Cardiac magnetic resonance based ablation procedures: ready for take-off?

Abstract

Recently, the first clinical applications of interventional cardiac magnetic resonance (iCMR)-based cardiovascular interventions have been published. In these series radiofrequency (RF) ablations of typical atrial flutter were performed actively tracking specially designed catheters using cardiac magnetic resonance (CMR) guidance. The number of available devices that can be used in this iCMR-setting is very limited— even obtaining femoral access had to be transferred to a non-CMR environment because of a lack of suitable, MR-compatible devices such as needles and wires. Hereby, one of the major limitations of iCMRguided cardiovascular procedures becomes obvious: the portfolio of products is still rather limited, and devices that we use in fluo labs on a routine and daily basis are still not available such as cardioverterdefibrillators or a 12-lead electrocardiograms (ECGs). In this issue of EP-Europace, Lichter et al. describe their initial experience in using MR-compatible cryoballoons and tip catheters in interventional CMR. These devices have been technically modified from their original characteristics: the circular mapping catheter, which is normally placed distal to the balloon was removed and some features such as the temperature sensor because of their non-MRcompatibility. After establishing access to the left chambers eight canines have been transferred into a 3T iCMR suite. One of the key questions when performing ablation procedures using iCMR is to be able to assess the acute lesion injury and especially to predict the chronic lesion size. Lichter et al. demonstrated that despite acute 100% circumferential ablation lesions the percentage decreased to 95% at 3months of follow-up. In focal ablations the size of the acute lesion was overestimated by CMR imaging almost by three-fold compared with chronic lesion estimation by enhancement imaging and gross pathology.