We conducted a pilot, single-center, observational and prospective study. From 28 March 2017 to 12 November 2020, 419 consecutive patients with severe symptomatic AS were referred by our heart team for TAVI and included in the present investigation. After exclusion, 226 patients were included for analysis. Details of excluded patients can be seen in our flow chart (figure 1). Since 2007, 807 patients underwent TAVI in our institution. All patients referred for aortic valve replacement were carefully evaluated by a multidisciplinary heart team. Patients referred for TAVI are followed up according to guidelines and systematic protocols by experienced interventional cardiologists in a specific TAVI outpatient clinic.10,11 All patients provided informed consent and the study was approved by the local ethics committee.

Figure 1.

Flow chart. TAVR, transcatheter aortic valve replacement.

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Considering previous reports suggesting an improvement of OID with the modification of implant projection,7,8 from 1 February 2019, the classic 3-cusp coplanar implantation technique (CIT) for self-expanding THV was modified in our center to a COP implantation technique to optimize ID. Our study took advantage of this modification in routine practice and, for the analysis and clinical investigation, compared 2 groups of consecutive patients: group A, 113 consecutive patients (28 March 2017 to 1 February 2019) with CIT and group B, 113 consecutive patients (2 February 2019 to 12 November 2020) with the COP implantation technique. The flow chart of our study provides an overview of patient distribution (figure 1).

Electrocardiography (ECG)-gated contrast-enhanced high-resolution MSCT was performed prospectively, according to a systematic protocol, by the same TAVI evaluation team, with experience of more than 900 studies. Image acquisition was performed following standardized recommendations.12 To complete all the specific preprocedural measurements, MSCT data were transferred to a dedicated workstation for evaluation (3Mensio Structural Heart, Pie Medical Imaging BV, The Netherlands) and measurements were performed, including complete assessment of relevant anatomic dimensions and working projections. The COP implantation technique modifies the CIT by overlapping the right coronary cusp and the left coronary cusp (LCC). Cusp-overlap view, as predicted by MSCT, was used for deployment of the device throughout the procedure. The valve size was based on perimeter-derived MSCT measurements with oversizing in borderline cases. The implantation team consisted of 2 interventional cardiologists. The first operator was the same in all the patients, with a wealth of experience with more than 1400 TAVI performed. All procedures were carried out in the cardiac catheterization laboratory under a minimally invasive approach with conscious sedation. The COP implantation technique was similar to CIT in the entire TAVI protocol, except for the deployment projection. A Safari preshaped guidewire (Boston Scientific, USA) was used to position the THV under temporary pacemaker stimulation in the aortic annulus when the prosthesis height was optimal according to the primary operator, the THV was partially released, and angiographic assessment was performed. If the valve hemodynamics were deemed optimal, the prosthesis was implanted. In selected patients, if the risk of coronary occlusion was high (coronary ostium <10 mm of the aortic annulus and sinus of Valsalva height <15 mm for size 23, 26, 29 THV and <16 mm for size 34) a guide catheter engaging the coronary ostium with an intracoronary guidewire was placed in case of acute obstruction. Predilatation was done when valves were heavily calcified and in critical AS with reduced LVEF. COP was identified by MSCT in the preprocedural assessment and subsequently confirmed by intraprocedural angiography during the TAVI procedure (figure 2A).

Figure 2.

COP to reduce the new pacemaker implantation rate after TAVI. A: multislice computed tomography and angiography images representing classic implantation technique and cusp overlapping projection technique; B: mean, standard deviation and 95%CI of implantation depth measured from the noncoronary cusp to the prosthesis; C: pacemaker rate according to the classic implantation technique vs the cusp overlapping projection technique. 3CP, 3-cusp coplanar projection; 95%CI, 95% confidence interval; COP, cusp-overlap projection technique; MSCT, multislice computed tomography; NCC, noncoronary cusp; PPMI, permanent pacemaker implantation; TAVI, transcatheter aortic valve replacement.

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Primary endpoints were ID and 30-day new pacemaker implantation. Secondary endpoints were the occurrence of HAVB and Valve Academic Research Consortium 2 (VARC-2) safety definitions.

The ID was measured angiographically by 2 experienced operators retrospectively using the SyngoDynamics software (Siemens Healthcare, USA). Since there are no standardized definitions in the current VARC-2 criteria on how to assess ID,10 we decided to use 3 of the most common methods used for THVs depth assessment (figure 2A): a) noncoronary cusp (NCC) distance: distance from the deepest portion of the NCC cusp to the distal end of the intraventricular edge of the THV; b) arithmetic mean of the NCC and LCC: the distance from the distal end of the intraventricular portion of the THV to the NCC and the LCC were measured, respectively and the mean was reported; c) deepest edge: the distance from the distal end of the intraventricular portion of the THV to the NCC and the LCC were measured, respectively and only the deepest of the 2 measurements was taken into account.

The ID was measured by angiography using 20mL of Optiray (ioversol) low-osmolality contrast medium at a flow rate of 20mL/s in the final projection in a perpendicular plane to the THV. Interobserver reliability was assessed by randomly measuring ID in 100 patients by 2 physicians from the NCC and the LCC, respectively, to the THV (figure 3A).

