Reoperation after relief of congenital subaortic stenosis☆

Abstract

We read with interest the paper by Dodge-Khatami et al. [1] on risk factors for reoperation after relief of congenital subaortic stenosis. We compliment them on their extensive statistical analysis and would like to discuss their results as well as our own [2]. Preoperative left ventricular outflow tract (LVOT) gradients in their series ranged from 5 to 120 mmHg, which would lead us to question the need for operation with a preoperative gradient of only 5 mmHg (unless the stenosis was mild or combined with other lesions), their definition of significant postoperative gradients and their threshold for a reoperation. In our experience, and in those of others [3], a peak instantaneous gradient 30 mmHg is considered significant even in the presence of normal left ventricular (LV) function. Progression of LV hypertrophy, LV dysfunction and new aortic incompetence may necessitate operation regardless of the gradient. At a median follow-up of 2.6 years (range 0.3—7.5 years), the authors [1] report a reoperation rate of 19% (n = 11), of which 12 % (5/43) were in the simple group and 40% (6/15) were in the complex group. However, there is no detailed information about patients with immediate postoperative gradients, which may significantly correlate with long-term results [4]. Our experience with discreet subaortic membrane (SAM) consisted of 45 patients with a preoperative gradient of 50— 154 mmHg (86.5 33.2 mmHg); 19 of these had significant LV dysfunction. Transaortic resection of SAM was performed in all patients and was combined with the excision of a wedge shaped segment of septal muscle underlying the membrane. There were no early or late deaths and our follow-up ranged from 18 to 113 months (mean 67 4 months). Only four patients had significant gradients. In all these patients, the immediate postoperative gradients were 25, 20, 25 and 8 mmHg, respectively and progressed to 30—60 mmHg over a 2—5 year period. The actuarial freedom from significant gradients was 89.9 0.4% at 96 months. In one of these, the