TRIAL REGISTRATION

https://www.clinicaltrials.gov. NCT01368250.

Validation of aortic valve calcium quantification thresholds measured by computed tomography in Asian patients with calcific aortic stenosis

AIMS

Sex-specific thresholds of aortic valve calcification (AVC) have been proposed and validated in Caucasians. Thus, we aimed to validate their accuracy in Asians.

METHODS AND RESULTS

Patients with calcific aortic stenosis (AS) from seven international centres were included. Exclusion criteria were ≥moderate aortic/mitral regurgitation and bicuspid valve. Optimal AVC and AVC-density sex-specific thresholds for severe AS were obtained in concordant grading and normal flow patients (CG/NF). We included 1263 patients [728 (57%) Asians, 573 (45%) women, 837 (66%) with CG/NF]. Mean gradient was 48 (26-64) mmHg and peak aortic velocity 4.5 (3.4-5.1) m/s. Optimal AVC thresholds were: 2145 Agatston Units (AU) in men and 1301 AU in women for Asians; and 1885 AU in men and 1129 AU in women for Caucasians. Overall, accuracy (% correctly classified) was high and comparable either using optimal or guidelines' thresholds (2000 AU in men, 1200 AU in women). However, accuracy was lower in Asian women vs. Caucasian women (76-78% vs. 94-95%; P < 0.001). Accuracy of AVC-density (476 AU/cm2 in men and 292 AU/cm2 in women) was comparable to absolute AVC in Caucasians (91% vs. 91%, respectively, P = 0.74), but higher than absolute AVC in Asians (87% vs. 81%, P < 0.001). There was no interaction between AVC/AVC-density and ethnicity (all P > 0.41) with regards to AS haemodynamic severity.

CONCLUSION

AVC thresholds defining severe AS are comparable in Asian and Caucasian populations, and similar to those proposed in the guidelines. However, accuracy of AVC to identify severe AS in Asians (especially women) is sub-optimal. Therefore, the use of AVC-density is preferable in Asians.

Prognosis of paradoxical low-flow low-gradient aortic stenosis after transcatheter aortic valve replacement

AIMS

In paradoxical low-flow low-gradient severe aortic stenosis (PLFLG AS) patients, stroke volume index (SVI) is reduced despite preserved left ventricular ejection fraction (LVEF). Although reduced SVI is already known as a poor prognostic predictor, the outcomes of PLFLG AS patients after transcatheter aortic valve replacement (TAVR) have not been clearly defined. We retrospectively investigated the post-TAVR outcomes of PLFLG AS patients in comparison with normal-flow high-gradient aortic stenosis (NFHG AS) patients.

METHODS

The current observational study included 245 patients with NFHG AS (mean transaortic pressure gradient ≥40 mmHg and LVEF ≥ 50%) and 48 patients with PLFLG AS (mean transaortic pressure gradient <40 mmHg, LVEF ≥ 50% and SVI < 35 ml/m2). The endpoints were all-cause mortality, hospitalization for valve-related symptoms or worsening congestive heart failure and New York Heart Association functional class III or IV.

RESULTS

PLFLG AS patients had a significantly higher proportion with a history of atrial fibrillation/flutter as compared with NFHG AS patients. All-cause mortality of PLFLG AS patients was worse than that of NFHG AS patients (P = 0.047). Hospitalization for valve-related symptoms or worsening congestive heart failure was more frequent in PLFLG AS patients than in NFHG AS patients (P = 0.041). New York Heart Association functional class III-IV after TAVR was more frequently observed in PLFLG AS patients (P = 0.019).

CONCLUSION

The outcomes of PLFLG AS patients were worse than those of NFHG AS patients in this study. Preexisting atrial fibrillation/flutter was frequent in PLFLG AS patients, and may affect their post-TAVR outcomes. Therefore, closer post-TAVR follow-up should be considered for these patients.

Moderate Aortic Stenosis in Patients With Heart Failure and Reduced Ejection Fraction

BACKGROUND

The study investigators previously reported that moderate aortic stenosis (AS) is associated with a poor prognosis in patients with heart failure (HF) with reduced left ventricular ejection fraction (LVEF) (HFrEF). However, the respective contribution of moderate AS versus HFrEF to the outcomes of these patients is unknown.

OBJECTIVES

This study sought to determine the impact of moderate AS on outcomes in patients with HFrEF.

METHODS

The study included 262 patients with moderate AS (aortic valve area >1.0 and <1.5 cm²; and peak aortic jet velocity >2 and <4 m/s, at rest or after dobutamine stress echocardiography) and HFrEF (LVEF <50%). These patients were matched 1:1 for sex, age, estimated glomerular filtration rate, New York Heart Association functional class III to IV, presence of diabetes, LVEF, and body mass index with patients with HFrEF but no AS (i.e., peak aortic jet velocity <2 m/s). The endpoints were all-cause mortality and the composite of death and HF hospitalization.

RESULTS

A total of 262 patients with HFrEF and moderate AS were matched with 262 patients with HFrEF and no AS. Mean follow-up was 2.9 ± 2.2 years. In the moderate AS group, mean aortic valve area was 1.2 ± 0.2 cm², and mean gradient was 14.5 ± 4.7 mm Hg. Moderate AS was associated with an increased risk of mortality (hazard ratio [HR]: 2.98; 95% confidence interval [CI]: 2.08 to 4.31; p < 0.0001) and of the composite of HF hospitalization and mortality (HR: 2.34; 95% CI: 1. 72 to 3.21; p < 0.0001). In the moderate AS group, aortic valve replacement (AVR) performed in 44 patients at a median follow-up time of 10.9 ± 16 months during follow-up was associated with improved survival (HR: 0.59; 95% CI: 0.35 to 0.98; p = 0.04). Notably, surgical AVR was not significantly associated with improved survival (p = 0.92), whereas transcatheter AVR was (HR: 0.43; 95% CI: 0.18 to 1.00; p = 0.05).

