Interventional procedure consultation document

Optical coherence tomography to guide percutaneous coronary intervention

Optical coherence tomography to guide procedures on the arteries to the heart.

Optical coherence tomography (OCT) is a method for creating pictures of the inside of blood vessels. A thin flexible tube (a catheter) with a tip emitting near-infrared light is inserted into an artery at the groin under local anaesthetic, in the same way as the balloon catheters and stents used to treat narrowings in the coronary arteries (which supply blood to the heart). The OCT pictures help to make decisions about treatment or show how well balloon and stent treatment has worked.

 

The National Institute for Health and Care Excellence (NICE) is examining optical coherence tomography to guide percutaneous coronary intervention 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 optical coherence tomography to guide percutaneous coronary intervention.

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• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.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

Through its guidance NICE is committed to promoting race and disability equality, 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 interventional procedures guidance. In particular, we aim to encourage people and organisations from groups who might not normally comment on our guidance to do so.

In order to help us promote equality through our guidance, we should be grateful if you would consider the following question:

Are there any issues that require special attention in light of NICE’s duties to have due regard to the need to eliminate unlawful discrimination, advance equality of opportunity, and foster good relations between people with a characteristic protected by the equalities legislation and others?

Please note that 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: 21st November 2013

 

Target date for publication of guidance: 26 February 2014

 

 

 

1     Provisional recommendations

1.1  The evidence on the safety of optical coherence tomography (OCT) to guide percutaneous coronary intervention (PCI) shows no major safety concerns. The evidence on efficacy is limited in quantity and quality. Therefore, this procedure should only be used with special arrangements for clinical governance, consent and audit or research.

1.2   Clinicians wishing to undertake OCT to guide PCI should take the following actions.

·      Inform the clinical governance leads in their NHS trusts.

·      Ensure that patients understand the uncertainty about the procedure’s efficacy and provide them with clear written information. In addition, the use of NICE’s information for the public is recommended.

·      Enter details about all patients undergoing OCT to guide PCI onto the Central Cardiac Audit Database and review local clinical outcomes.

1.3   NICE encourages further research into OCT to guide PCI compared against PCI with no intravascular imaging or PCI with intravascular ultrasound. Research outcomes should include data on medium- and long-term clinical outcomes, including the need for revascularisation.

 

 

2    Indications and current treatments

2.1  Optical coherence tomography (OCT) uses a catheter emitting near-infrared light to produce high-resolution images of blood vessel walls. It may be used to assess stenotic lesions in the coronary arteries and to image the result of stent deployment during percutaneous coronary interventions.

2.2   Alternative methods of imaging the coronary arteries include coronary angiography and intravascular ultrasound.

 

 

3    The procedure

3.1  Optical coherence tomography (OCT) is usually performed using local anaesthesia. A guide wire and delivery sheath are introduced percutaneously into either the femoral or radial artery and passed into the target coronary artery using fluoroscopic image guidance. OCT imaging needs a blood-free field, which may be achieved either by an occlusion technique, using an occlusion balloon; or by a non-occlusive technique, using continuous flushing of contrast. For occlusion OCT, an occlusion balloon catheter is delivered over a guide wire and moved to the site of interest. The guide wire is exchanged for an imaging catheter (which has dimensions similar to a coronary guide wire). The balloon is gradually inflated until blood flow is fully occluded and OCT imaging is performed using motorised pull-back. For non-occlusive OCT, a guide wire through which contrast can be injected is used. The imaging catheter is delivered over this wire. Injection of contrast and imaging take place concurrently.

3.2  OCT was initially performed using time-domain OCT devices (TD‑OCT). Second-generation frequency-domain OCT (FD‑OCT) devices have recently been introduced. This has improved image quality and, more importantly, increased the speed of image acquisition by a factor of 10. TD‑OCT can be performed using either the occlusive or non-occlusive technique; FD‑OCT is usually performed using the non-occlusive technique. FD‑OCT is superseding TD‑OCT in the UK.

3.3  The resolution of coronary OCT is reported to be 10 times higher than that of intravascular ultrasound. The aim is to provide more detailed images to inform subsequent stenting or angioplasty (including assessment of the procedural outcome) thereby improving clinical outcomes.

 

 

4   Efficacy

This section describes efficacy 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.

