A validated computational framework to predict outcomes in TAVI.

Transcatheter aortic valve implantation (TAVI) still presents complications: paravalvular leakage (PVL) and onset of conduction abnormalities leading to permanent pacemaker implantation. Our aim was testing a validated patient-specific computational framework for prediction of TAVI outcomes and possible complications. Twenty-eight TAVI patients (14 SapienXT and 14 CoreValve) were retrospectively selected. Pre-procedural CT images were post-processed to create 3D patient-specific implantation sites. The procedures were simulated with finite element analysis. Simulations' results were compared against post-procedural clinical fluoroscopy and echocardiography images. The computational model was in good agreement with clinical findings: the overall stent diameter difference was 2.6% and PVL was correctly identified with a post-processing algorithm in 83% of cases. Strains in the implantation site were studied to assess the risk of conduction system disturbance and were found highest in the patient who required pacemaker implantation. This study suggests that computational tool could support safe planning and broadening of TAVI.

Population-specific material properties of the implantation site for transcatheter aortic valve replacement finite element simulations.

Patient-specific computational models are an established tool to support device development and test under clinically relevant boundary conditions. Potentially, such models could be used to aid the clinical decision-making process for percutaneous valve selection; however, their adoption in clinical practice is still limited to individual cases. To be fully informative, they should include patient-specific data on both anatomy and mechanics of the implantation site. In this work, fourteen patient-specific computational models for transcatheter aortic valve replacement (TAVR) with balloon-expandable Sapien XT devices were retrospectively developed to tune the material parameters of the implantation site mechanical model for the average TAVR population. Pre-procedural computed tomography (CT) images were post-processed to create the 3D patient-specific anatomy of the implantation site. Balloon valvuloplasty and device deployment were simulated with finite element (FE) analysis. Valve leaflets and aortic root were modelled as linear elastic materials, while calcification as elastoplastic. Material properties were initially selected from literature; then, a statistical analysis was designed to investigate the effect of each implantation site material parameter on the implanted stent diameter and thus identify the combination of material parameters for TAVR patients. These numerical models were validated against clinical data. The comparison between stent diameters measured from post-procedural fluoroscopy images and final computational results showed a mean difference of 2.5 ±â€¯3.9%. Moreover, the numerical model detected the presence of paravalvular leakage (PVL) in 79% of cases, as assessed by post-TAVR echocardiographic examination. The final aim was to increase accuracy and reliability of such computational tools for prospective clinical applications.

Balloon-Expandable Transcatheter Aortic Valves Can Be Successfully and Safely Implanted Transfemorally Without Balloon Valvuloplasty.

OBJECTIVES: To assess the necessity for balloon aortic valvuloplasty (BAV) during transfemoral transcatheter aortic valve implantation (TAVI) when using balloon-expandable valves. BACKGROUND: BAV is a usual part of TAVI procedures, prior to valve implantation. However, the benefits and necessity of this are unknown and recent evidence in self-expanding valves suggests it may not be necessary. METHODS: Retrospective single-center study of 154 patients undergoing first-time, transfemoral TAVI for native aortic valve stenosis, with (N = 76), and without (N = 78), BAV as part of the procedure. Data collected included demographic, procedural, and outcome data. RESULTS: BAV did not alter VARC-2 defined procedural success or early safety compared to not performing a BAV, including mortality, degree of aortic regurgitation, or need for post-TAVI balloon dilatation, although there was a strong trend to reduced stroke when not performing a BAV. There was a significantly reduced procedural time (P = 0.01) and fluoroscopic time (P < 0.001) without performing a BAV. There were no differences in cerebral embolization (solid, gaseous, or total emboli) noted between the 2 groups, as measured on transcranial doppler (TCD). CONCLUSIONS: TAVI can be effectively and safely performed without a BAV and this results in reduced procedural and fluoroscopic times, although embolization to the brain is not reduced. There is a trend toward reduced stroke risk. (J Interven Cardiol 2016;29:319-324).

Post-procedural arterial hypertension: implications for clinical outcome after transcatheter aortic valve implantation.

BACKGROUND AND AIM OF THE STUDY: Persistent arterial hypertension (HT) has been associated with increased morbidity and mortality after surgical aortic valve replacement (AVR). The impact of increased blood pressure (BP) after transcatheter aortic valve implantation (TAVI) has not yet been fully elucidated. METHODS: The mean systolic and diastolic BP after TAVI were calculated from the last 10 non-invasive recordings performed before discharge in 176 patients. The primary end-point was symptomatic improvement after 6-12 months according to BP control at the time of discharge. RESULTS: In patients with controlled BP (<140/90 mmHg), the symptomatic response after TAVI was significantly better compared to patients with uncontrolled BP (> or =140/90 mmHg), as reflected by NYHA functional class (+1.4 +/- 0.8 versus +0.8 +/- 1.0, p = 0.002) and six-minute walk test (6-MWT) distance improvement (+100 +/- 71 m versus +30 +/- 64 m, p < 0.001) at 6-12 months' follow up. A 10 mmHg decrease in systolic BP was associated with an 18 m increase in 6-MWT distance (p = 0.001). In addition, reverse left ventricular (LV) remodeling was significantly impaired in uncontrolled BP individuals, as reflected by regression of LV mass (-15 +/- 61 g versus -37 +/- 54 g, p = 0.041) and relative wall thickness (-0.02 +/- 0.09 versus -0.07 +/- 0.1, p = 0.01). Cumulative all-cause and cardiovascular mortality were significantly lower in patients with controlled BP compared to those with uncontrolled BP (6.5% versus 16%, p = 0.04; cardiovascular 3.7% versus 11.6%, p = 0.035). CONCLUSION: Uncontrolled HT after TAVI may contribute to diminished symptomatic improvement.

