Prognostic Influence of Feature Tracking Multidetector Row Computed Tomography-Derived Left Ventricular Global Longitudinal Strain in Patients with Aortic Stenosis Treated With Transcatheter Aortic Valve Implantation

Comprehensive Myocardial Assessment by Computed Tomography: Impact on Short-Term Outcomes After Transcatheter Aortic Valve Replacement

BACKGROUND

Quantification of myocardial changes in severe aortic stenosis (AS) is prognostically important. The potential for comprehensive myocardial assessment pre-transcatheter aortic valve replacement (TAVR) by computed tomography angiography (CTA) is unknown.

OBJECTIVES

This study sought to evaluate whether quantification of left ventricular (LV) extracellular volume-a marker of myocardial fibrosis-and global longitudinal strain-a marker of myocardial deformation-at baseline CTA associate with post-TAVR outcomes.

METHODS

Consecutive patients with symptomatic severe AS between January 2021 and June 2022 who underwent pre-TAVR CTA were included. Computed tomography extracellular volume (CT-ECV) was derived from septum tracing after generating the 3-dimensional CT-ECV map. Computed tomography global longitudinal strain (CT-GLS) used semi-automated feature tracking analysis. The clinical endpoint was the composite outcome of all-cause mortality and heart failure hospitalization.

RESULTS

Among the 300 patients (80.0 ± 9.4 years of age, 45% female, median Society of Thoracic Surgeons Predicted Risk of Mortality score 2.80%), the left ventricular ejection fraction (LVEF) was 58% ± 12%, the median CT-ECV was 28.5% (IQR: 26.2%-32.1%), and the median CT-GLS was -20.1% (IQR: -23.8% to -16.3%). Over a median follow-up of 16 months (IQR: 12-22 months), 38 deaths and 70 composite outcomes occurred. Multivariable Cox proportional hazards model, accounting for clinical and echocardiographic variables, demonstrated that CT-ECV (HR: 1.09 [95% CI: 1.02-1.16]; P = 0.008) and CT-GLS (HR: 1.07 [95% CI: 1.01-1.13]; P = 0.017) associated with the composite outcome. In combination, elevated CT-ECV and CT-GLS (above median for each) showed a stronger association with the outcome (HR: 7.14 [95% CI: 2.63-19.36]; P < 0.001).

CONCLUSIONS

Comprehensive myocardial quantification of CT-ECV and CT-GLS associated with post-TAVR outcomes in a contemporary low-risk cohort with mostly preserved LVEF. Whether these imaging biomarkers can be potentially used for the decision making including timing of AS intervention and post-TAVR follow-up will require integration into future clinical trials.

Myocardial analysis from routine 4D cardiac-CT to predict reverse remodeling and clinical outcomes after transcatheter aortic valve implantation

PURPOSE

Our study aimed to determine whether 4D cardiac computed tomography (4DCCT) based quantitative myocardial analysis may improve risk stratification and can predict reverse remodeling (RRM) and mortality after transcatheter aortic valve implantation (TAVI).

METHODS

Consecutive patients undergoing clinically indicated 4DCCT prior to TAVI were prospectively enrolled. 4DCCT-derived left- (LV) and right ventricular (RV), and left atrial (LA) dimensions, mass, ejection fraction (EF) and myocardial strain were evaluated to predict RRM and survival. RRM was defined by either relative increase in LVEF by 5% or relative decline in LV end diastolic diameter (LVEDD) by 5% assessed by transthoracic echocardiography prior TAVI, at discharge, and at 12-month follow-up compared to baseline prior to TAVI.

RESULTS

Among 608 patients included in this study (55 % males, age 81 ± 6.6 years), RRM was observed in 279 (54 %) of 519 patients at discharge and in 218 (48 %) of 453 patients at 12-month echocardiography. While no CCT based measurements predicted RRM at discharge, CCT based LV mass index and LVEF independently predicted RRM at 12-month (ORadj = 1.012; 95 %CI:1.001-1.024; p = 0.046 and ORadj = 0.969; 95 %CI:0.943-0.996; p = 0.024, respectively). The most pronounced changes in LVEF and LVEDD were observed in patients with impaired LV function at baseline. In multivariable analysis age (HRadj = 1.037; 95 %CI:1.005-1.070; p = 0.022) and CCT-based LVEF (HRadj = 0.972; 95 %CI:0.945-0.999; p = 0.048) and LAEF (HRadj = 0.982; 95 %CI:0.968-0.996; p = 0.011) independently predicted survival.

CONCLUSION

Comprehensive myocardial functional information derived from routine 4DCCT in patients with severe aortic stenosis undergoing TAVI could predict reverse remodeling and clinical outcomes at 12-month following TAVI.

