Surgery for atrial fibrillation with radiofrequency ablation: four years experience

Comparison of modified MAZE with minimally invasive monopolar ablation and traditional bipolar radiofrequency ablation in the treatment of atrial fibrillation

Background and aim of the study

Atrial fibrillation (AF) is the most common atrial arrhythmia. Our aim was to compare the outcomes of atrial fibrillation treatment with original modified minimally invasive MAZE using monopolar radiofrequency ablation (mi-MAZE) and open surgery MAZE using bipolar radiofrequency ablation (os-MAZE).

Methods

We searched the associated patients’ information on the medical record system of the First Affiliated Hospital, School of Medicine, Zhejiang University. Statistical Package for Social Sciences (SPSS) was used to analyse the data. The primary outcome is the atrial fibrillation ablation rate 3 months, 6 months, 12 months after operation. And secondary outcome is the postoperative quality of life.

Results

The mi-MAZE group included 42 patients and the os-MAZE group had 65 patients. Three months after surgery, we found that 31 patients (77.5%) in the mi-MAZE group were sinus rhythm and 44 (71.0%) recovered sinus rhythm in the os-MAZE group. We followed up these patients on the phone or in person and scored them on the SF-36 scale. The results were found to be 120.2 ± 8.10 vs 110.6 ± 6.58 (mi-MAZE vs os-MAZE, P < 0.001).

Conclusions

There was no significant difference of atrial fibrillation ablation rate (sinus rhythm recovery rate) between the mi-MAZE group and the os-MAZE group. The postoperative quality of life in mi-MAZE group was higher than that in os-MAZE group.

A pilot prospective randomized, controlled trial comparing LigaSure™ tissue fusion technology with the ForceTriad™ energy platform to the electrosurgical pencil on rates of atrial fibrillation after pulmonary lobectomy and mediastinal lymphadenectomy

OBJECTIVES

The use of bipolar sealing devices during pulmonary resection is particularly useful in thoracoscopic surgery. Theoretically, a bipolar device, which contains the current in a smaller area and completes the current cycle only through the tissue between the electrodes, may reduce the proportion of patients experiencing atrial fibrillation compared with monopolar devices such as the electrosurgical pencil using which the current completes the cycle through the patient. We investigated the impact of the LigaSure™ (LS) tissue fusion technology with the ForceTriad™ energy platform device on the incidence of postoperative atrial fibrillation and on the reduction of postoperative chest tube output and hospital length of stay after open pulmonary lobectomy.

METHODS

A pilot prospective randomized, controlled trial comparing LS tissue fusion technology with the ForceTriad™ energy platform to the conventional electrosurgical pencil. Overall, 146 patients with resectable lung cancer were recruited at the Division of Thoracic Surgery of the Istituto Nazionale Tumori, Fondazione Pascale, IRCCS, between January 2011 and July 2013. Of these, 119 candidates to open lobectomy for non-small-cell lung cancer were randomized to either LS tissue fusion technology with the ForceTriad™ energy platform (LS: 57 patients) or standard haemostatic procedure (standard treatment, ST: 62 patients) for hilar and mediastinal nodal dissection. The primary end-point was to compare the incidence of postoperative atrial fibrillation of LS compared with ST. The secondary end-point was to compare the efficacy of LS compared with ST in terms of total chest tube drainage, daily chest tube drainage and chest tube duration.

RESULTS

There was no statistically significant difference between LS and ST in terms of postoperative atrial fibrillation (P=0.31). However, LS was associated to significant reduction of duration of both mediastinal nodal dissection (P=0.017) and the cumulative chest tube drainage (P=0.025).

CONCLUSIONS

The incidence of atrial fibrillation with LS tissue fusion technology with the ForceTriad™ energy platform is not reduced as compared with conventional electrosurgical pencil. However, the use of LS during mediastinal nodal dissection is associated to shorter duration of lymphadenectomy and duration of chest tube drainage.