CONCLUSIONS

In this series of patients with HFrEF, moderate AS was associated with a marked incremental risk of mortality. AVR, and especially transcatheter AVR during follow-up, was associated with improved survival in patients with HFrEF and moderate AS. These findings provide support to the realization of a randomized trial to assess the effect of early transcatheter AVR in patients with HFrEF and moderate AS.

Evaluation and Management of Aortic Stenosis in Chronic Kidney Disease: A Scientific Statement From the American Heart Association

Aortic stenosis with concomitant chronic kidney disease (CKD) represents a clinical challenge. Aortic stenosis is more prevalent and progresses more rapidly and unpredictably in CKD, and the presence of CKD is associated with worse short-term and long-term outcomes after aortic valve replacement. Because patients with advanced CKD and end-stage kidney disease have been excluded from randomized trials, clinicians need to make complex management decisions in this population that are based on retrospective and observational evidence. This statement summarizes the epidemiological and pathophysiological characteristics of aortic stenosis in the context of CKD, evaluates the nuances and prognostic information provided by noninvasive cardiovascular imaging with echocardiography and advanced imaging techniques, and outlines the special risks in this population. Furthermore, this statement provides a critical review of the existing literature pertaining to clinical outcomes of surgical versus transcatheter aortic valve replacement in this high-risk population to help guide clinical decision making in the choice of aortic valve replacement and specific prosthesis. Finally, this statement provides an approach to the perioperative management of these patients, with special attention to a multidisciplinary heart-kidney collaborative team-based approach.

Impact of Surgical and Transcatheter Aortic Valve Replacement in Low-Gradient Aortic Stenosis: A Meta-Analysis

OBJECTIVES

The aim of this study was to assess the impact of aortic valve replacement (AVR) on survival in patients with each subclass of low-gradient (LG) aortic stenosis (AS) and to compare outcomes following surgical AVR (SAVR) and transcatheter AVR (TAVR).

BACKGROUND

LG severe AS encompasses a wide variety of pathophysiology, including classical low-flow, LG (LF-LG), paradoxical LF-LG, and normal-flow, LG (NF-LG) AS, and uncertainty exists regarding the impact of AVR on each subclass of LG AS.

METHODS

PubMed and Embase were queried through October 2020 to identify studies comparing survival with different management strategies (SAVR, TAVR, and conservative) in patients with LG AS. Pairwise meta-analysis comparing AVR versus conservative management and network meta-analysis comparing SAVR versus TAVR versus conservative management were performed.

RESULTS

Thirty-two studies with a total of 6,515 patients and a median follow-up time of 24.2 months (interquartile range: 36.5 months) were included. AVR was associated with a significant decrease in all-cause mortality in classical LF-LG (hazard ratio [HR]: 0.42; 95% confidence interval [CI]: 0.36 to 0.48), paradoxical LF-LG (HR: 0.41; 95% CI: 0.29 to 0.57), and NF-LG (HR: 0.41; 95% CI: 0.27 to 0.62) AS compared with conservative management. SAVR and TAVR were each associated with a decrease in all-cause mortality in classical LF-LG (HR: 0.46 [95% CI: 0.38 to 0.55] and 0.49 [95% CI: 0.37 to 0.64], respectively), paradoxical LF-LG (HR: 0.42 [95% CI: 0.28 to 0.65] and 0.42 [95% CI: 0.25 to 0.72], respectively), and NF-LG (HR: 0.40 [95% CI: 0.21 to 0.77] and 0.46 [95% CI: 0.26 to 0.84], respectively) AS compared with conservative management. No significant difference was observed between SAVR and TAVR.

CONCLUSIONS

In all subclasses of LG AS, AVR was associated with a significant decrease in all-cause mortality regardless of surgical or transcatheter approach.

Athletes with valvular heart disease and competitive sports: a position statement of the Sport Cardiology Section of the European Association of Preventive Cardiology

This article provides an overview of the recommendations from the Sports Cardiology section of the European Association of Preventive Cardiology on sports participation in individuals with valvular heart disease (VHD). The aim of these recommendations is to encourage regular physical activity including sports participation, with reasonable precaution to ensure a high level of safety for all affected individuals. Valvular heart disease is usually an age-related degenerative process, predominantly affecting individuals in their fifth decade and onwards. However, there is an increasing group of younger individuals with valvular defects. The diagnosis of cardiac disorders during routine cardiac examination often raises questions about on-going participation in competitive sport with a high dynamic or static component and the level of permissible physical effort during recreational exercise. Although the natural history of several valvular diseases has been reported in the general population, little is known about the potential influence of chronic intensive physical activity on valve function, left ventricular remodelling pulmonary artery pressure, and risk of arrhythmia. Due to the sparsity of data on the effects of exercise on VHD, the present document is largely based on clinical experience and expert opinion.

Prognosis of Severe Low-Flow, Low-Gradient Aortic Stenosis by Stroke Volume Index and Transvalvular Flow Rate

OBJECTIVES

This study determined whether flow state classified by stroke volume index (SVi) or transvalvular flow rate (FR) improved risk stratification of all-cause mortality, hospitalization due to heart failure, and aortic valvular interventions for patients with severe aortic stenosis (AS).

BACKGROUND

SVi is a widely accepted classification for flow state in severe low-flow, low-gradient (LFLG) AS. Recent studies suggest that FR more closely approximates true AS severity and provides more useful prognostication than SVi.

METHODS

Patients with severe AS over a 7-year period were subclassified by echocardiographic parameters. LFLG-AS was defined as severe AS (aortic valve area index [AVAi]: <0.6 cm²/m²), with a mean transvalvular pressure gradient of <40 mm Hg in the setting of low flow state: SVi of <35 ml/m² and/or FR of <200 ml/s and subclassified into preserved (≥50%; paradoxical) or reduced (<50%; classical) left ventricular ejection fraction (LVEF).

