Multimodality Imaging for the Assessment of Severe Aortic Stenosis

Contemporary diagnosis and treatment of valvular heart disease in Korea: a nationwide hospital-based registry study

BACKGROUND

This study was designed to determine the current status of diagnosis and treatment of valvular heart disease (VHD) in Korea.

METHODS

A nationwide registry study was conducted in 45 hospitals in Korea involving adult patients with at least moderate VHD as determined by echocardiography carried out between September and October of 2019. Of a total of 4,094 patients with at least moderate VHD, 1,482 had severe VHD (age, 71.3 ± 13.5 years; 49.1% male). Echocardiographic data used for the diagnosis of each case of VHD were analyzed. Experts from each center determined the diagnosis and treatment strategy for VHD based on current guidelines and institutional policy. The clinical outcome was in-hospital mortality.

RESULTS

Each valve underwent surgical or transcatheter intervention in 19.3% cases of severe mitral stenosis, 31.4% cases of severe primary mitral regurgitation (MR), 7.5% cases of severe secondary MR, 43.7% cases of severe aortic stenosis, 27.5% cases of severe aortic regurgitation, and 7.2% cases of severe tricuspid regurgitation. The overall in-hospital mortality rate for patients with severe VHD was 5.4%, and for secondary severe MR and severe tricuspid regurgitation, the rates were 9.0% and 7.5%, respectively, indicating a poor prognosis. In-hospital mortality occurred in 73 of the 1,244 patients (5.9%) who received conservative treatment and in 18 of the 455 patients (4.0%) who received a surgical or transcatheter intervention, which was significantly lower in the intervention group (P = 0.037).

CONCLUSIONS

This study provides important information about the current status of VHD diagnosis and treatment through a nationwide registry in Korea and helps to define future changes.

Assessment of aortic valve area on cardiac computed tomography in symptomatic bicuspid aortic stenosis: Utility and differences from Doppler echocardiography

Background

In this study, we investigate the utility of geometric orifice area (GOA) on cardiac computed tomography (CT) and differences from effective orifice area (EOA) on Doppler echocardiography in patients with bicuspid aortic stenosis (AS).

Methods

A total of 163 patients (age 64 ± 10 years, 56.4% men) with symptomatic bicuspid AS who were referred for surgery and underwent both cardiac CT and echocardiography within 3 months were studied. To calculate the aortic valve area, GOACT was measured by multiplanar CT planimetry, and EOAEcho was calculated by the continuity equation with Doppler echocardiography. The relationships between GOACT and EOAEcho and patient symptom scale, biomarkers, and left ventricular (LV) functional variables were analyzed.

Results

There was a significant but modest correlation between EOAEcho and GOACT (r = 0.604, p < 0.001). Both EOAEcho and GOACT revealed significant correlations with mean pressure gradient and peak transaortic velocity, and the coefficients were higher in EOAEcho than in GOACT. EOAEcho of 1.05 cm2 and GOACT of 1.25 cm2 corresponds to hemodynamic cutoff values for diagnosing severe AS. EOAEcho was well correlated with the patient symptom scale and log NT-pro BNP, but GOACT was not. In addition, EOAEcho had a higher correlation coefficient with estimated LV filling pressure and LV global longitudinal strain than GOACT.

Conclusion

GOACT can be used to evaluate the severity of bicuspid AS. The threshold for GOACT for diagnosing severe AS should be higher than that for EOAEcho. However, EOAEcho is still the method of choice because EOAEcho showed better correlations with clinical and functional variables than GOACT.

Association of Myocardial Fibrosis and Stroke Volume by Cardiovascular Magnetic Resonance in Patients With Severe Aortic Stenosis With Outcome After Valve Replacement: The British Society of Cardiovascular Magnetic Resonance AS700 Study

Importance

Low-flow severe aortic stenosis (AS) has higher mortality than severe AS with normal flow. The conventional definition of low-flow AS is an indexed stroke volume (SVi) by echocardiography less than 35 mL/m2. Cardiovascular magnetic resonance (CMR) is the reference standard for quantifying left ventricular volumes and function from which SVi by CMR can be derived.

Objective

To determine the association of left ventricular SVi by CMR with myocardial remodeling and survival among patients with severe AS after valve replacement.

Design, Setting, and Participants

This multicenter longitudinal cohort study was conducted between January 2003 and May 2015 across 6 UK cardiothoracic centers. Patients with severe AS listed for either surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR) were included. Patients underwent preprocedural echocardiography and CMR. Patients were stratified by echocardiography-derived aortic valve mean and/or peak gradient and SVi by CMR into 4 AS endotypes: low-flow, low-gradient AS; low-flow, high-gradient AS; normal-flow, low-gradient AS; and normal-flow, high-gradient AS. Patients were observed for a median of 3.6 years. Data were analyzed from September to November 2021.

Exposures

SAVR or TAVR.