Figure 3.

Implantation depth. A: measurement from the NCC to the distal end of the intraventricular portion of the prosthesis (2.3mm). B: LCC and NCC distance to the distal end of the intraventricular portion of the valve are measured and the arithmetic mean is reported (2.3+8.2/2=5.25 mm). C: the deepest edge from the LCC and the NCC to the distal end of the prosthesis is reported (2.3 <8.2=8.2 mm). CIT, classic implantation technique; COP, cusp-overlap projection; LCC, left coronary cusp; NCC, noncoronary cusp.

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Follow-up of clinical and hemodynamic outcomes was prospectively assessed according to VARC-2 criteria.13 After TAVI, all patients remained under continuous ECG monitoring for at least 48hours. Before discharge and at the 30-day follow-up, 12-lead ECGs were recorded for each patient. A HAVB was defined as the development of second- or third-degree AVB on postprocedural ECG. PPMI was performed if the patient developed HAVB or if a persistent temporary pacemaker was necessary, in accordance with current guidelines recommendations.14–16 After discharge, each patient was followed up at the dedicated TAVI outpatient clinic with a predefined scheduled follow-up with a new ECG. There were no reported losses.

Study variables were included in a specifically dedicated database. Variables related to clinical follow-up were documented following VARC-2 criteria.13

Analysis of the normality of the continuous variables was performed with the Kolmogorov Smirnov test. Normally distributed continuous variables are expressed as the mean±standard deviation and were compared using the t-test. Continuous variables with nonnormal distribution are expressed as median values [interquartile intervals] and were compared with the Wilcoxon rank test. Categorical variables are expressed as counts (percentages) and compared using chi-square tests.

Logistic regression analysis was used to test the association between potential risk factors and 30-day PPMI. Variables with P <.1 on univariable analysis were entered into a multivariable model. Associations are expressed as odds ratios (OR) with 95% confidence interval (95%CI). To compare mortality, Kaplan-Meier curves were constructed, and the log-rank test was performed. Differences were considered to be statistically significant if the null hypothesis could be rejected with 95%CI. Statistical analyses were conducted using STATA 14 statistical software package (STATA Corp LP, USA).

The Pearson correlation coefficient was used to assess interobserver reliability for the depth measurements from the LCC and the NCC to the valve in 100 randomly chosen cases and were interpreted as follows:> 0.8, excellent agreement; 0.6 to 0.8, fair to good agreement; 0.4 to 0.6, moderate agreement; and <0.4, no agreement.

From February 2019, 113 patients were treated using the COP implantation technique and were compared with the previous consecutive 113 patients treated with the CIT (figure 1). The mean age was 83.5±6 years, 136 patients were male (60.2%), there was a similar distribution of cardiovascular risk factors between groups and relevant past medical history. Patients had an intermediate risk for surgery with a mean EuroSCORE II of 6.5 (± 4.4) and a Society of Thoracic Surgeons score of 5 (± 4.9) (table 1).

In the ECG analysis, 121 patients (53.3%) presented previous conduction disturbances, the most frequent were first-degree atrioventricular block in 35 patients (15.5%), left bundle branch block in 34 patients (15%) and right bundle branch block in 33 patients (14.7%). Regarding the echocardiographic findings, the mean gradient was 46.3mmHg (± 13.6) and the peak gradient was 76.7mmHg (± 21.6). The MSCT scan showed a mean perimeter of 75.8mm (± 8.3) and a calcium score of 3102 Agatston units (± 1428). There were no significant differences between groups (table 1).

Procedural success was achieved in 96.5% of the patients. The most frequent vascular access was the right femoral artery in 182 patients (80.5%). Evolut R pro 29 was used in 106 patients (46.9%), predilation was required in 34 (15%), and postdilatation was required in 78 (34.5%). Only 8 patients (3.5%) required a second valve due to severe aortic regurgitation assessed by angiography, there was 1 case (0.4%) of THV embolization in the CIT group, and the mean fluoroscopy time was 27.1minutes±13.4. HAVB appeared in 38 procedures (16.8%) with 25 cases (22.1%) in the CIT group and 13 (11.5%) in the COP group (P=.0328). There were no cases of acute coronary occlusion and no acute coronary syndromes in the first 30 days. Intraprocedural new-onset left bundle branch block was detected in 34 patients (17.7%). Only 1 patient (0.4%) died during the procedure due to a cardiac tamponade secondary to a ventricular laceration in the COP group (table 2).

The main limitations of this study are the modest sample size with a single-center and observational design and that the ID that was retrospectively measured. The primary operator was always the same person and so it could be difficult to extrapolate the data to other operators. Only a multivariable logistic regression analysis was used to predict the main event and, given the nature of the study, some MSCT measurements were not performed, such as the membranous septal anatomy. Finally, our study was focused solely on 1 type of self-expanding THV and therefore the results and conclusions should be interpreted in this context.