Discussion:
The m-FAM is a novel algorithm that was recently added to the CARTO 3 system. It allows the easy and fast creation of a 3-dimensional reconstruction of the LA based on very limited FAM mapping. The system applies machine learning techniques for LA reconstruction using an adaptive model trained from over 300 LA anatomies obtained from CTA scans. However, the accuracy of this reconstruction has not been verified as well as the feasibility and safety of atrial fibrillation ablation guided by the m-FAM reconstruction.
In the present study, we also evaluated the m-FAM reconstruction to the CTA of the LA in the same patient. We found that a precise reconstruction of the LA can be obtained within 4 minutes (including the algorithm reconstruction time) and with less than 2 minutes of fluoroscopy-time regardless to the mapping catheter used. In a minority of patients, adjustments are needed to improve the accuracy of the reconstruction. The algorithm performed just as well in patients with LA anatomy different from the classical four PV anatomy (Figure 5). The fastest m-FAM reconstruction was obtained with the use of a Pentaray for mapping. This approach might be preferable in patients in which a substrate mapping of the left atrium is also required, like patients with long standing persistent AF. Importantly, the voltage map of the left atrium can be displayed on the shell of the M-FAM reconstruction when needed (Figure 5). Despite the shortest mapping time required when using a Pentaray catheter, the accuracy of the m-FAM map was similar in patients in whom the maps were created solely with the ablation catheter. The m-FAM reconstruction closely resembled the LA anatomy obtained from cardiac CTA in all patients. Pulmonary veins angiography is routinely performed in our lab during AF ablation and therefore it was included in the two workflows analyzed in our study. Nevertheless we believe this step is not mandatory for operators who are not comfortable with it. The ablation guided with the use of the m-FAM reconstruction was effective with isolation of 100% of the pulmonary veins ablated. No complications occurred in any of the patients treated who underwent an m-FAM based ablation.