Takuya Ohashi

Left atrial low-voltage areas predict atrial fibrillation recurrence after catheter ablation in patients with paroxysmal atrial fibrillation

BACKGROUND Association between the presence of left atrial low-voltage areas and atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) has been shown mainly in persistent AF patients. We sought to compare the AF recurrence rate in paroxysmal AF patients with and without left atrial low-voltage areas. METHODS This prospective observational study included 147 consecutive patients undergoing initial ablation for paroxysmal AF. Voltage mapping was performed after PVI during sinus rhythm, and low-voltage areas were defined as regions where bipolar peak-to-peak voltage was <0.50mV. RESULTS Left atrial low-voltage areas after PVI were observed in 22 (15%) patients. Patients with low-voltage areas were significantly older (72±6 vs. 66±10, p<0.0001), more likely to be female (68% vs. 32%, p=0.002), and had higher CHA2DS2-VASc score (2.5±1.5 vs. 1.8±1.3, p=0.028). During a mean follow-up of 22 (18, 26) months, AF recurrence was observed in 24 (16%) and 16 (11%) patients after the single and multiple ablation procedures, respectively. AF recurrence rate after multiple ablations was higher in patients with low-voltage areas than without (36% vs. 6%, p<0.001). Low-voltage areas were independently associated with AF recurrence even after adjustment for the other related factors (Hazard ratio, 5.89; 95% confidence interval, 2.16 to 16.0, p=0.001). CONCLUSION The presence of left atrial low-voltage areas after PVI predicts AF recurrence in patients with paroxysmal AF as well as in patients with persistent AF.

The identification of conduction gaps after pulmonary vein isolation using a new electroanatomic mapping system

BACKGROUND The reconnection of left atrial-pulmonary vein (LA-PV) conduction after the initial procedure of pulmonary vein (PV) isolation is not rare, and is one of the main cause of atrial fibrillation (AF) recurrence after PV isolation. OBJECTIVE We investigated feasibility of a new ultrahigh-resolution mapping system using a 64-pole small basket catheter for the identification of LA-PV conduction gaps. METHODS This prospective study included 31 consecutive patients (20 with persistent AF) undergoing a second ablation after a PV isolation procedure with LA-PV reconnected conduction at any of the 4 PVs. An LA-PV map was created using the mapping system, and ablation was performed at the estimated gap location. RESULTS The propagation map identified 54 gaps from 39 ipsilateral PV pairs, requiring manual electrogram reannotation for 23 gaps (43%). Gaps at the anterior and carinal regions of left and right ipsilateral PVs required manual electrogram reannotation more frequently than the other regions. The voltage map could identify the gap only in 19 instances (35%). Electrophysiological properties of the gaps (multiple gaps in the same ipsilateral PVs, conduction time, velocity, width, and length) did not differ between those needing and not needing manual electrogram reannotation. During the gap ablation, either the activation sequence alteration or elimination of PV potentials was observed using a circular catheter placed in the PV, suggesting that all the identified gaps were correct. CONCLUSION This new electroanatomic mapping system visualized all the LA-PV gaps in patients undergoing a second AF ablation.

Comparison of Left Atrial Voltage between Sinus Rhythm and Atrial Fibrillation in Association with Electrogram Waveform: VOLTAGE DURING SR AND AF

The efficacy of low‐voltage‐guided ablation in addition to pulmonary vein (PV) isolation for atrial fibrillation (AF) has been reported with voltage mapping being performed during sinus rhythm (SR) or AF. The study aimed to compare the left atrial voltage between SR and AF in association with the electrogram waveform.

Comparison of the origin and coupling interval between ectopy with and without atrial fibrillation initiation

BACKGROUND Differentiation of atrial fibrillation (AF) trigger ectopy from other ectopy is often difficult. The purpose of this study was to compare the origin and coupling intervals (CI) between AF-trigger and non-AF-trigger ectopy. METHODS This study consisted of 120 patients with AF who underwent an initial ablation. Isoproterenol was infused up to 20μg/min to provoke ectopy and AF. We measured the CI of all ectopy provoked by an isoproterenol infusion. The %CI was calculated as the CI of the ectopy/P-P interval of the preceding 2 beats. RESULTS A total of 117 patients had at least one ectopy, and AF was induced in 56 (47%) patients. Of the 276 ectopies observed in this study, 211 (76%) originated from pulmonary veins and 77 (28%) were AF-trigger ectopy. AF-trigger ectopy more frequently originated from pulmonary veins (PVs) (74 vs. 3, p<0.001) and had a significantly shorter CI (201±70ms vs. 365±147ms, p<0.001) and lower %CI (29±11% vs. 55±14%, p<0.001) than that of non-AF-trigger ectopy. A receiver operating characteristics analysis revealed that a %CI of 40% was the best cut-off value for differentiating whether it was an AF-trigger or not. The identified trigger group, including patients with provoked AF-trigger ectopy or ectopy with a low %CI (<40%), had a significantly better AF recurrence-free survival rate than the other group (88% vs. 65%, p=0.004). CONCLUSIONS AF-trigger ectopy predominantly originated from PVs and had a short CI. These findings may be useful for estimating whether ectopies are an AF-trigger or not.

Centrifugal wave-front propagation speed for localizing the atrial tachycardia origin

BACKGROUND The earliest activation site (EAS) on a centrifugally-propagated atrial tachycardia (AT) map may represent the true AT origin (true-focal pattern), or the earliest site resulting from passive activation of AT originating from neighboring tissue (pseudo-focal pattern). We assessed the benefits of using the wave-front propagation speed to distinguish between the true- and the pseudo-focal pattern. METHODS AT mapping was performed using a novel ultra-high resolution mapping system with a 64-electrode mini-basket catheter. The true AT origin was defined as the site where radiofrequency application eliminated AT. The wave-front propagation speed was estimated from the area surrounded by the centrifugally-propagated wave front over a specific time interval. RESULTS Total of 46 centrifugally propagated AT maps from 34 patients were analyzed, including 18 true-focal and 28 pseudo-focal pattern. The area surrounded by the propagated wave front was significantly smaller for the true-focal pattern than for the pseudo-focal pattern, 1-20 msec after the earliest activation. The true-focal pattern was identified by the area 13 msec after the earliest activation, with the best cut-off area value of <4.5 cm2. CONCLUSION The presence or absence of a true origin of AT at the EAS on centrifugally-propagated AT maps can be distinguished using a wave-front propagation speed.