Introduction
Affecting 1 in 500 individuals; Hypertrophic cardiomyopathy (HCM) is an
autosomal dominant cardiovascular disorder which is prevalent throughout
the world. HCM can lie dormant and appear asymptomatic or can produce a
variety of symptoms involving dyspnoea, angina, syncope, and can even
result in sudden cardiac death. HCM is typically classified as
asymmetrical septal wall hypertrophy in the absence of other causes for
hypertrophy. When left ventricular outflow tract obstruction (LVOTO)
occurs the disease is termed as hypertrophic obstructive cardiomyopathy
(HOCM), these patients are initially managed through pharmacological
means such as the use of beta blockers and calcium channel blockers. To
those patients who remain symptomatic despite optimal medical
management, intervention is required in order to reduce both obstruction
and symptoms which can place the patient as risk of death. Surgical
myectomy and alcohol septal ablation (ASA) are two methods currently
used for the management of drug refractory HOCM while the former has
been in use since the 50s, the latter can come into prominent since the
90s and may prove to be a useful, less invasive tool when confronting
patients with HOCM especially those who are more elderly or deemed to be
a higher surgical risk.
HCM is an autosomal dominant disorder and is described as left
ventricular (LV) hypertrophy in the absence of any other cardiac or
systemic disease. The disorder typically causes mutations in proteins
involved in the contractile apparatus. There are several proteins which
have been identified to be affected in HCM; the two most common being
Myocyte binding protein C (MYBPC3) and Beta-Myosin heavy chain (MYH7)
both of which have a frequency of around 40%. [1]
ASA may play a role in those who develop symptoms despite optimal drug
therapy, it is less invasive, involves shorter hospital stays, and there
are numerous centres who are producing high volumes of work and have
good outcomes. The criteria for selecting these patients are crucial in
order to minimise peri and post procedural mortality and maximise
gradient reduction. Younger individuals tend to undergo surgical
myectomy, whereas ASA is directed toward patients with advanced age,
co-morbidities or deemed to be a surgical risk. [2] ASA uses
angiography and contrast echocardiography to identify septal perforator
arteries supplying the hypertrophied septum, this artery is then
injected with small quantities of alcohol (ranging from 1-5 ml), which
infarcts the region, causing necrosis and in the coming months results
in remodelling of the myocardium and thus reducing the left ventricular
outflow tract (LVOT) gradient. [3]