Combined atrial fibrillation and mitral valve surgery using radiofrequency technology

Ratio of preoperative atrial natriuretic peptide to brain natriuretic peptide predicts the outcome of the maze procedure in mitral valve disease

Background

Although the maze procedure is an established surgical treatment for eliminating atrial fibrillation (AF), its efficacy in patients with mitral valve disease has remained unsatisfactory. A useful predictive marker for the outcome of the maze procedure is needed. The aim of this study was to investigate whether the preoperative ratio of atrial natriuretic peptide (ANP) to brain natriuretic peptide (BNP) reflects atrial fibrosis and can be used to predict the maze procedure outcome in patients with mitral valve disease.

Methods

A total of 23 consecutive patients who underwent the radial approach to the maze procedure combined with mitral valve surgery were included in this study and were divided into a sinus rhythm (SR) group (n=16) and an AF group (n=7) based on postoperative cardiac rhythm. Plasma samples were obtained at rest before the operation and were analysed for ANP and BNP levels. Atrial tissue samples taken during surgery were used to quantify interstitial fibrosis.

Results

The preoperative ANP-to-BNP ratio in the SR group was significantly higher than that in the AF group (0.74 +/− 0.29 vs. 0.42 +/− 0.28, respectively; p=0.025). Receiver operating characteristic (ROC) curve analysis was used to identify factors that predict outcomes after the maze procedure. The area under the ROC curve for the ANP-to-BNP ratio (0.81) was greater than for any other preoperative factors. Moreover, the preoperative ANP-to-BNP ratio demonstrated a negative correlation with left atrial fibrosis (r=−0.69; p=0.003).

Conclusions

The preoperative ANP-to-BNP ratio can predict maze procedure outcome in patients with mitral valve disease, and it represents a potential biomarker for left atrial fibrosis.

Novel approaches for the surgical treatment of atrial fibrillation: time for a guideline revision?

Atrial fibrillation is a major health problem in Western countries, and is associated with considerable morbidity and resource consumption. Safe and reliable surgical techniques for the termination of this arrhythmia have been developed since the time of the original Cox "maze I" procedure. Novel equipment based on radiofrequency and microwave technologies can be employed to create transmural atrial lesions, even in the context of minimally invasive surgery to the atrioventricular valves via right minithoracotomy. The aim of this paper is to review the recent literature on this approach, and the clinical results in terms of arrhythmia termination and postoperative morbidity. With the aim to substantiate the practice of a simple, yet reliable, surgical ablation during minimally invasive heart valve surgery, we discuss the results of different patterns of atrial lesions having different degrees of surgical complexity. Finally, minimally invasive epicardial ablation for lone atrial fibrillation represents an emerging surgical indication. The results of state-of-the-art transcatheter ablation represent now its benchmark of comparison.

Surgical treatment of atrial fibrillation : a systematic review

BACKGROUND

The recently published overwhelming number of publications on the surgical treatment of AF, using a wide variety of techniques, blurred any precise appreciation of the nowadays surgical treatment of AF. As a consequence, the "state of the art" of the surgical technique of AF is ill-defined.

OBJECTIVES

In this review the efficacy of the alternative sources of energy (radiofrequency-microwave and cryoablation; (group I) and the classical "cut and sew" Cox-Maze III (group II), which claims a 97-99% sinus rhythm (SR) success rate, were evaluated in the surgical treatment of atrial fibrillation (AF).

METHODS

A computerized search in the PubMed and Medline database was conducted. Only original, English written, clinical manuscripts on the surgical treatment of atrial fibrillation citing the clinical outcome, including the postoperative sinus rhythm, were included. The following data were registered: the absolute numbers and percentages of treated patients, gender (male versus female) distribution, the type of arrhythmia (permanent or paroxysmal AF), type of surgery (mitral or non-mitral valve or a lone AF surgical procedure), postoperative morbidity (bleeding, the use of an intra-aortic balloon pump, cerebral vascular accident), postoperative pacemaker implantations, 30-day mortality, survival and sinus rhythm conversion. The mean values for age (years), left atrial diameter (mm), preoperative duration of AF (years) and left ventricular ejection fraction (%) were also recorded.

RESULTS

Forty-eight studies were included comprising 3832 patients: 2279 in group I and 1553 in group II. The mean duration of AF, left atrial diameter and LVEF were 5.4 versus 5.5 years (p=0.90), 55.5 versus 57.8 mm (p=0.23) and 57 versus 58% (p=0.63). The postoperative SR rates for group I and II were 78.3 versus 84.9% (p=0.03). However, the "cut and sew" Cox-Maze III was conducted in younger patients (55.0 versus 61.2 years; p=0.005), more often to treat paroxysmal (22.9 versus 8.0%) and lone AF (19.3 versus 1.6%). Alternative sources of energy were predominantly used to treat permanent AF (92.0%), almost always as a concomitant surgical procedure (98.4%) and increasingly in combination with non-mitral valve surgery (18.5%). After correction for these variations, the postoperative SR conversion rates for group I and II did not differ significantly anymore.

