Surgical Outcome of Discrete Subaortic Stenosis in Adults: A Multicenter Study

Study Questions:

What are the long-term outcomes for adult patients who as children underwent surgery for discrete subaortic stenosis (DSS)?

Methods:

Adult patients who previously underwent surgery for DSS were included in this retrospective multicenter cohort study. Mixed-effects and joint models were used to assess postoperative progression of DSS and aortic regurgitation (AR), and re-operation. A total of 313 patients at four centers were included (age at baseline, 20.2 years [interquartile range [IQR], 18.4-31.0]; 52% male). Median follow-up duration was 12.9 years (IQR, 6.-20.1), yielding 5,617 patient-years.

Results:

The peak instantaneous left ventricular outflow tract (LVOT) gradient decreased from 75.7 ± 28.0 mm Hg preoperatively to 15.1 ± 14.1 mm Hg postoperatively (p < 0.001), and thereafter increased over time at a rate of 1.31 ± 0.16 mm Hg per year (p = 0.001). Mild AR was present in 68%, but generally did not progress over time (p = 0.76). A preoperative LVOT gradient ≥80 mm Hg was a predictor for progression to moderate AR postoperatively. Eighty patients required at least one re-operation (1.8% per patient-year). Predictors for re-operation included female sex (hazard ratio [HR], 1.53; 95% confidence interval [CI], 1.02-2.30) and LVOT gradient progression (HR, 1.45; 95% CI, 1.31-1.62). Additional myectomy at the time of DSS surgery did not reduce the risk for re-operation (p = 0.92), but significantly increased the risk of a complete heart block requiring pacemaker implantation (8.1% vs. 1.7%; p = 0.005).

Conclusions:

Survival is excellent after surgery for DSS, although re-operation for recurrent DSS is not uncommon. Over time, the LVOT gradient slowly increases and mild AR is common, although generally nonprogressive over time. Myectomy does not show additional advantages; because it is associated with an increased risk of complete heart block, the authors concluded that it should not be performed routinely.

Perspective:

DSS is notable for unpredictable hemodynamic progression in childhood and high re-operation rates. This large multicenter experience suggests good outcomes in terms of survival, and ~1.8% per patient-year incidence of re-operation, with no outcome advantage (and an observed outcome disadvantage in terms of complete heart block and permanent pacemaker requirement) associated with concomitant myectomy at the time of DSS resection. This long-term outcome study in adults who underwent DSS resection as children, accompanied by another article recently published by the same group (van der Linde D, et al., Natural history of discrete subaortic stenosis in adults: a multicentre study. Eur Heart J 2012;Dec 13:[Epub ahead of print]) sheds light on the long-term outcomes of previously operated and previously unoperated adults with DSS.

Clinical Topics: Arrhythmias and Clinical EP, Congenital Heart Disease and Pediatric Cardiology, Valvular Heart Disease, Implantable Devices, EP Basic Science, Congenital Heart Disease, CHD & Pediatrics and Arrhythmias, CHD & Pediatrics and Quality Improvement

Keywords: Heart Defects, Congenital, Hemodynamics, Postoperative Period, Child, Discrete Subaortic Stenosis, Atrioventricular Block, Reoperation, Cardiology, Pacemaker, Artificial, Confidence Intervals


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