MUNICH – Left atrial ablative treatment for atrial fibrillation was safe when administered during open heart surgery in a multicenter, randomized trial of 224 patients who all had atrial fibrillation and required heart surgery for another reason.
The treatment was also effective, resulting in a significantly higher rate of sinus rhythm among the patients treated with ablation compared with the control patients who underwent open-heart surgery alone, Dr. Petr Widimsky reported at the annual congress of the European Society of Cardiology.
Some experts who heard the findings expressed some skepticism about the pattern of anti-arrhythmic effects and other atrial fibrillation–related outcomes during follow-up.
"The rhythm outcomes had some surprises. All the benefit was in patients with long-standing, persistent atrial fibrillation; that’s very surprising because it contrasts with previous findings from both catheter ablation and surgical ablation," said Dr. Gerhard Hindricks, a professor of medicine and director of the department of electrophysiology at the Heart Center of Leipzig (Germany) University.
"The secondary outcomes were also a surprise, because the atrial fibrillation response did not translate into a change in treatment" in the use of anti-arrhythmic drugs, and the two groups showed no differences in the 1-year rates of stroke, major bleeding, and all-cause mortality despite the reported different rates of continued AF. In an editorial that accompanied the published paper, Dr. Hindricks cited the inadequacy of assessing atrial arrhythmia at 1-year follow-up with 24-hour Holter ECG monitoring. "This follow-up regimen is by far not enough to generate reliable and solid results," Dr. Hindricks and his coauthor wrote (Eur. Heart J. 2012;33 [doi: 10.1093/eurheartj/ehs294]).
Despite these unexpected findings, "surgical ablation of atrial fibrillation should be cautiously indicated in asymptomatic patients scheduled for cardiac surgery," Dr. Hindricks said in comments he made at the meeting.
"This was the largest" of several randomized, prospective studies that have assessed ablation of atrial fibrillation during cardiac surgery, said Dr. Riccardo Cappato, director of the Center of Clinical Arrhythmia and Electrophysiology at the Policlinico San Donato in Milan. "The increased probability of maintaining sinus rhythm in patients with permanent atrial fibrillation does not seem to have been at the expense of higher perioperative risk exposure."
The PRAGUE-12 study enrolled 224 patients with AF who required cardiac surgery for coronary artery bypass, valve repair or replacement, or both at three centers in the Czech Republic and Slovakia during 2007-2011. The investigators randomized 117 patients to undergo atrial ablation during their surgery, and 107 who received no ablation with their surgery and served as controls. The surgeons could use whichever energy source for ablation they preferred, but 97% used cryoablation. The ablation-lesion set was the same for all patients in that treatment arm.
The patients averaged about 70 years old, and about 58% were men. Roughly half the patients had long-standing persistent AF, about a quarter had persistent AF, and the remaining quarter had paroxysmal AF.
All patients underwent open surgery using a median sternotomy with cardiopulmonary bypass and cardioplegic heart arrest. Adding ablation to the procedures increased the total surgical time by an average of 20 minutes, and increased the period of cardiopulmonary bypass and the cross-clamp time by an average of 28 minutes.
The primary safety end point was the combined rate of death, stroke, myocardial ischemia, or renal failure requiring dialysis at 30 days after surgery; this occurred in 10% of the patients who had ablation and 15% of the control patients, a nonsignificant difference, reported Dr. Widimsky, professor and head of the Cardiocenter of Charles University in Prague. Each component of the combined adverse event was similar between the two study arms. At 1 year after surgery, the combined adverse event rate was 41% in the patients treated with AF ablation and 40% in the controls.
The study’s primary efficacy end point was the prevalence of sinus rhythm in patients as measured by 24-hour Holter ECG monitoring, which occurred in 60% of the patients who underwent ablation and in 36% of the controls, a significant difference. This difference was driven by the outcome difference among the subgroup of patients who entered the study with long-standing persistent AF. In this subgroup, the proportion of patients in sinus rhythm when assessed after 1 year was 53% in the ablated group and 14% in the controls, a significant difference. In contrast, the prevalence of sinus rhythm at 1 year did not differ significantly between the two treatment arms in patients who entered the study with paroxysmal AF, or in those who entered with persistent AF.