We read with interest comments of Drs. Hof and Loh. They appropriately point out the facts that we discussed in the limitations section of our meta-analysis, which include the different methods used in these studies to determine left atrial (LA) size and function. We agree with Drs. Hof and Loh that LA volume is a better representation of true LA size, which was the basis of our study aim: to systematically review the effects of radiofrequency catheter ablation (RFCA) on LA volumes and function in addition to LA size in patients with atrial fibrillation (AF).
It should also be noted that, as detailed in the methods section, our search was conducted in April 2009, and the 2 studies referred to by the Drs. Hof and Loh (Nori et al and Tsao et al ) were published after this. Interestingly, Tsao et al concluded that LA volumes decreased and that LA function improved in patients without AF recurrence, but structural and functional reverse remodeling were not observed in patients with AF recurrence. In the study by Nori et al, patients with persistent AF were not cardioverted and underwent pre-RFCA imaging in AF and post-RFCA imaging in sinus rhythm. LA volumes decreased in patients with AF after RFCA, and LA function (global and regional) improved in the patients with persistent AF after RFCA. This is probably due to restoration of atrial function during the last third of left ventricular diastole and the differences in the rhythm before and after RFCA, which affect functional assessment. Data from the other 2 reports were included in our analysis.
We detailed in our discussion that currently, the amount and duration of RFCA in different areas of the left atrium required for creating an ideal extent of ablation lines that prevents AF recurrence without decreasing LA function are unknown. Factors that influence structural and functional remodeling of the left atrium include restoration of sinus rhythm and/or a reduction in AF burden. We agree with Drs. Hof and Loh that there is a great deal of variability in the parameters measured and the designs of the studies. Nevertheless, the subject is important, and in reviewing the diversity of approaches, perhaps a consensus on optimal parameters for assessment of post-RFCA LA function in patients with AF can be developed. Despite the methodologic differences among these studies, our meta-analysis shows that in patients with successful RFCA (defined by no AF recurrence), there was improved structural remodeling (reduced LA size and volume). These effects were not observed in those with AF recurrence. Also, as mentioned in our limitations, definite conclusions regarding LA functional change produced by RFCA could not be made, because of the aforementioned limitations. Future studies should consider these factors along with timing of studying LA dimensions and function.