'Paradoxical' low-flow, low-gradient severe aortic valve stenosis: an entity with limited improvement following transcatheter aortic valve implantation.

BACKGROUND AND AIM OF THE STUDY: The aim of this single-center observational study was to determine the outcome of patients with 'paradoxical' low-flow, low-gradient aortic valve stenosis (PLF-LG-AS) after transcatheter aortic valve implantation (TAVI). METHODS: Based on pre-procedural echocardiographic data, a total of 150 patients with severe aortic valve stenosis (AS) (indexed aortic valve area (AVA) ≤ 0.6 cm2/m2) who underwent TAVI at the authors' institution were allocated retrospectively to three groups: Group 1: PLF-LG-AS (ejection fraction (EF) ≥ 50%, indexed stroke volume (SV) ≤ 35 ml/m2, mean AV gradient < 40 mmHg; n = 30); Group 2: Classical low-flow, low-gradient AS (CLF-LG-AS: EF < 50%, SV ≤ 35 ml/m2, mean AV gradient < 40 mmHg; n = 21); and Group 3: High-gradient AS (HG-AS: EF < or ≥ 50%, mean AV gradient ≥ 40 mmHg; n = 99). RESULTS: PLF-LG-AS was associated with an increased relative wall thickness (RWT) and a higher post-procedural systolic blood pressure (sBP) and pulse pressure (PP) (RWT 60.6 ± 15.3%, sBP 144 ± 14 mmHg, PP 79 ± 15 mmHg) compared to patients with HG-AS or CLF-LG-AS: (RWT 52 ± 13% and 40 ± 9%, p < 0.001; sBP 138 ± 15 mmHg and 125 ± 25 mmHg, p = 0.006; PP 68 ± 16 mmHg and 60 ± 21 mmHg, p = 0.01). These patients experienced less improvement in a 6-min walk test (improvement for PLF-LG-AS 14 ± 84 m, for CLF-LG-AS 86 ± 83 m, for HG-AS 87 ± 66 m; intergroup p < 0.007). PLF-LG-AS and CLF-LG-AS were also associated with significantly increased one-year overall mortality (PLF-LG-AS 31%, CLF-LG-AS 19%, HG-AS 6%; p = 0.001) and cardiovascular mortality (PLF-LG-AS 20%, CLF-LG-AS 19%, HG-AS 3%; p = 0.002). CONCLUSION: Patients with PLF-LG-AS may represent a subgroup with a worse clinical outcome after TAVI.

The left axillary artery--a new approach for transcatheter aortic valve implantation.

OBJECTIVE: Transcatheter aortic valve implantation (TAVI) is an alternative treatment for aortic stenosis in selected cases, but requires appropriate vascular access. We report our initial clinical experience with a novel endovascular approach for TAVI. METHODS: Between 1 April 2007 and 31 August 2008, 48 patients underwent TAVI at our institution. Of these, eight patients (17%) were deemed to be best served through direct surgical exposure of the left axillary artery rather than a trans-femoral or TA approach. RESULTS: Procedural success was achieved in seven of eight cases. In one patient the axillary artery was too small to accept the 18 French sheath. In the remaining seven, the device was implanted without major complication and with only trivial paravalvular aortic regurgitation. The in-hospital mortality was 0%. The 30-day mortality was 12.5% (one patient). There was one localised dissection at the origin of the vertebral artery. There was one late pericardial effusion and a permanent pacemaker was implanted in five patients. CONCLUSIONS: TAVI can be performed through a left axillary artery approach. This is a technically simple procedure and, in this small initial clinical experience, was performed with encouraging results. It is a realistic option in patients in whom neither the trans-femoral or trans-apical approaches are optimal.

Generalizing results of randomized trials to clinical practice: reliability and cautions.

BACKGROUND: Well designed randomized controlled trials provide reliable evidence of treatment effects, but there is no consensus on how best to apply these results to clinical practice. The main concerns are that populations enrolled in trials are more selected than those treated in a clinical setting, and whether the treatment effects observed in trials will also be observed in clinical practice. METHODS: An informal literature review was undertaken to find studies analysing the issue of generalizing trial results (external validity) to clinical practice. RESULTS: Most of the studies focused on differences in patients characteristics (age, gender, severity of disease, concomitant treatments and so on) between the clinical trial population and a 'real world' clinical population. None provided good evidence of a reduction in the treatment effect in the trial compared to what might happen in clinical practice for simple pharmacological treatments. However complex treatments like surgery or percutaneous interventional procedures, had a greater potential for variation. Extrapolating treatments to different health care settings from the trial can result in important variations in treatment effects. CONCLUSIONS: Complex therapies need careful consideration before they can be applied routinely from trials into practice, and applying results from one health care environment to a different one should be carried out with caution. Generalizing results from well conducted trials to clinical practice can mostly be carried out with confidence, especially for simple therapies with good evidence of benefit.