The role of enucleation with or without septal myectomy for discrete subaortic stenosis.

OBJECTIVE

Substantial controversy persists regarding the need and efficacy of a routine myectomy in the treatment of discrete subaortic stenosis. Although some believe myectomy more effectively relieves subaortic narrowing, this is uncertain, and complications, including heart block and aortic valve injury, are concerns. The aims of the study were as follows: (1) to analyze the role of enucleation for relief of subaortic stenosis and the risk factors associated with recurrence and reoperation and (2) to delineate the characteristics of the patients who might benefit from enucleation alone.

METHODS

From January 1990 through May 2007, 221 patients with subaortic stenosis underwent biventricular repair. Of those, 106 patients had discrete subaortic stenosis. The preoperative peak left ventricular outflow tract gradient, as determined by means of transthoracic echocardiographic analysis, was 67.3 +/- 29 mm Hg. Forty patients had previous operations for other intracardiac anomalies. Mean age at repair was 7 years. Sixty-one patients underwent isolated enucleation, and 45 patients underwent concomitant myectomy. Patients with recurrent subaortic stenosis whose first operation was performed elsewhere were excluded from analysis.

RESULTS

There was 1 early death and 1 late death. The postoperative peak left ventricular outflow gradient decreased to 12.5 +/- 12.9 mm Hg (P < .001). No patient had development of heart block or required a pacemaker. A recurrent gradient of greater than 30 mm Hg was found in 26 (27%) patients, and 8 (7.5%) patients had reoperations. Actuarial freedom from reoperation rates at 5, 10, and 15 years were 94.7% +/- 1.8%, 89.6% +/- 3.5%, and 84.8% +/- 4.9%, respectively.Of those patients who had not undergone a previous cardiac operation, there were no significant differences in the rates of recurrence (28% vs 27%) or reoperation (4.7% vs 4.4%) between the enucleation group and the concomitant myectomy group. For the patients who had a previous cardiac operation, the concomitant myectomy group had a significantly lower rate of recurrence (44% for enucleation vs 13% for enucleation plus myectomy, P = .031).

CONCLUSIONS

For those patients undergoing primary operations for discrete subaortic stenosis, routine myectomy does not offer superior relief of left ventricular outflow tract obstruction; enucleation alone provides good results in this selected population. However, in those patients with associated cardiac anomalies, concomitant additional myectomy is recommended.