Incidence of Reoperation After Surgical Procedure for Left Ventricular Outflow Tract Obstruction in Children and Young Adults

[Redo surgical treatment of a patient with hypertrophic cardiomyopathy and recurrent left ventricular outflow tract obstruction]

Septal myectomy is the gold standard for patients with obstructive hypertrophic cardiomyopathy. Nevertheless, some patients develop postoperative recurrence of left ventricular outflow tract obstruction and clinical symptoms of heart failure. Such ones require redo surgery if optimal medical therapy is ineffective.

Treatment Strategies for Hypertrophic Cardiomyopathy: Surgical

Septal myectomy is a well-established procedure for septal reduction in patients with obstructive hypertrophic cardiomyopathy (HCM) who have not responded to medical treatment. The surgical approach is tailored to the unique pathophysiology and septal morphology of the patient. Extended transaortic myectomy is the standard procedure for patients with isolated subaortic obstruction, the most common type of HCM. However, transapical myectomy is a useful adjunct for patients with long or midventricular obstruction and is our preferred technique for ventricular enlargement in patients with severe symptomatic diastolic heart failure because of extensive apical hypertrophy. Septal myectomy provides excellent postoperative outcomes as regards symptom relief and functional improvement, and operative morbidity and mortality rates are low in experienced centers. This article summarizes our current surgical management of patients with HCM and details operative methods and outcomes.

Hypertrophic Cardiomyopathy: Preadolescence, Mitral Valve Disease, and Midventricular Obstruction

Septal myectomy is indicated in patients with obstructive hypertrophic cardiomyopathy (HCM) who have persistent symptoms despite medical therapy, intolerance of medication side effects, or severe resting or provocable gradients. Septal myectomy at high volume centers is safe, with low operative mortality (1%) and low rates of complications such as complete heart block or ventricular septal defect (3% and 0.5%, respectively). Additionally, improved survival following myectomy has been observed when compared to patients with obstructive HCM managed medically or those with nonobstructive HCM. As a longstanding, quaternary referral center for septal myectomy, our institution has built significant experience and expertise in the surgical and medical management of HCM, including atypical HCM, defined as preadolescent patients, those with mitral valve disease, and those with isolated midventricular obstruction. The most important factor of septal myectomy in achieving complete resolution of obstruction and avoiding recurrence is the apical extent of the myectomy trough, which must extend to the septum opposite the papillary muscles. If this cannot be fully achieved via a transaortic exposure, especially in preadolescents and patients with midventricular obstruction, then a transapical approach may be needed. Mitral valve repair is rarely necessary as SAM-mediated MR resolves with adequate myectomy alone, but mitral repair is performed in cases of intrinsic valvular disease. In this manuscript we provide a summary of current operative techniques and outcomes data from our institution on the management of these various categories of HCM.

Septal Myectomy Outcomes in Children and Adolescents With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Little data exist regarding characteristics and outcomes of pediatric patients undergoing septal myectomy. We evaluated this in a large referral population.

METHODS

Septal myectomy was performed in 199 consecutive patients aged ≤18 years with obstructive hypertrophic cardiomyopathy from January 1, 1976, to June 30, 2021.

RESULTS

Median age was 13 years (interquartile range [IQR], 8-15 years). Left ventricular myectomy approaches included transaortic (163 of 198 [82%]), transapical (16 of 198 [8%]), and combined (19 of 198 [10%]). Right ventricular interventions included myectomy (13 of 199 [7%]) and patch reconstruction of the outflow tract (15 of 199 [8%]). Maximum left ventricular outflow tract gradients decreased after myectomy (prebypass: 50 mm Hg [IQR, 31-73 mm Hg] vs postbypass: 4 mm Hg [IQR, 0-9 mm Hg], P < .001), and this was sustained long-term (5 mm Hg [IQR, 5-10 mm Hg] at 10 years). Iatrogenic aortic and mitral valve injuries occurred in 13 of 199 (7%) and 1 of 199 (1%), respectively; however, all were successfully repaired. Operative mortality was 2 of 199 (1%). The cumulative incidence of redo myectomy was low, at 5.8% at 5 and 8.3% at 10 years. Redo myectomy patients had higher maximum left ventricular outflow tract gradients on echocardiography at predischarge and 1 year and were younger at the index operation (8 years [IQR, 2.5-10 years] vs 13 years [IQR, 9-16 years], P < .001). Overall survival at 10 years was 90%, relative to 47% in a previously reported pediatric nonoperative cohort.

CONCLUSIONS

Pediatric septal myectomy provides safe, effective, and durable relief of ventricular outflow tract obstruction. Iatrogenic valve injury remains a low but nonnegligible risk. Recurrent obstruction requiring redo myectomy is infrequent and can be identified early. Long-term survival in this pediatric septal myectomy cohort appears to fare better than pediatric hypertrophic cardiomyopathy cohorts managed nonoperatively.