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]