Surgical perspectives in the management of atrial fibrillation

Table 1 The five types of atrial fibrillation as classified by European Heart Rhythm Association and European Association For Cardio Thoracic Surgery

Type of AF	Duration	Definition
First diagnosis	-	First episode of AF irrespective to duration or severity
Paroxysmal	48 h	Self-terminating (usually within 48 h); may continue for up to 7 d. After 48 h it is unlikely that spontaneous conversion will occur
		Anticoagulation must be considered
Persistent	> 7 d	Requires termination by cardio-eversion with drugs or direct current
Long standing persistent	≥ 1 yr	Rhythm control strategy
Permanent	-	Presence of arrhythmia is accepted and rhythm control interventions are not pursued1

¹In case of rhythm control interventions, the permanent AF should be re-designated as long standing persistent AF. AF: Atrial fibrillation.

Table 2 Comparing and contrasting the various available ablation modalitie

Ablationmodality	Mode of action	Advantages	Complications	Transmural lesions	Current limitations
RFA	Controlled thermal damage and lesions caused by electrical current	Less operating time Reduced technical difficulty	Intercavity thrombus Pulmonary vein stenosis Oesophageal and coronary artery injury	Variable	Confirmation of transmurality Variation between instruments
Cryoablation	Targeted scarring by cooling tissue using high-pressure argon and helium Initial cellular destruction followed by fibrosis and full thickness disruption	Visual confirmation of transmurality Less damage to surrounding tissues and vascularity Less endocardial thrombus Electrical isolation of atria	Coronary artery and phrenic nerve injury Atrioesophageal fistula	Yes	Variable success rate
Microwave	Production of lesions by thermal injury	Minimal collateral damage Minimal scar formation Lower risk of VTE	Coronary artery damage potential	Variable	Less effective compared to other modalities Limited evidence
HIFU	Creation of localised hyperthermic lesions using a focused beam of ultrasound energy	Fast epicardial lesions Future potential advantage visualisation of thickness by ultrasound and tailor made lesions	Atrioesophageal fistula Pericardial effusion Phrenic nerve injury	Yes endocardial only	High rate of complications Limited evidence currently not recommended outside trials
Laser	Use of high energy optical beams to create thermal lesions	Well demarcated lesions Non-arrythmogenic Rapid lesions	Crater formation Perforation Tissue loss Poor visibility of scar	Yes	Limited evidence currently not recommended outside trials

RAF: Radiofrequency ablation; HIUF: High intensity focused ultrasound.

Table 3 Adapted from 2012 Heart Rhythm Society/European Heart Rhythm Association/European Society of Cardiology guidelines

Indications for concomitant surgical ablation of AF
Symptomatic AF refractory or intolerant to at least one Class 1 or 3 antiarrhythmic medication
Paroxysmal: Surgical ablation is reasonable for patients undergoing surgery for other indications (IIa, C)
Persistent: Surgical ablation is reasonable for patients undergoing surgery for other indications (IIa, C)
Longstanding persistent: Surgical ablation is reasonable for patients undergoing surgery for other indications (IIa, C)
Symptomatic AF prior to initiation of antiarrhythmic drug therapy with a Class 1 or 3 antiarrhythmic agent
Paroxysmal: Surgical ablation is reasonable for patients undergoing surgery for other indications (IIa, C)
Persistent: Surgical ablation is reasonable for patients undergoing surgery for other indications (IIa, C)
Longstanding persistent: Surgical ablation may be considered for patients undergoing surgery for other indications (IIb, C)
Indications for standing alone surgical ablation of AF
Symptomatic AF refractory or intolerant to at least one Class 1 or 3 antiarrhythmic medication
Paroxysmal: Stand alone surgical ablation may be considered for patients who have not failed catheter ablation but prefer a surgical approach (IIb, C)
Paroxysmal: Stand alone surgical ablation may be considered for patients who have failed one or more attempts at catheter ablation (IIb, C)
Persistent: Stand alone surgical ablation may be considered for patients who have not failed catheter ablation but prefer a surgical approach (IIb, C)
Persistent: Stand alone surgical ablation may be considered for patients who have failed one or more attempts at catheter ablation (IIb, C)
Longstanding persistent: Stand alone surgical ablation may be considered for patients who have not failed catheter ablation but prefer a surgical approach (IIb, C)
Longstanding persistent: Stand alone surgical ablation may be considered for patients who have failed one or more attempts at catheter ablation (IIb, C)
Symptomatic AF prior to initiation of antiarrhythmic drug therapy with a Class 1 or 3 antiarrhythmic agent
Paroxysmal: Stand alone surgical ablation is not recommended (III, C)
Persistent: Stand alone surgical ablation is not recommended (III, C)
Longstanding persistent: Stand alone surgical ablation is not recommended (III, C)

AF: Atrial fibrillation.

