Subvalvular membranous aortic stenosis in Swedish children, a retrospective cohort study between 1994 and 2019.

Background and aim: Membranous subaortic stenosis is a CHD with high recurrence-rate despite surgical treatment. This study investigated the outcome of operated patients and possible predictors for recurrence.

Methods: Retrospective review of all patients (n = 38) ≤ 18 years of age operated for membranous subaortic stenosis between 1994-2019 at Sahlgrenska University Hospital. The primary outcomes were recurrence, reintervention, and mortality. Predictors of recurrence and reintervention were secondary outcomes.

Results: Median age (range) at diagnosis, initial intervention, and last follow-up were 2.3 (0.003-17.2), 5.3 (0.03-17.5) and 17.5 (3.6-20.4) years, respectively. Median follow-up time was 9.9 (0.01-19.5) years. 61% were males, and 53% had other associated CHD. 19 patients (56%) developed recurrence and 7 (21%) underwent reintervention. One patient died peri-operatively. Age <5 years at first intervention increased the likelihood of reintervention. Postoperative peak/mean gradients were higher in patients with disease recurrence.The median echocardiographic peak-/mean gradients at initial diagnosis, pre-, postoperative, and at last follow-up were 61/36, 83/50, 16/8, and 19/17 mmHg respectively (p < 0.0001 pre/post). Pre-/postoperative peak gradients were linearly correlated, decreasing by 80% pre-/postoperatively (p < 0.01). Presence of symptoms and the preoperative peak gradient were positively associated (p < 0.001) with a peak gradient threshold value of > 90 mmHg. The distance between the subaortic stenosis membrane and the aortic valve was inversely correlated to the preoperative peak-gradient (p < 0.01).

Conclusions: Reintervention following surgical intervention of membranous subaortic stenosis is common. A positive correlation exists between high pre- and postoperative peak-gradient. A low postoperative peak gradient may be important in avoiding recurrence.