Patients

From a cohort of 253 patients with symptomatic severe aortic stenosis who underwent TAVI at the Leiden University Medical Center, 68 patients (27%) were identified as having LFLGSAS according the baseline Doppler echocardiographic estimation of aortic valve area (AVA) index (≤0.6 cm ² /m ² ), mean pressure gradient across the aortic valve (≤40 mm Hg) and stroke volume index (≤35 mL/m ² ). LV remodeling and functional recovery were evaluated at follow-up after successful TAVI. LV mass index (LVMi) and indexed LV volumes were measured at baseline and at 6 and 12 months after TAVI. In addition, LVEF and speckle-tracking-derived GLS and global longitudinal strain rate (GLSr) were assessed. Further analysis by dividing the population into low-LVEF (<50%) and preserved-LVEF (≥50%) groups at baseline was performed. Patients who had high-gradient aortic stenosis, patients who underwent “valve-in-valve” procedures, and patients who had more than mild aortic regurgitation before TAVI were excluded from the analysis. For this retrospective evaluation, the institutional review board waived the requirement for patients’ written informed consent.

TAVI Procedure

TAVI was performed at the catheterization laboratory under general anesthesia and the 23-, 26-, or 29-mm Edwards SAPIEN and SAPIEN XT (Edwards Lifesciences, Irvine, CA) or the 26-, 29-, or 31-mm Medtronic CoreValve (Medtronic, Minneapolis, MN) was implanted. The preferred approach was transfemoral. The transapical approach was used in patients with unfavorable iliofemoral anatomy or in patients in whom 29-mm Edwards SAPIEN XT valves were implanted. A successful TAVI procedure was defined as the implantation of a well-functioning valve in the aortic annulus, without intraprocedural death.

Two-Dimensional Transthoracic Echocardiography

Transthoracic echocardiography was performed before TAVI and at 6 and 12 months after TAVI using a commercially available ultrasound system (Vivid 7 and Vivid E9; GE Vingmed Ultrasound AS, Horten, Norway) equipped with 3.5-MHz or M5S transducers. Two-dimensional grayscale images and color, continuous-wave, and pulsed-wave Doppler data were acquired from the parasternal, apical, and subcostal acoustic windows. Data were stored digitally and analyzed offline on a dedicated workstation (EchoPAC version 112.0.1; GE Vingmed Ultrasound AS).

Aortic stenosis severity was quantified by measuring the maximum velocity through the aortic valve using continuous-wave Doppler. The mean pressure gradient was estimated using the modified Bernoulli equation. The LV outflow tract was measured on two-dimensional transthoracic echocardiography, and subsequently, AVA was calculated using the continuity equation and indexed to body surface area (BSA). Energy loss index was calculated as [(AVA × A _A )/(A _A − AVA)]/BSA, where A _A is aortic cross-sectional area at the level of the sinotubular junction. LV dimensions were measured in the parasternal long-axis view on two-dimensional grayscale images. LV mass was then estimated according to the formula of Lang et al . (0.8 × {1.04[(LV end-diastolic diameter + posterior wall thickness in diastole + septal wall thickness in diastole) ³ − (LV end-diastolic diameter) ³ ]} + 0.6 g) and indexed to BSA. Relative wall thickness ([2 × posterior wall thickness in diastole]/LV end-diastolic diameter) and the ratio of LV mass to LV end-diastolic volume were then estimated. LV end-diastolic and end-systolic volumes were calculated from the apical four- and two-chamber views and then indexed to BSA. LVEF was derived using the biplane Simpson method. Stroke volume was calculated by multiplying the LV outflow tract cross-sectional area by the velocity-time integral derived from the pulsed-wave Doppler recordings acquired at the LV outflow tract. Cardiac output was estimated by multiplying stroke volume by heart rate and cardiac index by indexing cardiac output for BSA. Prosthesis-patient mismatch was defined as AVA index ≤ 0.85 cm ² /m ² .

Two-Dimensional Speckle-Tracking Echocardiography

LV systolic function was assessed using two-dimensional speckle-tracking echocardiography–derived GLS and GLSr. To estimate GLS, the three-, four-, and two-chamber apical views were optimized to achieve a frame rate of ≥40 frames/sec, recorded in two-dimensional grayscale and then analyzed offline on a workstation with commercially available software (EchoPAC version 112.0.1). Aortic valve closure timing was first defined at the apical LV long-axis view, and the LV endocardial border was then traced at each apical view at an end-systolic frame. A region of interest was automatically defined and adapted not to extend beyond the epicardial border. Finally, GLS and GLSr were calculated as the average of all three apical views. GLS was expressed as a percentage and GLSr per second. Two representative examples of GLS evaluation at the three time points (before TAVI and 6 and 12 months after TAVI) for a patient with a low LVEF and a patient with a preserved LVEF are presented in Figure 1 and Figure 2 , respectively.

Illustrative case of LV GLS evaluation in a patient with low LVEF and LFLGSAS: GLS assessed (A) before TAVI, (B) 6 months after TAVI, and (C) 12 months after TAVI.

Illustrative case of LV GLS evaluation in a patient with preserved LVEF and LFLGSAS: GLS assessed (A) before TAVI, (B) 6 months after TAVI, and (C) 12 months after TAVI.

Statistical Analysis

Statistical analyses were performed using SPSS version 20 (SPSS, Inc, Chicago, IL). All categorical values are expressed as frequency (percentage) and continuous variables as mean ± SD. Continuous variables were compared between the two groups at baseline using Student’s t test or the Mann-Whitney U test, as appropriate, and categorical variables using χ ² tests.

