title: Structural integrity of balloon-expandable stents after transcatheter aortic valve replacement: assessment by multidetector computed tomography.
abstract: OBJECTIVE
  This study sought to evaluate the structural integrity of balloon-expandable stents used in transcatheter aortic valve replacement.
  
  
  BACKGROUND
  Underexpansion, deformation, or fracture of stent frames may affect transcatheter heart valve (THV) function and durability.
  
  
  METHODS
  Patients >1 year after transcatheter aortic valve replacement underwent multidetector computed tomography. Geometry of the stent frame was assessed for circularity; eccentricity; minimum and maximum external diameter; and expansion at the inflow, mid-stent, and outflow levels, as well as for stent fracture. THV noncircularity was defined as stent eccentricity >10% (1 - minimum diameter/maximum diameter) and THV underexpansion when expansion <90% (multidetector computed tomography derived external valve area/nominal external valve area). Echocardiography was performed after implantation and annually.
  
  
  RESULTS
  Fifty patients underwent multidetector computed tomography at an average of 2.5 ± 0.9 years after transcatheter aortic valve replacement (35 Sapien, 8 Sapien XT, and 7 Cribier-Edwards valves [all Edwards Lifesciences, Irvine, California). The mean external diameter for the 23- and 26-mm valves was 23.3 ± 0.9 mm and 25.9 ± 0.9 mm, respectively. Circularity was present in 96% (48 of 50) and median eccentricity was 2.0% (interquartile range: 1.2% to 3.0%). Mean THV expansion was 104.1 ± 7.4%, which increased from stent inflow to outflow (100.8 ± 7.6% vs. 108.1 ± 6.9%, p < 0.001). Stent fracture was not observed. Underexpanded valves (8% [4 of 50]) and noncircular valves (4% [2 of 50]) demonstrated stable hemodynamic function on annual echocardiography.
  
  
  CONCLUSIONS
  Balloon-expandable aortic valves have excellent rates of circularity with low eccentricity and maintain full expansion without stent fracture at an average 2.5 years after implantation.
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Willson
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: John G
authors.initials: JG
authors.lastname: Webb
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Ronen
authors.initials: R
authors.lastname: Gurvitch
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: David A
authors.initials: DA
authors.lastname: Wood
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Stefan
authors.initials: S
authors.lastname: Toggweiler
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Ronald
authors.initials: R
authors.lastname: Binder
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Melanie
authors.initials: M
authors.lastname: Freeman
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Madden
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Cameron
authors.initials: C
authors.lastname: Hague
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, British Columbia, Canada. Electronic address: jleipsic@providencehealth.bc.ca.
authors.forename: Jonathon
authors.initials: J
authors.lastname: Leipsic
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001024:Aortic Valve Stenosis / Q000628:therapy*; D001955:British Columbia; D006328:Cardiac Catheterization / Q000009:adverse effects / Q000295:instrumentation*; D004452:Echocardiography; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D006801:Humans; D008297:Male; D061330:Multidetector Computed Tomography; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D011475:Prosthesis Failure; D015607:Stents; D013997:Time Factors; D016896:Treatment Outcome