in a head-to-head trial, an outcome that might favor PFA in the context of other considerations.
“The take-home message is that this is a new technology that has important safety benefits. Patients do not have to worry about the possibility – albeit rare – of esophageal fistulae and other problems. It is faster with at least the same efficacy,” reported Vivek Y. Reddy MD, director of cardiac arrhythmia services, Mount Sinai Hospital, New York.
As opposed to conventional catheter-based thermal ablation, which isolates pulmonary veins harboring AF triggers by heating or freezing the tissue, PFA uses microsecond high-voltage electrical fields to produce cellular necrosis. It is largely nonthermal, Dr. Reddy said.
New device might spare adjacent tissue
In experimental studies, PFA has demonstrated a high degree of ablative specificity, limiting effects on adjacent tissues, such as the esophagus and phrenic nerve, he explained.
Several previous clinical studies support the specificity of the PFA ablative effect, but the ADVENT trial, which Dr. Reddy presented Aug. 27 at the annual congress of the European Society of Cardiology, is the first trial in which patients have been randomly assigned to PFA or catheter-based ablation.
The study was published online in the New England Journal of Medicine simultaneously with the ESC presentation.
The primary efficacy endpoint was the absence of a composite of endpoints indicating incomplete ablation. These included an initial procedural failure, atrial tachyarrhythmias arising after a 3-month blanking period, subsequent use of antiarrhythmic drugs, cardioversion, or repeat ablation. The primary safety endpoint involved a composite of procedure-related adverse events.
The 607 patients enrolled in this trial had AF refractory to at least one antiarrhythmic drug class. They were randomly assigned in a 1:1 ratio to PFA with a catheter system (Farapulse–Boston Scientific) or to thermal ablation.
Of the thermal approaches, radiofrequency or cryoablation was permitted, but each center was required to use just one for the control arm. For the comparison to PFA, outcomes for the two thermal techniques, which were used in similar proportions of patients, were combined based on previous evidence that these approaches perform similarly.
At 1 year, 73.3% of patients in the PFA group and 71.3% of those in the control group met the primary outcome, meaning none of the events signaling ablation failure occurred. The numeric advantage of PFA confirmed noninferiority, although an evaluation of superiority for efficacy, which was triggered by the advantage of PFA, was not significant.
As predicted by previous studies, stratification of thermal ablation approaches showed that outcomes were similar, although the proportion of patients who remained free of events at 1 year was numerically higher in the cryoablation group relative to the radiofrequency group (73.6% vs. 69.2%).
An adverse safety event occurred in 2.1% of those who underwent PFA and in 1.5% of those who underwent thermal ablation. This 0.6–percentage point difference placed PFA well within the boundary of noninferiority for safety.
Of notable events, the only death in this study occurred in the PFA group, and the only stroke occurred in the control group. Phrenic nerve palsies occurred only in the control group (2 vs. 0) while pericarditis was seen only in the PFA group (2 vs. 0). One case of pulmonary edema occurred in each group.
“Catheter ablation is quite safe and effective,” said Dr. Reddy, explaining why this comparison was conducted on the basis of noninferiority.
Dr. Reddy emphasized that noninferiority for PFA was achieved by operators with little or no experience with this technology, whereas the catheter ablations were delivered by operators who typically had previously performed hundreds of interventions.
“With experience, one would expect even better rates of success. This is the floor,” Dr. Reddy said.