Mohammad Kashif

Cross-Sectional Computed Tomographic Assessment Improves Accuracy of Aortic Annular Sizing for Transcatheter Aortic Valve Replacement and Reduces the Incidence of Paravalvular Aortic Regurgitation

OBJECTIVES In an effort to define the gold standard for annular sizing for transcatheter aortic valve replacement (TAVR), we sought to critically analyze and compare the predictive value of multiple measures of the aortic annulus for post-TAVR paravalvular (PV) regurgitation and then assess the impact of a novel cross-sectional computed tomographic (CT) approach to annular sizing. BACKGROUND Recent studies have shown clear discrepancies between conventional 2-dimensional (2D) echocardiographic and CT measurements. In terms of aortic annular measurement for TAVR, such findings have lacked the outcome analysis required to inform clinical practice. METHODS The discriminatory value of multiple CT annular measures for post-TAVR PV aortic regurgitation was compared with 2D echocardiographic measures. TAVR outcomes with device selection according to aortic annular sizing using a traditional 2D transesophageal echocardiography-guided or a novel CT-guided approach were also studied. RESULTS In receiver-operating characteristic models, cross-sectional CT parameters had the highest discriminatory value for post-TAVR PV regurgitation: This was with the area under the curve for [maximal cross-sectional diameter minus prosthesis size] of 0.82 (95% confidence interval: 0.69 to 0.94; p < 0.001) and that for [circumference-derived cross-sectional diameter minus prosthesis size] of 0.81 (95% confidence interval: 0.7 to 0.94; p < 0.001). In contrast, traditional echocardiographic measures were nondiscriminatory in relation to post-TAVR PV aortic regurgitation. The prospective application of a CT-guided annular sizing approach resulted in less PV aortic regurgitation of grade worse than mild after TAVR (7.5% vs. 21.9%; p = 0.045). CONCLUSIONS Our data lend strong support to 3-dimensional cross-sectional measures, using CT as the new gold standard for aortic annular evaluation for TAVR with the Edwards SAPIEN device.

Aortic annular sizing for transcatheter aortic valve replacement using cross-sectional 3-dimensional transesophageal echocardiography.

OBJECTIVES This study compared cross-sectional three-dimensional (3D) transesophageal echocardiography (TEE) to two-dimensional (2D) TEE as methods for predicting aortic regurgitation after transcatheter aortic valve replacement (TAVR). BACKGROUND Data have shown that TAVR sizing using cross-sectional contrast computed tomography (CT) parameters is superior to 2D-TEE for the prediction of paravalvular aortic regurgitation (AR). Three-dimensional TEE can offer cross-sectional assessment of the aortic annulus but its role for TAVR sizing has been poorly elucidated. METHODS All patients had severe symptomatic aortic stenosis and were treated with balloon-expandable TAVR in a single center. Patients studied had both 2D-TEE and 3D imaging (contrast CT and/or 3D-TEE) of the aortic annulus at baseline. Receiver-operating characteristic curves were generated for each measurement parameter using post-TAVR paravalvular AR moderate or greater as the state variable. RESULTS For the 256 patients studied, paravalvular AR moderate or greater occurred in 26 of 256 (10.2%) of patients. Prospectively recorded 2D-TEE measurements had a low discriminatory value (area under the curve = 0.52, 95% confidence interval: 0.40 to 0.63, p = 0.75). Average cross-sectional diameter by CT offered a high degree of discrimination (area under the curve = 0.82, 95% confidence interval: 0.73 to 0.90, p < 0.0001) and mean cross-sectional diameter by 3D-TEE was of intermediate value (area under the curve = 0.68, 95% confidence interval: 0.54 to 0.81, p = 0.036). CONCLUSIONS Cross-sectional 3D echocardiographic sizing of the aortic annulus dimension offers discrimination of post-TAVR paravalvular AR that is significantly superior to that of 2D-TEE. Cross-sectional data should be sought from 3D-TEE if good CT data are unavailable for TAVR sizing.

