Treatment of hypertrophic cardiomyopathy

Treatment of hypertrophic cardiomyopathy in recent decades has not undergone significant changes and in essence remains largely symptomatic. Along with the use of various drugs, surgical correction of the disease is currently being carried out. Given that in recent years, the concept of the prognosis of hypertrophic cardiomyopathy has changed, the rationale for aggressive treatment tactics in most patients with hypertrophic cardiomyopathy raises doubts. When it is conducted, evaluation of the factors of sudden death is very important.

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

The following treatment methods are used:

• common activities;
• pharmacotherapy;
• surgery.

The general measures include, first of all, the prohibition of sports and the restriction of significant physical exertion, which can exacerbate myocardial hypertrophy, an increase in the intraventricular gradient and the risk of sudden death even in asymptomatic patients. To prevent infectious endocarditis in situations associated with the development of bacteremia, in obstructive forms of hypertrophic cardiomyopathy, antibiotic prophylaxis is recommended, similar to that in patients with heart defects.

Non-drug treatment of hypertrophic cardiomyopathy

Children with asymptomatic course of the disease do not need medication therapy. They are under dynamic observation, in its course evaluate the nature and severity of morphological and hemodynamic disorders. Of particular importance is the identification of factors determining the 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 (syncope, dyspnea, dizziness) with normal systolic function is an indication for the appointment of drugs that improve diastolic relaxation and reduce the pressure gradient in the left ventricle [calcium antagonists (verapamil) or beta adrenoblockers (propranolol, atenolol)]. They usually give a good symptomatic effect, although they do not prevent sudden death and do not affect the natural course of the disease.

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

It should be noted that the independent abolition of beta-blockers can lead to sudden death. Treatment should begin with very small doses of drugs, carefully monitoring hemodynamic parameters. The dose is increased gradually over several weeks while the clinical manifestations persist. With insufficient effectiveness of monotherapy, combined treatment with propranolol and verapamil is used.

To effective drugs in the treatment of hypertrophic cardiomyopathy include amiodarone. The drug contributes to the elimination of subjective manifestations and increased tolerance to physical activity. It has an antiarrhythmic effect, while preventing the occurrence of both supraventricular and ventricular tachyarrhythmias.

Often, in the far-reaching stage of the pathological process, predominantly in the non-obstructive form of hypertrophic cardiomyopathy, progressive systolic dysfunction and severe heart failure associated with remodeling of the left ventricle (thinning of its walls and dilatation of the cavity) develop. This evolution of the disease occurs in 2-5% of patients with hypertrophic cardiomyopathy and characterizes the final (dilatation) stage of a special, hard and accelerated process, independent of the age of the patient and the prescription of the disease. The increase in the systolic size of the left ventricle usually outstrips the diastolic expansion and predominates over it. Clinical features of this stage - a pronounced, often refractory congestive heart failure and an exceptionally poor prognosis. The therapeutic strategy for these patients varies and is based on the general principles of therapy for congestive heart failure, prescribes a cautious appointment of ACE inhibitors, angiotensin II receptor blockers, diuretics, cardiac glycosides, beta adrenoblockers and spironolactone. These patients are potential candidates for cardiac transplantation.

Surgical treatment of hypertrophic cardiomyopathy

In a significant number of patients with hypertrophic cardiomyopathy, traditional pharmacotherapy does not effectively control the symptoms of the disease, and low quality of life does not suit patients. In such cases, it is necessary to decide on the possibility of using other therapeutic approaches. Potential candidates for surgical treatment are at least 5% of all patients with hypertrophic cardiomyopathy (with marked asymmetric hypertrophy of the interventricular septum and a subaortic pressure gradient at rest equal to 50 mm Hg or more). Classical surgical technique includes excision of the zone of hypertrophic interventricular septum. The operation provides a good symptomatic effect with the complete elimination or significant reduction of intraventricular pressure gradient in 95% of patients and a significant decrease in end-diastolic pressure in the left ventricle of the majority of patients. In some cases, in the presence of additional indications to reduce the severity of obstruction and mitral regurgitation, valvuloplasty or prosthetics of the mitral valve with a low-profile prosthesis are performed concurrently. To improve the long-term results of the operation, subsequent long-term therapy with verapamil allows for improved diastolic function of the left ventricle, which is not achieved with surgical treatment.

In recent years, the growing interest is the study of the possibility of using as an alternative to surgical treatment of patients with obstructive hypertrophic cardiomyopathy by sequential two-chamber pacing with a shortened atrioventricular (AV) delay. However, the effectiveness of this method is currently unproven, so its use is limited.

Another alternative treatment for refractory obstructive hypertrophic cardiomyopathy is transcatheteral alcohol septal ablation. The technique involves infusion through a balloon catheter into the perforated septal branch of 1-3 ml of 95% ethyl alcohol, resulting in an infarction of the hypertrophic part of the interventricular septum, which seizes 3% to 10% of the left ventricular myocardial mass (up to 20% of the interventricular septum mass). This leads to a significant decrease in the severity of obstruction of the exit tract and mitral insufficiency, objective and subjective symptoms of the disease. At the same time, in 5-10% of cases there is a need for implantation of a permanent pacemaker in connection with the development of high-grade AV blockade. In addition, the positive effect of transcatheter ablation on prognosis has not been proven to date, and operational mortality (1-2%) does not differ from that for septal myomectomy, which is now considered the gold standard for the treatment of patients with hypertrophic cardiomyopathy with severe symptoms and obstruction of the left ventricular outflow tract, resistant to pharmacotherapy.

Thus, the strategy of therapeutic measures in hypertrophic cardiomyopathy is rather complicated and involves an individual analysis of the whole complex of clinical, anamnestic, hemodynamic indicators, the results of gene diagnosis and stratification of the risk of sudden death, an assessment 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 to obtain a good clinical effect, to prevent the occurrence of severe complications and improve the prognosis in a significant part of patients with hypertrophic cardiomyopathy.

Forecast

According to recent studies based on extensive use of EchoCG 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 the disease progresses rapidly, ending with a fatal outcome.

Long-term observations using echocardiography show that the development of left ventricular hypertrophy in hypertrophic cardiomyopathy occurs mainly during puberty (at the age of 12-14 years). The thickness of the myocardium of the left ventricle thus increases approximately twice within 1-3 years. The revealed remodeling of the left ventricle is usually not accompanied by clinical deterioration, and most of these children remain asymptomatic. In patients aged 18 to 40 years, a 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 proceed with gradual thinning of the myocardium and dilatation of the ventricular cavity.

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

Despite a relatively favorable course, with hypertrophic cardiomyopathy, complications often occur that become the direct 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.