CONCLUSIONS

We could not identify any significant difference in the postoperative SR conversion rates between the classical 'cut and sew' and the alternative sources of energy, which were used to treat atrial fibrillation.

Modified Maze During Endoscopic Mitral Valve Surgery: The OLV Clinic Experience

BACKGROUND

The use of radiofrequency ablation to perform the mini-maze procedure (pulmonary veins isolation) has been reported with good results. The aim of this study was to evaluate our practice with the association of the mini-maze procedure, done with the use of the Cardioblade pen, and minimally invasive mitral valve surgery.

METHODS

From January 1999 to November 2004, 103 patients underwent a minimally invasive mitral valve surgery with a concomitant pulmonary veins isolation (modified maze procedure) done with unipolar radiofrequency. All files were reviewed retrospectively.

RESULTS

In our group of patients, 41.2% were known to have intermittent atrial fibrillation and 58.8%, continuous atrial fibrillation; 67.7% of the patients were in atrial fibrillation at the time of surgery. Precise time of duration of atrial fibrillation was known in 47.6% (mean time, 30.3 +/- 28.9 months), but 47.7% were also known to have atrial fibrillation for many years. Mitral surgery included mitral valve repair in 71.8% and mitral valve replacement in 26.2%; 22 patients also received tricuspid annuloplasty. Major complications were mortality in 1%, myocardial infarction in 1%, stroke or transient ischemic attack in 1.9% and permanent pacemaker placement in 5.9%. At the time of discharge, 71.9% of patients were in sinus rhythm, 21.9% in atrial fibrillation, 1% in atrial flutter, and 5.2% in paced rhythm. Seventy-six and a half percent of the patients left the hospital with an antiarrhythmic drug (amiodarone 56.9%, sotalol 15.7%). At the time of follow-up, 99 patients were still alive with a mean follow-up time of 17.4 +/- 14.1 months; 69.7% of patients were in sinus rhythm, 28.3% in atrial fibrillation, and 2% were pacemaker-dependent. Patients received antiarrhythmic medication in 81.2% of cases (amiodarone 46.4%, sotalol 17.9%, beta-blocker 39.3%, digoxine 7.1%). Eleven new pacemakers were implanted (11.1%).

CONCLUSIONS

The use of unipolar radiofrequency ablation to perform a mini-maze during minimally invasive mitral valve surgery is a safe procedure and is associated with good early results.

Current Strategies in the Management of Atrial Fibrillation

Treatment of atrial fibrillation (AF) has been undergoing significant changes recently. This is due partly to different mechanisms proposed for persistent and permanent AF and partly due to the introduction of energy-based techniques, providing less invasive procedures. This article aims to review the mechanisms of AF leading to the changes in clinical practice and to review the results of surgery, energy-based, and percutaneous techniques. It is difficult to compare and contrast the results of reported series in the literature due to different definitions of AF; freedom from and recurrence of it. Furthermore, in most series it is difficult to distinguish results of surgery for lone AF and AF associated with valvular heart disease and coronary artery disease.

Surgical ablation as treatment for the elimination of atrial fibrillation: A meta-analysis

OBJECTIVE

The maze procedure is recognized as the most effective surgical treatment of atrial fibrillation. In the last few years, new surgical ablation techniques were developed involving the left atrium only and modifications of the maze procedure in ablating both atria. For this study, we evaluated the evidence regarding the effectiveness of the surgical ablation procedures (biatrial and left atrial) in reducing postoperative atrial fibrillation and subsequent survival.

METHODS

MEDLINE was searched for English-language studies using the terms "maze," "atrial fibrillation," and "surgical treatment" for 1995 through August 2005. Primary outcomes of interest were postoperative survival and postoperative freedom from atrial fibrillation. Survival data were collected at 1-, 2-, and 3-year intervals. Freedom from atrial fibrillation was collected at 3 months and at 1-, 2-, and 3-year intervals.

RESULTS

Sixty-nine studies were included in this analysis. Five thousand eight hundred eighty-five total patients were involved. Patients undergoing surgical ablation (range, 90.4-85.4) demonstrated significantly greater rates of freedom from atrial fibrillation compared with those seen in control patients (range, 47.2-60.9). Survival rates among patients with biatrial surgical procedures (range, 94.9-92.8) were similar to those who had left atrial procedures only (range, 93.9-89.4). However, patients undergoing biatrial ablation (range, 92.0-87.1 vs 86.1-73.4) demonstrated superior freedom from atrial fibrillation at all time points.

CONCLUSION

Biatrial ablation surgical procedures were more effective in controlling atrial fibrillation than procedures confined to the left atrium. To encourage the use of future meta-analysis within the surgical literature, we suggest the more frequent reporting of either through Kaplan-Meier survival analyses and the reporting of rates for specific time intervals.