Discordant severity criteria in patients with moderate aortic stenosis: prognostic implications

Grading of Aortic Valve Calcification Severity and Risk Stratification in Aortic Stenosis

BACKGROUND

Thresholds of aortic valve calcification (AVC) to define hemodynamically moderate aortic stenosis (AS) from mild are lacking. We aimed to establish a novel grading classification of AVC as quantified by computed tomography and determine its prognostic value.

METHODS AND RESULTS

This study included 915 patients with at least mild AS (mean age 70±12 years, 30% women) from a multicenter prospective registry. All patients underwent Doppler-echocardiography and noncontrast computed tomography within 3 months. Primary end point was the occurrence of all-cause death. Receiver operating characteristic curves analyses were used to determine the sensitivity and specificity of sex-specific thresholds of AVC to identify hemodynamically moderate AS. Optimal thresholds (ie, with best sensitivity/specificity) of AVC to distinguish moderate (aortic valve area 1.0-1.5 cm2 and mean gradient 20-39 mm Hg) from mild AS (aortic valve area >1.5 cm2 and mean gradient <20 mm Hg) were AVC ≥360 arbitrary units in women and ≥1037 arbitrary units in men. Based on the guidelines' thresholds for severe AS and the new thresholds in our study for moderate AS, 312 (34%) patients had mild, 253 (28%) moderate, and 350 (38%) severe AVC. During a mean follow-up of 5.6±3.9 years, 183 (27%) deaths occurred. In Cox multivariable models, AVC remained associated with an increased risk of death (adjusted hazard ratio per grade increase, 1.94 [95% CI, 1.53-2.56]; P<0.001).

CONCLUSIONS

A novel grading classification of anatomic AS severity based on sex-specific thresholds of AVC provides significant prognostic value for predicting mortality. These findings support the complementarity of computed tomography-calcium scoring to Doppler-echocardiography to corroborate AS severity and enhance risk stratification in patients with AS.

Accuracy of aortic valve calcification volume score for identification of significant aortic stenosis on non-electrocardiographic-gated computed tomography compared to the Agatston scoring system

BACKGROUND

Considering the absence of reports validating the precision of the volume score and the relationship between the volume and Agatston scores, this study evaluated the accuracy of the volume score compared to the Agatston score for the quantitative measurement of aortic valve calcification (AVC) on non-electrocardiographic-gated computed tomography (CT).

METHODS

We retrospectively analysed the AVC scores of 5385 patients who underwent transthoracic echocardiography between March 1, 2013 and December 26, 2019 ​at our institution, using non-contrast non-electrocardiographic-gated CT. The thresholds for significant aortic stenosis (AS) were computed using receiver operating characteristic curves based on the AVC scores. The area under the curve (AUC) of the Agatston and volume scores for significant AS were compared to evaluate the accuracy of the scoring method.

RESULTS

All sex-specific AVC thresholds of the volume score for significant AS (moderate and high AS severity, moderate and high AS severity without discordance, discordant severe AS, and concordant severe AS) showed high sensitivity and specificity (AUC, 0.978-0.996; sensitivity, 94.2-98.4%; specificity, 90.1-100%). No significant differences in the AUC were observed between the Agatston and volume scores for significant AS in male and female patients.

CONCLUSION

All volume score threshold values showed high sensitivity and specificity for identifying significant AS. The accuracy of the test for AVC thresholds of the volume score for significant AS was comparable to that of the Agatston score. Our findings raise questions about the significance of weighting calcium density in the Agatston score for assessing AS severity.

Echocardiographic and Clinical Outcomes in Symptomatic Patients With Less Than Severe Aortic Stenosis After Supra-Annular Self-Expanding Transcatheter Aortic Valve Replacement

Optimal timing for aortic valve replacement in symptomatic patients with less than severe aortic stenosis (AS) is not well defined. There is limited information on the benefit of valve replacement in these patients. Symptomatic patients with less than severe AS, defined as a mean aortic gradient ≥20 and <40 mm Hg, peak aortic velocity >3 and <4 m/s, and aortic valve area >1.0 and <1.5 cm2, enrolled in the Society for Thoracic Surgery/American College of Cardiology Transcatheter Valve Therapy Registry and who underwent attempted supra-annular, self-expanding transcatheter aortic valve replacement (TAVR) were reviewed. Site-reported valve hemodynamics, clinical events, and quality of life metrics were analyzed at 30 days and 1 year after the procedure. A total of 1,067 patients with attempted TAVR (mean age 78.4 ± 8.4 years; Society for Thoracic Surgery score 4.7 ± 3.4%) were found to have symptoms but less than severe AS. From baseline to postprocedure, mean gradient decreased (29.9 ± 4.9 vs 8.4 ± 4.8 mm Hg, p <0.001), and aortic valve area increased (1.2 ± 0.1 vs 2.2 ± 0.7 cm2, p <0.001). Clinical events included 30-day and 1-year all-cause mortality (1.5% and 9.6%), stroke (2.2% and 3.3%), and new pacemaker implantation (18.1% and 20.9%). There were statistically significant improvements in the New York Heart Association functional class and Kansas City Cardiomyopathy Questionnaire at 30 days and 1 year. In conclusion, patients with symptomatic but less than severe AS who underwent supra-annular, self-expanding TAVR experienced improved valve hemodynamics and quality of life measures 1 year after the procedure. Randomized studies of TAVR versus a control arm in symptomatic patients with less than severe AS are ongoing.

