Evaluating Predictors for Long-Term Atrial Fibrillation-Free Survival

Results from a recent study may help physicians decide when to use pulmonary vein isolation (PVI) on patients with paroxysmal atrial fibrillation (AF) and when to try an alternative treatment.

Researchers in the Netherlands used a twenty-polar catheter toperform 15-second electrograms on both the left and right atrial appendages of 28 patients while they were undergoing an episode of atrial fibrillation.

They then performed PVI on all of the patients and noted outcomes over a median follow-up period of 5.5 years.

The average patient was 53 years old when the study began, and 86% of the cohort suffered from paroxysmal atrial fibrillation before they underwent PVI, which is a form of catheter ablation.

Outcomes were mixed. Some 64% of the cohort still appeared to be free of atrial fibrillation at the end of the follow-up period, but the other 36% had suffered at least 1 more episode of atrial fibrillation.

The research team knew from earlier published studies that fractionation of atrial fibrillation patient electrograms is associated with the sort of structural and electrical remodeling in the heart that might affect PVI outcomes.

Team members hypothesized that fractionation might also be associated with atrial fibrillation cycle length and that the mean correlation coefficient between each patient’s atrial fibrillation cycle length and fractionation might, in turn, be associated with PVI outcomes.

After completing patient follow-up, the research team looked for associations between atrial fibrillation-free survival after PVI and a host of baseline characteristics that included the fractionation on each electrogram and the atrial fibrillation cycle length of each patient.

None of these single factors was significantly associated with atrial fibrillation-free survival.

However, the mean correlation coefficient between an individual’s atrial fibrillation cycle length and electrogram fractionation before PVI did help predict outcomes, just as the researchers had hoped, but only as measured by electrograms from left atrial appendages.

The area under the curve for correlation coefficients derived from left atrial measurements was 0.871 (P= .002). Analysis also found area under the curve for correlation coefficients taken from right atrial measurements, 0.690, but that analysis also showed a significant chance of a random finding (P= .131).

“Although not a significant predictor of AF free survival, there was a significant association between [the correlation coefficient] recorded at the right atrial appendage and AF free survival,” the study authors wrote in the International Journal of Cardiology.

However, they concluded, “the mean [correlation coefficient] recorded at the left atrial appendage was a significant predictor of long-term atrial fibrillation-free survival.”

The predictive power of that 1 correlation coefficient obviously isn’t strong enough to guide decisions on its own, but every new bit of information can help physicians who face tough choices about whether to recommend ablations or alternative treatments.

Many physicians expected ablation to be a radical improvement in the treatment of atrial fibrillation when it was first approved for use, but subsequent research has shown that the benefits of first-generation ablation techniques are only temporary for many patients.

Researchers have responded by working to improve ablation technology with ideas such as pressure sensing monitors, to improve ablation technique with analysis of what separates successful from unsuccessful procedures and, as with this study team from the Netherlands, to improve the ability to predict how different patients will respond to the procedures.