RESULTS

Among 621 consecutive patients with severe AS, the proportions of patients classified as LFLG-AS were different between SVi and FR (p < 0.001). Classification using SVi, FR, and LVEF was a strong predictor of the composite endpoint at the 2-year follow-up. The addition of SVi to the echocardiographic and clinical model provided significant improvement in reclassification (net reclassification improvement: 0.089; 95% confidence interval [CI]: 0.045 to 0.133; p = 0.04), whereas addition of FR did not (net reclassification improvement: 0.061; 95% CI: 0.016 to 0.106; p = 0.17). C-statistics indicated improved risk discrimination when AVAi, LVEF, and SVi or FR were added as predictive variables to the clinical model (p = 0.006).

CONCLUSIONS

Low SVi or FR was associated with adverse cardiovascular events and showed improvement in discrimination, but only SVi, not FR, significantly improved risk reclassification compared to other conventional clinical and echocardiographic predictors. This suggests that FR is not superior to SVi in distinguishing true severe from pseudosevere forms of AS and identification of patients with LFLG-AS who have worse outcomes.

Development of a deep learning-based algorithm for the automatic detection and quantification of aortic valve calcium

PURPOSE

We aimed to develop a deep learning (DL)-based algorithm for automated quantification of aortic valve calcium (AVC) from non-enhanced electrocardiogram-gated cardiac CT scans and compare performance of DL-measured AVC volume and Agatston score with those of visual gradings by radiologist readers for classification of AVC severity.

METHOD

A total of 589 CT examinations performed at a single center between March 2010 and August 2017 were retrospectively included. The DL algorithm was designed to segment AVC and to quantify AVC volume, and Agatston score was calculated using attenuation values. Manually measured AVC volume and Agatston score were used as ground truth. To validate AVC segmentation performance, the Dice coefficient was calculated. For observer performance testing, four radiologists determined AVC grade in two reading rounds. The diagnostic performance of DL-measured AVC volume and Agaston score for classifying severe AVC was compared with that of each reader's assessment.

RESULTS

After applying the DL algorithm, the Dice coefficient score was 0.807. In patients with AVC, accuracy of DL-measured AVC volume for AVC grading was 97.0 % with area under the curve (AUC) of 0.964 (95 % confidence interval [CI] 0.923-1) in the test set, which was better than the radiologist readers (accuracy 69.7 %-91.9 %, AUC 0.762-0.923) with manually measured AVC volume as ground truth. When manually measured AVC Agatston score was used as ground truth, accuracy of DL-measured AVC Agatston score for AVC grading was 92.9 % with AUC of 0.933 (95 % CI 0.885-0.981) in the test set, which was also better than the radiologist readers (accuracy 77.8-89.9 %, AUC 0.791-0.903).

CONCLUSIONS

DL-based automated AVC quantification may be comparable with manual measurements. The diagnostic performance of the DL-measured AVC volume and Agatston score for classification of severe AVC outperforms radiologist readers.

The Usefulness of [18F]F-Fluorodeoxyglucose and [18F]F-Sodium Fluoride Positron Emission Tomography Imaging in the Assessment of Early-Stage Aortic Valve Degeneration after Transcatheter Aortic Valve Implantation (TAVI)-Protocol Description and Preliminary Results

Transcatheter aortic valve implantation (TAVI) is now a well-established treatment for severe aortic stenosis. As the number of procedures and indications increase, the age of patients decreases. However, their durability and factors accelerating the process of degeneration are not well-known. The aim of the study was to verify the possibility of using [¹⁸F]F-sodium fluoride ([¹⁸F]F-NaF) and [¹⁸F]F-fluorodeoxyglucose ([¹⁸F]F-FDG) positron emission tomography/computed tomography (PET/CT) in assessing the intensity of TAVI valve degenerative processes. In 73 TAVI patients, transthoracic echocardiography (TTE) at initial (before TAVI), baseline (after TAVI), and during follow-up, as well as transesophageal echocardiography (TEE) and PET/CT, were performed using [¹⁸F]F-NaF and [¹⁸F]F-FDG at the six-month follow-up (FU) visit as a part of a two-year FU period. The morphology of TAVI valve leaflets were assessed in TEE, transvalvular gradients and effective orifice area (EOA) in TTE. Calcium scores and PET tracer activity were counted. We assessed the relationship between [¹⁸F]F-NaF and [¹⁸F]F-FDG PET/CT uptake at the 6 = month FU with selected indices e.g.,: transvalvular gradient, valve type, EOA and insufficiency grade at following time points after the TAVI procedure. We present the preliminary PET/CT ([¹⁸F]F-NaF, [¹⁸F]F-FDG) results at the six-month follow-up period as are part of an ongoing study, which will last two years FU. We enrolled 73 TAVI patients with the mean age of 82.49 ± 7.11 years. A significant decrease in transvalvular gradient and increase of effective orifice area and left ventricle ejection fraction were observed. At six months, FU valve thrombosis was diagnosed in four patients, while 7.6% of patients refused planned controls due to the COVID-19 pandemic. We noticed significant correlations between valve types, EOA and transaortic valve gradients, as well as [¹⁸F]F-NaF and [¹⁸F]F-FDG uptake in PET/CT. PET/CT imaging with the use of [¹⁸F]F-FDG and [¹⁸F]F-NaF is intended to be feasible, and it practically allows the standardized uptake value (SUV) to differentiate the area containing the TAVI leaflets from the SUV directly adjacent to the ring calcifications and the calcified native leaflets. This could become the seed for future detection and evaluation capabilities regarding the progression of even early degenerative lesions to the TAVI valve, expressed as local leaflet inflammation and microcalcifications.

