Treatment of hypertrophic cardiomyopathy

Treatment of hypertrophic cardiomyopathy has not undergone significant changes in recent decades and remains essentially symptomatic. Along with the use of various drugs, surgical correction of the disease is currently also carried out. Considering that in recent years, ideas about the prognosis of hypertrophic cardiomyopathy have changed, the advisability of aggressive treatment tactics in most patients with hypertrophic cardiomyopathy is questionable. When conducting it, the assessment of sudden death factors is of paramount importance.

Symptomatic treatment of hypertrophic cardiomyopathy is aimed at reducing diastolic dysfunction, hyperdynamic function of the left ventricle and eliminating cardiac arrhythmia.

The following treatment methods are used:

• general events;
• pharmacotherapy;
• surgical treatment.

General measures primarily include prohibition of sports activities and limitation of significant physical exertion that can cause aggravation of myocardial hypertrophy, increase of intraventricular gradient and risk of sudden death even in asymptomatic patients. To prevent infective endocarditis in situations associated with the development of bacteremia, antibiotic prophylaxis is recommended for obstructive forms of hypertrophic cardiomyopathy, similar to that in patients with heart defects.

Non-drug treatment of hypertrophic cardiomyopathy

Children with asymptomatic disease do not require drug therapy. They are under dynamic observation, during which the nature and severity of morphological and hemodynamic disorders are assessed. Of particular importance is the identification of factors that determine an unfavorable prognosis and an increased risk of sudden death, in particular hidden prognostically significant arrhythmias.

Drug treatment of hypertrophic cardiomyopathy

The presence of clinical manifestations of obstructive hypertrophic cardiomyopathy (fainting, dyspnea, dizziness) with normal systolic function is an indication for the administration of drugs that improve diastolic relaxation and reduce the pressure gradient in the left ventricle [calcium antagonists (verapamil) or beta-blockers (propranolol, atenolol)]. They usually have a good symptomatic effect, although they do not prevent sudden death and do not affect the natural course of the disease.

In patients with obstructive pulmonary disease, it is advisable to use the cardioselective beta-blocker atenolol, although experience with its use in hypertrophic cardiomyopathy in children is somewhat less than that of propranolol.

It should be noted that self-cancellation of beta-blockers can lead to sudden death. Treatment should be started with very small doses of drugs, carefully monitoring hemodynamic parameters. The dose is increased gradually over several weeks, while clinical manifestations persist. If monotherapy is insufficiently effective, combined treatment with propranolol and verapamil is used.

Amiodarone is considered an effective drug for the treatment of hypertrophic cardiomyopathy. The drug helps eliminate subjective symptoms and increase tolerance to physical activity. It has an antiarrhythmic effect, preventing the occurrence of both supraventricular and ventricular tachyarrhythmias.

Often, in the advanced stage of the pathological process, mainly in the non-obstructive form of hypertrophic cardiomyopathy, progressive systolic dysfunction and severe heart failure associated with left ventricular remodeling (thinning of its walls and dilation of the cavity) develop. Such evolution of the disease occurs in 2-5% of patients with hypertrophic cardiomyopathy and characterizes the final (dilated) stage of a special, severe and accelerated process that does not depend on the patient's age and the duration of the disease manifestation. The increase in the systolic size of the left ventricle usually outpaces diastolic dilation and prevails over it. The clinical features of this stage are severe, often refractory congestive heart failure and an extremely poor prognosis. The treatment strategy for such patients changes and is based on the general principles of therapy for congestive heart failure, and includes careful administration of ACE inhibitors, angiotensin II receptor blockers, diuretics, cardiac glycosides, beta-blockers, and spironolactone. These patients are potential candidates for heart transplantation.

