How effective is unipolar radiofrequency ablation for atrial fibrillation during concomitant cardiac surgery?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether in patients undergoing cardiac surgery, concomitant unipolar radiofrequency ablation had a sufficiently acceptable success rate to justify the additional procedure. A total of 256 papers were found using the reported search; of which, 9 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. Major exclusion criteria included studies using bipolar ablation, ambiguous or unspecified ablation techniques, other energy modalities and studies with highly variable or undisclosed follow-up time. All of the studies showed concomitant unipolar ablation to have an acceptable success rate in restoring patients to sinus rhythm (SR), with follow-ups ranging from 12 months to 5 years. At 12-month follow-up, one study showed that this rate was as high as 83%. Ablations were more likely to be successful in patients with paroxysmal or persistent atrial fibrillation (AF) as defined by ACC/AHA/ESC criteria. One paper showed that paroxysmal/persistent AF at baseline was predictive of likely success of ablation in patients with permanent AF (P = 0.0004). Restoration and maintenance of SR after ablation was not significantly affected by the type of cardiac surgery performed (P = 0.262). Unipolar ablation does have limitations such as high tissue temperature and no predictable transmurality. However, it appears to compare favourably in the long term to energy modalities such as microwave. The lack of level I evidence was a major drawback in the analysis, as was the lack of continuous electrocardiogram monitoring in the methodology of the studies. Figures quoted from the data could therefore be under-representations of the true instances of AF recurrence. With the current evidence, concomitant ablation to treat AF during cardiac surgery appears safe in terms of adding no additional risks, and effective at restoring SR regardless of the type of cardiac surgery. This is particularly true of younger patients with paroxysmal or persistent AF and those with smaller atrial diameters.