Multimodality Imaging for Discordant Low-Gradient Aortic Stenosis: Assessing the Valve and the Myocardium

Aortic stenosis (AS) is a disease of the valve and the myocardium. A correct assessment of the valve disease severity is key to define the need for aortic valve replacement (AVR), but a better understanding of the myocardial consequences of the increased afterload is paramount to optimize the timing of the intervention. Transthoracic echocardiography remains the cornerstone of AS assessment, as it is universally available, and it allows a comprehensive structural and hemodynamic evaluation of both the aortic valve and the rest of the heart. However, it may not be sufficient as a significant proportion of patients with severe AS presents with discordant grading (i.e., an AVA ≤ 1 cm² and a mean gradient <40 mmHg) which raises uncertainty about the true severity of AS and the need for AVR. Several imaging modalities (transesophageal or stress echocardiography, computed tomography, cardiovascular magnetic resonance, positron emission tomography) exist that allow a detailed assessment of the stenotic aortic valve and the myocardial remodeling response. This review aims to provide an updated overview of these multimodality imaging techniques and seeks to highlight a practical approach to help clinical decision making in the challenging group of patients with discordant low-gradient AS.

Prognostic value of the H2 FPEF score in patients undergoing transcatheter aortic valve implantation

Aims

The aim of this study was to assess the prognostic value of the H₂FPEF score in patients undergoing transcatheter aortic valve implantation (TAVI) for severe aortic stenosis (AS) and preserved left ventricular ejection fraction (EF).

Methods and results

In this multicentre study, a total of 832 patients from two German high‐volume centres, who received TAVI for severe AS and preserved EF (≥50%), were identified for calculation of the H₂FPEF score. Patients were dichotomized according to low (0–5 points; n = 570) and high (6–9 points; n = 262) H₂FPEF scores. Kaplan–Meier and Cox regression analyses were applied to assess the prognostic impact of the H₂FPEF score. We observed a decrease in stroke volume index (−2.04 mL/m²/point) and mean transvalvular gradients (−1.14 mmHg/point) with increasing H₂FPEF score translating into a higher prevalence of paradoxical low‐flow, low‐gradient AS among patients with high H₂FPEF score. One year after TAVI, the rates of all‐cause (low vs. high H₂FPEF score: 8.0% vs. 19.4%, P < 0.0001) and cardiovascular (CV) mortality (1.9% vs. 9.0%, P < 0.0001) as well as the rate of CV mortality or rehospitalization for congestive heart failure (6.4% vs. 23.2%, P < 0.0001) were higher in patients with high H₂FPEF score compared with those with low H₂FPEF score. After multivariable analysis, a high H₂FPEF score remained independently predictive of all‐cause mortality [hazard ratio 1.59 (1.28–2.35), P = 0.018] and CV mortality or rehospitalization for congestive heart failure [hazard ratio 2.92 (1.65–5.15), P < 0.001]. Among the H₂FPEF score variables, atrial fibrillation, pulmonary hypertension, and elevated left ventricular filling pressure were the strongest outcome predictors.

Conclusions

The H₂FPEF score serves as an independent predictor of adverse CV and heart failure outcome among TAVI patients with preserved EF. A high H₂FPEF score is associated with the presence of paradoxical low‐flow, low‐gradient AS, the HFpEF in patients with AS. By identifying patients in advanced stages of HFpEF, the H₂FPEF score might be useful as a risk prediction tool in patients with preserved EF scheduled for TAVI.

Aortic pulse wave velocity and its relationship with transaortic flow and gradients in patients with severe aortic stenosis undergoing aortic valve replacement

Background

Low-flow, low-gradient severe aortic stenosis (LFLGAS) is a common clinical entity and is associated with poor prognosis. Increased left ventricular (LV) afterload is one of the mechanisms contributing to low LV stroke volume index (SVi) in these patients. Aortic stiffness is an important determinant of LV afterload, but no previous study has evaluated its relationship with LVSVi in patients with AS.

Methods

Fifty-seven patients (mean age 66 ± 8 years, 71.9% men) with severe AS [aortic valve area (AVA) < 1.0 cm²] undergoing aortic valve replacement (AVR) were included in this study. Echocardiographic parameters of AS were correlated with carotid-femoral pulse wave velocity (cfPWV), a measure of aortic stiffness, derived using PeriScope® device.

Results

Mean AVA was 0.63 ± 0.17 cm² with mean and peak transvalvular gradient 56.5 ± 18.8 mmHg and 83.2 ± 25.2 mmHg, respectively. Nearly half (26 of 57, 45.6%) of the subjects had SVi <35 mL/m², indicative of low-flow severe AS. These subjects had lower AVA, lower aortic valve gradient, and LV ejection fraction. CfPWV was numerically lower in these subjects [median 1467 (interquartile range 978, 2259) vs 1588 (1106, 2167)] but the difference was not statistically significant (p = 0.66). However, when analyzed as a continuous variable, cfPWV had significant positive correlation with SVi (Pearson's r 0.268, p = 0.048) and mean aortic valve gradient (Pearson's r 0.274, p = 0.043).

Conclusions

In patients with severe AS undergoing AVR, aortic stiffness measured using cfPWV is not a determinant of low-flow state. Instead, an increasing cfPWV tends to be associated with increasing transvalvular flow and gradient in these patients.