4.1  A retrospective case series compared 335 matched pairs of patients undergoing percutaneous coronary intervention (PCI) with either angiographic guidance alone or a combination of angiographic and frequency-domain optical coherence tomography (FD‑OCT) guidance. Cardiac death or myocardial infarction (MI) were less frequent in patients treated by PCI with a combination of angiographic and FD‑OCT guidance than in those treated by PCI with angiographic guidance alone over a follow-up period of 1 year. There were 15 cardiac deaths and 29 MIs in the angiography-only group, and 4 cardiac deaths and 18 MIs in the combined angiography and FD-OCT group; odds ratio 0.49; 95% confidence interval 0.25 to 0.96, p=0.037.

4.2  A randomised controlled trial comparing FD‑OCT against intravascular ultrasound for PCI optimisation in 70 patients, reported that there was inferior stent expansion, both focal (65% versus 80%, p=0.002) and diffuse (84% versus 99%, p=0.003), when FD‑OCT had been used for guidance. PCI guided by FD‑OCT also showed a significant increase in residual stent-edge plaque burden (51% versus 42%, p<0.001). There were no significant differences in stent apposition.

4.3  In the retrospective case series comparing 335 matched pairs of patients undergoing PCI with either angiographic guidance or a combination of angiographic and FD‑OCT guidance, FD‑OCT led to additional interventions (further stenting and additional balloon dilation) in 116 patients (35%).

4.4  In a case series of 40 patients in whom OCT was performed to evaluate ambiguous or intermediate lesions, 60% (24/40) were treated by PCI and 40% (16/40) had PCI deferred. None of the patients for whom PCI was deferred had a coronary event within an average follow-up of 4.6 months.

4.5   The specialist advisers listed a key efficacy outcome as a change in diagnosis or management due to OCT imaging results. They cited as examples identifying culprit or non-culprit plaques in acute coronary syndromes, identifying intracoronary or intra-stent thrombus, identifying dissections and complications after stenting, examining stent deformation and conformation, identifying modes of stent failure including neoatherogenesis, and documenting stent tissue coverage.

 

 

5   Safety

This section describes 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.  

5.1  A large coronary perforation occurred (no further details of cause available) during optical coherence tomography (OCT) imaging in 1 patient presented in a case report, leading to reduced blood pressure and loss of consciousness. Surgical repair was done but the patient died of cardiac arrest after 7 days.

5.2  A minor type‑A coronary dissection occurred in 1 patient in the case series of 468 patients during time-domain OCT (TD‑OCT) imaging. Coronary blood flow was not impaired and further treatment was not indicated.

5.3  Ventricular fibrillation occurred in 5 patients in a case series of 468 patients during TD‑OCT imaging, 3 out of 256 during occlusive imaging and 2 out of 212 during non-occlusive imaging. In all cases, sinus rhythm was promptly restored after stopping OCT imaging and external defibrillation. Ventricular ectopic beats were noted in 3 patients in a case series of 90 patients undergoing 114 OCT image acquisitions.

5.4   Air embolism occurred in 3 patients in the case series of 468 patients during TD‑OCT imaging. All responded promptly to air aspiration, treatment with nitrates and in 1 patient, nitroprusside administration.

5.5  Mechanical device failure occurred in 1 patient in the case series of 468 patients. The imaging wire became trapped within the struts of a stent and the tip fractured and remained within the stent. At 4-month follow-up there had been no clinical consequences and angiography showed no flow abnormalities.

5.6  Multiple thrombi were reported during OCT imaging in 3 patients presented in case reports. These formed during OCT imaging in the left anterior descending artery causing total occlusion in 1 patient and subtotal occlusion in 2 others. All resolved with appropriate management and all patients recovered uneventfully.

5.7   Vessel spasm during withdrawal of the OCT wire was reported in a single case report. This caused chest pain and ST elevation but resolved with an intracoronary injection of nitrate.

5.8   Self-limiting chest pain was reported by 48% of patients (225/468) during TD‑OCT imaging in the case series of 468 patients. This was significantly more common when the occlusive rather than the non-occlusive technique was used (70% [180/256] compared against 21% [45/212], p<0.001).

5.9    Self-limiting widening QRS or ST depression and ST elevation occurred in 192 (46%) of 468 patients treated by occlusive or non-occlusive TD‑OCT. These were significantly more common when the occlusive rather than the non-occlusive technique was used (61% [139/256] compared against 27% [53/212], p<0.001).

5.10  The specialist advisers described the possibility that emergency revascularisation might be needed as a result of some of the complications of OCT which were reported in the literature.

Bruce Campbell
Chairman, Interventional Procedures Advisory Committee
October, 2013

 

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