The modeling approach for assessing the overall change of LVEF, GLS, GLSr, LVMi, LV end-diastolic volume index, and LV end-systolic volume index over the 12-month period after TAVI was linear mixed modeling with these variables as the dependent variables and time (baseline and 6 and 12 months after TAVI) and LVEF category at baseline (<50% vs ≥50%) as the main fixed effects. Main effects were compared using Bonferroni confidence interval (CI) adjustment. Parameter estimates and tests for covariance estimates were tested with 95% CIs. Post hoc testing was done to determine the time points at which the dependent variables differed between the two LVEF groups. Clinical and echocardiographic parameters were then tested as covariates to assess their influence on LV function and remodeling over time. Improvement in GLS or GLSr over time was defined by the amplitude of increase in GLS or GLSr, regardless of whether these are expressed in positive or negative numbers. To identify baseline parameters associated with LV mass regression and GLS improvement, binary logistic regression was performed by defining at 12 months the improvement in GLS as a 10% increase in absolute amplitude and the LV mass decrease as a 10% reduction. P values < .05 were considered statistically significant.

Patient Characteristics

Table 1 summarizes the demographic characteristics of the patients (39 men; mean age, 79.1 ± 7.1 years). The mean logistic European System for Cardiac Operative Risk Evaluation score was 26.6 ± 16.3%. Baseline echocardiographic characteristics are presented in Table 2 . The mean AVA index was 0.4 ± 0.1 cm ² /m ² , the mean transaortic pressure gradient was 28.1 ± 8.1 mm Hg, and the mean stroke volume index was 26.6 ± 4.6 mL/m ² . The mean LVEF was 45.8 ± 16.2%.

There were 35 patients with LFLGSAS and low LVEF, whereas the remaining 33 patients had preserved LVEF. Patients with preserved LVEF had significantly smaller LV volumes and more concentrically remodeled left ventricles compared with patients with reduced LVEF. In addition, patients with preserved LVEF had more preserved LV GLS and GLSr (−13.3 ± 3.5% vs −8.3 ± 2.6%, P < .001, and −0.7 ± 0.1 vs −0.4 ± 0.1 1/sec, P < .001, respectively) compared with patients with reduced LVEF ( Tables 1 and 2 ). Prosthesis-patient mismatch was observed in 14 patients (20%) and paravalvular regurgitation in 32 patients (47%).

LV Functional Recovery and Remodeling in Patients with LFLGSAS after TAVI

LV systolic function significantly improved over 12 months after TAVI in the overall cohort of patients with LFLGSAS. Although LVEF had no significant change over time (from 45.8 ± 16.2% before TAVI to 49.7 ± 15.9% 6 months after TAVI and 49.8 ± 15.2% at 12 months, P = .08), LV GLS and GLSr improved significantly during the 12 months of follow-up (–10.7 ± 3.9% vs −11.9 ± 4.5% vs −12.6 ± 4.5%, P = .002, and −0.5 ± 0.1 vs −0.6 ± 0.2 vs −0.7 ± 0.2 1/sec, P < .001, respectively, for the same time period; Figure 3 ). This improvements in GLS and GLSr occurred mainly during the first 6 months after TAVI. No significant changes were observed in these variables between 6 and 12 months after TAVI. The improvement in GLS over time remained significant after adjusting for age, gender, diabetes, hypertension, coronary artery disease, logistic European System for Cardiac Operative Risk Evaluation score, use of β-blockers and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, TAVI valve type (self-expandable vs balloon expandable), TAVI access (transfemoral vs transapical), LVMi, and LVEF category at baseline (adjusted coefficient, −1.82; CI, −0.51 to −3.13; P = .007). The extent of improvement in GLS was comparable between patients who underwent transfemoral versus transapical TAVI (coefficient, −1.01; CI, 0.81 to −2.84; P = .27). GLS improvement over time was influenced by the presence of prosthesis-patient mismatch (coefficient, 3.29; CI, 0.97 to 5.60; P = .006) but not by the presence of paravalvular regurgitation (coefficient, 0.33; CI, −2.03 to 2.70; P = .78) at 6 months after TAVI. From the baseline variables, GLS was independently associated (odds ratio, 1.69; CI, 1.18 to 2.42; P = .004) with a 10% GLS improvement after adjusting for LVEF category at baseline.

Changes in LV systolic function assessed by (A) LVEF, (B) LV GLS and (C) GLSr in the total LFLGSAS population ( black line ), in the low-LVEF group ( red line ), and in the preserved-LVEF group ( green line ) over a 12-month period after TAVI. GLS and GLSr improved over time in the total cohort and in both groups; GLS and GLSr improvement is expressed by more negative numbers (i.e., the lower the value, the better the systolic function). All parameters are expressed as mean ± SD. P values are presented for the changes of parameters over the total 12-month follow-up period after TAVI.

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. Proximal Flow Convergence Method by Three-Dimensional Color Doppler Echocardiography for Mitral Valve Area Assessment in Rheumatic Mitral Stenosis
2. Outcomes of Asymptomatic Adults with Combined Aortic Stenosis and Regurgitation
3. Effect of Chronic Right Ventricular Volume Overload on Ventricular Interaction in Patients after Tetralogy of Fallot Repair
4. Application of a Parametric Display of Two-Dimensional Speckle-Tracking Longitudinal Strain to Improve the Etiologic Diagnosis of Mild to Moderate Left Ventricular Hypertrophy

Stay updated, free articles. Join our Telegram channel

Join