番茄社区

Adding more complex ablation to pulmonary vein isolation for persistent atrial fibrillation (Afib) didn't zap recurrences, the STAR AF II trial showed.

Pulmonary vein isolation alone left 59% of patients free from recurrence without additional procedures compared with 49% when adding ablation of complex fractionated electrograms and 46% when adding linear ablation across the left atrial roof and mitral valve isthmus (P=0.15).

More complex ablation also failed to excel on any other outcomes and appeared to carry more risk, , of Southlake Regional Health Center in Newmarket, Ontario, and colleagues found.

Their trial results appeared in the May 7 issue of the New England Journal of Medicine, following a previous presentation at the European Society of Cardiology meeting.

Implications

Persistent Afib has been an attractive target for more extensive ablation, because ablation outcomes have been poorer than in paroxysmal cases.

"Despite the paucity of data, guidelines suggest that 'operators should consider more extensive ablation based on linear lesions or complex fractionated electrograms' for ablation of persistent atrial fibrillation," the researchers noted.

The reasons that didn't pan out in the trial weren't clear.

More extensive ablation causing "new, iatrogenic areas of arrhythmogenesis where tissue is incompletely ablated or linear block is not achieved" didn't appear to be the explanation, Verma's group suggested, citing high rates of successful complex electrogram ablation and achievement of linear block and no change in results after two procedures.

"Perhaps neither complex electrograms nor lines are the correct supplemental targets for ablation," they proposed. "More selective targets may be needed to better characterize an individual patient's specific arrhythmic substrate."

Notably, the RADAR AF trial in paroxysmal Afib also showed potentially worse outcomes when adding ablation beyond the standard suspected triggers in the pulmonary vein, leading some to call for a better way to ablate the substrate.

What the studies have lacked is a no-ablation arm, commented , an electrophysiologist at the University of Iowa in Iowa City.

"A success rate of 50% is rather poor by any means and yet better than many other studies out there," he told 番茄社区. "One wonders if this procedure, ablation, is even justified in these patients. Maybe less really is more -- no procedure is more than pulmonary vein isolation alone."

"And freedom from atrial fibrillation does not necessarily translate into anything else of benefit for the patient," while carrying costs and risks, he added.

Risks

In STAR AF, nearly all of the most common adverse events occurred in the more complex ablation groups. Only two of the 23 events among the 589 persistent Afib patients in the randomized trial occurred in the isolation-alone group (two hematomas at the access site).

The only death occurred in the isolation plus complex electrogram-ablation group. That case of procedure-related atrioesophageal fistula complicated by stroke was successfully treated by esophageal stenting, but the patient still died 3 months later of aspiration pneumonia.

Other serious adverse events included cases of cardiac tamponade and three of stroke or transient ischemic attack.

Verma's group also pointed to increased duration of the procedure with the more complex approaches as a potential risk.

"Procedure time in this study was longer by almost an hour in the additional-ablation groups and was associated with increased exposure to fluoroscopy for the patient and the operator," they wrote.

Limitations

The researchers pointed to rigorous monitoring for Afib in the study in assessing the endpoints, but pointed out that "the 1:4:4 randomization ratio of pulmonary vein isolation to other strategies means that the trial was underpowered to show whether pulmonary vein isolation alone was superior to the combined strategies."

The primary endpoint counted only recurrences of any Afib lasting longer than 30 seconds and occurring after the performance of a single ablation procedure (beyond the 3-month blanking period), regardless of antiarrhythmic medication use. Second ablation procedures were also counted as recurrence.

Secondary outcomes included freedom from any documented atrial arrhythmia (including Afib, flutter, or tachycardia) after one ablation procedure and after two, use of antiarrhythmic medication, and repeat procedures.

The study didn't look at more recently developed supplemental targets, such as non-pulmonary-vein triggers and rotational activity within the atria, the researchers noted.

"Although these targets may be important, our results suggest that any new strategy must be subjected to larger-scale study before wide implementation," they wrote.

From the American Heart Association:

Comment