Machine learning prediction of progressive subclinical myocardial dysfunction in moderate aortic stenosis

Background

Moderate severity aortic stenosis (AS) is poorly understood, is associated with subclinical myocardial dysfunction, and can lead to adverse outcome rates that are comparable to severe AS. Factors associated with progressive myocardial dysfunction in moderate AS are not well described. Artificial neural networks (ANNs) can identify patterns, inform clinical risk, and identify features of importance in clinical datasets.

Methods

We conducted ANN analyses on longitudinal echocardiographic data collected from 66 individuals with moderate AS who underwent serial echocardiography at our institution. Image phenotyping involved left ventricular global longitudinal strain (GLS) and valve stenosis severity (including energetics) analysis. ANNs were constructed using two multilayer perceptron models. The first model was developed to predict change in GLS from baseline echocardiography alone and the second to predict change in GLS using data from baseline and serial echocardiography. ANNs used a single hidden layer architecture and a 70%:30% training/testing split.

Results

Over a median follow-up interval of 1.3 years, change in GLS (≤ or >median change) could be predicted with accuracy rates of 95% in training and 93% in testing using ANN with inputs from baseline echocardiogram data alone (AUC: 0.997). The four most important predictive baseline features (reported as normalized % importance relative to most important feature) were peak gradient (100%), energy loss (93%), GLS (80%), and DI < 0.25 (50%). When a further model was run including inputs from both baseline and serial echocardiography (AUC 0.844), the top four features of importance were change in dimensionless index between index and follow-up studies (100%), baseline peak gradient (79%), baseline energy loss (72%), and baseline GLS (63%).

Conclusions

Artificial neural networks can predict progressive subclinical myocardial dysfunction with high accuracy in moderate AS and identify features of importance. Key features associated with classifying progression in subclinical myocardial dysfunction included peak gradient, dimensionless index, GLS, and hydraulic load (energy loss), suggesting that these features should be closely evaluated and monitored in AS.

Natural history of moderate aortic stenosis and predictors for mortality: Systematic review and Meta-analysis

Although the current guidelines advocate imaging surveillance for moderate aortic stenosis (AS), recent studies suggest a worse prognosis associated with moderate AS than previously reported. Considering the recent paradigm shift in AS management, the risk/benefit profile of aortic valve replacement (AVR) for moderate AS needs to be re-evaluated. Herein, we conducted meta-analyses of natural history and risk predictors in patients with moderate AS. PubMed and EMBASE were searched through May 2022 to identify studies that investigated the natural history of patients with moderate AS. Meta-analyses with random effects model were conducted. Our analysis included 20 observational studies which enrolled a total of 11,114 patients with moderate AS. The rate of all-cause death was 11.0 [95 % confidence interval (CI), 7.6-14.4] per 100 patients per year. Surgical or transcatheter AVR occurred at a rate of 8.5 (95 % CI, 6.2-10.8; I², 98.9 %) per 100 patients per year. Occurrence of AVR during follow-up [hazard ratio (HR) (95 % CI) =0.56 (0.42-0.75), p < 0.001] and early AVR for moderate AS [HR (95 % CI) = 0.47 (0.25-0.90), p = 0.02] were associated with significantly lower all-cause mortality, while left ventricular ejection fraction <50 % [HR (95 % CI) =1.84 (1.33-2.57), p = 0.0003] and symptomatic status [HR (95 % CI) = 1.52 (1.32-1.75), p < 0.0001] were associated with increased all-cause mortality. Sex difference was not related to all-cause mortality. Our meta-analysis suggested that moderate AS was associated with high mortality, especially in low left ventricular systolic function or symptomatic patients. In addition, significant portion of the patients underwent AVR during follow-up.

Optimal threshold score of aortic valve calcification for identification of significant aortic stenosis on non-electrocardiographic-gated computed tomography

OBJECTIVES

This study evaluated the association between aortic valve calcification (AVC) and aortic stenosis (AS) by scoring the AVC to determine the threshold scores for significant AS on non-electrocardiographic (ECG)-gated computed tomography (CT).

