The more you look, the more you see
The new secondary analysis included a demonstration that success rates based on the 30-second endpoint indeed vary depending on how subsequent arrhythmias are monitored.
As described by Dr. Verma, PULSED-AF data were assessed for the 30-second endpoint captured using three separate intermittent monitoring strategies that it and other recent ablation trials have used:
- Strategy A: Transtelephonic monitoring weekly and in the event of symptoms, plus 24-hour Holter monitoring at 6 and 12 months and 12-lead ECG at 3, 6, and 12 months
- Strategy B: Transtelephonic monitoring weekly and at symptoms for 3-6 months followed by monthly and at symptoms from 6 to 12 months, plus 24-hour Holter monitoring at 6 and 12 months, plus 12-lead ECG at 3, 6, and 12 months
- Strategy C: The median of two 24-hour Holter monitoring sessions per patient over 12 months
As Dr. Verma reported, rates of freedom from the 30-second endpoint climbed with successive monitoring strategies. The rates for PAF and persistent AFib patients, respectively, were: Strategy A – 70% and 62%, Strategy B – 71% and 68%, Strategy C – 91% and 86%.
“If you’re using the ‘freedom-from-30-seconds’ endpoint, the results that you are going to get are highly dependent on the monitoring strategy,” Dr. Verma said. “The more you look, the more you see.”
Valid estimation of burden
For the main PULSED-AF secondary analysis, the investigators defined AA burden according to findings on either Holter monitoring or the 12-lead ECG. “So as not to bias these results,” Dr. Verma said, “for every patient, we picked the method that gave us the highest atrial arrhythmia burden.”
Ideally, Dr. Verma said in an interview, arrhythmia burden would be determined using devices such as implantable loop recorders. “The problem is, this is expensive and not practical” in both clinical practice and many trials, so PULSED-AF investigators went with the intermittent monitoring strategy to estimate burdens.
Their method appears valid, he said, given that the study identified a statistically relevant 10% AA burden cut off for predicting quality of life improvement or less health care resource use.
“If their residual atrial arrhythmia burden was greater than 10%, they did not have a statistically significant improvement in quality of life,” Dr. Verma observed. And “very few” of them had cardioversions or repeat ablation.
“I couldn’t agree more” that residual AA burden is preferable to the 30-second endpoint for gauging AFib ablation success, Kenneth Ellenbogen, MD, Virginia Commonwealth University Medical Center, Richmond, said in an interview. Dr. Ellenbogen is also director of clinical cardiac electrophysiology and pacing at VCU Health Pauley Heart Center and not associated with PULSED-AF.
That AA burden was linked to health care resource use in the study “is absolutely brilliant,” he said, “because that’s what the bean counters really want at the end of the day. And as doctors we care about patients feeling better – improving quality of life.”
PULSED-AF was funded by Medtronic. Dr. Verma disclosed financial relationships with Bayer, Biosense Webster, Medtronic, Thermedical, Kardium, and Galaxy Medical, as well as and research grants from Adagio Medical. Dr. Ellenbogen disclosed financial relationships with Boston Scientific, Medtronic, Kestra, Hylomorph, Biotronik, MediLynx, Impulse Dynamics USA, Abbott, Biosense Webster, Milestone Pharmaceuticals, Sanofi, Medpace, and Elsevier. Dr. Pathak disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.