Paediatric subvalvular aortic stenosis: a systematic review and meta-analysis of natural history and surgical outcome.

Sub-valvular aortic stenosis (SAS) is a common form of left ventricular outflow tract (LVOT) obstruction, which can lead to aortic valve damage. Although surgery for SAS is an accepted treatment, the timing of surgical intervention of SAS remains controversial. This review aims to establish an overview of the natural history and outcome after surgery and factors associated with prognosis in paediatric SAS patients. We searched PubMed and EMBASE for studies that reported factors that negatively affected the prognosis of patients with SAS. Studies were included if they were written in English, published between 1 January 1997 and 31 December 2012 and the mean patient age was <18 years at the time of study entry. Studies were excluded if the study size was <20 patients. A distinction was made between natural history and surgical cohorts. Twenty-four studies were included in this review, encompassing a total of 809 natural history and 1476 surgical patients. Fifty-one percent of natural history patients required surgery. After surgery, there was a substantial reoperation rate. Higher LVOT gradient and the presence of aortic regurgitation (AR) were identified as the foremost independent predictors of a worse outcome. Valve-to-membrane distance was also found to be associated with prognosis, although the results were contradictory. This systematic review underlines the importance of LVOT gradient, aortic valve-to-membrane distance and AR in surgical decision-making in paediatric SAS patients. There is need for collaborative effort to further study the optimal timing of surgery based on LVOT gradient, valve-to-membrane distance and the presence of AR.