A revised methodology for aortic-valvar complex calcium quantification for transcatheter aortic valve implantation

AIMS We sought to optimize a method for quantification of the calcium in the aortic-valvar complex for the prediction of significant paravalvular leak (PVL) after transcatheter aortic valve implantation (TAVI). METHODS AND RESULTS All patients had severe symptomatic aortic stenosis and were treated with balloon-expandable TAVI (Sapien/Sapien-XT, Edwards Lifesciences LLC, Irvine, CA, USA). In order to correct for precise annular sizing, only patients with available contrast computed tomography (CT) data for measurements were included (n = 198). Paravalvular leak was quantified using peri-procedural transoesophageal echocardiography by Valve Academic Research Consortium-2 (VARC-2) criteria (grade ≥ moderate was considered significant). A detailed region-of-interest methodology separated quantification of calcium in each of the aortic leaflets to that in the left ventricular outflow tract (LVOT) and was used to predict PVL in receiver operator characteristic curve analyses. For non-contrast scans, the greatest discriminatory value for PVL was seen at the 450 Hounsfield Unit (HU) threshold for detection (volume ≥626 mm(3)), whereas for contrast scans it was at 850 HU (≥235 mm(3)). Left ventricular outflow tract calcium predicted PVL but only as a binary variable with no incremental value of quantification. In a multivariable binary logistic regression model, annulus area ≥ prosthesis area (OR 3.5, 95% CI 1.5-8.2, P = 0.005), contrast leaflet calcium volume (850-HU threshold) ≥235 mm(3) (OR 2.8, 95% CI 1.2-6.7, P = 0.023), and presence of LVOT calcium (OR 2.8, 95% CI 1.2-7.0, P = 0.022) were independent predictors for PVL ≥ moderate. CONCLUSION Both leaflet and LVOT calcium are significant predictors of PVL and exert an important synergistic influence on this complication, even in appropriately sized valves. With careful attention to thresholds for detection, clinically relevant leaflet calcium volumes can be identified with either non-contrast or contrast CT scans.

Comparison of SAPIEN 3 and SAPIEN XT transcatheter heart valve stent-frame expansion: evaluation using multi-slice computed tomography

Aims Stent-frame morphology of the newer-generation, balloon-expandable transcatheter heart valve (THV), the SAPIEN 3 (S3), after transcatheter aortic valve implantation (TAVI) is unknown. We evaluated the THV stent-frame morphology post TAVI of the S3 using multi-slice computed tomography (MSCT) compared with the prior-generation THV, SAPIEN XT (S-XT). Methods and results A total of 94 consecutive participants of RESOLVE registry (NCT02318342) had MSCT after balloon-expandable TAVI (S3 = 39 and S-XT = 55). The morphology of the THV stent-frame was evaluated for expansion area and eccentricity at the THV-inflow, native annulus, mid-THV and THV-outflow levels. Mean %-expansion area for the S3 and the S-XT was 100.9 ± 5.7 and 96.1 ± 5.5%, respectively (P < 0.001). In the S3 group, the THV-inflow level had the largest value of %-expansion area, which decreased from THV-inflow to mid-THV level (105.2 ± 6.4 to 96.5 ± 5.9%, P < 0.001). However, in the S-XT group, %-expansion area increased from THV-inflow level to mid-THV level (93.2 ± 6.2 to 95.1 ± 6.1%, P = 0.0058). On nominal delivery balloon volume, the S3 in 88.5% of cases had overexpansion at the THV-inflow level. The observed degree of THV oversizing of the S3 was significantly lower than the S-XT (6.3 ± 8.6 vs. 11.8 ± 8.5%, P = 0.0027). Nonetheless, the incidence of post-procedural paravalvular aortic regurgitation (PVR) ≥ mild following the S3 TAVI was also significantly lower than the S-XT TAVI (17.9 vs. 43.6%, P = 0.014). Conclusion The newer-generation, balloon-expandable device, the S3, has a flared inflow morphology, whereas the prior-generation device, the S-XT, has relatively constrained inflow morphology post TAVI. This may contribute to a lesser degree of PVR with the S3.

