suggests a new analysis.
It’s the first study tying those outcomes to residual AFib burden after ablation achieved using the emerging pulsed-field ablation (PFA) technology, say researchers. These associations are already established for cath ablation using traditional radiofrequency energy or cryoablation.
The new findings come from a secondary analysis of the recently published PULSED-AF study, which highlighted the ablation efficacy of Medtronic’s investigational PulseSelect PFA system in patients with either paroxysmal AFib (PAF) or persistent AFib.
The trial had entered 300 adult candidates for catheter ablation of recurrent, symptomatic PAF or persistent AFib at 41 centers in Australia, Canada, Europe, Japan, and the United States.
After ablation, 69% of PAF patients and 62% of those who had persistent AFib showed no sign of atrial arrhythmia (AA) over 12 months, based on the trial’s method for estimating AA burden.
Residual AA burden less than 10% was seen in 87% and 82% of those initially with PAF and persistent AFib, respectively. Burdens in that lowest range, compared with greater AA burden, predicted a “clinically meaningful” improvement in QoL scores in PAF patients.
Those who entered the study with persistent AFib showed such improvement – defined as a more than 19-point gain on the Atrial Fibrillation Effect on Quality-of-Life Questionnaire – regardless of postablation AA burden.
Moreover, patients initially with either type of AFib and residual burdens in the lowest range went on to have fewer cardioversions and repeat ablations (P < .01), Atul Verma, MD, McGill University Health Centre, Montreal, reported at the annual scientific sessions of the Heart Rhythm Society.
Dr. Verma, the trial’s principal investigator, is also lead author on the same-day publication of the secondary analysis in Heart Rhythm.
Binary endpoint lacks relevance
The PULSED-AF primary analysis defined ablation efficacy partly as freedom from AA recurrence lasting at least 30 seconds, with or without symptoms, a traditional AFib-ablation trial endpoint that is nonetheless considered clinically unhelpful.
The secondary analysis recasts that binary endpoint as degree of reduction in AFib burden, a continuous variable. That potentially allows AFib ablation efficacy to be assessed in a more nuanced way likely to be more meaningful to patients and the health care system, observed Dr. Verma and colleagues.
The “30-second endpoint” is limited in clinical usefulness and “doesn’t mean much to the patient,” he said at a press conference on the analysis before formally presenting it at the HRS sessions.
Recent AFib ablation trials have explored AA burden as possibly a superior way to assess the procedure’s success “but also to see if it’s better correlated with quality of life and health care outcomes,” Dr. Verma said. “So that’s exactly what we’ve tried to do here using the PULSED-AF data.”
In the secondary analysis, he said, patients’ rate of freedom from the 30-second endpoint was about 70%, but “more than 85% of them had an AFib burden of less than 10%.”
“This efficacy endpoint of 30 seconds of atrial arrhythmia has been challenged and has been seen clinically as insignificant,” agreed Rajeev Pathak, MBBS, PhD, of Australian National University and director of cardiac electrophysiology at Canberra (Australia) Hospital.
In AFib radiofrequency ablation and cryoablation studies “there is clear disconnect between these 30-second episodes of atrial arrhythmias we see and the clinical relevance of health care utilization and quality of life,” said Dr. Pathak, invited discussant for Dr. Verma’s presentation at the sessions.
Now an AFib ablation trial using PFA catheters has yielded similar results, finding AA burden to be “a more objective and relevant measure of success,” he said. “A 30-second endpoint is arbitrary, lacks significance, and is highly dependent on the monitoring strategy.”