Po-03-173 incidence and risk factors for ventricular arrhythmias following transcatheter pulmonary valve replacement with harmony valves and alterra pre-stenting

Transcatheter pulmonary valve replacement (TCPVR) has increasingly been utilized as a replacement for surgical intervention. Valve stability has been a challenge in native outflow tracts with large diameters, and the Harmony™ valve (Medtronic Inc, Minneapolis, MN) and Alterra™ pre-stent (Edwards Lifesciences, Irvine, CA) were developed to accommodate this. The large diameter and length of these valves/stents may result in ventricular arrhythmias (VA) although the acute incidence and subsequent course is unknown. Characterize the incidence, risk factors, and clinical course of VAs following Harmony/Alterra implant. Single center retrospective cohort review of all patients undergoing Harmony valve or Alterra pre-stent implant at Children’s Hospital Colorado and University of Colorado Hospital. VAs were defined as any new ventricular ectopy post implant, significant VAs as those with hemodynamic compromise or symptoms. From August 2019-September 2022, 27 patients (female, n=9, 33%; median age 23 yrs [17-38], weight 70.6 kg [65-89], height 169 cm [162-176]) underwent successful implant with Harmony (n=14, 52%) or Alterra (n=13, 48%). Underlying diagnoses included tetralogy of Fallot (n=15, 56%), congenital pulmonary stenosis (PS) (n=10, 37%), and other (n=2, 7%). Following implant, 18 patients (67%) developed VAs including single PVCs or couplets only (n=4, 22%), NSVT (n=13, 72%), and VF/torsades (n=1, 6%). Initiation or augmentation of antiarrhythmics occurred in 12 (66%): metoprolol (n=5, 42%), mexiletine (n=7, 58%), and amiodarone (n=1, 8%). Significant VAs occurred in five (18%) with risk factors including congenital PS (p=0.002), pre-implant RVOT contractility by CT (p=0.04), and absence of pre-implant VAs (p=0.04). Over a median f/u of 14 mo (IQR 11-20), 24 (89%) were weaned off or returned to pre-implant antiarrhythmics, two (7%) remain on increased antiarrhythmics, and one patient (4%) died (post Harmony valve implant torsades de Pointes requiring ECMO cannulation). TCPVR with Harmony™ valves and Alterra™ pre-stenting is associated with post implant ventricular arrhythmias. Significant arrhythmias are correlated with congenital pulmonary stenosis, pre-implant RVOT contractility by CT, and the absence of pre-implant arrhythmias. Most VAs resolve 3-6 months post implant though long-term follow-up may be required.