From the Guidelines
Septal myectomy is a highly effective surgical procedure for patients with hypertrophic cardiomyopathy (HCM) who have severe symptoms despite optimal medical therapy, with a low operative mortality of less than 1% and clinical success rate of over 90% to 95%. The main indication for septal myectomy is significant left ventricular outflow tract (LVOT) obstruction with a resting or provoked gradient of ≥50 mmHg, accompanied by symptoms such as dyspnea, chest pain, syncope, or heart failure that remain refractory to medications including beta-blockers, calcium channel blockers, and disopyramide 1.
Preoperative Workup
Preoperative workup includes a comprehensive cardiac evaluation with:
- Echocardiography to assess septal thickness and LVOT gradient
- Cardiac MRI to evaluate anatomy and fibrosis
- Cardiac catheterization to exclude coronary artery disease
- A thorough clinical assessment of symptoms and functional capacity
Procedure
The procedure involves a median sternotomy approach under cardiopulmonary bypass, where the surgeon removes a portion of the thickened interventricular septum through the aortic valve. Typically, 3-10 mm of septal muscle is resected to widen the LVOT and reduce obstruction. The extent of resection is guided by intraoperative transesophageal echocardiography to ensure adequate relief of obstruction while avoiding complications such as ventricular septal defect or complete heart block.
Postoperative Care
Postoperatively, patients require close monitoring in an intensive care setting, with gradual resumption of beta-blocker therapy and anticoagulation as needed. Recovery typically takes 6-8 weeks, with most patients experiencing significant symptom improvement and reduction in LVOT gradient. Septal myectomy is especially advantageous in patients who have associated cardiac disease requiring surgical correction, and long-term survival after surgical myectomy is similar to an age-matched general population, with recurrent outflow tract obstruction being rare 1.
Key Considerations
Key considerations for septal myectomy include:
- The procedure is highly effective with low operative mortality
- Provides more durable symptom relief compared to alcohol septal ablation, particularly in younger patients with severe septal hypertrophy
- Techniques of myectomy have evolved and allow gradient relief at any level of obstruction within the ventricle
- Successful myectomy eliminates or reduces SAM-mediated MR and leads to a reduction in left atrial size and a small degree of LV reverse remodeling 1.
From the Research
Indications for Septal Myectomy
- Septal myectomy is indicated for patients with obstructive hypertrophic cardiomyopathy (HCM) who have severe symptoms unresponsive to medical therapy 2
- The procedure is suitable for both adults and children with HCM 3, 4
- Patients with abnormalities of the mitral valve and subvalvar mitral apparatus can be managed without the need for mitral valve replacement 3
Procedure for Septal Myectomy
- The surgical approach is tailored to the unique pathophysiology and septal morphology of the patient 5
- Extended transaortic myectomy is the standard procedure for patients with isolated subaortic obstruction 5
- Transapical myectomy is a useful adjunct for patients with long or midventricular obstruction 5
- The procedure involves resection of the hypertrophied septum to relieve left ventricular outflow tract obstruction 6, 3, 4
Outcomes and Complications
- Septal myectomy provides excellent postoperative outcomes in terms of symptom relief and functional improvement 3, 4, 5
- Operative morbidity and mortality rates are low in experienced centers 3, 4, 2
- The perioperative mortality rate for isolated septal myectomy is approximately 1% 3, 2
- Late survival in patients with obstructive HCM who undergo myectomy exceeds that of patients who do not receive surgical treatment 3