Pre-procedural computed tomography (CT) screening should be performed for “redo” transcatheter aortic valve replacement (TAVR) cases, particularly for patients with low sinotubular junction (STJ) height, researchers urged in a study released Monday.
However, in an accompanying editorial, Ole De Backer, MD, PhD, and Lars Søndergaard, MD, DMSC of the University of Copenhagen, Denmark, and colleagues warned that the study’s definition of risk is “questionable” and noted that the paper’s conclusions are based on a theoretical model.
The study was published in the Nov 23. issue of JACC: Cardiovascular Interventions by Cedars-Sinai Medical Center’s Tomoki Ochiai, MD, and colleagues. Researchers in the team report industry links with Medtronic and Edwards Lifesciences – the companies respectively behind the Evolut and SAPIEN 3 transcatheter aortic valves (TAVs) assessed in the study.
The use of TAVR has risen over the last decade, bringing with it technology advancements and operator experience, and significant increase in safety and efficacy, the researchers noted. Despite a significant body of data demonstrating TAV durability up to 5 years, they said valve degeneration can occur over time leading to TAVR-in-TAVR procedures – the so-called redo operations in which a second TAV is implanted inside a prior device.
A major concern of TAV-in-TAV is the risk of coronary obstruction caused by sinus of Valsava sequestration, they said, but data over these events are still limited. Coronary obstruction during TAVR is a life-threatening condition if revascularization is unsuccessful, they added, citing research led by Henrique Ribeiro, MD, of the University of Sao Paulo, in 2013 and 2018.
Defining the risk is therefore important, particularly with redo procedure numbers expected to grow as TAVR use expands further to younger patients with lower surgical risk and longer life expectancy, defining the risk is important.
The study, therefore, set out to evaluate this risk in 411 redo TAVR patients using post-procedural CT. Of these, 66 received an Evolut R or Evolut PRO valve, while 345 received a SAPIEN 3.
Patients were considered at risk of coronary obstruction due to sinus sequestration if the prior TAV commissure level was above the STJ and the distance between TAV and STJ was less than 2 mm in each coronary sinus.
The definition was based on visualizations using three orthogonal multiplanar reconstruction planes, a centerline perpendicular to the TAV was generated, and the inflow level of each TAV was identified.
“In this study, we assumed that the first TAV leaflets would be pushed completely open by the second TAV and seal the stent frame circumferentially up to the commissure level after TAV-in-TAV. Consequently, TAV frame would become a stent graft and cause sinus sequestration, leading to coronary obstruction,” the researchers said – a “worst case scenario.”
In the Evolut devices group, 45.5% had CT-identified risk of sinus sequestration at one or both coronary arteries, per the study definition, compared to 2% of patients with the same risk in the SAPIEN 3 group.
The study’s CT-defined risk of sinus sequestration was observed in 39.4% for the left coronary artery and 24.2% for the right in the Evolut devices group, while the same percentages were 2% for left and 0.6% for right coronary artery in the SAPIEN 3 cohort.
A coronary-level analysis showed overlaps between the first TAV commissural posts and coronary ostium among the reportedly at risk arteries in 45.2% of the Evolut cohort and 11.1% of the SAPIEN 3 group, Ochiai and team noted.
De Backer and Søndergaard said the study does raise the importance of paying close attention to coronary obstruction risk when planning a redo TAVR for patients with a degenerated THV.
Otherwise, they aired skepticism, stressing that the study and its conclusions are based on a theoretical model of reporting the estimated CT-identified risk of sinus sequestration in case of redo procedures.
“Whether the proposed definition of ‘risk of coronary obstruction due to sinus sequestration’ is true to reality is questionable,” they said.
“Even if the commissure level of the first THV (transcatheter heart valve) is above the STJ, it is not likely that a distance (less than 2 mm but more than 1.0 mm) between the first THV and STJ would result in coronary flow obstruction,” they added, although they pointed out studies that show “it would certainly make coronary access with a coronary catheter impossible.”
The editorialists added that the distinction in risk for coronary occlusion, coronary flow obstruction and impossible coronary access after redo TAVR should have been drawn.
“The observation that nearly one half of the patients in the Evolut R/PRO group had CT-identified risk of ‘coronary obstruction’ due to sinus sequestration of 1 or both coronary arteries should have been interpreted as the proportion of patients in which coronary access with a catheter would be impossible,” they added.
They highlighted that the investigators performed an additional analysis using modified criteria, with the distance between THV and STJ less than 1 mm in the left and right coronary sinuses, and found only 13.6% of the Evolut group had risk of coronary obstruction due to sinus sequestration – a more likely “true risk” for this complication.
In any case, De Backer and Søndergaard called for future THVs to be designed with the built-in option for later redo TAVR given the expansion of the procedure into younger and lower-surgical-risk groups with longer life expectancy.
Besides Edwards Lifesciences and Medtronic, some of the study’s researchers list associations with Boston Scientific, Cordis, Entourage Medical and Abbott.
Ochiai T, Oakley L, Sekhon N, et al. Risk of Coronary Obstruction Due to Sinus Sequestration in Redo Transcatheter Aortic Valve Replacement. JACC Cardiovasc Interv 2020;13:2617-27.
De Backer O and Søndergaard L. Redo-TAVR: What About the Coronary Arteries? JACC Cardiovasc Interv 2020;76:2628-30.