Haemodynamic Patterns of Severe Aortic Stenosis

The authors present up-to-date review of clinical pathophysiology of aortic stenosis (AS) based on differentiation of its haemodynamic patterns, and some actual issues of instrumental diagnostics and classification of AS. The variety of clinical presentations of AS is based on diverse combination of pathological changes of haemodynamics. In Russian cardiology, there is no clear pathophysiological classification of AS despite of its relevance under the progress of surgical and transcatheter treatment of AS. The authors suggest the pilot haemodynamic classification of AS which includes 6 types (0-5) based on different combination of the following variables: left ventricle ejection fraction, stroke volume, mean aortic systolic pressure gradient. Severe AS with low transaortic pressure gradient in patients with depressed systolic function of the left ventricle (so called «low flow-low» gradient phenomenon) is referred to as the most frequent, classical haemodynamic pattern of low-gradient AS. The prevalence of this variant is about 10% among European population of patients with severe AS. The inconsistence between aortic valve area and mean pressure gradient is as common as in 35-40% of patients with AS, however, in 30-50% of these cases, AS is not severe. Severe AS is a surgical disease that should be treated in a surgical way in all patients but those in whom predicted risk overbalances potential benefits of the procedure. The use of integrated clinical and instrumental approach for identification of a true sever AS is the matter of great concern, as both overestimation and underestimation can misguide the clinical decision-making process. Verification of severe AS in patients with classical and paradoxical low flow-low gradient AS with specific indications for surgical treatment regarded is further emphasized in the paper. Since transcatheter aortic valve implantation has become a commonly recognized alternative to surgical aortic valve replacement, its role in the treatment of severe AS with different haemodynamic patterns is also discussed. The authors stress on the necessity of using tailored approach for treatment of AS regarding different clinical and pathophysiological scenarios: high gradient AS with preserved ejection fraction, classical and paradoxical low flow-low gradient AS.

Performance of Prediction Models for Diagnosing Severe Aortic Stenosis Based on Aortic Valve Calcium on Cardiac Computed Tomography: Incorporation of Radiomics and Machine Learning

OBJECTIVE

We aimed to develop a prediction model for diagnosing severe aortic stenosis (AS) using computed tomography (CT) radiomics features of aortic valve calcium (AVC) and machine learning (ML) algorithms.

MATERIALS AND METHODS

We retrospectively enrolled 408 patients who underwent cardiac CT between March 2010 and August 2017 and had echocardiographic examinations (240 patients with severe AS on echocardiography [the severe AS group] and 168 patients without severe AS [the non-severe AS group]). Data were divided into a training set (312 patients) and a validation set (96 patients). Using non-contrast-enhanced cardiac CT scans, AVC was segmented, and 128 radiomics features for AVC were extracted. After feature selection was performed with three ML algorithms (least absolute shrinkage and selection operator [LASSO], random forests [RFs], and eXtreme Gradient Boosting [XGBoost]), model classifiers for diagnosing severe AS on echocardiography were developed in combination with three different model classifier methods (logistic regression, RF, and XGBoost). The performance (c-index) of each radiomics prediction model was compared with predictions based on AVC volume and score.

RESULTS

The radiomics scores derived from LASSO were significantly different between the severe AS and non-severe AS groups in the validation set (median, 1.563 vs. 0.197, respectively, p < 0.001). A radiomics prediction model based on feature selection by LASSO + model classifier by XGBoost showed the highest c-index of 0.921 (95% confidence interval [CI], 0.869-0.973) in the validation set. Compared to prediction models based on AVC volume and score (c-indexes of 0.894 [95% CI, 0.815-0.948] and 0.899 [95% CI, 0.820-0.951], respectively), eight and three of the nine radiomics prediction models showed higher discrimination abilities for severe AS. However, the differences were not statistically significant (p > 0.05 for all).

CONCLUSION

Models based on the radiomics features of AVC and ML algorithms may perform well for diagnosing severe AS, but the added value compared to AVC volume and score should be investigated further.

Prognostic Value of Computed Tomography-Derived Extracellular Volume in TAVR Patients With Low-Flow Low-Gradient Aortic Stenosis

OBJECTIVES

The association between extracellular volume (ECV) measured by computed tomography angiography (CTA) and clinical outcomes was evaluated in low-flow low-gradient (LFLG) aortic stenosis (AS) patients undergoing transcatheter aortic valve replacement (TAVR).

BACKGROUND

Patients with LFLG AS comprise a high-risk group with respect to clinical outcomes. Although ECV, a marker of myocardial fibrosis, is traditionally measured with cardiac magnetic resonance, it can also be measured using cardiac CTA. The authors hypothesized that in LFLG AS, increased ECV may be associated with adverse clinical outcomes.

METHODS

In 150 LFLG patients with AS who underwent TAVR, ECV was quantified using pre-TAVR CTA. Echocardiographic and clinical information including all-cause death and heart failure rehospitalization (HFH) was obtained from electronic medical records. A Cox proportional hazards model was used to evaluate the association between ECV and death+HFH.

RESULTS

During a median follow-up of 13.9 months (range 0.07 to 28.9 months), there were 31 death+HFH events (21%). Patients who experienced death+HFH had a greater median Society of Thoracic Surgery score (9.9 vs. 4.7; p < 0.01), lower left ventricular ejection fraction (42.3 ± 20.2% vs. 52.7 ± 17.2%; p < 0.01), lower mean transvalvular gradient (24.9 ± 8.9 mm Hg vs. 28.1 ± 7.3 mm Hg; p = 0.04) and increased mean ECV (35.5 ± 9.6% vs. 29.9 ± 8.2%; p < 0.01) compared with patients who did not experience death+HFH. In a multivariable Cox proportional hazards model, increase in ECV was associated with increase in death+HFH, (hazard ratio per 1% increase: 1.04, 95% confidence interval: 1.01 to 1.09; p < 0.01).

CONCLUSIONS

In patients with LFLG AS, CTA measured increase in ECV is associated with increased risk of adverse clinical outcomes post-TAVR and may thus serve as a useful noninvasive marker for prognostication.

Reclassification of aortic stenosis by fusion of echocardiography and computed tomography in low-gradient aortic stenosis

Background

The integration of computed tomography (CT)-derived left ventricular outflow tract area into the echocardiography-derived continuity equation results in the reclassification of a significant proportion of patients with severe aortic stenosis (AS) into moderate AS based on aortic valve area indexed to body surface area determined by fusion imaging (fusion AVA_i). The aim of this study was to evaluate AS severity by a fusion imaging technique in patients with low-gradient AS and to compare the clinical impact of reclassified moderate AS versus severe AS.

