New Discovery of Left Atrial Macroreentry Tachycardia: Originating from the Spontaneous Scarring of Left Atrial Anterior Wall

Figure 1. Left atrial macroreentry tachycardia promoted by anterior scar. (a) The low voltage areas were not found in RA. (b) A nonreentrant activation with the earliest site in the atrial septum and the total activation time in the RA < 90% of the TCL. (c) Bipolar voltage map of the left atrium in anterior-posterior and posterior-anterior wall (insets). A central scar was seen in left atrial anterior wall (LAAW). (d) Left atrial activation maps of the patients with a double-loop reentry, a counterclockwise loop around the mitral valve (white solid lines), and a clockwise loop (white dotted lines) around the scar of LAAW. SVC: superior vena cava; TA: tricuspid annulus; LAA: left atrial appendage; MV: mitral valve; RSPV: right superior pulmonary vein; LAAW: left atrial anterior wall.

Figure 2. The electrophysiological characteristics of arrhythmogenic substrate. Left atrial activation maps of a patient (a–c) with a double-loop reentry by a critical isthmus (a, c, black dotted lines), which is shown through early meet late in CARTO 3 V6 (action time of more than 25 percent of the TCL between adjacent points indicates block lines (a, red boxes)). The electrograms and conduction velocities of isthmus are shown and selected for ablation (a, white boxes). In contrast, the conventional anatomical isthmus located at the mitral isthmus exhibited normal electrogram characteristics (b, white boxes). The voltage maps (purple ≥ 0.45 mV; red: <0.1 mV) characterized by a central scar at the mid anterior level (c, e). A patient presented with single-loop reentry, and a clockwise loop revolved around the right pulmonary vein (d, e). The isthmus (black dotted lines) located between LAAW scar and the roof adjacent to the RSPV. Tachycardia was terminated in 10 seconds by ablation of the isthmus, where it showed a conduction slowing highly fractionated electrograms (d, e, white boxes) (see Supplementary Material Video 1,2). LAA: left atrial appendage; MV: mitral valve; LSPV: left superior…

Figure 3. Fusion of the voltage map and the enhanced cardiac CT. Low-voltage area on the LAAW at the left atrium (LA)-aorta (Ao) (a–d) or LA-pulmonary artery (PA) (e–h) or both (i–l) contiguity. The three-dimensional (3D) electroanatomic voltage maps in anteroposterior views (a, e, i) and merged (b, f, j) with 3D enhanced cardiac computed tomography (CT) (c, g, k) corresponding images of enhanced cardiac CT (d, h, l). Ao: aorta; LA: left atrium; PA: pulmonary artery; LAA: left atrial appendage; MV: mitral valve; LSPV: left superior pulmonary vein; RSPV: right superior pulmonary vein.

Figure 4. Subsegmentation of the low-voltage area on the left atrial anterior wall. (a) Area 1 was near the anterior MV at 11-12 o'clock; area 2 is the critical isthmus; area 3 was located at the mid anterior level of the left atrial anterior wall (LAAW); area 4 was located at the anterior top of the left atrium (LA) near the basal of left atrial appendage (LAA). (Top left illustration) the three-dimensional (3D) enhanced cardiac computed tomography shows the anatomical relationship between the LA, aorta, and pulmonary artery. (b) Voltage maps show patients with different degrees of scarring have a critical isthmus (black dotted lines) between the scar of LAAW and the MV. LAA: left atrial appendage; MV: mitral valve; LSPV: left superior pulmonary vein; RSPV: right superior pulmonary vein.

Figure 5. The receiver operating characteristic (ROC) analysis of age and combination of gender and age for predicting the LAMRT originating from the LAAW. The area under the curve (AUC) of age and combination of gender (and age for predicting the LAMRT originating from the LAAW) were 0.918 (a) and 0.951 (b), respectively. (c) Although the comparison between the two was not statistically significant, the combination of gender and age showed a higher specificity. LAAW: left atrial anterior wall; LAMRT: left atrial macroreentry tachycardia.