Impact of epicardial ablation of concomitant atrial fibrillation on atrial natriuretic peptide levels and atrial function in 6 months follow-up: does preoperative ANP level predict outcome of ablation?

Background

Epicardial ablation concomitant to cardiac surgery is an easy and safe approach to treat atrial fibrillation (AF), but its efficacy in longstanding persistent (LsPe) AF remains intermediate. Although larger left atrial size has been associated with worse outcome after ablation, biochemical predictors of success are not well established. The aim of this study was to evaluate relationship between biochemical marker, echo-characteristic and cardiac rhythm in 6 months follow-up after epicardial ultrasound (HIFU) ablation.

Methods

We included 78 consecutive patients, who underwent elective cardiac surgery. 42 patients with AF (11.9% paroxysmal, 23.8% persistent, 64.3% LsPeAF) underwent concomitant HIFU ablation (AF ablation group), 16 with AF underwent cardiac surgery without ablation (AF control) and 20 had preoperatively normal sinus rhythm (SR control). We measured plasma ANP secretion before, on postoperative day (POD) 1, POD 7 as well as 3 and 6 months after surgery. Moreover, we estimated cardiac rhythm and atrial mechanical function by Atrial Filling Fraction (AFF) and A-wave velocity in follow-up.

Results

Baseline ANP levels were higher in patients with LsPeAF, as compared to the paroxysmal and permanent AF and to the SR control group. Patients with LsPeAF (n = 27) who converted to SR had preoperatively smaller left atrial diameter (LAD) and LA area (p < 0.05) and higher ANP level (p = 0.009) than those who remained in AF at 6 months after ablation. Multivariate regression analysis revealed that only preoperative ANP level was an independent predictor of cardiac rhythm after ablation. Patients with LsPeAF and preoperative ANP >7.5 nmol/l presented with SR in 80%, in contrast to those with ANP <7.5 nmol/l who converted to SR in 20%. We detected gradual increase of AFF and A-velocity at 6 months after ablation (p < 0.05) solely in AF ablation group. ANP levels were increased on POD 1 in ablation group (p < 0.05), without changes in further follow-up.

Conclusion

Our results indicate that preoperative ANP levels may be a new biochemical predictor of successful epicardial ablation in patients with concomitant LsPeAF. HIFU ablation caused a significant improvement of atrial mechanical function and gradual increase of AFF and did not associate with alteration of atrial endocrine secretion at 6 months follow-up.

Guideline for the surgical treatment of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and its prevalence is ∼1-2% of the general population, but higher with increasing age and in patients with concomitant heart disease. The Cox-maze III procedure was a groundbreaking development and remains the surgical intervention with the highest cure rate, but due to its technical difficulty alternative techniques have been developed to create the lesions sets. The field is fast moving and there are now multiple energy sources, multiple potential lesion sets and even multiple guidelines addressing the issues surrounding the surgical treatment of AF both for patients undergoing this concomitantly with other cardiac surgical procedures and also as stand-alone procedures either via sternotomy or via videothoracoscopic techniques. The aim of this document is to bring together all major guidelines in this area into one resource for clinicians interested in surgery for AF. Where we felt that guidance was lacking, we also reviewed the evidence and provided summaries in those areas. We conclude that AF surgery is an effective intervention for patients with all types of AF undergoing concomitant cardiac surgery to reduce the incidence of AF, as demonstrated in multiple randomized studies. There is some evidence that this translates into reduced stroke risk, reduced heart failure risk and longer survival. In addition, symptomatic patients with AF may be considered for surgery after failed catheter intervention or even as an alternative to catheter intervention where either catheter ablation is contraindicated or by patient choice.

A minimally invasive cox-maze procedure: operative technique and results

OBJECTIVE

The Cox-Maze procedure (CMP) for the surgical treatment of atrial fibrillation (AF) traditionally has required a median sternotomy and cardiopulmonary bypass. This study describes a method using ablation technologies to create the full Cox-Maze lesion set through a 5- to 6-cm right minithoracotomy.

