What is the most appropriate management for a 2-year-old boy with known (k/c) hypertrophic cardiomyopathy and significant aortic stenosis, presenting with increased shortness of breath during physical activity and a diastolic murmur, with computed tomography (CT) showing 68% aortic stenosis and left ventricular (LV) hypertrophy?

Management of 2-Year-Old with Hypertrophic Cardiomyopathy and Severe Aortic Stenosis

This child requires urgent surgical intervention with mechanical aortic valve replacement combined with septal myectomy, as the combination of symptomatic severe aortic stenosis (68% stenosis) and hypertrophic cardiomyopathy with worsening dyspnea represents a life-threatening condition demanding definitive surgical correction. 1

Why Surgical Intervention is Mandatory

The presence of both conditions creates a "double obstruction" scenario where the fixed valvular stenosis combines with dynamic left ventricular outflow tract obstruction from the hypertrophic cardiomyopathy, making medical management or isolated interventions inadequate. 2, 1

Key Clinical Indicators for Surgery:

• Symptomatic severe aortic stenosis (68% stenosis with increasing dyspnea during activity) meets Class I indication for valve replacement 2
• Associated hypertrophic cardiomyopathy requires concurrent septal myectomy to address both obstructions simultaneously 2, 1
• Diastolic murmur suggests possible aortic regurgitation, which can complicate the hemodynamics further 2
• Age 2 years necessitates modified surgical approach but does not contraindicate intervention 1

Surgical Approach for This Patient

The modified Konno procedure is the preferred technique in young children with small aortic annuli, providing satisfactory long-term results for both aortic valve replacement and relief of basal obstruction. 2, 1

Intraoperative Considerations:

• Transesophageal echocardiography is mandatory to assess adequacy of septal myectomy and valve function 1
• Transaortic septal myectomy adds minimal risk to the valve replacement procedure and prevents postoperative hemodynamic instability 2, 1
• Single-procedure correction addresses all structural abnormalities (valve stenosis, septal hypertrophy, any mitral valve involvement) 2

Why Other Options Are Inappropriate

Reassurance is Dangerous:

• Symptomatic severe aortic stenosis requires urgent surgery (Class I recommendation) 2
• Progressive obstruction is very common in pediatric patients, and delaying intervention increases mortality risk 2
• Medical therapy does not address fixed valvular stenosis and cannot prevent sudden cardiac death in this setting 1

TAVR is Contraindicated:

• TAVR has no place in congenital aortic stenosis management, particularly in children 2
• Recent data shows TAVR in HCM patients (even adults) has significantly higher mortality (OR 5.79), cardiogenic shock (OR 4.55), and aortic dissection (OR 4.95) compared to non-HCM patients 3
• Undiagnosed or inadequately treated HCM during TAVR can lead to catastrophic hemodynamic collapse from unmasked left ventricular outflow tract obstruction 4

Activity Restriction Alone is Inadequate:

• Restricting physical activity is appropriate for mild obstruction or after successful surgical resection, but not as primary treatment for severe symptomatic disease 2
• This child already has symptoms at baseline activity levels, indicating advanced disease that requires definitive intervention 1
• Activity restriction does not treat the underlying severe aortic stenosis and leaves the patient at risk for sudden cardiac death 2

Post-Operative Management

Immediate Follow-Up:

• Echocardiography within 3-6 months to evaluate procedural results and residual obstruction 1
• Serial echocardiography every 1-2 years to monitor valve function and progression of hypertrophy 2, 1

Long-Term Considerations:

• Beta-blocker therapy to manage residual HCM symptoms and reduce arrhythmia risk 1
• Continued restriction from competitive sports given the underlying HCM diagnosis 2
• Lifelong anticoagulation required with mechanical valve 2
• Annual sudden cardiac death risk stratification as HCM carries ongoing arrhythmia risk 2

Pediatric-Specific Monitoring:

• Maximum LV wall thickness and Z-scores should be tracked as major risk factors for sudden cardiac death in children 2
• Ambulatory ECG monitoring yearly to detect non-sustained ventricular tachycardia 2

Critical Pitfall to Avoid

Do not attempt staged intervention or medical optimization first in this symptomatic child with severe stenosis. The combination of symptomatic severe aortic stenosis and HCM requires immediate surgical correction to prevent sudden cardiac death or progressive heart failure. 2, 1 While staged approaches (alcohol septal ablation followed by TAVR, or mavacamten before intervention) are being explored in high-risk adults 5, these strategies are not applicable to pediatric patients with congenital aortic stenosis who require definitive surgical correction. 2, 1