Methods

We included 359 consecutive patients who underwent transcatheter aortic valve implantation for low-gradient, severe AS at two academic institutions and created a joint database. The primary endpoint was a composite of all-cause mortality and rehospitalisations for heart failure at 1 year.

Results

Overall, 35% of the population (n = 126) were reclassified to moderate AS [median fusion AVAi 0.70 (interquartile range, IQR 0.65–0.80) cm²/m²] and severe AS was retained as the classification in 65% [median fusion AVAi 0.49 (IQR 0.43–0.54) cm²/m²]. Lower body mass index, higher logistic EuroSCORE and larger aortic dimensions characterised patients reclassified to moderate AS. Overall, 57% of patients had a left ventricular ejection fraction (LVEF) <50%. Clinical outcome was similar in patients with reclassified moderate or severe AS. Among patients reclassified to moderate AS, non-cardiac mortality was higher in those with LVEF <50% than in those with LVEF ≥50% (log-rank p = 0.029).

Conclusions

The integration of CT and transthoracic echocardiography to obtain fusion AVAi led to the reclassification of one third of patients with low-gradient AS to moderate AS. Reclassification did not affect clinical outcome, although patients reclassified to moderate AS with a LVEF <50% had worse outcomes owing to excess non-cardiac mortality.

Aortic valve area calculation using 3D transesophageal echocardiography: Implications for aortic stenosis severity grading

AIMS

Aortic stenosis (AS) grading by 2D-transthoracic echocardiography (2D-TTE) aortic valve area (AVA) calculation is limited by left ventricular outflow tract (LVOT) area underestimation. The combination of Doppler parameters with 3D LVOT area obtained by multidetector computed tomography (MDCT) can improve AS grading, reconciling discordant 2D-TTE findings. This study aimed to systematically evaluate the role of 3D-transesophageal echocardiography (3D-TEE) in AS grading using MDCT as reference standard.

METHODS AND RESULTS

288 patients (81 ± 6.3 years, 52.4% female) with symptomatic AS underwent 2D-TTE, 3D-TEE, and MDCT for transcatheter aortic valve implantation. Doppler parameters were combined with 3D LVOT areas measured by manual and semi-automated software 3D-TEE and by MDCT to calculate AVA, reassessing AS severity. Both 3D-TEE modalities demonstrated good correlation with MDCT, with excellent intra-observer and inter-observer variability. Compared to MDCT, 3D-TEE measurements significantly underestimated AVA (P_ANOVA  < .0001), although the difference was clinically acceptable. Compared to 2D-TTE, 3D-TEE manual and semi-automated software reclassified severe AS in 21.9% and 25.2% of cases, respectively (P < .0001), overcame grading parameters discordance in more than 40% of cases in patients with low-gradient AS (P < .0001) and reduced the proportion of low-flow states in nearly 75% of cases when combined to stroke volume index assessment (P < .0001). 3D-TEE imaging modalities showed a reduction in the proportion of patients with low-gradient and pathological AVA as defined by 2D-TTE, and improved AVA and mean pressure gradient agreement with current guidelines cutoff values.

CONCLUSION

3D-TEE AVA calculation is a reliable tool for AS grading with excellent reproducibility and good correlation with MDCT measurements.

A novel method to assess valvulo-arterial load in patients with aortic valve stenosis

INTRODUCTION

Ventricular function in elderly patients with aortic stenosis is impeded both by restricted aortic flow and arterial stiffening. A number of patients continue to have exertional intolerance after relief of aortic valvular obstruction due to unrecognized ventriculo-arterial coupling mismatch.

HYPOTHESIS

Quantification of valvulo-arterial load (VAL), using a simultaneous applanation tonometry/cardiac magnetic resonance (CMR) technique, can accurately assess the relative contributions of aortic stiffness and valve gradient in older patients with aortic stenosis.

METHODS

Elderly patients with aortic stenosis underwent a simultaneous applanation tonometry/CMR protocol. CMR provided left ventricular volume and aortic flow simultaneously with radial applanation tonometry pressure acquisition. Central aortic pressure was derived by transformation of the radial applanation tonometry waveform. VAL was determined as the relationship of derived aortic pressure to CMR aortic flow in frequency domain (central illustration).

RESULTS

Twenty patients (age 80 ± 9 years; 12 males; blood pressure 140/75 ± 20 mmHg) with aortic stenosis on transthoracic echocardiogram (16 severe; mean gradient 45 ± 16 mmHg; aortic valve area 0.8 ± 0.2 cm2) were enrolled. Derived aortic pressure and flow waveforms correlated well with invasive data. Increased VAL was significantly associated with advanced age (P = 0.04) and raised SBP (P < 0.01), irrespective of aortic stenosis severity.

CONCLUSION

Difficulties in the measurement and accuracy of ventriculo-arterial coupling means that it is not routinely measured in patients with aortic stenosis. We describe a new noninvasive index that provides an accurate assessment of valvular and arterial load on the left ventricle. VAL may help detect those at risk of ventriculo-arterial coupling mismatch and assist in selection of those most likely to benefit from an invasive procedure.

Does the severity of low-gradient aortic stenosis classified by computed tomography-derived aortic valve calcification determine the outcome of patients after transcatheter aortic valve implantation (TAVI)?

OBJECTIVES

Aortic valve calcification (AVC) determined by computed tomography has emerged as a complementary measure of aortic stenosis (AS) severity and as a predictor of adverse events. Thus, AVC can guide further treatment decisions in patients with low-gradient AS (LG-AS). We compared the symptomatic and prognostic outcome of patients with low vs. high AVC after transcatheter aortic valve implantation (TAVI).

