Measuring both left atrial size and the amount of left atrial fibrosis may improve identification of patients who have a high likelihood of successful ablation

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A study, published in Heart, indicates that the combined assessment of left atrial size and the amount of left atrial fibrosis may improve the identification of patients who have a high likelihood of successful ablation.

Patients with a severely enlarged left atrium are known to be at high risk of atrial fibrillation recurrence after radiofrequency catheter ablation; however, the value of left atrial size as an independent predictor of atrial fibrillation recurrence is limited as patients with mild-to-moderate left atrial enlargement have a varying response to radiofrequency catheter ablation (ie, having mild left atrial enlargement does not necessarily mean you are at low risk of having atrial fibrillation recurrence). Therefore, there is a need to find additional methods of assessing the risk of atrial fibrillation recurrence.

Dennis den Uijil, Department of Cardiology, Leiden University Medical Center, The Netherlands, and his co-authors investigated left atrial fibrosis because it is associated with a high probability of atrial fibrillation recurrence. They assessed the presence of fibrosis using two-dimensional echocardiography-derived calibrated integrated backscatter because it “allows non-invasive tissue characterisation based on tissue ultrasound reflectivity and may provide a good surrogate of myocardial fibrosis.”

den Uijil et al reviewed 170 patients undergoing radiofrequency catheter ablation for atrial fibrillation. All patients underwent transthoracic echocardiography to assess left atrial size and all underwent IBS analysis to assess the presence (and extent) of left atrial fibrosis. After ablation, all patients were followed-up for 12 months.

Patients with a small left atrium and a small amount of fibrosis had the best outcome following ablation (94% non-recurrence) whereas patients with a large left atrium and high amount of fibrosis had the worse outcome (28% non-recurrence). den Uijil et al reported: “Interestingly, patients with a large left atrial but with low fibrosis (n=33) had a good prognosis compared with patients with a small left atrium and high fibrosis (82% non-recurrence vs. 38% non-recurrence, respectively).”

Additionally, most patients with a value of calibrated IBS >-13.9dB had atrial fibrillation recurrence at follow-up but the investigators did not find a cut off value for left atrial volume to differentiate between patients who continued to be in sinus rhythm and those who had atrial fibrillation recurrences. They reported: “Therefore, calibrated IBS may be a more accurate parameter to identify the patients who will show atrial fibrillation recurrences after radiofrequency catheter ablation.”

According to den Uijil et al, their study could help to improve patient selection for catheter ablation (and as a result, improve outcomes of catheter ablation). They added: “Alternatively, this information could be used to better inform patients about their likelihood of maintaining sinus rhythm.”

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