Multimodality imaging for the global evaluation of aortic stenosis: The valve, the ventricle, the afterload

Aortic stenosis (AS) is the most common valvular heart disease growing in parallel to the increment of life expectancy. Besides the valve, the degenerative process affects the aorta, impairing its elastic properties and leading to increased systemic resistance. The composite of valvular and systemic afterload mediates ventricular damage. The first step of a thorough evaluation of AS should include a detailed assessment of valvular anatomy and hemodynamics. Subsequently, the ventricle, and the global afterload should be assessed to define disease stage and prognosis. Multimodality imaging is of paramount importance for the comprehensive evaluation of these three elements. Echocardiography is the cornerstone modality whereas Multi-Detector Computed Tomography and Cardiac Magnetic Resonance provide useful complementary information. This review comprehensively examines the merits of these imaging modalities in AS for the evaluation of the valve, the ventricle, and the afterload and ultimately endeavors to integrate them in a holistic assessment of AS.

Routine 4D Cardiac CT to Identify Concomitant Transthyretin Amyloid Cardiomyopathy in Older Adults with Severe Aortic Stenosis

Background Transthyretin amyloid cardiomyopathy (ATTR-CM) often coexists with severe aortic stenosis (AS). Although strain analysis from cardiac MRI and echocardiography was demonstrated to predict coexisting ATTR-CM, comparable data from four-dimensional (4D) cardiac CT are lacking despite wide availability. Purpose To evaluate the diagnostic performance of 4D cardiac CT-derived parameters in identifying ATTR-CM in older adults considered for transcatheter aortic valve implantation (TAVI). Materials and Methods This prospective single-center screening study for ATTR-CM included consecutive patients with severe AS considered for TAVI who underwent 4D cardiac CT between August 2019 and August 2021 approximately 1 day before technetium 99m (99mTc) 3,3-diphosphono-1,2-propanodicarboxylic-acid (DPD) scintigraphy. The diagnostic performance of CT-based left ventricular (LV), right ventricular, and left atrial dimensions, ejection fraction (EF), and myocardial strain were evaluated against 99mTc-DPD scintigraphy as the reference standard to identify ATTR-CM. Predictors and an unweighted cardiac CT score were validated with internal bootstrapping. The assignment of variables to the score was based on cutoff values achieving the highest Youden index J. Results Among 263 participants (mean age, 83 years ± 4.6 [SD]; 149 male and 114 female participants), 99mTc-DPD scintigraphy (Perugini grade 2 or 3) confirmed coexisting ATTR-CM in 27 (10.3%). CT-derived LV mass index, LV and LA global longitudinal strain (GLS), and relative apical longitudinal strain each predicted the presence of ATTR-CM with an area under the curve (AUC) of at least 0.70. Implementing these parameters with cutoff values of 81 g/m2 or higher, -14.9% or higher, less than 11.5%, and 1.7 or higher in the CT score, respectively, yielded high diagnostic performance (AUC = 0.89; 95% CI: 0.81, 0.94; P < .001) robust to internal bootstrapping validation (AUC = 0.88; 95% CI: 0.82, 0.94). If two criteria were fulfilled, the sensitivity and specificity in the detection of ATTR-CM were 96.3% (95% CI: 81.0, 99.9) and 58.9% (95% CI: 52.3, 65.2), respectively. Conclusion When compared against 99mTc-DPD scintigraphy as the reference standard, routine 4D cardiac CT in older adults considered for TAVI provided high diagnostic performance in the detection of concomitant ATTR-CM by assessing LV and left atrial GLS, relative apical longitudinal strain, and LV mass index. ClinicalTrials.gov registration no.: NCT04061213 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Tavakoli and Onder in this issue.

Cardiac CT in CRT as a Singular Imaging Modality for Diagnosis and Patient-Tailored Management

Between 30-40% of patients with cardiac resynchronization therapy (CRT) do not show an improvement in left ventricular (LV) function. It is generally known that patient selection, LV lead implantation location, and device timing optimization are the three main factors that determine CRT response. Research has shown that image-guided CRT placement, which takes into account both anatomical and functional cardiac properties, positively affects the CRT response rate. In current clinical practice, a multimodality imaging approach comprised of echocardiography, cardiac magnetic resonance imaging, or nuclear medicine imaging is used to capture these features. However, with cardiac computed tomography (CT), one has an all-in-one acquisition method for both patient selection and the division of a patient-tailored, image-guided CRT placement strategy. This review discusses the applicability of CT in CRT patient identification, selection, and guided placement, offering insights into potential advancements in optimizing CRT outcomes.

