Results from Cox-Maze IV Procedure Are Superior to Catheter Ablation and Other Forms of Surgical AF Ablation

New research suggests that the Cox maze IV ablation procedure (CMP-IV) leads to better long-term outcomes than catheter-based ablation procedures in patients with atrial fibrillation.

New research suggests that the Cox maze IV ablation procedure (CMP-IV) leads to better long-term outcomes than catheter-based ablation procedures in patients with atrial fibrillation (AF).

Researchers from the Washington University School of Medicine and Barnes-Jewish Hospital in St. Louis prospectively collected data between January 2002 and September 2014 on 532 patients who underwent a CMP-IV and 44 who underwent a left-sided CMP-IV.

The study team collected 5 years of follow-up data on each patient and reported that 78% of all patients remained free from AF and 66% of all patients remained free from AF without the use of antiarrhythmic drugs. There were no significant differences in the rate of freedom from AF, either with or without medication, between the 204 patients who were treated for paroxysmal AF and the 305 patients who were treated for persistent or long-standing persistent AF. Outcomes were also comparable for patients who underwent CMP-IV as a stand-alone procedure and patients who received concomitant heart surgery.

“The outcomes of the CMPIV remain good at late follow up,” the study authors wrote in The Journal of Thoracic and Cardiovascular Surgery.“The type of preoperative AF or the addition of a concomitant procedure did not affect late success. The results of the CMPIV remain superior to those reported for catheter ablation and other forms of surgical AF ablation, especially for patients with persistent or long-standing AF.”

The original Cox maze ablation procedure was developed at Barnes Hospital in 1987 by James Cox, MD, who sought to eliminate AF by making a maze-like pattern of incisions in the atria and thus blocking the multiple macroreentrant circuits that were thought to cause AF. The third evolution of the procedure produced excellent results — up to 97% of study patientsemerged from the operating room with no symptoms of AF — but the complexity and invasiveness of the CMP-III prevented its widespread adoption.

The advent of alternative energy sources allowed for the creation of the CMP-IV, which uses bipolar radiofrequency and cryoenergy to mimic the cut-and-sew lesion set of the older procedure. The new procedure is simpler, shorter and less invasive than its predecessor. A study published in 2011 found thatthe new and old procedures achieved comparable success in the short term (2 years or less) but lacked the data to make long-term comparisons. It did, however, note that both versions of CMP produced higher response rates than catheter ablations.

“The results of catheter ablation have been variable, with single-procedure success rates between 16% and 84%. A recent study from the group of Haïssaguerre et al, who pioneered the isolation of the pulmonary vein, reported a single-procedure success rate as low as 29% after 5 years. Certain patient subgroups have performed particularly poorly, such as patients with long-standing persistent AF and large atria. A recent review suggested a success rate for a single procedure ranging from 22% to 45% in patients with persistent or long-standing persistent AF…

“Our data would suggest that more patients should be referred for the CMP, particularly symptomatic patients in whom a catheter ablation has failed or who belong to a subgroup who have poor results with catheter ablation.”