Interventional procedure consultation document

Off-pump coronary artery bypass grafting

Off-pump coronary artery bypass grafting

Coronary artery disease (also called coronary heart disease or ischaemic heart disease) happens when the build-up of a fatty substance narrows or blocks the arteries restricting supply of blood to the heart muscle, which may cause chest pain (angina) or a heart attack.

Coronary artery bypass grafting aims to improve the flow of blood to the heart muscle. The surgeon uses a healthy blood vessel, usually taken from the chest or the leg, and attaches it on the heart muscle so that blood can get round (‘bypass’) the affected part of the coronary artery.

The National Institute for Health and Clinical Excellence (NICE) is examining off-pump coronary artery bypass grafting (CABG) and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. NICE’s Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisers, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about off-pump CABG.

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

• comments on the provisional recommendations
• the identification of factual inaccuracies
• additional relevant evidence, with bibliographic references where possible.

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

The process that NICE 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• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.

For further details, see the Interventional Procedures Programme manual, which is available from the NICE website (www.nice.org.uk/ipprogrammemanual).

NICE is committed to promoting through its guidance race and disability equality and equality between men and women, and to eliminating all forms of discrimination. One of the ways we do this is by trying to involve as wide a range of people and interest groups as possible in the development of our guidance on interventional procedures. In particular, we aim to encourage people and organisations from groups in the population who might not normally comment on our guidance to do so. We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and give suggestions for how it might be improved. NICE reserves the right to summarise and edit comments received during consultations, or not to publish them at all, where in the reasonable opinion of NICE, the comments are voluminous, publication would be unlawful or publication would otherwise be inappropriate.

Closing date for comments: 28 September

Target date for publication of guidance: January 2010

1 Provisional recommendations

1.1 Current evidence on the safety and efficacy of off-pump coronary artery bypass grafting (CABG) is adequate to support the use of this procedure provided that normal arrangements are in place for clinical governance, consent and audit.

1.2 During the consent process, patients should be informed that they will be having off-pump CABG rather than on-pump surgery. They should be informed about the uncertainties in relation to longer-term risks of graft occlusion and mortality, as well as the likely advantages of off-pump CABG, including the lower incidence of stroke.

1.3 Patient selection and treatment should be carried out by cardiac surgical teams who are skilled in both off-pump and on-pump surgery.

1.4 NICE encourages clinicians to submit data on patients having off-pump CABG to the UK Central Cardiac Audit Database (ww.ccad.org.uk), with a view to ultimately providing information about longer-term outcomes by linking the database to national statistics records.

2 The procedure

2.1 Indications and current treatments

2.1.1 Coronary artery disease (CAD) refers to the hardening and narrowing of the coronary arteries as a result of atherosclerosis. This can cause angina and myocardial infarction and can result in heart failure. One treatment option for CAD is CABG, which is most often performed ‘on pump’, maintaining the circulation and oxygenating the blood extracorporeally using a cardiopulmonary bypass machine, while the heart is arrested (not beating).

2.2 Outline of the procedure

2.2.1 Off-pump CABG aims to avoid the potential hazards of cardiopulmonary bypass, mainly in relation to the risk of stroke. With the patient under general anaesthesia, and following a thoracotomy, the heart is displaced and snares are placed around target coronary arteries to occlude them while the bypass grafts are sutured in place. An immobilising device is used to minimise movement of the beating heart while the anastomoses are performed. Donor vessel harvesting is performed in the standard way.

Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview, available at www.nice.org.uk/IP35aoverview

2.3 Efficacy

2.3.1 Some studies reported outcomes that could be interpreted as relating either to efficacy or to safety, depending on whether or not they occurred in the immediate postoperative period (for example death and myocardial infarction), but their timing was not documented. In this guidance, outcomes with unclear timing of occurrence have been considered as efficacy outcomes (assuming that they occurred after the immediate peri- or postoperative period because they were reported with long-term follow-up data).