METHODS

Twenty-two consecutive patients underwent a CMP through a right mini-thoracotomy and cardiopulmonary bypass. All patients were followed prospectively with electrocardiogram and 24-hour Holter monitoring at 3, 6, and 12 months. The CMP lesion set was created using bipolar radiofrequency energy and cryotherapy.

RESULTS

There was no operative mortality or major complications.Two patients required a permanent pacemaker. Five patients (23%) had early atrial tachyarrhythmias. At last follow-up(mean, 18 ± 12 months), all the patients (n=22) were free from atrial dysrhythmias. At 3 months (n=19), 84% of patients were off antiarrhythmic drugs. At 6 months (n=18), 94% of patients were free from AF and off antiarrhythmic medications. At 12 months (n=16), 81% of patients were free from AF and off antiarrhythmic drugs and three patients remained on warfarin for a mechanical mitral valve.

CONCLUSIONS

A full CMP can be performed through a right mini-thoracotomy with outstanding short-term results. This less invasive procedure can be offered to patients without compromising efficacy.

How effective is bipolar radiofrequency ablation for atrial fibrillation during concomitant cardiac surgery?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether, in patients undergoing cardiac surgery, concomitant bipolar radiofrequency ablation had an acceptable success rate to justify the additional procedure. Altogether 263 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The consensus in the literature was that bipolar radiofrequency ablation was highly successful in restoring sinus rhythm. One meta-analysis of six non-randomized studies demonstrated that 76% of patients were in sinus rhythm compared with 16% in atrial fibrillation 3 months postoperatively. One randomized controlled trial found that the sinus rhythm conversion rate for any maze procedure was highly significant compared with the control group (P = 0.001). Another found that Cardioblate radiofrequency ablation was significantly better at restoring sinus rhythm at 1 year (75 vs 39% control, P = 0.019). Prospective studies showed a similar rate of sinus rhythm return at 1 year (89%). Notably some studies demonstrated a significant reduction in the New York Heart Association class when sinus rhythm was restored compared with those remaining in atrial fibrillation (P < 0.0001), demonstrating the value of this procedure beyond simply restoring sinus rhythm. In another study, the investigators found that both ablation and total procedure times were shorter with bipolar compared with monopolar ablation. These authors strongly recommend bipolar radiofrequency ablation due to a shorter procedure time, ability to avoid performing a standard left atriotomy and a greater guarantee of transmurality. With the current limited evidence, we conclude that bipolar radiofrequency ablation has a higher success rate in restoring sinus rhythm as an adjunct to cardiac surgery compared with no ablation for at least 1 year. The procedure had a high survival rate. There is randomized evidence to suggest the superiority of bipolar radiofrequency ablation over microwave ablation but limited evidence to suggest the superiority of bipolar over unipolar radiofrequency ablation. Factors found to be accurate predictors of ablation failure include a larger preoperative atrial diameter, permanent vs paroxysmal atrial fibrillation and longer duration of atrial fibrillation.

Mid-term results of endoscopic mitral valve repair in combination with endocardial or epicardial ablation

OBJECTIVE

Concomitant ablative therapy for atrial fibrillation can be effective at converting patients to normal sinus rhythm and at maintaining a regular rhythm for at least 5 years. We provide herein a comparison of an endocardial approach using Cryoablation with an epicardial approach using a suction-based RF ablation technology.

METHODS

Between February 2004 and January 2009, 325 patients underwent an endoscopic mitral valve repair. Of those patients, 112 (35%) had a history of atrial fibrillation prior to the procedure, all of whom underwent a concomitant ablation procedure. The first group of 78 concomitant ablation patients underwent a left-sided endocardial ablation procedure using a Cryoablation device. The second group of 34 ablation patients underwent a left-sided epicardial ablation procedure using an internally cooled monopolar RF device. No significant differences existed between groups in the preoperative data. All ablated patients were treated by the same Amiodarone protocol. Patients were followed for a minimum of 6 months for determining each ablated patient's rhythm, medication use, and overall health status.

