CardioExchange Archive

For this post, CardioExchange invited the authors of MANTRA-PAF study (Radiofrequency Ablation as Initial Therapy in Paroxysmal Atrial Fibrillation) to elucidate their findings.

The Trial

In this study, Danish researchers randomized 294 treatment-naive patients with paroxysmal atrial fibrillation to receive either radiofrequency catheter ablation or standard therapy with class IC or class III antiarrythmic drugs. At 2 years, the burden of a-fib was significantly lower in those receiving ablation than in those receiving antiarrythmic drug therapy (90th percentile, 9% vs. 18%; P=0.007). Three patients in the ablation group had cardiac tamponade related to the procedure. One patient in the ablation group died from a procedure-related stroke. About a third of the patients in the drug treatment group underwent supplementary ablation. An accompanying editorial can be found here.

How does your study change which patients with A-fib you consider for ablation in your own practice? 

The MANTRA-PAF trial documents that antiarrhythmic drug treatment is pretty effective in a large proportion of patients with paroxysmal a-fib, most notably relatively young patients without much comorbidity. Therefore, we still advise the majority of our patients to try at least one antiarrhythmic drug as the initial therapy. However, the study also shows that radiofrequency ablation is at least as effective as drug therapy. Thus, we offer ablation as initial therapy as an option for younger, healthier patients. Further analysis of these data may help to clarify which patients are most suitable for initial therapy with ablation versus drug therapy.

Are these results generalizable given the evolving ablation techniques (your study focused on reduction of atrial electrograms versus the new method of focusing on electrical isolation of target regions) and differences in outcome that can be seen between centers and between experts?

We recognize that ablation techniques have changed significantly since this study was initiated. Outcomes after ablation may well be significantly better today using more effective procedural techniques and verifying complete isolation of the pulmonary veins. Despite the now dated methods used in the study we still found significantly improved quality of life and a trend towards less atrial fibrillation after two years with initial ablation. The findings therefore support that ablation could be considered as initial treatment.

The procedures in this study were performed by qualified electrophysiologists, but the centers involved had differing levels of experience in performing ablation. Whether better results can be achieved at larger centers and by electrophysiologists doing a higher number of procedures is unknown.

Ablation is associated with rare but clinically significant risks. How do you recommend discussing these risks with patients who have not yet experienced treatment failure on anti-arrythmic drugs?

We recommend that risks and advantages of each treatment — antiarrhythmic drug or radiofrequency ablation — be discussed openly with the patients before deciding between the two.

What do you anticipate the CABANA trial adding to our understanding here and how is that distinct from your findings?

The CABANA trial includes a larger number of patients, and more of the patients will have concomitant heart disease or other comorbidities. It is also being conducted with current ablation methods that may be superior to those used during our MANTRA-PAF trial. The CABANA trial hopefully will add to our knowledge of whether initial ablation improves harder clinical outcomes that the MANTRA-PAF trial powered to analyze. It will also increase our understanding whether initial ablation is beneficial in a wider population of patients. The MANTRA-PAF results should not be extrapolated to elderly patients who have significant concomitant heart disease.