Table 4 Adapted from the surgical treatment of atrial fibrillation guidelines by the European Association for Cardio-Thoracic Surgery Clinical Guidelines Committee guidelines

Use of ablative modalities
Unipolar radiofrequency ablation
Concomitant unipolar RFA for AF treatment together with cardiac surgery is effective in restoration of sinus rhythm
Success rates vary between 54%-83% at medium term follow up (at least 12 mo)
Safe procedure - no additional risks
Success rates are higher with: paroxysmal or persistent AF, younger age, smaller LAD
Class IIa recommendation based on multiple small retrospective studies (Level C)
Bipolar radiofrequency ablation
Higher success rates in restoring sinus rhythm compared to no ablation in concomitant cardiac surgery
On average the cross clamp time is increased by 15 min
There is limited evidence to suggest superiority of bipolar over unipolar RFA
1 prospective trial has provided evidence demonstrating superiority of bipolar RFA over microwave ablation
Class I recommendation based on 3 RCTs and multiple small prospective studies (Level A)
Cryoablation
Acceptable intervention for AF treatment during concomitant surgery with acceptable sinus rhythm conversion rates between 60%-82% at 12 mo
Cryoablation is most successful in patients suffering from paroxysmal as opposed to permanent AF (suggested by 6 out of 9 studies reviewed)
Class IIa recommendation based on 1 small RCT and multiple prospective and retrospective studies (Level B)
Microwave ablation
Less effective intervention for AF treatment based on the limited evidence
Success rates in the longer term are less clear - the only RCT to date has found outcomes inferior to RFA
Class III recommendation based on 1 small RCT and multiple small prospective and retrospective studies (Level B)
HIFU
Currently not recommended as an intervention for the treatment of AF during concomitant surgery outside clinical trials due to limited evidence
Success rates seem to be inferior to those of other devices
Significant concerns have been reported
Class III recommendation based on cohort studies (Level C)
Exclusion of laa and standing alone surgical ablation
Exclusion of LAA
No proven benefit of surgical LAA exclusion in terms of stroke reduction or mortality
Ineffective LAA occlusion and potentially increased stroke risk due to poor technique was seen in many studies
Devices designed for LAA exclusion should be preferentially used rather than a cut and sew or stapling technique, if LAA is to be performed
Class IIa recommendation based on multiple cohort studies and one pilot RCT (Level B)
Stand alone surgical ablation
Surgery can be considered for symptomatic patients who are refractory or intolerant to at least 1 anti-arrhythmic medication
Considered for patients with paroxysmal, long standing and persistent AF who prefer surgery to catheter ablation or have failed catheter ablation
Results of both catheter-based and surgery-based ablation should be discussed with the patient
Class IIa recommendations based on 1 RCT and multiple cohort studies (Level B)

RFA: Radiofrequency ablation; AF: Atrial fibrillation; LAD: Left anterior descending; RCT: Randomized controlled trial; HIFU: High intensity focused ultrasound; LAA: Left atrial appendage.

Table 5 Summary of results from studies included looking at Cox-Maze procedures

Procedure	Ref.	Sample size	Mean follow-up period	Outcome	Important findings
Cox-Maze	Cox et al[7]	178 patients	8.5 yr	93% freedom from AF	Cox-Maze procedure developed
Cox-Maze	McCarthy et al[16]	100 patients	3 yr	90.4% in sinus rhythm or atrial pacing	Associated with low perioperative and late morbidity rates
Cox-Maze	Schaff et al[17]	221 patients	6 yr	90% in sinus rhythm	CM procedure was useful in patients requiring valvuloplasty for mitral regurgitation
Modified Cox-Maze with bipolar RFA	Gaynor et al[18]	40 patients	6 mo	91% in sinus rhythm	Modification of CM-III shortened and simplified the procedure with no change in short-term efficacy

RFA: Radiofrequency ablation; AF: Atrial fibrillation.

