Interventional procedure consultation document

Percutaneous balloon cryoablation for pulmonary vein isolation in atrial fibrillation

Treating atrial fibrillation using a balloon catheter to freeze parts of the heart

Atrial fibrillation is the irregular and rapid beating of the upper two chambers of the heart (the atria). This is caused by the disorganisation of the electrical impulses that control the heartbeat as a result of electrical triggers that may originate at the mouth of the pulmonary veins (large blood vessels that carry blood from the lungs to the left atrium). Typical symptoms can include palpitations, dizziness, shortness of breath and fatigue. Complications can include stroke. This procedure uses a probe attached to a balloon catheter to freeze tissue in one of the chambers on the left side of the heart. The aim is to produce scarring, which may interrupt the electrical signals and help regulate the heartbeat.

The National Institute for Health and Clinical Excellence (NICE) is examining percutaneous balloon cryoablation for pulmonary vein isolation in atrial fibrillation 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 percutaneous balloon cryoablation for pulmonary vein isolation in atrial fibrillation.

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• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.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

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 and promote equality 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: 24 January 2012

Target date for publication of guidance: April 2012

1   Provisional recommendations

1.1   Current evidence on the efficacy and safety of percutaneous balloon cryoablation for pulmonary vein isolation in atrial fibrillation is adequate to support the use of this procedure provided that normal arrangements are in place for clinical governance, consent and audit.

1.2   Patient selection and treatment should only be carried out by interventional cardiologists with expertise in electrophysiology and complex ablation procedures.

1.3   This procedure should be carried out only in units with arrangements for emergency cardiac surgical support in case of complications.

1.4   Clinicians should enter details about all patients undergoing percutaneous balloon cryoablation for pulmonary vein isolation in atrial fibrillation onto the UK Central Cardiac Audit Database.

1.5   NICE encourages clinicians to enter patients into research studies, with the particular aims of guiding selection of patients and of defining the place of percutaneous balloon cryoablation in relation to other procedures for treating atrial fibrillation. Further research should define patient selection criteria clearly and should document adverse events and long-term control of atrial fibrillation.

2   The procedure

2.1   Indications and current treatments

2.1.1   Atrial fibrillation is the irregular and rapid beating of the atria. It is caused by uncoordinated electrical stimulation of the atrial walls. Atrial fibrillation may be classified as paroxysmal, persistent or permanent. Patients may be asymptomatic or have symptoms such as palpitations, fatigue and chest pain.

2.1.2   Patients considered to be at high risk of embolic stroke from thrombus in the fibrillating left atrium are usually treated with anticoagulation therapy. Medical treatment for atrial fibrillation includes drugs to control heart rate or to help maintain a normal cardiac rhythm following cardioversion. Ablation procedures, designed to disrupt abnormal conduction pathways, may be used when drug therapy is either not tolerated or is ineffective. There are several methods available to deliver cardiac ablation including cryoablation with or without a balloon.

2.2   Outline of the procedure

2.2.1   Percutaneous balloon cryoablation for pulmonary vein isolation in atrial fibrillation aims to help maintain normal heart rhythm by isolating the electrical impulses originating in the pulmonary veins that are thought to be responsible for ‘triggering’ atrial fibrillation.

2.2.2   With the patient under general anaesthesia, or using local anaesthesia and sedation, catheters are introduced percutaneously via the femoral vein. Electrode catheters may be placed into the heart or veins to stimulate the heart or phrenic nerve. Two sheaths are advanced into the left atrium transseptally. A multipolar circular mapping catheter (to record electrical signals from the pulmonary vein ostia) and the cryoablation catheter are passed through the two sheaths. The balloon cryoablation catheter is placed at one of the pulmonary vein ostia and the balloon is inflated to allow continuous contact between the balloon and the atrial myocardium. Good contact is confirmed fluoroscopically by injecting contrast into the pulmonary vein through the lumen of the balloon catheter.

2.2.3   When the balloon catheter has been positioned satisfactorily, it is cooled in bursts of approximately 4 minutes, to achieve circumferential isolation of the cells responsible for the arrhythmia. This is assessed using the circular mapping catheter and each of the 4 or more pulmonary veins is treated in the same way, until all are electrically isolated.

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/guidance/IP/950/overview

2.3   Efficacy

2.3.1   A comparative case series of 94 patients treated by balloon cryoablation (n = 30), radiofrequency ablation (RFA) (n = 29) or robotically assisted RFA (n = 35) reported procedure success (defined as no symptomatic or asymptomatic atrial tachyarrhythmias lasting ≥ 30 seconds, identified on surface electrocardiogram [ECG], Holter monitoring or 7-day ECG recording) without antiarrhythmic drugs in 66% (23), 66% (19) and 67% (20) of patients respectively at a mean follow-up of 13 months (p = 0.625) (denominator not reported).

2.3.2   In a case series of 346 patients treated by balloon cryoablation (treatment completed by cryoablation catheter if isolation was not achieved), sinus rhythm was maintained without antiarrhythmic drugs in 74% (159, denominator not reported) of patients with paroxysmal atrial fibrillation and 42% (13/31) of patients with persistent atrial fibrillation (follow-up not stated).

2.3.3   A case series of 141 patients reported recurrence of atrial fibrillation in 51% (71/139) of patients after one procedure (follow-up 457 days).

2.3.4   A non-randomised comparative case series of 177 patients treated by balloon cryoablation or RFA reported that 14% (17) and 23% (12) of patients respectively needed retreatment for recurrent atrial fibrillation (denominators and timing of events not reported; mean follow-up 13 months).

2.3.5   The Specialist Advisers listed key efficacy outcomes as electrical isolation of all 4 pulmonary veins, procedure duration, freedom from atrial fibrillation, avoidance of repeat procedures and reduced use of antiarrhythmic drug.

2.4   Safety

2.4.1   The case series of 346 patients reported periprocedural pericardial tamponade in 2 patients, both successfully treated by pericardial drainage and without the need for surgery. The comparative case series of 133 patients reported pericardial effusion within 24 hours in 11% (5/46) of patients treated by balloon cryoablation and in 16% (14/87) of patients treated by RFA (drainage was needed in 1 patient in each group; all the other effusions resolved spontaneously).

2.4.2   The case series of 346 patients reported right phrenic nerve injury in 8% (26/346) of patients during balloon cryoablation of the right superior pulmonary vein. Of these, 2 resolved during the procedure and full function recovered in all patients during follow-up of less than 1 year.

2.4.3   A comparative case series of 74 patients treated by balloon cryoablation (n = 67) or cryocatheter (n = 7) reported oesophageal ulceration identified by endoscopy in 17% (6/35) of patients and 0/7 patients respectively within 1 week of the procedure. All were asymptomatic and resolved within 3 months.

2.4.4   In the case series of 141 patients, 2 patients had haemoptysis during the first month after pulmonary vein isolation. This resolved after temporary cessation of oral anticoagulation therapy.

2.4.5   The Specialist Advisers listed adverse events reported in the literature as transient ischaemic attack, pulmonary vein stenosis, groin haematoma at venous entry site and pseudoaneurysm. They reported anecdotal adverse events of air embolus and phrenic nerve injury, and they considered theoretical adverse events to include death, stroke, atrio-oesophageal fistula, permanent phrenic nerve palsy, damage to structures anatomically close to pulmonary veins and deep vein thrombosis.

2.5   Other comments

2.5.1   The Committee noted the advances in the understanding of the causes of atrial fibrillation and acknowledged that this procedure is likely to be more effective in paroxysmal than persistent atrial fibrillation.

3   Further information

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

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

December, 2011

_{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.}