Shifting from Left Ventricular Ejection Fraction to Strain Imaging in Aortic Stenosis

Adverse ventricular remodeling is an inflexion point of disease progression in aortic stenosis (AS) and a major determinant of prognosis. Intervention before irreversible myocardial damage is of paramount importance to sustain favorable post-operative outcomes. Current guidelines recommend a left ventricular ejection fraction (LVEF)-based strategy to determine the threshold for intervention in AS. However, LVEF has several pitfalls: it denotes the left ventricular cavity volumetric changes and it is not suited to detecting subtle signs of myocardial damage. Strain has emerged as a contemporary imaging biomarker that describes intramyocardial contractile force, providing information on subclinical myocardial dysfunction due to fibrosis. A large body of evidence advocates its use to determine the switch from adaptive to maladaptive myocardial changes in AS, and to refine thresholds for intervention. Although mainly studied in echocardiography, studies exploring the role of strain in multi-detector row computed tomography and cardiac magnetic resonance are emerging. This review, therefore, summarizes contemporary evidence on the role of LVEF and strain imaging in AS prognosis, aiming to move from an LVEF-based to a strain-based approach for risk stratification and therapeutic decision-making in AS.

Changes in Computed-Tomography-Derived Segmental Left Ventricular Longitudinal Strain After Transcatheter Aortic Valve Implantation

Patients with severe aortic stenosis (AS) may show left ventricular (LV) apical longitudinal strain sparing. Transcatheter aortic valve implantation (TAVI) improves LV systolic function in patients with severe AS. However, the changes in regional longitudinal strain after TAVI have not been extensively evaluated. This study aimed to characterize the effect of the pressure overload relief after TAVI on LV apical longitudinal strain sparing. A total of 156 patients (mean age 80 ± 7 years, 53% men) with severe AS who underwent computed tomography before and within 1 year after TAVI (mean time to follow-up 50 ± 30 days) were included. LV global and segmental longitudinal strain were assessed using feature tracking computed tomography. LV apical longitudinal strain sparing was evaluated as the ratio between the apical and midbasal longitudinal strain and was defined as an LV apical to midbasal longitudinal strain ratio >1. LV apical longitudinal strain remained stable after TAVI (from 19.5 ± 7.2% to 18.7 ± 7.7%, p = 0.20), whereas LV midbasal longitudinal strain showed a significant increase (from 12.9 ± 4.2% to 14.2 ± 4.0%, p ≤0.001). Before TAVI, 88% of the patients presented with LV apical strain ratio >1% and 19% presented with an LV apical strain ratio >2. After TAVI, these percentages significantly decreased to 77% and 5% (p = 0.009, p ≤0.001), respectively. In conclusion, LV apical sparing of strain is a relatively common finding in patients with severe AS who underwent TAVI and its prevalence decreases after the afterload relief after TAVI.

Prognostic Value of Global Longitudinal Strain in Asymptomatic Aortic Stenosis: A Systematic Review and Meta-Analysis

Backgrounds

The presence of impaired global longitudinal strain (GLS) may be a valuable bio-marker in the early diagnosis for left ventricle (LV) impairment, which would help scrutinize asymptomatic aortic stenosis (AS) patients with high risk of adverse outcomes, such as major adverse cardiovascular events (MACE).

Methods

The study was prospectively registered in PROPSERO (CRD 42021223472). Databases, such as Pubmed, Embase, Cochrane Library, Web of science, and Scopus were searched for studies evaluating the impact of impaired GLS on MACE, all-cause mortality, and aortic valve replacement (AVR) in asymptomatic AS. Hazard ratios (HRs) with 95% CIs were calculated with meta-analysis for binary variants. Meta-regression, subgroup analysis, and sensitivity analyses were applied as needed to explore the heterogeneity.

Results

Eventually, a total of nine studies reporting 1,512 patients were enrolled. Compared with the normal GLS group, impaired GLS significantly increased MACE (HR = 1.20, 95% CI: 1.10–1.30, I² = 79%) with evident heterogeneity, all-cause mortality (HR = 1.42, 95% CI: 1.24–1.63), and AVR (HR = 1.17, 95% CI: 1.07–1.28). Subgroup analyses stratified by left ventricular ejection fraction (LVEF) > 50% or LVEF without precise cut-off point found that compared with the normal GLS group, impaired GLS remarkably increased MACE both in two subgroups (LVEF > 50%: HR: 1.22, 95% CI: 1.05–1.50; LVEF without cutpoint: HR: 1.25, 95% CI: 1.05–1.50). The results stratified by AS severity (mild/moderate and severe) or follow-up time resembled those stratified by LVEF. In addition, when subgroup analysis was stratified by mean aortic valve pressure gradient (MG ≥ 40 mm Hg and MG <40 mm Hg), compared with normal GLS, impaired GLS significantly increased MACE both in two subgroups (MG ≥ 40 mm Hg: HR: 3.41, 95% CI: 1.64–7.09; MG below 40 mm Hg: HR: 3.17, 95% CI: 1.87–5.38). Moreover, the effect sizes here were substantially higher than those in the former two stratified factors.

