The National Institute for Clinical Excellence is examining intraoperative fluorescence angiography for the evaluation of coronary artery bypass graft patency and will publish guidance on its safety and efficacy to the NHS in England, Wales and Scotland. 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 intraoperative fluorescence angiography for the evaluation of coronary artery bypass graft patency.

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 preliminary recommendation
• the identification of factual inaccuracies
• additional relevant evidence.

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• The Advisory Committee will then prepare draft guidance which will be the basis for the Institute's guidance on the use of the procedure in the NHS in England, Wales and Scotland.

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: 22 June 2004

Target date for publication of guidance: September 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 intraoperative fluorescence angiography suggests that the procedure is safe enough for routine use in the evaluation of coronary artery bypass graft patency. However, the diagnostic utility¹ of the procedure remains uncertain.

Further research into the diagnostic utility of this procedure will be useful in reducing the current uncertainty, and clinicians should audit and review the clinical value of intraoperative fluorescence angiography in all patients having the investigation. The Institute may review the procedure upon publication of further evidence.

Coronary artery bypass grafting is one of the most common cardiac surgical interventions. In this procedure a section of vessel from another part of the body is used to reroute (bypass) blood around a blocked coronary artery and improve blood flow to the heart. Early blockage of the graft caused by narrowing and poor blood flow is a significant cause of morbidity and mortality in patients who have undergone coronary artery bypass grafting. Complications include arrhythmia, refractory angina and myocardial infarction.

Several techniques are used intraoperatively to assess graft patency. These include digital palpation, electromagnetic flow measurement, Doppler studies, and conventional and thermal coronary angiography techniques. A limitation with many of the imaging techniques is that they provide poor resolution and definition of the grafts.

Intraoperative fluorescence angiography allows confirmation of the location of the coronary arteries and assessment of bypass graft function during coronary artery bypass procedures. The intraoperative fluorescence imaging system consists of a video camera and a laser diode that emits monochromatic light. The camera, guided by a range-detector diode, is positioned a safe distance above the heart. A small amount of indocyanine green (ICG) dye is then administered as a central venous injection. This dye fluoresces when illuminated using laser energy and the images are recorded digitally. Currently the technique is only semiquantitative, in that it permits assessment of graft flow as 'excellent', 'satisfactory' or 'poor' - it cannot provide an exact measure of graft flow. The penetrating depth of the laser beam is only around 1 mm, limiting the use of this technique to certain grafts. For more details, refer to the sources of evidence (see Appendix).

There is currently limited information on the use of this procedure in evaluating the patency of coronary bypass grafts. The evidence on efficacy is based on two full-text studies, with only one study reporting on clinically relevant results. In this study, intraoperative graft patency was assessed in 84 patients; graft patency was confirmed in 80 patients (95%), with the additional information provided by the procedure resulting in graft revision of four patients. No other outcomes were reported. For more details, refer to the sources of evidence (see Appendix).

One Specialist Advisor considered there to be too little information available regarding efficacy.

Complications associated with this procedure appear to be uncommon. The authors of the two full-text papers included in the review stated that there were no adverse events associated with the use of the ICG dye. Six additional papers were identified that described complications following the administration of ICG dye for indications other than coronary graft patency. Most of these were reports of patients developing anaphylactoid reactions, with an incidence ranging from 0.02% to 0.3%. For more details, refer to the sources of evidence (see Appendix).

One Specialist Advisor stated that anaphylactic/allergic reactions may occur very rarely as a result of this procedure.

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

• Interventional procedure overview of intraoperative fluorescence angiography for the evaluation of coronary artery bypass graft patency, October 2003

Available from: www.nice.org.uk/ip238overview