History

‘He was a bold man that first ate an oyster’ – Jonathan Swift

Boldness was also required on behalf of both cardiologist and patient to experience the effects of injecting alcohol down the coronary artery for the first time. In 1994, following preliminary experiments involving temporary balloon occlusion of the first septal artery, Ulrich Sigwart injected 3ml of absolute alcohol down the septal artery of a woman with hypertrophic cardiomyopathy at the Royal Brompton Hospital. The procedure was effective in reducing her outflow tract obstruction and her symptoms improved. In the 11 years since its birth, the efficacy and safety of septal ablation has led to its acceptance as a valid treatment option by even its fiercest original critics.

Indications

The role of septal ablation is to reduce symptoms of outflow tract obstruction (exertional chest pain, breathlessness and pre-syncope/syncope). There is no evidence for any effect on prognosis. Patients are suitable for the procedure if they have evidence of outflow tract obstruction ( 50 mmHg) and symptoms unresponsive to medical therapy. Such patients can be treated with either surgery (myotomy-myectomy) or septal ablation. The results of surgery are excellent in experienced high-volume centres (particularly in the USA), and there are more long-term data on safety and efficacy than for septal ablation. Following surgery there is also a lower incidence of the need for pacemaker implantation than after septal ablation. Surgery also allows concomitant treatment of any structural abnormalities of the mitral valve. On the other hand, septal ablation avoids all the problems associated with open heart surgery. There are no large surgical programs in the UK at present.

Results and Complications

In general, the short/medium term results of septal ablation are similar to that of myotomy-myectomy. Reports in around 600 patients show that the procedure is effective in reducing outflow tract obstruction, improving symptoms and exercise performance to a similar degree to that seen after surgery. The mortality is 1-2%. Heart block is relatively common at the time of alcohol injection but is usually only transient. A small number of patients develop heart block later at 3-4 days post-operatively. This always requires treatment with a permanent pacemaker and means that patients without pre-existing pacemakers/ICD’s need to have in-patient monitoring for around 5 days after septal ablation. The overall incidence of heart block requiring permanent pacemaker following septal ablation is around 10%, but the risk is higher in female patients and in those with pre-existing conducting system disease (e.g. LBBB pre-op).

Numbers of Procedures

In the UK the procedure is performed in relatively small numbers (around 30 pa) in a few centres. This is probably appropriate. Patients requiring septal ablation are rare and the procedure should be performed as part of a comprehensive HCM service rather than to enhance the interventional cardiologists CV! NICE published general guidance on septal ablation in 2003 and BCIS is in the process of formulating more specific guidance for individuals and institutions.

Future Directions

In the last few years, around 3500 septal ablations have been performed worldwide – more than all the myotomy-myomectomies in the last 45 years. Whilst some of this may reflect septal ablation’s greater acceptability to patients, there is a concern about proper patient selection. Some HCM experts are also uneasy about the long term consequences on cardiac rhythm of septal ablation and feel that there are important differences between the scar induced by surgery and that induced by septal ablation. Whilst there are no data to suggest long-term arrhythmic problems following septal ablation, interventional cardiologists performing the procedure need to be vigilant in collecting and reporting long term results. Despite these concerns septal ablation is now firmly established as a therapeutic option for patients with hypertrophic obstructive cardiomyopathy, offering results that compare very favourably with surgical treatment – boldness sometimes pays off!

Charles Knight
London Chest Hospital