michael s
(Michael S)
#1
49 What is the medical therapy for patients with
hypertrophic cardiomyopathy, and what surgical
options are of use?
Krishna Prasad
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.