2.3.2 A meta-analysis of 5537 patients reported no significant difference in pooled mortality rate between off-pump and on-pump CABG (relative risk 0.98, 95% CI 0.66 to 1.44) (follow-up not stated). A non-randomised controlled study of 3014 patients treated by off-pump or on-pump CABG reported major adverse events (death, stroke or myocardial infarction) in 11% (72/637) and 15% (367/2377) of patients respectively at 1-year follow-up (p = 0.012). An RCT of 2203 patients treated by off-pump or on-pump CABG reported death, MI or revascularisation between 1 month and 1 year follow-up in 10% (105/1104) and 7% (78/1099) of patients respectively (p = 0.04).

2.3.3 A UK national register report of 86,047 patients treated since 1999 reported that 1-year survival for patients treated in the period 2004 to 2008 was 97% for off-pump CABG and 96% for on-pump CABG. By 5-year follow-up (for patients who had reached that time point), survival was 89% for off-pump CABG and 89% for on-pump CABG (significance and absolute figures not stated).

2.3.4 The meta-analysis of 5537 patients and a meta-analysis of 297,000 patients reported no significant difference between off-pump and on-pump CABG in pooled relative risk of revascularisation: 1.35 (95% CI 0.83 to 2.18) and 1.35 (95% CI 0.76 to 2.39) respectively (follow-up not stated).

2.3.5 The non-randomised controlled study of 3014 patients reported graft failure (≥ 75% stenosis) in 45% (181/402) of patients in the off-pump group and in 46% (697/1518) of patients in the on-pump group at angiographic follow-up between 12 and 18 months (p = 0.75). In the same study, occlusion of 1 or more vein grafts occurred in 42% (167/402) and 42% (633/1518) of patients respectively (p = 0.92).

2.3.6 An RCT of 2203 patients treated by off-pump or on-pump CABG reported that fewer grafts were inserted during the procedure than were planned pre-operatively in 18% of patients in the off-pump group and 11% in the on-pump group (p < 0.001) (absolute figures not stated).

2.3.7 The Specialist Advisers listed key efficacy outcomes as requirement for additional revascularisation, symptom relief and length of stay.

2.4 Safety

2.4.1 A meta-analysis of 297,000 patients reported that 30-day mortality was significantly lower following off-pump rather than on-pump CABG (pooled OR 0.72 [95%] CI 0.66 to 0.78) (p < 0.00001). The RCT of 2203 patients reported no significant difference in 30-day mortality between the off-pump group and the on-pump group (2% [18/1104] and 1% [13/1099] respectively, p = 0.47).

2.4.2 Stroke occurred significantly less frequently following off-pump CABG than on-pump CABG in the meta analysis of 297,000 patients (pooled odds ratio 0.62, 95% CI 0.55 to 0.69) (p < 0.00001) (follow-up not stated).

2.4.3 The Specialist Advisers listed theoretical adverse events as infection, bleeding and renal dysfunction. They commented that inaccurate suturing may lead to graft failure.

2 Other comments

2.5.1 This review of existing guidance was precipitated by recent evidence of higher graft occlusion rates in the longer term after off-pump CABG compared with on-pump surgery (see the RCT of 2203 patients). The Committee considered this evidence carefully in the context of other evidence on large numbers of patients for whom off-pump CABG had shown advantages without additional safety concerns.

2.5.2 The Committee was advised that OPCAB may have a particular role in the management in particular of patients with gross calcification of the ascending aorta and those with low ejection fractions.

3 Further information

3.1 This guidance is a review of IPG 35 ‘Off-pump coronary artery bypass’ published in 2004.

3.2 For related NICE guidance see www.nice.org.uk

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

September 2010

_{Personal data will not be posted on the NICE website. In accordance with the Data Protection Act names will be anonymised, other than in circumstances where explicit permission has been given.}

_{It is the responsibility of consultees to accurately cite academic work in order that they can be validated.}