Surgical treatment of hypertrophic cardiomyopathy

In a significant number of patients with hypertrophic cardiomyopathy, traditional pharmacotherapy does not allow effective control of the disease symptoms, and the low quality of life does not satisfy patients. In such cases, it is necessary to decide on the possibility of using other treatment approaches. Potential candidates for surgical treatment are at least 5% of all patients with hypertrophic cardiomyopathy (with pronounced asymmetric hypertrophy of the interventricular septum and a subaortic pressure gradient at rest equal to 50 mm Hg or more). The classical surgical technique includes excision of the hypertrophied interventricular septum zone. The operation provides a good symptomatic effect with complete elimination or significant reduction of the intraventricular pressure gradient in 95% of patients and a significant decrease in the end-diastolic pressure in the left ventricle of most patients. In some cases, if there are additional indications to reduce the severity of obstruction and mitral regurgitation, valvuloplasty or mitral valve replacement with a low-profile prosthesis is performed simultaneously. Subsequent long-term therapy with verapamil improves the long-term results of the operation, as it improves the diastolic function of the left ventricle, which is not achieved with surgical treatment.

In recent years, there has been growing interest in exploring the possibility of using sequential dual-chamber pacing with shortened atrioventricular (AV) delay as an alternative to surgical treatment in patients with obstructive hypertrophic cardiomyopathy. However, the effectiveness of this method remains unproven at present, so its use is limited.

Another alternative method of treating refractory obstructive hypertrophic cardiomyopathy is transcatheter alcohol septal ablation. The technique involves infusion of 1-3 ml of 95% ethyl alcohol through a balloon catheter into the perforating septal branch, resulting in an infarction of the hypertrophied section of the interventricular septum, which affects 3 to 10% of the left ventricular myocardial mass (up to 20% of the interventricular septum mass). This leads to a significant reduction in the severity of outflow tract obstruction and mitral insufficiency, objective and subjective symptoms of the disease. In 5-10% of cases, there is a need for implantation of a permanent pacemaker due to the development of high-degree AV block. In addition, to date, the positive effect of transcatheter ablation on prognosis has not been proven, and surgical mortality (1-2%) does not differ from that during septal myomectomy, which is currently considered the “gold standard” for the treatment of patients with hypertrophic cardiomyopathy with severe symptoms and left ventricular outflow tract obstruction resistant to drug therapy.

Thus, the strategy of treatment measures for hypertrophic cardiomyopathy is quite complex and involves an individual analysis of the entire complex of clinical, anamnestic, hemodynamic parameters, results of gene diagnostics and stratification of the risk of sudden death, an assessment of the characteristics of the course of the disease and the effectiveness of the treatment options used. In general, rational pharmacotherapy in combination with surgical treatment and electrocardiotherapy allows for a good clinical effect, preventing the occurrence of severe complications and improving the prognosis in a significant proportion of patients with hypertrophic cardiomyopathy.

Forecast

According to recent research data based on the widespread use of echocardiography and (especially) genetic studies of families of patients with hypertrophic cardiomyopathy, the clinical course of this disease is obviously more favorable than previously thought. Only in isolated cases does the disease progress rapidly, ending in death.

As shown by long-term observations using echocardiography, the development of left ventricular hypertrophy in hypertrophic cardiomyopathy occurs mainly during puberty (at the age of 12-14 years). The thickness of the left ventricular myocardium in this case approximately doubles over 1-3 years. The identified left ventricular remodeling is usually not accompanied by clinical deterioration, and most of these children remain asymptomatic. In patients aged 18 to 40 years, further thickening of the interventricular septum occurs rarely and is not accompanied by changes in cardiohemodynamics. In adulthood, the process of left ventricular remodeling can occur with gradual thinning of the myocardium and dilation of the ventricular cavity.

Based on the results of long-term observations, in some patients, including children, the transformation of hypertrophic cardiomyopathy into dilated cardiomyopathy was established. The development of left ventricular dilation and systolic heart failure is associated with dyspnea, syncope, atrial fibrillation and a significant increase in ventricular myocardial mass.

Despite the relatively favorable course, complications often arise with hypertrophic cardiomyopathy, which become the immediate cause of death of patients. In young children, the most common cause of death is refractory congestive heart failure. Older children and adults in most cases die suddenly.