RESULTS

The AF-free rates of group I and group II patients were statistically equivalent for both ablation groups at all evaluation time points. None of the 112 patients treated with endoscopic mitral valve repair and ablative therapy experienced a specific patient injury attributable to ablation; no ablated patients died in hospital following the procedure; there were no esophageal perforations and no coronary artery stenosis due to the ablations in either ablation group. The rate of patients without AF was 74% in group I and 82% in group II in the 6-month follow-up. The group I pacemaker implantation rate of 14% was significantly higher than non-ablated group (4.7%), but the group II rate of 5.9% observed did not differ significantly from the non-ablated group.

CONCLUSIONS

It was shown with our results that one succeeds with the en bloc-ablation in treating patients with different kinds of atrial fibrillation with concurrent intervention in the mitral valve reliably and with a high rate. The combination of this procedure with endocardial interventional ablation technologies can possibly develop to a promising strategy in the hybrid therapy of the isolated chronic atrial fibrillation as a standalone procedure.

Epicardial Ablation on the Beating Heart: Limited Efficacy of a Novel, Cooled Radiofrequency Ablation Device

OBJECTIVE: To perform a minimally invasive procedure for atrial fibrillation without cardiopulmonary bypass, it is necessary to create transmural lesions on the beating heart. Although bipolar radiofrequency clamps can isolate the pulmonary veins, they have difficulty in performing any other left atrial lesions, particularly those of the traditional Cox-Maze procedure. This study examined the performance of an internally cooled, bipolar radiofrequency device designed for such an application. METHODS: Eleven domestic pigs underwent median sternotomy. Five animals had eight atrial lesions created with the radiofrequency device at times of 20, 30, 40, and 50 seconds. In six other pigs, the device was compared with another technology that has been used clinically for epicardial, beating heart ablation, the Guidant Flex 4 microwave device. The tissue was stained with 2,3,5-triphenyl-tetrazoluim chloride, and the lesions were sectioned at 5-mm intervals. Lesion width, depth, and transmurality were evaluated. RESULTS: The radiofrequency device had a linear dose-response relationship. Lesions were wider and deeper with increasing ablation times. A total of 40%, 45%, 60%, and 67% of lesions were transmural at times of 20, 30, 40, and 50 seconds, respectively. Ninety-one percent of lesions in tissue up to 4-mm thick were transmural after 50 seconds. However, performance in thicker tissue was poor. Lesions created by the device were deeper and more likely to be transmural than the Flex 4. CONCLUSIONS: This internally cooled, bipolar radiofrequency device can reliably create transmural lesions on tissue up to 4-mm thick and performs better than a microwave device.

Predictors of Sinus Rhythm after Radiofrequency Maze and Mitral Valve Surgery

The prevalence and predictors of postoperative sinus rhythm in patients undergoing a radiofrequency ablation maze operation and mitral valve surgery were assessed in 63 patients of whom 54 (86%) were in permanent atrial fibrillation. Operative mortality was 3.17%. At a median follow-up of 18 months, 54 (88.5%) patients were in sinus rhythm and 7 (11.5%) were in atrial fibrillation. The probability of sinus rhythm at 30 months was 92%. Left atrial diameter was the most significant prognostic factor for sinus rhythm on multivariate proportional-hazard regression analysis. The cutoff value of preoperative left atrial diameter for predicting persistent atrial fibrillation at 6 months was 6 cm (100% sensitivity and 73.6% specificity). The radiofrequency ablation maze operation can be performed in addition to mitral surgery with a high rate of successful conversion to sinus rhythm. Preoperative left atrial diameter < 6 cm is an important prognostic factor for sinus rhythm conversion.