Surgery for hypertrophic cardiomyopathy benefits pediatric patients

March 31, 2022

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy, affecting 1 in 500 individuals. It is also the most common cause of sudden death in young people, especially young athletes.

HCM manifests as left ventricular hypertrophy absent other etiologies. Approximately 60% to 70% of people have an identifiable genetic pathogenic variant.

Family history is critical in the evaluation of these patients. All first-degree relatives of any adult or pediatric patient with HCM require screening with echocardiography, and affected adults have a 50% chance of passing along a pathogenic variant to their children.

Echocardiograms performed due to a positive family history may need to be repeated at intervals throughout life, often every few years in childhood, every 1 to 2 years in adolescence and every 3 to 5 years in adulthood.

Echocardiography is used to identify left ventricular hypertrophy and outflow tract obstruction, which are present in 70% of patients. Magnetic resonance imaging with gadolinium enhancement also is recommended to complement echocardiography and determine the amount of muscle fibrosis present.

Medical treatment is the first line therapy for symptomatic patients with HCM. This treatment most commonly includes blood pressure medications, such as beta-blocker or calcium channel blocker medications, or anti-arrhythmics.

Symptoms can include:

  • Shortness of breath, especially during exercise
  • Chest pain or pressure, especially during exercise
  • Fainting, especially during or just after exercise or exertion
  • Heart murmur
  • Heart palpitations

Extended left ventricular septal myectomy — an open-heart operation that includes resection of thickened septal myocardium that contributes to left ventricular outflow tract obstruction — is the procedure of choice if medical treatment is unsuccessful or intolerable side effects of medical therapy occur.

"Mayo Clinic doctors evaluate and treat more than 2,100 children and adults for HCM each year," says Joseph A. Dearani, M.D., director of pediatric and adult congenital heart surgery at Mayo Clinic in Rochester, Minnesota. "About two-third of patients will be candidates for septal myectomy, including our pediatric patients."

The overall myectomy experience at Mayo Clinic is approximately 4,500 patients. The pediatric myectomy experience now exceeds 200 procedures.

Septal myectomy is indicated in patients with HCM who have symptoms refractory to medical therapy and severe left ventricular outflow tract obstruction, defined as a resting or provoked gradient of greater than 30 mm Hg. Additional indications now include symptomatic patients with low resting outflow gradients and latent obstruction, the presence of pulmonary hypertension or atrial tachyarrhythmias, or severe concomitant mitral regurgitation. Finally, the Mayo Clinic experience suggests that a subgroup of patients with favorable septal anatomy responds exceptionally well and could be considered for surgery prior to failing medical therapy.

Consideration for surgery in pediatric patients

Medical treatment and indications for surgery are generally the same for pediatric and adult patients. But younger children often don't have symptoms. Frequently, the hypertrophy begins to develop in adolescence or during growth spurts. Lack of symptoms makes the surgery decision more difficult.

Pediatric myectomy is technically more challenging due the smaller structures, resulting in increased chances of incomplete myectomy or a complication such as aortic or mitral valvular injury. While symptom improvement can be expected following myectomy in children, the prognosis of pediatric patients with HCM is poorer than that for adults. Despite this, the Mayo Clinic experience demonstrates that septal myectomy can be safe and effective in symptomatic children, producing greater late survival and a better quality of life than the expected survival of patients with obstruction treated with medical therapy alone.

"Surgical myectomy is a very successful operation for most of our patients. The operation can be performed safely in experienced centers. Although many children require placement of an implantable cardioverter-defibrillator at the time of myectomy to reduce the incidence of sudden death, the quality of life is improved, and medicine requirements are often reduced in the short term," says Dr. Dearani. At experienced centers, including Mayo Clinic, early mortality for isolated septal myectomy is less than 1%.

"Our results indicate that myectomy could benefit more patients with HCM," Dr. Dearani says. "There are some prior perceptions about increased risk or lack of experienced surgeons for this procedure. With Mayo Clinic's experienced care team, the complication rates are very low and our success rates are very high."

For more information

Refer a patient to Mayo Clinic.