February 05, 2014
2 min read

Atrial tissue fibrosis estimated by MRI linked to likelihood of recurrent arrhythmia

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In patients with atrial fibrillation undergoing catheter ablation, atrial tissue fibrosis estimated by delayed-enhancement MRI was independently associated with the likelihood of recurrent arrhythmia, according to results from the prospective, observational DECAAF study.

The DECAAF researchers enrolled 329 patients to examine the feasibility of estimation of atrial tissue fibrosis by delayed-enhancement MRI and its association with outcomes from AF ablation. Of the patients enrolled, 279 had MRI images of adequate quality, and 260 were followed up after a 90-day blanking period. The patients’ mean age was 59 years, 31% were women and 64% had paroxysmal AF.

For this study, atrial tissue fibrosis was categorized into four stages:

  • Stage 1: <10% of the atrial wall.
  • Stage 2: ≥10% to <20% of the atrial wall.
  • Stage 3: ≥20% to <30% of the atrial wall.
  • Stage 4: ≥30% of the atrial wall.

Researchers estimated the cumulative incidence of recurrent arrhythmia by stage at 325 days and 475 days after the blanking period.

Nassir F. Marrouche, MD

Nassir F. Marrouche

According to results reported by Nassir F. Marrouche, MD, of the Comprehensive Arrhythmia and Research Management Center, University of Utah School of Medicine, and colleagues, the unadjusted overall HR for recurrent arrhythmia per 1% increase in left atrial fibrosis was 1.06 (95% CI, 1.03-1.08).

The estimated unadjusted cumulative incidence of recurrent arrhythmia 325 days after the blanking period was 15.3% (95% CI, 7.6-29.6) for stage 1 fibrosis, 32.6% (95% CI, 24.3-42.9) for stage 2 fibrosis, 45.9% (95% CI, 35.6-57.5) for stage 3 fibrosis and 51.1% (95% CI, 32.8-72.2) for stage 4 fibrosis, Marrouche and colleagues found. At 475 days, the unadjusted rates were 15.3% (95% CI, 7.6-29.6) for stage 1 fibrosis, 35.8% (95% CI, 26.2-47.6) for stage 2 fibrosis, 45.9% (95% CI, 35.6-57.5) for stage 3 fibrosis and 69.4% (95% CI, 48.6-87.7) for stage 4 fibrosis. At both time points, covariate adjustment did not change the results.

Adding fibrosis to a recurrence prediction model including traditional clinical covariates increased predictive accuracy, the researchers found. The C statistic rose from 0.65 to 0.69 (risk difference of 0.05; 95% CI, 0.01-0.09).

“Atrial fibrosis is essential to perpetuate atrial arrhythmias and leads to increased AF burden,” Marrouche and colleagues wrote. “Every patient with AF possesses some degree of atrial fibrotic changes that varies between minimal and severe or extensive. The clinical implications of this association warrant further investigation.”

Disclosure: See the full study for a list of the researchers’ relevant financial disclosures.