The objective of the Maze procedure is to render the atria incapable of fibrillating by precluding or interrupting the development of macro-reentrant circuits (drivers) that sustain atrial fibrillation (AF) drivers and to restore the ability of a sinus-generated impulse to activate both atria and the ventricles in a shychronous fashion. Therefore, it reasonable to expect that the procedure would also prevent early perioperative AF, but this has never been the case. , The atria have shorter refractory periods in the milieu of the postoperative inflammatory state, meaning that smaller macro-reentrant circuits can develop between the lesions of the Maze procedure, resulting in early perioperative AF (see Chapter 4 ). Efforts to control early postoperative AF (POAF) in following a Maze procedure center around the use of drugs that either prolong the atrial refractory periods (rhythm control) or control the ventricular rate (rate control) until the inflammatory response subsides and the atrial refractory periods return to normal. After the refractory periods return to their preoperative status with time, only large reentrant circuits can develop in the atria, and the lesions of the Maze procedure usually prevent them from developing without the need for continuing the antiarrhythmic drugs. This practice of allowing for tissue healing (maturation of the atrial lesions) and electrophysiologic recovery of the atria from surgery is the basis of the standard 90-day blanking period observed after both surgical and catheter ablation.
Reports on the original series of Maze procedure patients and many of the large clinical series reports that followed included the incidence of early perioperative AF but offered little useful information regarding how it should be treated. Despite the availability of guideline recommendations, there is still no universally accepted prophylactic protocol for preventing early POAF after any type of cardiac surgery, including the Maze procedure, and its incidence has changed little over the past four decades. Likewise, there is no generally accepted anticoagulation regimen for patients after Maze procedures either with or without POAF. All iterations of the Maze procedure include removal or occlusion (LAAO) of the left atrial appendage (LAA) because it is believed that the LAA is the site of origin of the vast majority of thromboembolic strokes associated with AF. However, some of the non-Maze surgical procedures currently used for the treatment of patients with AF include LAAO and others do not. There are general guidelines from various societies about new-onset POAF in patients after cardiac surgery, and most surgeons treat POAF following the Maze procedure in the same way. In addition, the importance and validity of the CHADs 2 VASC score remains unclear after AF is ablated and/or the LAA is closed. Therefore, the need for anticoagulation, what type, and for how long remain unanswered questions.
Treatment of Early Postoperative Atrial Fibrillation After Surgical Atrial Fibrillation Ablation Procedures
The treatment of new-onset POAF after cardiac surgery in patients with no history of preoperative AF is based on either rate control or rhythm control with a variety of antiarrhythmic medications. Meta-analyses and randomized trials have failed to show a treatment advantage of one strategy over the other. , However, patients who develop postoperative AF after cardiac surgery that was performed specifically to ablate preoperative AF are like no other patients. Are they to be considered in the same category as patients with no history of preoperative AF who develop new-onset POAF after cardiac surgery? Should the treatment of the two be the same? We do not know the answer to these questions, but the patients should probably be considered to be in two different groups. As discussed in Chapter 47 , patients who have no history of AF but then develop new-onset POAF after cardiac surgery most likely have a preoperative maldistribution of their local atrial refractory periods. However, patients with a history of preoperative AF who undergo a Maze procedure for that AF are thought to develop early POAF because of a shortening of their refractory periods caused by the general perioperative inflammatory response to the surgery. Despite these potential differences in the underlying electrophysiologic derangements responsible for early POAF in patients with and without preoperative AF, we have little choice currently but to treat them in the same manner. Cardioversion during the postoperative period may be required depending on the patient’s clinical status. , Recommendations for treatment of new-onset POAF from the joint guidelines of the American College of Cardiology (ACC), American Heart Association (AHA), American College of Clinical Pharmacy (ACCP), and Heart Rhythm Society (HRS) are shown in Table 49.1 .
TABLE 49.1
Joint Guideline Recommendations of the American College of Cardiology, American Heart Association, American College of Clinical Pharmacy, and Heart Rhythm Society for the Treatment of Patients with New-Onset Postoperative Atrial Fibrillation After Cardiac Surgery
| Guidelines: ACC/AHA/ACCP/HRS | Recommendations: Treatment of AF After Cardiac Surgery | Class of Recommendation | Level of Recommendation |
|---|---|---|---|
| Joglar et al. | In postoperative cardiac surgery patients, beta-blockers are recommended to achieve rate control for AF unless contraindicated or ineffective, in which case a nondihydropyridine calcium channel blocker is recommended. | I | A (beta-blocker) |
| B-R (nondihydropyridine calcium channel blocker) | |||
| In hemodynamically stable cardiac surgery patients with postoperative AF, rate-control (target heart rate, <100 beats/min) and/or rhythm-control medications are recommended as initial therapy, with the choice of strategy according to patient symptoms, hemodynamic consequences of the arrhythmia, and physician preference. | I | B-R | |
| In patients who develop poorly tolerated AF after cardiac surgery, direct current cardioversion in combination with antiarrhythmic drug therapy is recommended, with consideration of imaging to rule out LAA thrombus before cardioversion in patients in whom AF has been present >48 hours and who have not been on anticoagulation. | I | B-R | |
| In patients who develop postoperative AF after cardiac surgery, it is reasonable to administer anticoagulation when deemed safe in regard to surgical bleeding for 60 days after surgery unless complications develop and to reevaluate the need for longer term anticoagulation at that time. | IIa | B-R | |
| In patients who develop AF after cardiac surgery and who are treated with rate-control strategy, at 30- to 60-day follow-up, it is reasonable to perform rhythm assessment, and if AF does not revert to sinus rhythm spontaneously, consider cardioversion after an adequate duration of anticoagulation. | IIa | B-R |
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