Resection of subaortic stenosis; can a more aggressive approach be justified?

Objectives: Discrete subaortic stenosis causes left ventricular outflow tra ct (LVOT) obstruction and often produces aortic regurgitation (AR) which al one may precipitate surgical intervention. Conventional resection relieves the obstruction, but the recurrence rate is high, and the AR is little chan ged as the thick fibrous membrane which extends onto the valve leaflets rem ains. We studied whether an aggressive surgical approach could reduce both the severity of AR and rate of recurrence of obstruction associated with di screte subaortic stenosis, and whether this aggressive approach could be ju stified. Methods: Between June 1992 and April 1996, 37 patients aged 0.5-35 years (median 7.5) underwent resection of a discrete subaortic membrane. T en underwent re-operation for recurrent obstruction and eight followed prev ious ventricular septal defect closure. LVOT gradient was measured using th e modified Bernoulli equation and AR was graded on a scale of 0-4 (0 = none , 4 = severe). Postoperative assessment was performed early (<7 days) and a t mid-term (27.0 months; range 2-59 months). Results: There was significant improvement in AR from mild/moderate to none/trivial (P = 0.019) immediate ly postoperatively and LVOT gradient from 66.9 +/- 30.4 to 15.1 +/- 12.2 mm Hg (P < 0.0001). By stepwise logistic regression preoperative gradient corr elated significantly with postoperative mild/moderate AR (P = 0.015) and LV OT gradient (P = 0.0036). Preoperative mild/moderate AR also correlated wit h postoperative mild/moderate AR (P = 0.034). Five patients developed compl ete heart block, four undergoing reoperation for recurrent obstruction, and one preoperatively had right bundle branch block from previous ventricular septal defect repair. At mid-term follow-up there was no increase in AR or LVOT gradient (14.8 +/- 12.8 mmHg). Early post-operative AR was the strong est predictor of late mild/moderate AR (P = 0.02). Early post-operative gra dient was a weaker predictor (P = 0.04). Pre-operative and early post-opera tive gradient were significant predictors of late gradient (P = 0.0038; <0. 0001, respectively). No patient required reoperation for recurrent obstruct ion; one underwent late aortic valve replacement for severe AR. Conclusions : An aggressive surgical approach to discrete subaortic stenosis produces e xcellent relief of obstruction and frees the valve leaflets, significantly reducing associated AR at early and mid-term follow-up with low morbidity f or primary operation. Long-term follow-up is required to confirm whether th is early benefit is maintained. (C) 1999 Elsevier Science B.V. All rights r eserved.