Clinical impact of coronary protection during transcatheter aortic valve implantation: first reported series of patients.

AIMS Coronary protection with guidewires and an undeployed coronary balloon or stent positioned in the coronary artery is a pre-emptive technique to manage coronary obstruction during transcatheter aortic valve implantation (TAVI). We investigated the feasibility and safety of left main (LM) protection during TAVI. METHODS AND RESULTS Twenty-five out of 623 patients who underwent TAVI at our institute were deemed to be at increased risk of LM compromise mainly due to a low LM ostium height, significant LM disease or a previous bioprosthetic valve. A pre-emptive LM protection technique was therefore used in these cases. Five patients (20%) had pre-TAVI significant non-revascularised LM stenosis, and four patients (16%) had a prior LM ostial stent without pre-TAVI in-stent restenosis. Twelve patients had extremely low LM height (mean height 6.7±2.4 mm; range 1.1-8.9 mm). Seven patients (25%) had valve-in-valve (VIV) procedures. LM compromise occurred in five out of 25 cases; all were treated successfully with emergency LM stenting. Nine patients underwent successful planned LM procedures following TAVI. CONCLUSIONS The LM protection technique should be considered in patients deemed to be at increased risk of LM compromise. This was found to be helpful in the prompt diagnosis and treatment of LM compromise following TAVI.

Heart-rate adjustment of transcatheter haemodynamics improves the prognostic evaluation of paravalvular regurgitation after transcatheter aortic valve implantation.

AIMS Paravalvular aortic regurgitation (PVAR) after balloon-expandable transcatheter aortic valve implantation (TAVI) remains difficult to quantify, and the utility of the AR index (ARi) to create a composite aortic insufficiency (CAI) score was an important advance. Heart rate (HR) influences the ARi but the clinical relevance of this phenomenon remains poorly appreciated. We sought to validate a new composite heart-rate-adjusted haemodynamic-echocardiographic aortic insufficiency (CHAI) score in the prognostic evaluation of PVAR after balloon-expandable TAVI. METHODS AND RESULTS The severity of PVAR was assessed immediately post TAVI by transoesophageal echocardiography (TOE) with simultaneous assessment of transcatheter haemodynamics. A total of 303 patients were studied. The CHAI score, incorporating the HR-adjusted diastolic-delta (HRA-DD, the difference between left ventricular and aortic diastolic pressures/HR*80), had a greater discriminatory value for one-year mortality than both PVAR by TOE (p=0.0018) and the previously proposed CAI score, based on the ARi without HR adjustment (p=0.0029). The CHAI score also better stratified percentage increases in left ventricular systolic chamber dimensions at one month and serum natriuretic peptide levels at one to three months. CONCLUSIONS Prognostication of PVAR in the intermediate range of echocardiographic severity remains unreliable and is greatly enhanced by the integration of heart-rate-adjusted transcatheter haemodynamics.

Natural history of subclinical leaflet thrombosis affecting motion in bioprosthetic aortic valves