METHODS

Patients with an aortic valve area index ≤ 0.6 cm²/m² and a mean pressure gradient (MPG) < 40 mmHg were classified as low-flow, low-gradient AS (LFLG-AS; stroke volume index [SVI] ≤ 35 ml/m², left ventricular ejection fraction [LVEF] < 50%, n = 173), paradoxical LFLG-AS (pLFLG-AS, SVI ≤ 35 ml/m², LVEF ≥ 50%, n = 233), or normal-flow, low-gradient AS (NFLG-AS, SVI > 35 ml/m², LVEF ≥ 50%, n = 244); patients with MPG ≥ 40 mmHg (n = 1142) served as controls. Patients were further categorized according to published AVC thresholds.

RESULTS

Demographic characteristics and cardiovascular risk were not different between patients with high vs. low AVC in any of the subgroups. Patients with low AVC had a lower MPG. Symptom improvement at 30 days was observed in the majority of patients but was less pronounced in LFLG-AS patients with low vs. those with high AVC. Kaplan-Meier 1-year survival curves were identical between patients with low and high AVC in all three LG-AS groups.

CONCLUSIONS

The severity of LG-AS based on AVC has no impact on 1-year prognosis once TAVI has been performed.

KEY POINTS

• Aortic valve calcification (AVC) determined by computed tomography has emerged as a complementary measure of aortic stenosis (AS) severity and is of prognostic value in selected patients. • Patients with inconsistent echocardiographic measures can be classified as having severe or nonsevere AS by the computed tomography-derived AVC score. • The prognostic value of AVC in patients with low-gradient AS is abrogated after correction of afterload by TAVI.

18F-Sodium Fluoride (18F-NaF) for Imaging Microcalcification Activity in the Cardiovascular System

Accumulating preclinical and clinical evidence suggests that calcification is one of the body's primary responses to injury and a key pathological feature of cardiovascular disease. Calcification activity can now be imaged using 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) in combination with either computed tomography or magnetic resonance. These techniques allow visualization of calcification activity and, therefore, provide different information to the established macroscopic calcium imaged with computed tomography. Indeed, 18F-NaF PET has been used to investigate a wide range of valvular conditions, including aortic stenosis, mitral annular calcification, and bioprosthetic valve disease, as well as vascular conditions, including abdominal aortic aneurysm disease, coronary, and carotid atherosclerosis, peripheral vascular disease, and erectile dysfunction. In this brief review, we will focus on how 18F-NaF PET has improved our pathophysiological understanding of cardiovascular calcification and how it can be used as a marker of vascular calcification, providing a useful tool that can be utilized in clinical trials investigating the prediction of both disease progression and clinical events. Finally, we will discuss how 18F-NaF might be employed clinically to improve patient assessment and to guide decision-making.

Why and How to Measure Aortic Valve Calcification in Patients With Aortic Stenosis

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.

Evolution of Transcatheter Aortic Valve Replacement | Review of Literature

Aortic valve stenosis is the most common primary valvular heart disease leading to either surgical or transcatheter valve replacement in the United States with its prevalence on the rise due to the elderly population. Over the recent years, the rise of transcatheter aortic valve replacement has been exponential due to technologic developments and randomized control trials. In this review article, we aim to review current literature on transcatheter aortic valve replacements.

Priorities for Patient-Centered Research in Valvular Heart Disease: A Report From the National Heart, Lung, and Blood Institute Working Group

Over the past decade, the field of valvular heart disease (VHD) has rapidly transformed, largely as a result of the development and improvement of less invasive transcatheter approaches to valve repair or replacement. This transformation has been supported by numerous well-designed randomized trials, but they have centered almost entirely on devices and procedures. Outside this scope of focus, however, myriad aspects of therapy and management for patients with VHD have either no guidelines or recommendations based only on expert opinion and observational studies. Further, research in VHD has often failed to engage patients to inform study design and identify research questions of greatest importance and relevance from a patient perspective. Accordingly, the National Heart, Lung, and Blood Institute convened a Working Group on Patient-Centered Research in Valvular Heart Disease, composed of clinician and research experts and patient advocacy experts to identify gaps and barriers to research in VHD and identify research priorities. While recognizing that important research remains to be done to test the safety and efficacy of devices and procedures to treat VHD, we intentionally focused less attention on these areas of research as they are more commonly pursued and supported by industry. Herein, we present the patient-centered research gaps, barriers, and priorities in VHD and organized our report according to the "patient journey," including access to care, screening and diagnosis, preprocedure therapy and management, decision making when a procedure is contemplated (clinician and patient perspectives), and postprocedure therapy and management. It is hoped that this report will foster collaboration among diverse stakeholders and highlight for funding bodies the pressing patient-centered research gaps, opportunities, and priorities in VHD in order to produce impactful patient-centered research that will inform and improve patient-centered policy and care.

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.

Clinical significance of energy loss index in patients with low-gradient severe aortic stenosis and preserved ejection fraction

Aims 

We hypothesized that among patients with low-gradient severe aortic stenosis (AS) and preserved left ventricular ejection fraction (LVEF), reclassification of AS severity as moderate by pressure recovery adjusted indexed aortic valve area (AVAi) = energy loss index (ELI), may identify a subgroup of patients with a better outcome.

Methods and results 

Three hundred and seventy-nine patients with low-gradient AS (defined by AVAi ≤ 0.6 cm2/m2 and mean aortic pressure gradient &lt; 40 mmHg) and preserved LVEF ≥50% were studied. Reclassification as moderate AS by ELI was defined as AVAi ≤0.6 cm2/m2 but with an ELI &gt;0.6 cm2/m2. Cardiac events [cardiac mortality and/or need for aortic valve replacement (AVR)] during follow-up were studied. One hundred and forty-eight patients (39%) were reclassified as moderate AS by ELI. Reclassification as moderate AS was independently associated with decreased body surface area, normal flow status, decreased left ventricular mass index, and left atrial volume index (all P &lt; 0.05). After adjustment for variables of prognostic interest, reclassification as moderate AS by ELI was associated with a considerable reduction of risk of cardiac events {adjusted hazard ratio (HR) 0.49 [95% confidence interval (CI) 0.33–0.72]; P &lt; 0.001}, need for AVR [adjusted HR 0.52 (95% CI 0.34–0.81); P = 0.004], and cardiac mortality [adjusted HR 0.46 (95% CI 0.22–0.98); P = 0.044].

