What is the treatment for mild septal hypertrophy?

Treatment for Mild Septal Hypertrophy

For patients with mild septal hypertrophy causing symptomatic left ventricular outflow tract obstruction (LVOTO), septal reduction therapy should be considered when symptoms persist despite optimal medical therapy, with surgical myectomy being the preferred option for younger patients and alcohol septal ablation for older patients or those with high surgical risk.

Medical Management

• Initial management focuses on beta-blockers, calcium channel blockers, or disopyramide to reduce outflow obstruction and improve symptoms in patients with mild septal hypertrophy 1
• QTc interval should be monitored during up-titration of disopyramide, with dose reduction if it exceeds 480 ms 1
• Medical therapy should be optimized before considering invasive interventions 1

Indications for Septal Reduction Therapy

• Septal reduction therapy is recommended for patients with:

  • Resting or maximum provoked LVOT gradient ≥50 mm Hg 1
  • NYHA functional Class III-IV symptoms despite maximum tolerated medical therapy 1
  • Recurrent exertional syncope despite optimal medical therapy 1

• Even patients with mild septal hypertrophy (≤15 mm) can develop severe heart failure symptoms requiring intervention when they have dynamic LVOTO due to elongated mitral valve leaflets 2

Septal Reduction Options

Surgical Myectomy

• Preferred treatment for most symptomatic patients with obstructive HCM, especially younger, healthy adults 1

• Advantages:

  • Direct visualization allows tailoring of resection to address specific anatomic abnormalities 1
  • Lower risk of permanent pacemaker implantation compared to alcohol septal ablation 1
  • Effective in patients with massive septal thickness (≥30 mm) 1
  • Can address concomitant mitral valve abnormalities 1

• Complications:

  • Risk of complete heart block is approximately 2% 1
  • Iatrogenic ventricular septal defect occurs in 1% of patients 1

Alcohol Septal Ablation

• Preferred for patients in whom surgery is contraindicated or considered high risk, particularly the elderly 1

• Advantages:

  • Absence of surgical incision and general anesthesia 1
  • Less overall discomfort and shorter recovery time 1
  • Similar benefit in advanced age patients compared to younger patients 1

• Limitations:

  • May be less effective in patients with extensive septal scarring on CMR 1
  • Less effective in patients with very severe hypertrophy (≥30 mm) 1
  • Higher risk (4-5 fold) of permanent pacemaker requirement compared to myectomy 1
  • Dependent on suitable septal perforator artery anatomy 1
  • Not indicated in children 1

• Special considerations for mild septal hypertrophy:

  • Higher risk of ventricular septal defect in patients with mild hypertrophy (≤16 mm) at the point of mitral leaflet-septal contact 1
  • In such cases, alternatives such as dual chamber pacing or mitral valve repair/replacement may be considered 1

Procedural Considerations

• Septal reduction therapies should be performed by experienced operators working as part of a multidisciplinary team expert in HCM management 1
• A minimum caseload of 10 septal alcohol ablations and 10 septal myectomies per operator per year is recommended 1
• For alcohol septal ablation, myocardial contrast echocardiography is essential prior to alcohol injection to ensure proper localization 1
• Injection of large volumes of alcohol in multiple septal branches is not recommended due to high risk of complications 1

Long-term Outcomes

• Both myectomy and alcohol septal ablation have shown similar improvements in functional status and hemodynamics over 3-5 years 1
• Alcohol septal ablation does not appear to increase the risk of arrhythmic events in high-risk HCM patients, with ICD discharge rates of approximately 8% per year in a high-risk cohort 3
• A greater extent of septal hypertrophy is associated with higher risk of developing atrial fibrillation, which should be considered in long-term management 4

Special Considerations for Mild Septal Hypertrophy

• Patients with mild septal hypertrophy but significant LVOTO should be assessed using physiological provocation and stress echocardiography 1
• Patients with basal septal hypertrophy may have distinctive ECG findings, including an R/S ratio >0.2 in lead V1 and Q waves in lead V4 5
• Septal curvature measurement may provide a more reproducible metric than thickness ratios for characterizing basal septal hypertrophy 6