The National Institute for Clinical Excellence is examining non-surgical reduction of the myocardial septum and will publish guidance on its safety and efficacy to the NHS in England and Wales. The Institute's Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisors, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about non-surgical reduction of the myocardial septum.

This document has been prepared for public consultation. It summarises the procedure and sets out the provisional recommendations made by the Advisory Committee.

Note that this document is not the Institute's formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that the Institute will follow after the consultation period ends is as follows:

• The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
• The Advisory Committee will then prepare the Final Interventional Procedure Document (FIPD) and submit it to the Institute.
• The FIPD may be used as the basis for the Institute's guidance on the use of the procedure in the NHS in England and Wales.

For further details, see the Interim Guide to the Interventional Procedures Programme, which is available from the Institute's website (www.nice.org.uk/ip).

Closing date for comments: 25 November 2003

Target date for publication of guidance: May 2004

Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation.

Current evidence on the safety and efficacy of non-surgical reduction of the myocardial septum appears adequate to support the use of the procedure, provided that normal arrangements are in place for consent, audit and clinical governance.

The procedure should only be performed in specialist units by clinicians specially trained in its use. NICE has asked the British Cardiovascular Intervention Society to produce standards for training.

Non-surgical reduction of the myocardial septum is used to treat outflow tract obstruction in patients with hypertrophic obstructive cardiomyopathy (HOCM). Patients with HOCM have abnormally thickened heart muscle, which narrows the outflow tract from the left ventricle often causing chest pain, breathlessness, palpitations and fainting spells. There is an increased risk of sudden death from heart attacks or abnormal heart rhythms.

Most patients with HOCM are treated with medication. More invasive treatments may be considered in patients who still get symptoms despite drug treatment. The standard surgical treatment is ventricular septal myotomy-myectomy, using an open surgical technique that requires cardiopulmonary bypass.

Non-surgical ablation of the myocardial septum does not require open chest surgery or cardiopulmonary bypass. It involves inserting a catheter into the femoral artery and passing it up into the heart under X-ray control. Alcohol is injected into an artery supplying blood to the septum. This destroys a part of the muscle in the septum, which then becomes thinner.

The studies showed that non-surgical reduction of the myocardial septum is efficacious in the short term. In three non-randomised studies the mean reduction in gradient across left ventricular outflow tract (LVOT) ranged from 22 mm Hg to 42 mmHg, and compared favourably to the mean reduction in LVOT gradient for open surgery. The studies also reported reduced numbers of patients suffering from severe breathlessness and fainting spells after treatment. There is, however, a lack of long term follow-up. For more details, refer to the Overview (see Appendix).

The Specialist Advisors considered the procedure to be an established alternative to surgical relief of outflow tract obstruction in patients with HOCM.

In the studies the most commonly reported complication was the need for patients to have a permanently implanted pacemaker due to complete heart block following the procedure. In one non-randomised study of 41 patients, 9 patients required a permanent pacemaker. The same study reported one procedure-related death. For more details refer, to the Overview (see Appendix).

The Specialist Advisors cited a 10% risk of complete heart block, requiring patients to have a permanent pacemaker after having this procedure. The Advisors considered the procedure to be safe when performed by experienced operators in specialist units with an established interest in HOCM.

Skilled use of ultrasound is required to identify the blood supply to the hypertrophic myocardium, and thus control the infarct size.

Appropriate patient selection is essential.

The following document, which summarises the evidence, was considered by the Interventional Procedures Advisory Committee when making it's provisional recommendations.

• Interventional Procedure Overview of Non-surgical reduction of myocardial septum, December 2002

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