Aims Four-dimensional volume-rendered computed tomography (4DCT) has demonstrated instances of hypo-attenuating leaflet thickening (HALT) with or without hypo-attenuation affecting motion (HAM) after transcatheter and surgical aortic valve implantation (TAVI, SAVR). The temporal pattern of evolution of these phenomena is uncertain. Methods and results The SAVORY registry enrolled patients treated by TAVI (n = 75) or SAVR (n = 30) with two 4DCT scans fully interpretable for HALT and HAM as well as unchanged anti-thrombotic medication between the scans. Logistic regression analysis was performed to examine the evolution of HALT and HAM while accounting for demographic and baseline variables, timing of both CT scans, valve type and antithrombotic therapy. The analysis population consisted of 84 patients, in whom first and second CT scans were performed at 140 ± 152 days and 298 ± 141 days after valve implantation, respectively. Hypo-attenuating leaflet thickening was noted in 32 patients (38.1%), with HAM in 17 (20.2%). Both findings were dynamic, showing progression in 13 (15.5%) and regression and 9 (10.7%) patients. Compared with antiplatelet therapy, progression was less likely among patients on oral anticoagulation with vitamin-K antagonists or non-VKA oral anticoagulants (odds ratio: 0.014, P = 0.036). Maintenance on chronic oral anticoagulation was not a significant predictor of regression. These findings were similar for both transcatheter and surgical bioprosthetic aortic valves. No patients developed symptoms of valve dysfunction and leaflet thickening was not clearly associated with any clinical events. Conclusions Subclinical leaflet thrombosis is a common finding after TAVI and SAVR, and may progress from normal leaflet over HALT to the more severe HAM. The phenomenon can develop and regress at variable intervals after valve implantation. Anticoagulants may have a protective effect against the development of HALT, but HALT can also regress without anticoagulation therapy. Registered at ClinicalTrials.gov NCT02426307.

Major thrombocytopenia after balloon-expandable transcatheter aortic valve replacement: prognostic implications and comparison to surgical aortic valve replacement.

We sought to investigate the magnitude and clinical importance of thrombocytopenia post transcatheter aortic valve replacement (TAVR).

Pre‐emptive positioning of a coronary stent in the left anterior descending artery for left main protection: A prerequisite for transcatheter aortic valve‐in‐valve implantation for failing stentless bioprostheses?

Transcatheter aortic valve‐in‐valve (VIV) implantation in high‐risk patients with degenerative surgical bioprosthetic aortic valves is a novel application of transcatheter aortic valve replacement technology. Although transcatheter aortic VIV procedure is clinically effective in most patients, it is a more demanding procedure in terms of the technical aspects of procedural planning. VIV carries a higher risk of coronary occlusion which is associated with a higher rate of in‐hospital mortality. We hereby report a technique of pre‐emptive left main (LM) protection, by positioning a coronary stent in the proximal left anterior descending artery prior to VIV implantation. The patient treated was considered to be at an increased risk of LM occlusion as a result of the procedure. The technique was performed in anticipation of emergent bailout stenting of the LM. As predicted, the LM occluded during the procedure and LM protection facilitated the safe and effective treatment of an otherwise life‐threatening procedure.

Feasibility and safety of balloon-expandable transcatheter aortic valve implantation with moderate or without predilatation.

AIMS Aortic valve preparation by performing balloon aortic valvuloplasty (BAV) has always been considered mandatory during transcatheter aortic valve implantation (TAVI) procedures. We aimed to investigate the feasibility and safety of performing balloon-expandable TAVI with moderate or with no predilatation (PD). METHODS AND RESULTS Overall, 121 patients underwent TAVI with no PD and 392 with moderate PD. TAVI endpoints and adverse events were considered according to the Valve Academic Research Consortium (VARC)-2 definitions. Device success for the entire cohort was 95.1%. Post-dilatation was performed in nine patients in the no PD group (7.4%) and in 40 patients in the moderate PD group (10.2%) (p=0.06). Total fluoroscopy time and the amount of contrast used were lower in the no PD group. All-cause mortality up to 30 days was 3.3% in the no PD group vs. 3.6% in the moderate PD group (p=0.89). VARC-2 defined complication rates at 30 days including cerebrovascular accident (CVA)/transient ischaemic attack (TIA) were similar between groups. Overall, there was no significant difference in survival rates between the two groups (HR 1.33, 95% CI: 0.75-2.35; p=0.34). CONCLUSIONS Balloon-expandable TAVI with moderate or without balloon PD is feasible and safe. The omission of PD in appropriate cases was associated with reduced fluoroscopy time without affecting procedural success.