Post Ablation Left Atrial Tachycardia: Understanding Mechanism, Prevention and Treatment

Abstract

Currently, post-ablation Atrial Tachycardias (ATs) represent a growing clinical problem particularly in patients with persistent AF undergoing a more extensive substrate ablation. Understanding mechanisms and location of potentially widely located arrhythmogenic substrates in the left atrium is crucial for successful ablation. Mapping and ablation are challenging since complex and multiple ATs may frequently develop during the index procedure and before conversion to sinus rhythm. Use of irrigated ablation guided by detailed 3-D electroanatomic activation maps combined with entrainment pacing is effective with excellent acute and long-term success rates, rarely requiring multiple procedures.

Figure 1.. A color-coded three-dimensional electroanatomic activation map as performed by CARTO system shows a focal left AT from a reconnected left superior PV in the posterior-anterior (PA) view. Activation spreads away from this focal red region in all directions centrifugally

Figure 2.. For the same patient in Figure 1, the activation map shows the activation sequence in the antero-posterior (AP) view. The AT cycle length was 348 ms; the activation time during mapping covered 100 ms before to 40 ms after the reference point accounting for a total of 140 ms, which is less than 40% of the AT cycle length of 348 ms, consistent with a focal origin of AT. The deep red dots around LSPV ostium indicate the sites where radiofrequency current was applied

Figure 3.. An activation map of a septal left macro-reentrant AT by NavX system in the antero-posterior (AP) view is shown. The map was created with a temporal reference located in the coronary sinus. Orientation of the left atrium is indicated by the orientation of the body at the top of the panel. Activation propagates from the middle septum (area of earliest activation, white color) to the anterior septum (area of latest activation, violet color). AT cycle length was 218 ms; the activation time during mapping covered 110 ms before to 85 ms after accounting for a total of 195 ms, which is more than 90% of the AT cycle length, consistent with a macro-reentrant circuit. Also shown is the reference catheter positioned in the coronary sinus

Figure 4.. For the same patient in Figure 3, the activation map shows the late activation progression in scale color of the reentrant circuit in the postero-anterior (PA) view

Figure 5.. Same map as in Figure 4. The activation map shows changes in the color-coded activation sequence caused by changing window of interest settings. Frames of the window of interest extend from 130 ms before to 65 ms after the reference point. The reference point is the same as well the AT cycle length and the duration of window of interest, but the early area is markedly shifted from middle septum to the posterior wall with changes in activation sequence

Figure 6.. AT ablation guided by an activation map of a left focal microreentrant AT from reconnected PVs by CARTO system in the antero-posterior (AP) view. A point-by-point long-linear lesion around LSPV ostium resulted in termination of AT

Figure 7.. For the same patient in Figure 3, a point-by-point long-linear lesion line on the septum resulted in termination of a macroreentrant septal AT. The yellow circle marks the successful site of AT termination

Figure 8.. A color-coded activation map sequence by NavX system of a mitral macro-reentrant AT rotating around the mitral annulus in different views is shown. RAO indicates right anterior oblique; AP indicates antero-posterior and PA postero-anterior

Figure 9.. For the same patient shown in Figure 8, perimitral AT ablation guided by three-dimensional electroanatomic activation map is shown in the postero-anterior (PA) view. Orientation of the left atrium is indicated by the orientation of the face at the top right corner of the panel. A point-by-point long-linear lesion (brown dots) connecting mitral annulus to the inferior left PV ostium resulted in termination of AT with restoration of normal sinus rhythm (bottom panel). The yellow circle marks the site of successful ablation. On the bottom: ECG, intracardiac recordings from coronary sinus (CS), and ablation catheter electrograms (ABL) during successful termination