Hypertrophic cardiomyopathy (HCM) is an inherited heart condition characterized by abnormal thickening of the heart muscle, particularly in the left ventricle. This thickening makes the heart chamber smaller and stiffer, impeding the flow of blood out to the body and preventing the heart from relaxing fully to fill with blood. Management is a highly personalized strategy based on symptoms, the degree of obstruction, and the patient’s overall risk profile. Treatment plans range from targeted medications to procedural interventions and device implantations.
Initial Management and Symptom Relief Through Medication
The primary goal of initial drug therapy for symptomatic patients is to control physical manifestations of HCM, such as shortness of breath, chest pain, and palpitations. First-line pharmacological management focuses on slowing the heart rate, allowing the heart muscle more time to relax and fill with blood. This improved filling reduces the pressure gradient caused by the thickened muscle blocking the outflow tract.
Beta-blockers are typically the first choice of medication, working to reduce the force of heart muscle contraction and slow the heart rate. By decreasing the heart’s demand for oxygen and extending the relaxation phase, they effectively alleviate symptoms in many patients. When beta-blockers are not tolerated or insufficient, non-dihydropyridine calcium channel blockers (e.g., verapamil or diltiazem) are often used as an alternative. These medications also slow the heart rate and improve the heart’s ability to relax, though they must be used with caution in patients with low blood pressure.
A newer class of targeted drugs, cardiac myosin inhibitors, has emerged for the treatment of obstructive HCM. Mavacamten is an inhibitor that acts directly on the fundamental cause of the disease: hypercontractility of the heart muscle. The medication works by decreasing the number of myosin heads in the “on” state, which reduces the formation of force-producing cross-bridges within the sarcomere. This action normalizes the excessive contractility and directly reduces the left ventricular outflow tract (LVOT) obstruction, leading to symptomatic relief and improved exercise capacity.
Procedural Interventions for Obstructive Hypertrophic Cardiomyopathy
When pharmaceutical management is unable to control symptoms in patients with significant LVOT obstruction, procedural interventions become necessary to physically reduce the blockage. These procedures, known collectively as septal reduction therapy (SRT), are chosen based on the patient’s age, medical history, and the specific anatomy of the heart. The two main options are surgical septal myectomy and alcohol septal ablation.
Septal myectomy is an open-heart surgical procedure considered the gold standard for relieving obstruction, especially in specialized centers. The surgeon removes a precise amount of the thickened septal muscle that is bulging into the left ventricular outflow tract. This surgical approach offers the most complete and durable relief of the obstruction, resulting in a greater reduction of the pressure gradient and a higher rate of long-term functional improvement. The procedure also allows for the repair of associated problems, such as a leaky mitral valve, at the same time.
Alcohol septal ablation (ASA) is a less invasive, catheter-based alternative reserved for patients who are not suitable candidates for open-heart surgery due to advanced age or other medical conditions. The procedure involves threading a catheter into a small coronary artery that supplies blood to the obstructing part of the septum. Alcohol is injected into this artery, causing a controlled, localized heart attack that shrinks the targeted muscle tissue. The resulting scar tissue is thinner and less bulky, which reduces the severity of the LVOT obstruction.
While ASA is less invasive, it carries a higher risk of damaging the heart’s electrical conduction system, which can result in a complete heart block. Consequently, up to 12% of patients undergoing ASA may require a permanent pacemaker, a significantly higher rate than seen after septal myectomy. Myectomy, due to its surgical precision, is associated with a lower risk of this complication (approximately 3% to 4%). Furthermore, the reduction in the pressure gradient and the long-term functional improvement are superior and more predictable with the surgical myectomy approach.
Implantable Devices for Sudden Cardiac Death Prevention
The prevention of sudden cardiac death (SCD) is a crucial component of HCM management, as this risk exists even in asymptomatic patients. Risk is assessed through stratification, and for those deemed high-risk, the implantation of an Implantable Cardioverter-Defibrillator (ICD) is the recommended intervention. An ICD is a small device surgically placed under the skin near the collarbone, with wires leading to the heart.
The ICD continuously monitors the heart’s electrical activity and is programmed to deliver an electrical shock to restore a normal rhythm if a life-threatening, rapid arrhythmia, such as ventricular fibrillation, is detected. The decision to implant an ICD for primary prevention is based on several major risk factors. These factors include a personal history of unexplained fainting (syncope), a family history of premature SCD in a first-degree relative, or the finding of non-sustained ventricular tachycardia (NSVT) on Holter monitoring.
Massive thickening of the heart wall (30 mm or greater in any segment) is a strong indicator for ICD placement. The device acts as a permanent safeguard, offering protection against the most feared complication of HCM. While the device does not treat the underlying thickening of the heart muscle, it is an effective, life-saving measure for patients with a heightened risk of electrical instability.
Long-Term Monitoring and Lifestyle Adjustments
Long-term management of HCM requires consistent monitoring and significant lifestyle modifications beyond medications and procedures. Patients must maintain regular follow-up with a cardiologist, including periodic echocardiograms and electrocardiograms (ECGs). This surveillance monitors the stability of heart muscle thickness, assesses the degree of obstruction, and screens for changes in cardiac rhythm.
Lifestyle adjustments play an important role in managing symptoms and maintaining cardiovascular health. While historically exercise was restricted, current guidelines encourage mild-to-moderate intensity aerobic activity, such as walking or cycling. However, participation in intense competitive sports and activities involving sudden bursts of high energy, like heavy weightlifting, is discouraged to avoid dangerous fluctuations in blood pressure and heart rhythm.
Hydration is important, as dehydration can temporarily worsen the obstruction and lower blood pressure. Patients are advised to follow a heart-healthy diet and to be cautious with over-the-counter medications that contain stimulants, such as cold remedies, which can strain the heart. Given the genetic nature of the condition, genetic counseling is a fundamental part of long-term care, providing information on the risk of transmission and guiding cascade screening efforts for family members.