• Double S-Curve Technique Removes Parallax Reliably Compared to the Cusp-Overlap Technique, with Excellent Procedural Success

    The double S-curve and cusp-overlap techniques demonstrated comparable right anterior oblique (RAO) caudal projections during transcatheter aortic valve replacement (TAVR), with high rates of procedural success and few complications, according to a study released Monday.

    Balloon-expandable transcatheter heart valve (THV) deployment during TAVR has remained stable over the years. However, the optimal projection technique for self-expanding THV deployment in TAVR continues to evolve.

    Recently, the cusp-overlap technique has been described, in which the parallax is removed from both the native aortic annulus and the self-expanding THV. An optimal fluoroscopic projection curve, consisting of pairs of C-arm angulations, exists for both the native aortic annulus and the THV. Their intersection represents the double S-curve, in which the parallax is removed from both the native annulus and the THV. Both of these techniques aim to identify the optimal fluoroscopic projection for self-expanding THV deployment in TAVR.

    Jeremy Ben-Shoshan, MD, PhD, of McGill University, Montreal, and co-investigators, sought to compare the double S-curve technique to the cusp-overlap technique in TAVR with self-expanding THVs. In this retrospective study, which appears in the Jan. 25 issue of JACC: Cardiovascular Interventions, they included 100 consecutive patients who underwent TAVR using self-expanding THVs, planned by multidetector computed tomography. TAVR was performed using the double S-curve technique, while the cusp-overlap projection was retrospectively determined from pre-TAVR computed tomography.

    For most patients (92%), both the intra-procedural double S-curve and retrospective cusp-overlap views were located in the RAO caudal projection. The median 3-dimensional angular difference between the two was 10 degrees. There was no significant deviation between the average angulation of both techniques (1.49 degrees; p=0.349). Additionally, there were no significant differences between average coordinates (RAO: 14.7 vs. 12.9; p=0.36; and caudal: 27.0 vs. 26.9; p=0.90). Procedural success was achieved in 98% of patients using the double S-curve technique.

    Didier Tchétché, MD, and Saifullah Siddiqui, MD, of Clinique Pasteur, Toulouse, France, wrote an accompanying editorial to the study. In it, they applauded the authors’ comparative study and results.

    However, they raised concerns over the practicality of using either technique during TAVR. Both techniques require steep and lateral angulation, which is not always feasible during TAVR. Additionally, the editorialists pointed out that despite the study’s reported high procedural success, pacemaker implantation rates remained unacceptable, at 20%.

    “As often occurs in medicine, the patient’s disease and anatomy will finally dictate which technique can be used and the final result to expect,” Tchétché and Siddiqui wrote. “To conclude, these technical refinements keep on helping us to improve our patients’ outcomes.

    “Let’s be adaptive, integrative, and avoid dogma.”



    Ben-Shoshan J, Alosaimi H, Thériault Lauzier P, et al. Double S-Curve Versus Cusp-Overlap Technique: Defining the Optimal Fluoroscopic Projection for TAVR With a Self-Expanding Device. JACC Cardiovasc Interv  2021;14:185–94.

    Tchétché D, Siddiqui S. Optimizing Fluoroscopic Projections for TAVR: Any Difference Between the Double S-Curve and the Cusp-Overlap Technique? JACC Cardiovasc Interv  2021;14:195–7.

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