Percutaneous radiofrequency ablation in AF

• percutaneous radiofrequency ablation is a treatment option for symptomatic patients with atrial fibrillation refractory to anti-arrhythmic drug therapy or where medical therapy is contraindicated because of co-morbidity or intolerance (1)
  • discovery of the pulmonary veins as the site for initiation of AF has led to the development of curative catheter-based procedures. These involve the delivery of radiofrequency energy with an aim to isolate the pulmonary veins electrically from the left atrium. There has been an evolution of such techniques since 1997 and currently the expected success rate is around 80% in experienced hands (2)
    
    
• procedure (1)
  • a minimally invasive procedure that is usually carried out under sedation
  • catheter is inserted into the femoral vein and advanced into the heart, using X-ray fluoroscopic guidance to ensure correct positioning
    • attachment at the tip of the catheter sends out radiofrequency energy, producing heat that damages the targeted area of the conduction pathway
  • electrophysiological testing is undertaken before the procedure to identify and map the source of the abnormal electrical signals
  • different strategies may be used, including linear ablation in the left or right atrium and focal pulmonary vein to isolate triggers of atrial fibrillation that arise from within the pulmonary vein
    
    
• efficacy (1)
  • results from a large survey revealed that 76% (6644/8745) of treated patients had resolution of symptoms of atrial fibrillation after a median follow-up of 12 months (this proportion ranged from 22% to 91% among different centres)
    
    
• complications (1)
  • complication rate of 6% (524/8745) was reported in the survey of 8745 patients who had undergone percutaneous radiofrequency ablation for atrial fibrillation
    • most significant complications reported in this study were four early deaths (< 1%), 20 strokes (< 1%), 47 transient ischaemic attacks (1%), 117 cases of pulmonary vein stenosis (1%), 107 episodes of cardiac tamponade (1%) and 37 cases of arteriovenous fistula (< 1%)
  • studies show that 2% and 4% of patients (12/589 and 340/8745, respectively) developed atypical atrial flutter of new onset after undergoing percutaneous radiofrequency ablation
  • one case series of 632 procedures a cardiac perforation rate of 2% (15 procedures) was reported, each case requiring pericardiocentesis: all the patients affected survived

Percutaneous balloon cryoablation for pulmonary vein isolation in atrial fibrillation is also a treatment option (3)

• procedure:
  • with the patient under general anaesthesia, or using local anaesthesia and sedation, catheters are introduced percutaneously through one or both femoral veins
    • one or more electrode catheters are placed in the heart to allow pacing. An additional electrode catheter is placed in a vein or the heart to allow stimulation of the phrenic nerve
    • one or 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 balloon 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
      • 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 mapping catheter. Each of the pulmonary veins is treated in the same way, until all are electrically isolated
        
        
• efficacy:
  • 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 anti-arrhythmic 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)
    
    
• complications
  • case series of 346 patients reported periprocedural pericardial tamponade in 2 patients, both successfully treated by pericardial drainage and without the need for surgery
    • 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 radiofrequency ablation (drainage was needed in 1 patient in each group; all the other effusions resolved spontaneously)
    • right phrenic nerve injury in 8% (26/346) of patients during balloon cryoablation of the right superior pulmonary vein.
    • 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
    • stroke or transient ischaemic attack was reported in less than 1% of patients (4/1241) in the systematic review

NICE atrial fibrillation guidance states (4):

• pace and ablate strategy
  • consider pacing and atrioventricular node ablation for people with permanent atrial fibrillation with symptoms or left ventricular dysfunction thought to be caused by high ventricular rates
    
    
  • when considering pacing and atrioventricular node ablation, reassess symptoms and the consequent need for ablation after pacing has been carried out and drug treatment further optimised
    
    
  • consider left atrial catheter ablation before pacing and atrioventricular node ablation for people with paroxysmal atrial fibrillation or heart failure caused by non-permanent (paroxysmal or persistent) atrial fibrillation
    
    
• left atrial ablation
  
  
  • if drug treatment is unsuccessful, unsuitable or not tolerated in people with symptomatic paroxysmal or persistent atrial fibrillation:
    • consider radiofrequency point-by-point ablation or
    • if radiofrequency point-by-point ablation is assessed as being unsuitable, consider cryoballoon ablation or laser balloon ablation
      
      
  • consider left atrial surgical ablation at the same time as other cardiothoracic surgery for people with symptomatic atrial fibrillation
    
    
• preventing recurrence after ablation
  • consider antiarrhythmic drug treatment for 3 months after left atrial ablation to prevent recurrence of atrial fibrillation, taking into account the person's preferences, and the risks and potential benefits
  • reassess the need for antiarrhythmic drug treatment at 3 months after left atrial ablation

Notes (2):

• a number of studies have shown that catheter ablation is superior to antiarrhythmic drugs in maintaining sinus rhythm
• success rates with ablation are highest in patients with paroxysmal AF, and in persistent AF of less than 12 months duration
• ablation is less likely to be successful in the presence of advanced structural heart disease, or in long standing persistent AF

Reference:

1. NICE (April 2006). Percutaneous radiofrequency ablation for atrial fibrillation
2. British Heart Foundation Factfile (May 2012). Atrial fibrillation - diagnosis and management.
3. NICE (May 2012). Percutaneous balloon cryoablation for pulmonary vein isolation in atrial fibrillation
4. NICE (April 2021). Atrial Fibrillation