METHODS

We retrospectively analyzed the AVC scores of 5385 patients on non-contrast non-ECG-gated CT, who underwent transthoracic echocardiography (TTE) from March 1, 2013, to December 26, 2019, at our institution. Multivariable logistic regression models were used to identify potential risk factors for significant AS. The thresholds for significant AS were computed using receiver operator characteristic (ROC) curves, based on the AVC scores after propensity score matching.

RESULTS

A significant association was found between AS and age (p < 0.001; odds ratio [OR], 1.04; 95% confidence interval [CI], 1.02-1.06), female sex (p < 0.001; OR, 4.5; 95% CI, 2.75-7.36), bicuspid aortic valve (p < 0.001; OR, 23.2; 95% CI, 7.35-72.9), and AVC score (AVC score/100) (p < 0.001; OR, 1.82; 95% CI, 1.71-1.95). All sex-specific AVC thresholds for significant AS (moderate and over AS severity, moderate and over AS severity without discordance, discordant severe AS, and concordant severe AS) showed high sensitivity and specificity (AUC, 0.939-0.968; sensitivity, 84.6-96%; specificity, 84.2-97.1%).

CONCLUSIONS

We determined the optimal AVC threshold scores for significant AS, which may aid in diagnosing significant asymptomatic AS on incidental detection of AVC through non-ECG-gated CT for non-cardiac indications.

KEY POINTS

• Increased frequency of non-electrocardiographic (ECG)-gated computed tomography (CT) for non-cardiac indications has led to the increased incidental identification of aortic valve calcification (AVC). • It is important to identify patients with significant aortic stenosis (AS) who require additional echocardiographic assessment on incidental detection of AVC via non-ECG-gated CT. • We determined the AVC thresholds with high sensitivity and specificity to identify significant AS on non-ECG-gated CT, which could lead to early diagnosis of asymptomatic significant AS and improved prognosis.

Managing Patients With Moderate Aortic Stenosis

Current guidelines recommend that clinical surveillance for patients with moderate aortic stenosis (AS) and aortic valve replacement (AVR) may be considered if there is an indication for coronary revascularization. Recent observational studies, however, have shown that moderate AS is associated with an increased risk of cardiovascular events and mortality. Whether the increased risk of adverse events is caused by associated comorbidities, or to the underlying moderate AS itself, is incompletely understood. Similarly, which patients with moderate AS need close follow-up or could potentially benefit from early AVR is also unknown. In this review, the authors provide a comprehensive overview of the current literature on moderate AS. They first provide an algorithm that helps to diagnose moderate AS correctly, especially when discordant grading is observed. Although the traditional focus of AS assessment has been on the valve, it is increasingly acknowledged that AS is not only a disease of the aortic valve but also of the ventricle. The authors therefore discuss how multimodality imaging can help to evaluate the left ventricular remodeling response and improve risk stratification in patients with moderate AS. Finally, they summarize current evidence on the management of moderate AS and highlight ongoing trials on AVR in moderate AS.

Prognosis in asymptomatic patients with discordantly graded aortic valve stenosis based on pressure recovery adjusted valve area

Objective

We hypothesised that patients with asymptomatic aortic stenosis (AS) who remain with discordantly graded aortic valve stenosis (DGAS) after adjustment for pressure recovery in the aortic root represents a subgroup of patients with increased cardiovascular risk.

Methods

Data from 1353 patients with asymptomatic mild–moderate AS and preserved left ventricular ejection fraction enrolled in the Simvastatin and Ezetimibe in AS study was used. DGAS was identified as combined pressure adjusted valve area (energy loss) <1.0 cm² and mean aortic gradient<40 mm Hg (DGASEL). Outcome was assessed in Cox regression analysis and reported as HR and 95% CI.

Results

DGASELwas found in 196 (14.5%) patients at baseline, and was associated with older age, female sex, smaller aortic annulus diameter, lower heart rate, more extensive valve calcification and low flow (all p<0.05). In Cox regression analysis, DGASELwas associated with higher rate of heart failure (HF) hospitalisation (HR 3.31 (95% CI 1.54 to 7.09)), cardiovascular death (HR 2.63 (95% CI 1.34 to 5.17)) and all-cause mortality (HR 1.73 (95% CI 1.04 to 2.87)) independent of confounders including low flow and aortic valve calcification (all p<0.05).

Conclusions

Patients with asymptomatic AS who remain with discordant grading after adjustment for pressure recovery have increased risk for HF and death.

Trial registration number

NCT00092677.