Impact of cavotricuspid isthmus morphology in CRYO versus radiofrequency ablation of typical atrial flutter

[Isthmus-dependent right atrial flutter : Clinical course after isthmus ablation]

Ablation of the cavotricuspid isthmus (CTI) to create bidirectional isthmus blockade is the most effective way to achieve rhythm control in typical atrial flutter. Compared with drug therapy, ablation reduces cardiovascular mortality, all-cause mortality, stroke risk, and the risk of cardiac decompensation. Concomitant arrhythmia of atrial flutter is atrial fibrillation (AF); therefore the duration of oral anticoagulation should be adapted according to the risk of stroke and bleeding. A combined procedure of CTI ablation and pulmonary vein isolation (PVI) in patients with typical atrial flutter but without evidence of AF should be evaluated individually especially in patients aged > 54 years depending on (cardiac) comorbidities. The comprehensive diagnostic view should keep in mind not only arrhythmias but also possibly underlying coronary artery disease.

Non-invasive characterisation of macroreentrant atrial tachycardia types from a vectorcardiographic approach with the slow conduction region as a cornerstone

BACKGROUND AND OBJECTIVES

Macroreentrant atrial tachyarrhythmias (MRATs) can be caused by different reentrant circuits. The treatment for each MRAT type may require ablation at different sites, either at the right or left atria. Unfortunately, the reentrant circuit that drives the arrhythmia cannot be ascertained previous to the electrophysiological intervention.

METHODS

A noninvasive approach based on the comparison of atrial vectorcardiogram (VCG) loops is proposed. An archetype for each group was created, which served as a reference to measure the similarity between loops. Methods were tested in a variety of simulations and real data obtained from the most common right (peritricuspid) and left (perimitral) macroreentrant circuits, each divided into clockwise and counterclockwise subgroups. Adenosine was administered to patients to induce transient AV block, allowing the recording of the atrial signal without the interference of ventricular signals. From the vectorcardiogram, we measured intrapatient loop consistence, similarity of the pathway to archetypes, characterisation of slow velocity regions and pathway complexity.

RESULTS

Results show a considerably higher similarity with the loop of its corresponding archetype, in both simulations and real data. We found the capacity of the vectorcardiogram to reflect a slow velocity region, consistent with the mechanisms of MRAT, and the role that it plays in the characterisation of the reentrant circuit. The intra-patient loop consistence was over 0.85 for all clinical cases while the similarity of the pathway to archetypes was found to be 0.85 ± 0.03, 0.95 ± 0.03, 0.87 ± 0.04 and 0.91 ± 0.02 for the different MRAT types (and p<0.02 for 3 of the 4 groups), and pathway complexity also allowed to discriminate among cases (with p<0.05).

CONCLUSIONS

We conclude that the presented methodology allows us to differentiate between the most common forms of right and left MRATs and predict the existence and location of a slow conduction zone. This approach may be useful in planning ablation procedures in advance.