The biatrial maze procedure and, more commonly, pulmonary vein isolation (PVI) are used to reduce the burden of atrial fibrillation (AF) that’s present in 30 to 50 percent of patients undergoing mitral valve surgery. New results from a Cardiothoracic Surgical Trials Network (CTSN) study now show the biatrial maze procedure to be superior to PVI for treatment of AF in this population.
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The findings, presented as a late-breaking trial May 2 at the annual meeting of the American Association for Thoracic Surgery, were achieved using weekly transtelephonic monitoring (TTM), rather than standard Holter monitoring, to assess the effect of lesion set on AF.
“It’s safe to say the biatrial maze procedure is superior to PVI in mitral valve surgery patients who also need surgical ablation of AF,” says lead investigator A. Marc Gillinov, MD, Chair of Cleveland Clinic’s Department of Thoracic and Cardiovascular Surgery, who presented the results on behalf of CTSN. “I am now more likely to do a biatrial maze than a PVI in these patients.”
Delineating the differences
The multicenter study involved 260 patients with persistent or long-standing persistent AF who also required mitral valve surgery. Patients were randomized to mitral valve surgery alone or with surgical ablation; those randomized to ablation were further randomized to PVI or biatrial maze.
During the 12 months following surgery, 228 patients (88 percent) submitted 7,949 TTM assessments, which were analyzed longitudinally.
Freedom from AF was found to be higher after biatrial maze than after PVI (odds ratio [OR] = 2.31; 95% CI, 0.95-5.65; P = .07).
At 12 months, the estimated prevalence of AF by TTM was as follows:
- 59 percent for patients who had mitral valve surgery alone
- 40 percent for patients who had PVI
- 25 percent for patients who had biatrial maze (P < .04 vs. PVI)
Moreover, the cumulative estimated AF burden (median total duration of AF over the 12 months following surgery) was lower after biatrial maze than after PVI (1.5 vs. 2.6 months).
Expanding on earlier findings
These findings build on an earlier report from this CTSN study published in the New England Journal of Medicine in 2015. That report, which assessed patients by 72-hour Holter monitoring, found that freedom from AF at both six and 12 months was significantly greater with surgical ablation than with mitral valve surgery alone, but no difference between lesion sets was observed.
The new report shows that assessing patients more frequently, with weekly TTM rather than three-day Holter monitoring at six and 12 months, changed that. “Weekly transtelephonic monitoring showed a lower estimated prevalence of AF and AF burden after biatrial maze compared with PVI,” says Dr. Gillinov.
Likely impacts on both surgical and monitoring practice
These new results may shift AF ablation during mitral valve surgery back toward the maze procedure and change the method of postoperative monitoring used, he adds.
“Since no difference between PVI and maze could be seen with 72-hour Holter monitoring, the value of TTM in understanding the effects of these procedures on AF cannot be underestimated,” he says. “TTM enables a more rigorous comparison of surgical strategies and provides more complete results concerning AF treatment success.”
Dr. Gillinov adds that weekly TTM readings in this study also enabled examination of the effects of PVI versus maze on cumulative AF burden, AF load and estimated AF prevalence, none of which was possible with a single Holter monitoring assessment.
“The discrepancy between AF prevalence at a specific point in time and AF prevalence as a continuous measure suggests the need to reassess current definitions of success and failure after ablation procedures,” he says.