Table 6 Summary of results from studies included looking at pulmonary vein isolation and left atrial appendage

Procedure	Ref.	Sample size	Mean follow-up period	Outcome	Important findiNGS
PVI	Haïssaguerre et al[9]	45 patients	8 ± 6 mo	Sinus rhythm achieved in 28 patients (62%)	69 foci identified as the source of ectopic atrial beats in 45 patients
PVI	Chao et al[21]	88 non-paroxysmal AF patients	36.8 mo	The long-term freedom period of AF was 28.4% after a single procedure	CHADS2 score of >/3 and left atrial diameter found to be significant predictors of recurrences
LAA obliteration	Healy et al[27]	RCT - 77 patients with risk factors for stroke	8 wk follow-up with trans-oesophageal echocardiography	Complete occlusion achieved in 45% (5/11) of patients through the use of sutures and in 72% (24/33) using a stapler	Surgical LAA can be safely done during a routine CABG; expertise is key to its success rates
LAA excision or exclusion	Kenderian et al[28]	137 patients	Post-operative trans-oesophageal echocardiography	Successful LAA closure 73% with surgical excision and 23% with suture exclusion. Evidence of stroke in 11% of successful LAA closure and 15% of unsuccessful LAA closure (P = 0.61)	High proportion of surgical LAA closure. LAA excision more successful than exclusion
LAA obliteration + Mitral valve replacement	García-Fernández et al[29]	58 patients	69.4 mo trans-oesophageal echocardiography	46% of patients had an embolism. Risk of embolism increased by 11.6 in incomplete/absence of LAA ligation	Absence of LAA ligation and presence of left atrial thrombus identified as independent predictors for stroke
LAA exclusion during mitral valve surgery	Almahameed et al[30]	136 patients	3.6 ± 1.3 yr	12.3% of patients had thromboembolic events, 71% of which occurred in patients undergoing mitral valve repair	There were more thromboembolic events in patients not prescribed warfarin on discharge

PVI: Pulmonary vein isolation; LAA: Left atrial appendage.

Table 7 Summary of results from studies included looking at radiofrequency ablation

Procedure	Ref.	Sample size	Mean follow-up period	Outcome	Important findings
Concomitant RFA	Johansson et al[32]	39 patients undergoing CABG	32 ± 11 mo	62% freedom from AF in ablation group compared to 33% in non-ablation group	Sinus rhythm at 3 mo was highly predictive of long-term sinus rhythm
Concomitant RFA	Khargi et al[33]	128 patients in permanent AF (Group 1: mitral valve surgery, group 2: aortic valve surgery or CABG)	3, 6 and 12 mo ECG and sinus rhythm confirmed with 24hrs ECG	71% post-operative sinus rhythm in group 1 vs 79% in group 2	Concomitant RFA in mitral valve surgery and aortic valve surgery or CABG is equally effective
Concomitant RFA	Beukema et al[34]	258 patients with permanent AF	43.7 ± 25.9 mo	Sustained sinus rhythm in 69% of patients at 1 yr, 56% at 3 yr, 52% at 5 yr and 57% at the latest follow up	RF modified maze procedure abolished AF in the majority of patients
Concomitant RFA	Chiappini et al[35]	Review of 6 studies - 451 patients in total	13.8 ± 1.9 mo	97.1% overall survival rate, 76.3% ± 5.1% overall freedom from AF	RFA is a safe and efficient procedure to cure AF in patients undergoing concomitant heart surgery
Concomitant RFA	Von Opell et al[36]	49 patients with AF of more than 6 mo duration	At discharge, 3 and 12 mo post procedure	Return to sinus rhythm 29% 57% and 75% (at discharge, 3 mo and 12 mo post-procedure) in the cardioblate group vs 20%, 43% and 29% respectively in the control group	Concomitant RFA resulted in 75% conversion rate to sinus rhythm compared to the control group (39%)
Concomitant RFA	Budera et al[38]	Multicentre RCT involving 224 patients with AF undergoing cardiac surgery with ( n = 117) or without ablation (n = 107)	30 d	At 1 yr follow up, 60.2% of patients were in sinus rhythm in the ablation group compared to 35.5% in the control group. 1 yr mortality was 16.2% and 17.4% respectively	Concomitant ablation increases postoperative sinus rhythm with no effect on peri-operative complications
Concomitant RFA	Blomström-Lundqvist et al[40]	Double-blind randomized study of 69 patients undergoing mitral valve surgery with or without epicardial left atrial cryoablation	6 and 12 mo	At 6 mo follow-up, 73.3% of patients in the cryoablation group regained sinus rhythm vs 45.7% of patients with mitral valve surgery alone (P = 0.024). At 12 mo follow-up, the results were 73.3% vs 42.9% respectively (P = 0.013)	Concomitant left atrial epicardial cardioablation is significantly better in regaining sinus rhythm in patients with permanent AF compared to mitral valve surgery alone
Concomitant RFA	Chevalier et al[61]	Prospective, multicentre, double-blinded RCT involving 43 patients with mitral valve disease and permanent AF	12 mo	At 12 mo, sinus rhythm was maintained without any arrhythmia recurrences in 57% of patients in the RFA group vs 4% in the control group (undergoing mitral valve surgery only)	Left atrial RFA is an effective procedure in patients suffering with long-term AF and co-existing valvular disease
Concomitant RFA	Veasey et al[62]	100 patients in paroxysmal or persistent AF undergoing cardiac surgery were enrolled	6 mo	75% freedom of AF at 6 mo follow-up post concomitant RFA. The AF burden decreased from 56.2% post-operatively to 27.5% at 6 mo post-operatively. 13% of patients had asymptomatic AF episodes identified via continuous monitoring	Concomitant RFA successfully reduces AF burden but based on these results, the importance of post-operative antiarrhythmic medication and anticoagulation should be evaluated