Conclusion 

In patients with low-gradient severe AS and preserved LVEF, calculation of ELI permits to reclassify almost 40% of patients as having moderate AS. These reclassified patients have a considerable reduction of the risk of cardiac events during follow-up. Calculation of ELI is useful for decision-making in patients with low-gradient severe AS and preserved ejection fraction.

Moderate Aortic Stenosis and Heart Failure With Reduced Ejection Fraction: Can Imaging Guide Us to Therapy?

Clinical management of patients with only moderate aortic stenosis (AS) but symptoms of heart failure with a reduced left ventricular ejection fraction (HFrEF) is challenging. Current guidelines recommend clinical surveillance with multimodality imaging; aortic valve replacement (AVR) is deferred until the stenosis becomes severe. Given the known benefits of afterload reduction in management of patients with HFrEF, it has been hypothesized that AVR may be beneficial in patients with only moderate AS who present with HFrEF. In this article, we first review the current approach for management of patients with moderate AS and HFrEF based on close clinical and imaging surveillance with AVR delayed until AS is severe. We then discuss the case for transcatheter AVR (TAVR) earlier in the disease course, when AS is moderate, based on stress echocardiographic data. We conclude with a detailed summary of the TAVR UNLOAD (Transcatheter Aortic Valve Replacement to UNload the Left Ventricle in Patients With ADvanced Heart Failure) trial, in which patients with moderate AS and HFrEF are randomized to guideline-directed heart failure therapy alone versus guideline-directed heart failure therapy plus TAVR.

Prognostic Impact of the Ratio of Acceleration Time to Ejection Time in Patients With Low Gradient Severe Aortic Stenosis and Preserved Ejection Fraction

The clinical management of patients with low gradient severe aortic stenosis (LG-SAS) and preserved left ventricular ejection fraction (LVEF) remains challenging owing to their heterogeneity. The aim to this study was to evaluate the relation between an ejection dynamic parameter linked to AS severity and outcome, the ratio of acceleration time (AT) to ejection time (ET), in a cohort of patients with LG-SAS and preserved LVEF. Three hundred and fifty-six patients with LG-AS (defined by AVA ≤1 cm² and/or AVAi ≤0.6 cm²/m² and mean aortic pressure gradient <40 mm Hg) and preserved LVEF ≥50% were studied. The relation between AT/ET and all-cause and cardiac mortality during follow-up was studied. Median follow-up was 41 months (interquartile range, 35 to 47 months). Median AT/ET was 0.32 (interquartile range, 0.29 to 0.36). The 5-year estimates of all-cause and cardiac mortality were respectively 57 ± 7%, 36 ± 7% for patients with AT/ET >0.36 versus 43 ± 4%, 16 ± 3% for patients with AT/ET ≤0.36 (p = 0.024 and p <0.001, respectively). After adjustment on known predictors of outcome including aortic valve replacement used as a time-dependent covariate, there was a significant increase in all-cause mortality risk for patients with AT/ET >0.36 (adjusted hazard ratio 2.04 [95% confidence interval, 1.32 to 3.13]; p = 0.001) and cardiac mortality risk (adjusted hazard ratio 2.89 [95% confidence interval, 1.54 to 5.43]; p<0.001) compared with patients with AT/ET ≤0.36. The association of AT/ET >0.36 and all-cause or cardiac mortality risk was consistent in subgroups of patients with LG-SAS and preserved EF. In conclusion, an AT/ET ratio of more than 0.36 is an independent predictor of mortality in patients with LG-SAS and preserved EF.

Management of aortic valve replacement according to the gradient across symptomatic aortic valve stenosis and its prognostic impact

BACKGROUND

Treatment strategy for low-gradient (LG) aortic stenosis (AS) remains an unresolved issue. The presence of a low aortic gradient and preserved left ventricular ejection fraction (LVEF) might lead toward the underestimation of aortic stenosis severity and a more conservative management. We sought (a) to describe the nature and timing of intervention according to flow/gradient subgroups in patibents with LG-AS, (2) to determine the factors associated with the decision to intervene, and (c) to describe prognosis.

METHODS AND RESULTS

One hundred and ten patients prospectively included in this study underwent a standardized clinical and imaging evaluation at inclusion and at 1-year follow-up. According to aortic flow, gradient and LVEF, patients were divided into 4 groups: LG-normal flow [n = 27], LG-low flow-low LVEF [n = 27], LG-low flow-normal LVEF [n = 16], and high gradient (HG) [n = 40]). 73% of patients underwent AVR 86 ± 59 days after the initial assessment. The HG subgroup had significantly higher intervention rates (P < .001). In multivariable analysis, four parameters were associated with the AVR: aortic gradient (HR 1.52 [1.10-2.11], P = .012), LVEF (HR 0.58 [0.40-0.85], P = .006), atrial fibrillation (HR 0.43 [0.021-0.87], P = .019), and NT-proBNP (HR 0.92[0.86-0.98), P = .008]. Patients operated earlier had better outcomes than those having a delayed AVR (P = .042). LG-AS patients had worse outcomes than HG-AS patients (P < .001).

CONCLUSION

Compared to HG-AS, LG-AS is less likely to benefit from an AVR and had a significantly worse outcome. Further interventional studies are needed to investigate the timing of AVR in these patients.