MedicalResearch.com Interview with:
Dr. Carina Blomström-Lundqvist, MD
Professor of Cardiology
Department of Cardioloy
Institution of Medical Science
MedicalResearch.com: What is the background for this study?
Response: While all previous trials comparing atrial fibrillation (AF) ablation and antiarrhythmic drugs to our best knowledge have evaluated the efficacy of these treatments in terms of atrial fibrillation (AF) recurrences (with an AF episode of 30 seconds duration as standard primary endpoint) we wanted to use quality of Life (QoL) – general health – as primary endpoint, since the indication for treatment is improving QoL.
This was important since, despite the fact that the indication for treatment is to improve (QoL) and reduce symptom, all prior trials have used 30 seconds AF episodes as standard primary endpoint, which if occurred it would be defined as a failed treatment.
We also wanted to assess effects on various clinical outcome events.
We know from registries such as ORBIT AF registry that around 60 % of AF patients have symptoms resulting in repeated hospitalisation visits in at least 30-40% of patients annually, and that only around 5 % of the AF population are being referred for AF ablation.
Previous trials have used intermittent 24 hours Holter recordings whioch does not give the true AF burden (% of time in AF). We therefore also wanted to assess and compare treatments effects on true AF burden by implanting an implantable cardiac monitor (ICM) which continuosly records the heart rhythm. We would then be able to prove that improvement in QoL was directly related to a reduction in AF burden and that treatment differences in QoL was related to a difference in reduction in AF burden.
We also wanted to study an AF population in their early AF disease state so that we could offer atrial fibrillation ablation to a broader AF population before their atria have become remodelled and too damaged for a pulmonary vein isolation to be effective.
MedicalResearch.com: What are the main findings?
Response: The main finding was that although the General Health (QoL) increased significantly in both treatment groups after 1 years follow-up, QoL improved significantly more in the ablation group versus medication Group, a difference that was clinically meaningful.
Symptoms also improved more in the ablation vs the medication group.
Moreover, atrial fibrillation burden decreased significantly more in the ablation versus the medication Group (from 24.9%to 5.5%in the ablation group vs 23.3%to 11.5% in the medication group).
An important finding was that the improvement in QoL / General Health at 12 months vs baseline was inversely related to the reduction in atrial fibrillation burden on the ICM, whereas the effects of randomized treatment and number of antiarrhythmic
drugs tested disappeared during follow-up, favored a true treatment effect by ablation.
The atrial fibrillation recurrence rate was markedly higher when measured with the implantable cardiac monitor than with Holter recordings. The almost 7-fold underestimation of atrial fibrillation recurrence rate by the 24-hour Holter monitor has not previously been described in randomized trials, to our knowledge, indicating that atrial fibrillation burden may be underestimated unless an implantable cardiac monitor is used.
Moreover the freedom from a composite of first clinical outcome events related to atrial fibrillation (first cardioversion, cardiovascular-related hospitalization, reablation, and change of antiarrhythmic medication) from baseline to 12-month follow-up was
significantly higher in the ablation group than in the medication group.
MedicalResearch.com: What should readers take away from your report?
Response: Among patients with symptomatic atrial fibrillation despite use of antiarrhythmic medication, the improvement in quality of life at 12 months was greater for those treated with catheter ablation compared with antiarrhythmic medication. Although the study was limited by absence of blinding, catheter ablation may offer an advantage for quality of Life since the improvement in QoL was inversely related to the reduction in atrial fibrillation burden on the ICM (whereas the effects of randomized treatment and number of antiarrhythmic drugs tested disappeared during follow-up) and favored a true treatment effect by ablation.
The almost 7-fold underestimation of atrial fibrillation recurrence rate by the 24-hour Holter monitor not previously described in randomized trials, to our knowledge, indicate that atrial fibrillation burden may be so underestimated that an implantable cardiac monitor should be used to assess atrial fibrillation burden.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Blomström-Lundqvist C, Gizurarson S, Schwieler J, et al. Effect of Catheter Ablation vs Antiarrhythmic Medication on Quality of Life in Patients With Atrial Fibrillation: The CAPTAF Randomized Clinical Trial. JAMA.2019;321(11):1059–1068. doi:10.1001/jama.2019.0335
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