Hypertrophic obstructive cardiomyopathy: the Mayo Clinic experience

Area of Science:

• Cardiology
• Cardiac Surgery
• Genetics

Background:

• Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease causing left ventricular hypertrophy.
• Symptoms range from asymptomatic to sudden cardiac death, with medical therapy as first-line treatment.
• Septal myectomy is the preferred surgical option for medically refractory or intolerant symptomatic patients.

Purpose of the Study:

• To evaluate the efficacy and safety of septal myectomy for obstructive hypertrophic cardiomyopathy.
• To assess long-term outcomes and complications of the procedure.

Main Methods:

• Retrospective analysis of over 3,000 patients undergoing septal myectomy for HCM at Mayo Clinic (1993-2016).
• Evaluation of transaortic and transapical approaches for basal, midventricular, and apical HCM variants.
• Assessment of symptom relief, functional class improvement, and reduction in left ventricular outflow tract gradients.

Main Results:

• Hospital mortality for isolated septal myectomy is <1%, comparable to elective mitral valve repair.
• Over 90% of severely symptomatic patients experience significant improvement in functional class.
• Complications like heart block are uncommon (2%); left bundle branch block is frequent post-surgery.
• Transapical approach in 115 patients with midventricular/apical HCM showed gradient relief without major complications.

Conclusions:

• Septal myectomy is an effective and definitive treatment for relieving left ventricular outflow tract obstruction and symptoms in obstructive HCM.
• In experienced centers, early mortality is <1%, with excellent and improving outcomes.