Abstract 13233: Does Fetal Aortic Valvuloplasty alter the Natural History of Aortic Stenosis?

Introduction: Fetal aortic valvuloplasty (FV) is proposed as therapy to achieve biventricular circulation (BV) in fetuses where univentricular circulation (UV) is likely. Hypothesis: FV cannot alter natural history (NH) outcome. Methods: Hybrid of case-control and repeated samples cohort study. Fetuses with aortic stenosis (AS) were enrolled in a multicenter study (2005-2012). FV was considered in 70 / 214 AS and successful in 59/67 (88.0%) performed. Six salvage cases (hydrops) were excluded and 47 liveborn FV could be matched with 95 controls (NH) by scan closest to 23 +/- 3 weeks and +/- 1 Z-score for MV, LV and AV, producing a best match group for each. Results: Procedure-related death occurred in 7/67 (10.4%). Overall 151/214 (71%) were liveborn, but outcome unknown in 5. Serial left sided growth was similar in FV and NH: Z score differences MV = 0.11, LV = 0.08, AV = 0.11, p>0.90. Hazard ratio for FV survival was similar to NH at 30 d, 1 and 4 yrs after birth [0.68 (95% CI 0.347 - 1.315), p= 0.25]. Cohorts matched for MV, LV and AV did not show survival advantage after FV and survival with freedom from UV circulation showed fewer BV survivors in FV than NH. (Fig 1) Funnel plots show improved BV survival by center volume for FV, but more BV-UV conversions in one with limited surgical options where 17% vs 82% FV remain BV. (Fig 2) Conclusions: Data show no survival advantage or improved chance of BV at 4 years in fetuses matched for morphology at 23 wks undergoing FV. Centralization of FV may improve survival, but BV - UV conversion suggests a specialized surgical approach is also essential to maintain BV outcome. A carefully designed prospective study is indicated to better evaluate FV. procedure.