A Swedish consensus on the surgical treatment of concomitant atrial fibrillation

Effect of cryothermic and radiofrequency Cox-Maze IV ablation on atrial size and function assessed by 2D and 3D echocardiography, a randomized trial. To freeze or to burn

BACKGROUND

Atrial linear scars in Cox-Maze IV procedures are achieved using Cryothermy (Cryo) or radiofrequency (RF) techniques. The subsequent postoperative left atrial (LA) reverse remodelling is unclear. We used 2- and 3-dimensional echocardiography (2-3DE) to compare the impact of Cryo and RF procedures on LA size and function 1 year after Cox-maze IV ablation concomitant with Mitral valve (MV) surgery.

METHODS

Seventy-two patients with MV disease and AF were randomized to Cryo (n = 35) or RF (n = 37) ablation. Another 33 patients were enroled without ablation (NoMaze). All patients underwent an echocardiogram the day before and 1 year after surgery. The LA function was assessed on 2D strain by speckle tracking and 3DE.

RESULTS

Forty-two ablated patients recovered sinus rhythm (SR) 1 year after surgery. They had comparable left and right systolic ventricular function, LA volume index (LAVI), and 2D reservoir strain before surgery. At follow-up, the 3DE extracted reservoir and booster function were higher after RF (37 ± 10% vs. 26 ± 6%; p < 0.001) than Cryo ablation (18 ± 9 vs. 7 ± 4%; p < 0.001), while passive conduit function was comparable between groups (24 ± 11 vs. 20 ± 8%; p = 0.17). The extent of LAVI reduction depended on the duration of AF preoperatively.

CONCLUSIONS

SR restoration after MV surgery and maze results in LA size reduction irrespective of the energy source used. Compared to RF, the extension of ablation area produced by Cryo implies a structural LA remodelling affecting LA systolic function.

Pre- and postoperative atrial fibrillation in CABG patients have similar prognostic impact

OBJECTIVES

To study pre- and postoperative atrial fibrillation and its long-term effects in a cohort of aortocoronary bypass surgery patients.

DESIGN

Altogether 615 patients undergoing aortocoronary bypass graft surgery in 1999-2000 were studied. Forty-four (7%) had preoperative atrial fibrillation. Postoperative atrial fibrillation occurred in 165/615 patients (27%) while 406/615 patients (66%) had no atrial fibrillation. After a median follow-up of 15 years, symptoms and medication in survivors were recorded, and cause of death in the deceased was obtained.

RESULTS

Death due to cerebral ischaemia was most common in the pre- and postoperative atrial fibrillation groups (7% and 5%, respectively, v. 2% among those without atrial fibrillation, p = .038), as were death due to heart failure (18% and 14%, v. 7%, p = .007) and sudden death (9% and 5%, v. 2%, p = .029). The presence of pre- or postoperative atrial fibrillation was an independent risk factor for late mortality (hazard ratios 1.47 (1.02-2.12) and 1.28 (1.01-1.63), respectively).

CONCLUSIONS

Patients with pre- or postoperative atrial fibrillation undergoing aortocoronary bypass surgery have increased long-term mortality and risk of cerebral ischemic and cardiovascular death compared with patients in sinus rhythm.

Surgical Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common chronic arrhythmia in the adult population. Ablation lines have largely replaced the historical and challenging cut and sew techniques. Surgical ablation of AF is commonly performed in cases with other indications for cardiac surgery and less commonly as a stand-alone therapy. Pulmonary vein isolation is the cornerstone of this procedure. Extended left atrial ablation lines may increase efficacy in cases with longstanding persistent or permanent AF. Additional efficacy by adding right atrial ablation is controversial but is often performed in cases undergoing right atrial or atrial septal surgery. Left atrial volume reduction is recommended in cases with large left atria and AF undergoing another cardiac surgery. Arrhythmia recurrence is not uncommon after surgical ablation of AF and varies among studies due to heterogeneity in patient population, lesion set and endpoints. Freedom from AF recurrence was 65-87% at 12 months and 58-70% at 2 years follow-up. Long-term monitoring is recommended due to an increased prevalence of asymptomatic recurrences. The strongest predictors of AF recurrence are longstanding or persistent AF and a large left atrium. The most common mechanisms of recurrence are pulmonary vein reconnection, nonpulmonary vein triggers, and gaps in the ablation lines. About 20% of atrial tachyarrhythmia recurrences are atrial flutter or atrial tachycardia. There are not enough data in the surgical literature to support withdrawal of anticoagulation after surgical AF ablation. Patients selected for stand-alone surgical ablation usually have low risk profiles and low postoperative mortality rates (0.2%).

The Berglin apical stitch: a simple technique to straighten things out in atrial fibrillation surgery

In the Cox-Maze IV procedure, or in endocardial left atrial ablation, correct positioning of the surgical ablation probe within the left atrium might be difficult due to bulging or folds in the posterior left atrial wall. The Berglin apical stitch is a simple trick of the trade to create a smooth surface in the posterior left atrium that facilitates performing a safe transmural lesion and, consequently, may increase antiarrhythmic efficiency.

A brief overview of surgery for atrial fibrillation

The Maze procedure was the first surgical technique developed to ablate, rather than isolate, atrial fibrillation and was first performed clinically in 1987. The experimental and clinical electrophysiological maps on which the Maze procedure was based demonstrated the presence of two or more large (5-6 cm diameter) macro-reentrant circuits during established atrial fibrillation (AF). Eleven years later, focal triggers were identified, primarily in and around the pulmonary veins, and were shown to be responsible for the induction of individual episodes of AF. Thus, it became clear that episodes of paroxysmal AF could be treated in most patients by isolating or ablating the region of the pulmonary veins, but that once AF became non-paroxysmal and thus dependent upon the macro-reentrant circuits for its maintenance, it would still be necessary to perform some type of additional procedure to interrupt those circuits. Approximately 100,000 patients who undergo coronary artery bypass grafting (CABG), aortic valve replacement (AVR) or mitral valve surgery in the US also have associated AF, but only 20% of them undergo a concomitant procedure to ablate the AF. However, multiple studies have demonstrated that treating the AF at the time of these other primary operations results in an improved quality of life, fewer long-term strokes and improved long-term survival while adding no risk to the overall surgical procedure. Moreover, the major cardiology and surgery societies recommend that concomitant AF surgery be performed in all cases when feasible. Patients undergoing CABG and AVR who have paroxysmal AF should undergo pulmonary vein isolation, while those with non-paroxysmal AF (persistent or long-standing persistent AF) should have a Maze procedure. Patients undergoing mitral valve surgery who have either paroxysmal AF or non-paroxysmal AF should undergo a Maze procedure.