Q. Asymptomatic or Mildly Symptomatic Patients?
The treatment is controversial. Some give them betablockers/or calcium channel blockers like verapamil, in the hope of preventing progression of the disease. However there is no evidence for the same. Amiodarone is given, if Holter shows episodes of nonsustained ventricular tachycardia.
b) Moderate/Severe Symptoms
i) Medical Management
β-blocking drugs or verapamil are useful. Beta-blocker blunt heart's chronotropic response, thus limiting oxygen demand and improving diastolic dysfunction. 1/3 - 2/3 rd of patients have symptomatic improvement. Ca channel blockers are useful because both the hyper contractile systolic function and abnormalities of diastolic filling may be related to abnormal Ca kinetics. They block inward transport of Ca across myocardial cell. Verapamil improves exercise performance better than β-blockers. In non-obstructive patients,usually verapamil is preferred because of its greater effect on diastolic dysfunction. When either of them is not effective, a trial of disopyramide may be useful. Disopyramide is useful as it alters Ca kinetics. It is particularly useful with beta-blocker in reducing outflow gradient.
ii) Interventional Treatment
This is usually reserved for severely symptomatic patients with obstruction who do not respond to medical treatment. It is performed to relieve the sub aortic obstruction and normalize markedly increased LV systolic pressure. The indications are:
- refractory to standard medical treatment and
- gradient of at least 50mmHg across LV outflow tract, at rest or on provocation.
DDD Pacing
Although true benefit is uncertain, it is used as an appropriate medical therapy in persistently symptomatic patients, viz.
i) in whom there is an independent need for permanent pacing
ii) Severe bradycardia due to b-Blockers
iii) contraindications to surgery/septal ablation.