Main Outcomes and Measures

All-cause and cardiovascular (CV) mortality after aortic valve intervention.

Results

Of 674 included patients, 425 (63.1%) were male, and the median (IQR) age was 75 (66-80) years. The median (IQR) aortic valve area index was 0.4 (0.3-0.4) cm2/m2. Patients with low-flow AS endotypes (low gradient and high gradient) had lower left ventricular ejection fraction, mass, and wall thickness and increased all-cause and CV mortality than patients with normal-flow AS (all-cause mortality: hazard ratio [HR], 2.08; 95% CI, 1.37-3.14; P < .001; CV mortality: HR, 3.06; 95% CI, 1.79-5.25; P < .001). CV mortality was independently associated with lower SVi (HR, 1.64; 95% CI, 1.08-2.50; P = .04), age (HR, 2.54; 95% CI, 1.29-5.01; P = .001), and higher quantity of late gadolinium enhancement (HR, 2.93; 95% CI, 1.68-5.09; P < .001). CV mortality hazard increased more rapidly in those with an SVI less than 45 mL/m2. SVi by CMR was independently associated with age, atrial fibrillation, focal scar (by late gadolinium enhancement), and parameters of cardiac remodeling (left ventricular mass and left atrial volume).

Conclusions and Relevance

In this cohort study, SVi by CMR was associated with CV mortality after aortic valve replacement, independent of age, focal scar, and ejection fraction. The unique capability of CMR to quantify myocardial scar, combined with other prognostically important imaging biomarkers, such as SVi by CMR, may enable comprehensive stratification of postoperative risk in patients with severe symptomatic AS.

Diagnosis and Management of Aortic Valve Stenosis: The Role of Non-Invasive Imaging

Aortic stenosis is the most common heart valve disease necessitating surgical or percutaneous intervention. Imaging has a central role for the initial diagnostic work-up, the follow-up and the selection of the optimal timing and type of intervention. Referral for aortic valve replacement is currently driven by the severity and by the presence of aortic stenosis-related symptoms or signs of left ventricular systolic dysfunction. This review aims to provide an update of the imaging techniques and seeks to highlight a practical approach to help clinical decision making.

Timing of Intervention in Asymptomatic Aortic Stenosis

The decision to perform an intervention for asymptomatic severe aortic stenosis (AS) requires careful weighing of the risks of early intervention against those of watchful observation, and the optimal timing of intervention remains controversial. With improvements in surgical and postoperative care, long-term survival after surgical aortic valve (AV) replacement (AVR) is excellent in low-risk patients, and the emergence of transcatheter AVR may change the thresholds for early preemptive intervention, although a durability issue has to be resolved. A watchful observation strategy also has a risk of sudden death, irreversible myocardial damage, and increase in operative risk while waiting for symptoms to develop. We have been waiting for a prospective randomized trial to solve the intense debate between early AVR and watchful observation, and the RECOVERY (Randomized Comparison of Early Surgery versus Conventional Treatment in Very Severe Aortic Stenosis) trial provides the evidence to support early AVR for asymptomatic severe AS. Risk assessment with severity of AS and staging classification may help to facilitate the identification of patients who may benefit from early intervention. Based on the results of the RECOVERY trial, early surgical AVR is reasonable for asymptomatic patients with very severe AS (aortic jet velocity ≥4.5 m/s) and low surgical risk. Further evidence is required to extend the indications of surgical AVR and to consider transcatheter AVR in asymptomatic patients with severe AS.

Asymptomatic Patients with Severe Aortic Stenosis and the Impact of Intervention

Objectives the exact timing of aortic valve replacement (AVR) in asymptomatic patients with severe aortic stenosis (AS) remains a matter of debate. Therefore, we described the natural history of asymptomatic patients with severe AS, and the effect of AVR on long-term survival. Methods: Asymptomatic patients who were found to have severe AS between June 2006 and May 2009 were included. Severe aortic stenosis was defined as peak aortic jet velocity Vmax ≥ 4.0 m/s or aortic valve area (AVA) ≤ 1 cm². Development of symptoms, the incidence of AVR, and all-cause mortality were assessed. Results: A total of 59 asymptomatic patients with severe AS were followed, with a mean follow-up of 8.9 ± 0.4 years. A total of 51 (86.4%) patients developed AS related symptoms, and subsequently 46 patients underwent AVR. The mean 1-year, 2-year, 5-year, and 10-year overall survival rates were higher in patients receiving AVR compared to those who did not undergo AVR during follow-up (100%, 93.5%, 89.1%, and 69.4%, versus 92.3%, 84.6%, 65.8%, and 28.2%, respectively; p < 0.001). Asymptomatic patients with severe AS receiving AVR during follow-up showed an incremental benefit in survival of up to 31.9 months compared to conservatively managed patients (p = 0.002). Conclusions: The majority of asymptomatic patients turn symptomatic during follow-up. AVR during follow-up is associated with better survival in asymptomatic severe AS patients.