I’m pleased to shared that our sex-based differences in AF is now published in @JACCJournals clinical electrophysiology.

@UBCmedicine @msfhr @HSF_science https://electrophysiology.onlinejacc.org/content/early/2020/07/23/j.jacep.2020.04.032

This was a pre-specified substudy of our prospective, multicenter, randomized CIRCA-DOSE study, which examined patients with predominantly paroxysmal AF refractory to AAD therapy and referred for catheter ablation.

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.119.042622

We observed several interesting points, some of which challenge postulated reasons for the sex-based differences and some of which have implications for the interpretation of contemporary studies.

@hvanspall @thaiscoutinhoCV @ShelleyZieroth

First - female participants were more likely to present with palpitations and chest pain as their AF symptoms, and were less likely to report alcohol as a trigger.

They were more likely to have a history of thyroid dysfunction (21% vs 4% - predominantly hypothyroid).

Second - the ablation procedure was similar between the sexes - in terms of procedure time (left) and fluoro time (right).

However, phrenic nerve palsy happened more frequently in women. All other complications were similar.

But - where it starts to get interesting is the combination of the following:

Third - freedom from recurrent arrhythmia and AF burden did not differ between the sexes.

Importantly, there was no difference between second generation cryoballoon and CF-RF when analysed by sex (which is a bit of a contrast from the recent paper in @hrs_journal - https://www.heartrhythmjournal.com/article/S1547-5271(20)30352-0/fulltext)

Four - there was no significant difference between male and female participants in emergency visits (22.9% vs. 29.6%; P=0.19), hospitalization >24 hours (13.0% vs. 10.8%; P=0.41), cardioversion (10.8% vs. 8.7%; P=0.58), or repeat ablation (16.5% vs. 13.9%; P=0.64)

Fifth - but, despite these lack of differences, at all time points female participants had a worse symptom score...

...a worse quality of life on generic instruments...

...and a worse quality of life on disease specific instruments.

Previous studies have postulated that thw difference in “symptomatology may be related to females having higher mean heart rates in AF and experiencing longer AF episodes compared with males” however, using an ILR we can say this isn’t the case.

So. How can we put this together to explain why our paper stands somewhat in contrast to other sex-based analyses?

I think there are two potential explanations.

First - female patients with AF tend to be referred for ablation later in the course, with more advanced substrate.

In our series the co-morbidity profile was similar, and the age difference relatively smaller. So the podtablation outcomes being similar makes sense.

Second - Studies reliant non-invasive monitoring could be influenced by sex-specific reporting bias (as females are more symptomatic) leading to more efforts to document arrhythmia recurrence and apparent higher rates of recurrence in women (e.g. sex-specific ascertainment bias)

As we had continuous monitoring in all patients we were able to observe the disconnect between the subjective symptomatic impact of AF and the objective AF burden/episode recurrence.

As a final word, it is important to recognise that despite the objectively worse QOL at all time points, female participants with AF did derive a similar magnitude of improvement with ablation, with similar procedure times and post ablation rhythm outcomes.