CMR-Guided TAVR Noninferior to CT-Guided TAVR for Device Implantation Success

Cardiac magnetic resonance (CMR)-guided transcatheter aortic valve replacement (TAVR) is noninferior to computed tomography (CT)-guided TAVR for device implantation success, researchers reported in Circulation.

The randomized, open-label, noninferiority TAVR-CMR (Cardiac Magnetic Resonance Imaging Versus Computed Tomography to Guide Transcatheter Aortic Valve Replacement; ClinicalTrials.gov Identifier: NCT03831087) trial was conducted at 2 heart centers in Austria and assessed the noninferiority of CMR vs CT for guiding TAVR.

Potential TAVR candidates were randomly assigned in a 1:1 fashion to have a predefined TAVR-CMR protocol or a standard contrast-enhanced TAVR-CT protocol to evaluate anatomic characteristics of the aortic annulus and access route. Eligible participants had severe aortic stenosis diagnosed based on guidelines of the European Society of Cardiology/European Association for Cardiothoracic Surgery and had typical symptoms of severe aortic stenosis.

The primary outcome was defined per the Valve Academic Research Consortium (VARC)-2 criteria as device success at discharge including absence of procedural mortality, correct positioning of a single prosthetic heart valve into the proper anatomic location, and proper intended performance of the prosthetic heart valve.

A total of 380 potential TAVR candidates were randomly assigned to CMR-guided (191 patients) or CT-guided (189 patients) TAVR planning from September 11, 2017, to December 16, 2022. Among the cohort, 138 participants in the CMR-guided group and 129 patients in the CT-guided group had TAVR (modified intention-to-treat [mITT] population). The per-protocol cohort included 248 patients (121 in the CMR group, 127 in the CT group). The median age for both populations was 82 years, and 50% were women.

For the mITT cohort, device implantation success occurred in 93.5% of patients in the CMR group and in 90.7% of patients in the CT group (between-group difference, 2.8%; 90% CI, -2.7 to 8.2%; P <.01 for noninferiority). In the per-protocol cohort, device implantation success occurred in 92.6% of the CMR-guided patients and in 90.6% of the CT-guided patients (between-group difference, 2.0%; 90% CI, -3.8 to 7.8%; P <.01 for noninferiority).

Stroke or transient ischemic attack (TIA) and the need for permanent pacemaker implantation occurred more frequently in the CT-guided group (stroke/TIA: 5.4% vs 0.7%; P =.02 in the mITT population; 5.5% vs 0.8%; P =.04 in the per-protocol population; permanent pacemaker: 11.6% vs 3.6%; P =.01; 11.8% vs 3.3%; P =.01, respectively).

The CMR and CT groups had comparable all-cause mortality at a median of 6 months (8.7% vs 7.0%, respectively; P =.60 in the mITT population; 8.3% vs 7.1%, respectively; P =.73 in the per-protocol population).

Sensitivity analyses with use of VARC-3 device success criteria were consistent with the primary outcome (mITT: 88.4% vs 85.3%; P =.01 for noninferiority; per-protocol: 90.1% vs 85.0%; P <.01 for noninferiority).

Among several limitations, the prespecified noninferiority margin of 9% absolute risk difference is liberal for an expected failure rate of 8%, the investigators noted. Also, the use of an alpha of 0.10 instead of 0.05 for nominal significance is different from convention. Other limitations included the open-label design, and contrast volume was not systematically evaluated.

“…CMR-guided TAVR was noninferior to CT-guided TAVR in terms of device implantation success at hospital discharge, with no difference between the groups in the proportion undergoing the TAVR procedure,” the study authors wrote.