RFA: Radiofrequency ablation; AF: Atrial fibrillation; ECG: Electrocardiogram; CABG: Coronary artery bypass grafting.

Table 8 Summary of results from studies included looking at high intensity focused ultrasound

Procedure	Ref.	Sample size	Mean follow-up period	Outcome	Important findings
HIFU	Neven et al[45]	Two-year follow-up of 28 people with paroxysmal AF 9 (n = 19) and persistent AF (n = 9) undergoing	Median follow-up 738 d	Following a median follow-up of 738 d, 79% of patients were free of AF. Following a repeat procedure with radiofrequency ablation, 18% of patients maintained freedom of AF	Success rates of HIFU are comparable to radiofrequency ablation but complication rates remain higher for HIFU
HIFU	Klinkenberg et al[47]	15 patients with AF refractory to antiarrhythmic medication underwent HIFU for PVI	24 mo	At 6 mo 40% of patients with 1 epicardial PVI gained sinus rhythm. After 1.3 ± 0.6 yr, 27% of patients had sinus rhythm after 1 epicardial pulmonary vein isolation	Success rate was low in epicardial pulmonary vein isolation done through right-sided VATS using HIFU and was associated with substantial complications
HIFU	Schmidt et al[48]	22 patients with paroxysmal AF who underwent PVI using HIFU	median follow-up of 342 d	71% of patients remained free of any AF/AT recurrence without antiarrhythmic drugs after a procedure	The 12F-HIFU induces a very rapid pulmonary venous isolation in patients

HIFU: High intensity focused ultrasound; PVI: Pulmonary vein isolation; LAA: Left atrial appendage.

Table 9 Summary of results from studies included looking at the hybrid approach

Procedure	Ref.	Sample size	Mean follow-up period	Outcome	Important findings
Hybrid approach	Kuman et al[55]	A cohort of 7 patients with AF undergoing a hybrid procedure	Follow-up at 3, 6, 9 and 12 mo post-procedure	After a follow-up of 40 ± 3 mo, 6 out of 7 patients were in sinus rhythm	The hybrid approach is a safe and feasible technique to AF ablation
Hybrid approach	Bulava et al[56]	50 consecutive patients with long-standing AF who underwent the procedure	Follow-up at 3, 6, 9 and 12 mo post-procedure and thereafter after every 6 mo	94% of patients were in sinus rhythm, 12 mo after the procedure No arrhythmias were present in any patient after 12 mo	The hybrid approach is extremely effective in maintaining sinus rhythm compared to radiofrequency catheter ablation or surgical ablation alone
Hybrid approach vs Cox-Maze vs epicardial ablation	Je et al[57]	Systematic review of 37 studies with a total of 1877 patients	12 mo	Operative mortality for the Cox-Maze, epicardial ablation and hybrid approach were 0%, 0.5% and 0.9% At 12 mo, rates of sinus rhythm restoration for the above were 93%, 80% and 70% respectively	The Cox-Maze procedure with cardiopulmonary bypass revealed the highest success rate 12 mo post-procedure compared to the hybrid approach and epicardial approach

AF: Atrial fibrillation.