COMMENTARY

Less AF Ablation in Women: Gender Bias or Appropriate Care?

John Mandrola, MD

Disclosures

August 09, 2016

The question is not whether gender influences atrial fibrillation (AF) treatment; it's how and why women experience AF and its treatment differently from men.

Provocative findings from a recent study[1] published in JACC Electrophysiology inform the conversations we have with patients and expose how little we understand about AF.

Researchers from Stanford used medical claims of 45 million US patients enrolled in employee-sponsored and fee-for-service plans to explore gender differences in the real-world outcomes of AF ablation. They studied more than 20,000 patients who underwent AF ablation from 2007 to 2011.

Similar to the findings of previous studies[2,3,4], women were older (62 vs 58 years) and had higher CHA2DS2-VASc scores (2.9±1.5 vs 1.6±1.4) at the time of AF ablation than men.

At 30-days, women had higher complication rates.

Table 1. 30-Day Complication Rates by Gender

Complication Women (n=6137), % Men (n=14,954), % P
Vascular complications 2.7 2.0 <0.001
Hematoma/hemorrhage 2.3 1.6 <0.001
Perforation/tamponade 3.8 2.9 <0.001
Stroke or TIA 0.85 0.64 0.09
All-cause hospitalization 9.4 8.6 0.07

At 1 year, gender-related outcomes differed.

Table 2. 1-Year Outcomes by Gender

Outcome Women (n=6137), % Men (n=14,954), % Adjusted hazard ratio P
All-cause hospitalization 32 27 1.14 <0.0001
AF re hospitalization 13 12 1.12 0.009
Cardioversion 17 21 0.75 <0.001
Repeat ablation 13 15 0.92 0.04

The cumulative event-free survival, defined as freedom from any AF hospitalization, was lower among women than among men (87% vs 89%; adjusted HR 0.88; 95% CI 0.78–0.97; P<0.01).

Comments:

Two strengths of this study are its large numbers of patients and its use of real-world experiences. Real-world data are vital because much AF ablation is done outside of high-volume centers of excellence. Multiple studies confirm that low operator and hospital volumes are associated with higher rates of complications.[5,6]

Since replication of science is valuable, another strength of the study is that it confirms previous data[4,7] showing that women have a higher risk of procedural complications from AF ablation.

Let's not skim over the issue of procedural harm. Given the elective nature of AF ablation, the odds of incurring harm from the procedure may be the most important factor in the decision to proceed. The tough work of AF ablation comes before the EP lab: Patients must know, and it is our job to make sure they know, that seeking a better quality of life through ablation means taking the small but real risk of sustaining a major decline in quality of life from a complication. For women, this gamble features less favorable odds.

This study had an intriguing observation—the discordance between an increased rate of postprocedural hospitalizations and the decreased rate of cardioversion and repeat ablation in women. Why are women getting less rhythm control? Is this a bad thing?

The Stanford-based authors made careful word choices (emphasis mine): "Our findings, in context, may be indicative of potential barriers to optimal or sustained rhythm-control strategies in women. . . . These data call for greater examination of barriers and facilitators to sustain rhythm-control strategies in women."

A reader could infer two benevolent biases in these words: women are getting stiffed out of more cardioversions and AF ablation, and that's bad because rhythm-control strategies are good.

Viewing rhythm control as beneficial may not be the correct anchoring point of the argument. The AFFIRM trial[8] taught us that rhythm control established with medical therapy increased hospitalizations without improving outcomes.

Would rhythm control with ablation fare better? Although ablation has proved superior[9] to medical therapy for reducing 30-second episodes of AF, there is no evidence that affecting this surrogate would deliver better outcomes.

Consider another take of the Stanford study. Women who undergo first AF ablation present with greater comorbidity, older age, and more advanced forms of AF. They also experience more procedural complications. It's possible, therefore, that more rhythm control (with ablation) in women could worsen a gender gap in outcomes.

I posed this contrarian view to senior author, Dr Mintu Turakhia (Stanford University). In an email, he wrote: "I totally agree. What is missing from all studies, including ours, are rigorous studies in quality of life. An outcome of a study should map to indications. The indication for AF ablation almost always is symptoms. But AF recurrence has been the outcome of most studies. Furthermore, for statistical purposes, we conflate AF recurrence to death . . . and we look at time to first recurrence. Yet, studies have repeatedly shown that quality of life and AF recurrence are not perfectly correlated."

Dr Turakhia's comments expose a core knowledge deficit in AF treatment.

Pulmonary-vein isolation was first described as a cure for a focal tachycardia coming from a pulmonary vein. It has now been extended to people with diffuse atrial disease, metabolic risk factors, and inflammation. Since women present with more of these risk factors and more advanced atrial disease at the time of ablation, it's easy to understand why an anatomic procedure designed for people with focal triggers would perform less well. A higher burden of structural atrial disease is a possible reason that women are more likely than men to have AF triggers outside the area of the pulmonary veins.[4]

Until we better understand AF, the barrier to ablation in both sexes may be too low, not too high. Perhaps women do worse after ablation not just because they are more susceptible to complications but because AF affects men and women differently.

There is a basic rule in the electrophysiology lab: when something is not working, do something else. We should consider the possibility that more AF ablation, after failed ablation, may not be the right choice for women.

JMM

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