What is the medical therapy for patients with hypertrophic cardiomyopathy, and what surgical options are of use?

About 40% of patients with hypertrophic cardiomyopathy (HCM) are symptomatic and a third have risk factors for sudden death. Each situation must be individually assessed. Asymptomatic patients do not need treatment routinely unless they are at risk of sudden death.

Treatment of symptoms
Typical symptoms include dyspnoea, palpitations and chest pain. Dyspnoea is usually due to left ventricular diastolic dysfunction while chest pain is frequently due to myocardial ischaemia. The pain may however be atypical and occur in the absence of demonstrable epicardial coronary disease. The treatment chosen will depend on whether there is significant outflow tract obstruction (outflow gradient  30mmHg). In those without obstruction, the choice is between either a beta blocker or a calcium
antagonist, such as high dose verapamil (up to 480mg/day). In those with obstruction a beta blocker with or without disopyramide is usually the first choice for those patients with outflow obstruction (~25% of patients). Both drugs reduce the outflow gradient and improve diastolic function by their negative inotropism. Verapamil
should only be used with caution as it may worsen the outflow obstruction (through the increased vasodilatation and consequent ventricular emptying with contraction). Palpitations may be due to supraventricular or ventricular arrhythmias. Supraventricular arrhythmias including atrial fibrillation may be controlled with beta blockers, verapamil or amiodarone.

Patients with refractory symptoms may be candidates for invasive treatment modalities such as dual chamber pacing with a short AV delay, alcohol septal ablation or surgical myectomy. Surgical septal myectomy is long established and can be combined with mitral valve replacement in patients with associated significant mitral regurgitation. When patients present with progressive ventricular dilatation and reduced systolic function, cardiac transplantation may need to be considered.

Prevention of sudden death
Identification and treatment of those at risk of sudden death is an important part of the management of patients with HCM. The known risk factors are family history of sudden death, recurrent syncope, non-sustained ventricular tachycardia and abnormal BP response during exercise. Patients with isolated risk factors need to be monitored carefully. Those with more than two risk factors clearly need treatment. Oral amiodarone and/or an implantable cardiac defibrillator are the available options.