Conclusions

The presence of impaired GLS substantially worsens the outcomes for adverse cardiovascular events in asymptomatic patients with AS regardless of LVEF or AS severity or follow-up time or mean aortic valve pressure gradient, which highlights the importance of incorporating impaired GLS into risk algorithms in asymptomatic AS.

Systematic Review Registration

PROSPERO (registration number: CRD42021223472).

Association of baseline and change in global longitudinal strain by computed tomography with post-transcatheter aortic valve replacement outcomes

AIMS

Transcatheter aortic valve replacement (TAVR) procedural planning requires computed tomography angiography (CTA) which allows for the assessment of left ventricular global longitudinal strain (CTA-LVGLS). There is, however, limited data on the feasibility of CTA-LVGLS, and its prognostic value. This study sought to evaluate the incremental prognostic value of baseline CTA-LVGLS, change in CTA-LVGLS after TAVR, and their association with post-TAVR outcomes.

METHODS AND RESULTS

A total of 431 patients who underwent multiphasic gated CTA using dual-source system for TAVR planning at baseline and 1-month follow-up were included [median (interquartile range) age, 83 (77-87) years; 44% female, STS-PROM score: 3.3 (2.3-5.1)%, Echo-left ventricular ejection fraction (LVEF): 60 (55-65)%, CTA-LVGLS: -18.0 (-21.6 to -14.2)%, feasible in 97% of patients]. CTA-LVGLS was measured using dedicated feature-tracking software. Over a median follow-up of 19 (13-27) months, 99 endpoints of all-cause death or heart failure hospitalization occurred. The relative hazard of the endpoint increased as baseline CTA-LVGLS worsened with -18.2% as the threshold for higher events (P = 0.005). After adjustment for baseline characteristics, CTA-LVGLS remained associated with the endpoint [hazard ratio (HR) (95% confidence interval, CI), 1.08 (1.03-1.14); P = 0.005] and incrementally improved prognostication (C-index difference, 0.026). Although CTA-LVGLS improved after TAVR [-18.3 (-21.6 to -14.3)% vs. -18.7 (-21.9 to -15.4)%, P < 0.001], patients without CTA-LVGLS improvement had higher risk of the endpoint than those with improvement or preserved baseline global longitudinal strain [HR (95% CI), 1.92 (1.19-3.12); P = 0.008].

CONCLUSIONS

In this predominantly low-risk TAVR cohort of patients, mostly with normal LVEF, assessment of CTA-LVGLS is highly feasible improving risk stratification by providing independent and incremental prognostic value over clinical and echocardiographic characteristics.

Comparison of left atrial strain measured by feature tracking computed tomography and speckle tracking echocardiography in patients with aortic stenosis

AIMS

Peak left atrial longitudinal strain (PALS) is a marker of the left atrial (LA) reservoir function. Novel feature tracking (FT) software allows assessment of LA strain from multidetector computed tomography (MDCT) data. This study aimed at evaluating the agreement between speckle tracking echocardiography (STE) and FT MDCT for the measurement of PALS in patients with sinus rhythm (SR) and with atrial fibrillation (AF).

METHODS AND RESULTS

The current study included 318 patients (80 ± 7 years, 54% male) with dynamic MDCT data acquired prior to transcatheter aortic valve implantation. PALS was measured by transthoracic echocardiography using STE (PALSecho) and MDCT using dedicated FT software (PALSCT). In the overall population, the median values of PALSecho and PALSCT were 19.0 [interquartile range (IQR) 12.0-25.0] % and 15.3 (IQR 9.2-19.7) %, respectively. High correlation between PALSecho and PALSCT was observed (r = 0.789, P < 0.001) with a mean bias of -3.7%. The correlation between PALSecho and PALSCT was better among patients with SR (N = 258; r = 0.704, P < 0.001) as compared to patients with AF (N = 60; r = 0.622, P < 0.001).

CONCLUSION

PALSecho and PALSCT showed a good agreement in patients with severe aortic stenosis (AS) regardless of the cardiac rhythm. FT MDCT may be an important adjuvant modality for assessing LA reservoir function in patients with severe AS.