P‐wave morphology and multipolar intracardiac atrial activation to facilitate nonpulmonary vein trigger localization

Long-term atrial arrhythmia characterization and treatment efficacy evaluation using non-invasive echocardiography-based electromechanical cycle length mapping: a case series

Background

Atrial fibrillation (AF) is a prevalent cardiac condition characterized by irregular heart rhythm. Conventional non-invasive diagnostic techniques, while useful, have limitations in providing comprehensive information for treatment planning. To address this gap, electromechanical cycle length mapping (ECLM), a non-invasive echocardiography-based technique, has emerged as a promising approach. Electromechanical cycle length mapping offers quantitative and spatially specific insights into atrial electromechanical activation rate mapping, thereby enhancing our understanding of arrhythmia disease progression in AF patients.

Case summary

In this case series, we present two patient cases demonstrating the potential utility of ECLM in monitoring and evaluating treatment responses in atrial arrhythmia. The 1st case involved a 61-year-old male with persistent AF who underwent multiple procedures, including direct current cardioversion (DCCV) and radiofrequency ablation. Over three different DCCV encounters, pre- and post-procedure ECLM scans were performed, and the results showed the localization and incomplete elimination of arrhythmic triggers post-DCCV, which were used as early indicators of AF recurrence. The 2nd case involved a 71-year-old male with paroxysmal AF who also underwent cardioversion and ablation procedures. Electromechanical cycle length mapping imaging demonstrated a progressive reduction and elimination of arrhythmia triggers after each encounter, resulting in long-term maintenance of sinus rhythm.

Discussion

The findings from this case series highlight the potential of ECLM as a non-invasive imaging tool for long-term monitoring and evaluating immediate and long-term treatment responses in AF patients. The integration of ECLM with standard echocardiograms holds promise in guiding clinical decisions and improving patient outcomes in managing atrial fibrillation.

Incremental Benefit of Stepwise Nonpulmonary Vein Trigger Provocation During Catheter Ablation of Atrial Fibrillation

BACKGROUND

The importance of nonpulmonary vein (PV) triggers for the initiation/recurrence of atrial fibrillation (AF) is well established.

OBJECTIVES

This study sought to assess the incremental benefit of provocative maneuvers for identifying non-PV triggers.

METHODS

We included consecutive patients undergoing first-time AF ablation between 2020 and 2022. The provocation protocol included step 1, identification of spontaneous non-PV triggers after cardioversion of AF and/or during sinus rhythm; step 2, isoproterenol infusion (3, 6, 12, and 20-30 μg/min); and step 3, atrial burst pacing to induce AF followed by cardioversion during residual or low-dose isoproterenol infusion or induce focal atrial tachycardia. Non-PV triggers were defined as non-PV ectopic beats triggering AF or sustained focal atrial tachycardia.

RESULTS

Of 1,372 patients included, 883 (64.4%) underwent the complete stepwise provocation protocol with isoproterenol infusion and burst pacing, 334 (24.3%) isoproterenol infusion only, 77 (5.6%) burst pacing only, and 78 (5.7%) no provocative maneuvers (only step 1). Overall, 161 non-PV triggers were found in 135 (9.8%) patients. Of these, 51 (31.7%) non-PV triggers occurred spontaneously, and the remaining 110 (68.3%) required provocative maneuvers for induction. Among those receiving the complete stepwise provocation protocol, there was a 2.2-fold increase in the number of patients with non-PV triggers after isoproterenol infusion, and the addition of burst pacing after isoproterenol infusion led to a total increase of 3.6-fold with the complete stepwise provocation protocol.

CONCLUSIONS

The majority of non-PV triggers require provocative maneuvers for induction. A stepwise provocation protocol consisting of isoproterenol infusion followed by burst pacing identifies a 3.6-fold higher number of patients with non-PV triggers.

Utility of noninvasive electrocardiographic imaging in the localization of nonpulmonary vein triggers of atrial fibrillation determined by pacing common trigger sites

INTRODUCTION

Identifying the origin of nonpulmonary vein atrial fibrillation (AF) triggers (NPVTs) after pulmonary vein isolation (PVI) can be challenging. We aimed to determine if noninvasive electrocardiographic imaging (ECGi) could localize pacing from common NPVT sites. ECGi combines measured body surface potentials with heart-torso geometry acquired from computed tomography (CT) to generate an activation map.

METHODS

In 12 patients with AF undergoing first time ablation, the ECGi vest was fitted for preprocedural CT scan and worn during the procedure. After PVI, we performed steady-state pacing from 15 typical anatomic NPVT sites at a cycle length of 700-800 ms. We co-registered the invasive anatomic map with the CT-based ECGi epicardial activation map to compare ECGi predicted to true pacing origin.

RESULTS

In the study cohort (67% male, 58% persistent AF, and 67% with left atrial dilation), 148 (82%) pacing sites had both capture and adequate anatomy acquired from the three-dimensional mapping system to co-register with ECGi activation map. Median distance between true pacing sites and point of earliest epicardial activation derived from the ECGi maps for all sites was 17 mm (interquartile range, 10-22 mm). Assuming paced sites treated as regions with a radius of 2.5 cm, the earliest activation site on ECGi map falls within the region with 94% accuracy.

CONCLUSION

ECGi can approximate the origin of paced beats from common NPVT sites to within a median distance of 17 mm. A rapidly identified region may then be the focus of more detailed catheter-based mapping techniques to facilitate successful localization and ablation of NPVTs.

Identifying Origin of Nonpulmonary Vein Triggers Using 2 Stationary Linear Decapolar Catheters: A Novel Algorithm

BACKGROUND

Targeting nonpulmonary vein triggers (NPVTs) of atrial fibrillation (AF) after pulmonary vein isolation can be challenging. NPVTs are often single ectopic beats with a surface P-wave obscured by a QRS or T-wave.

OBJECTIVES

The goal of this study was to construct an algorithm to regionalize the site of origin of NPVTs using only intracardiac bipolar electrograms from 2 linear decapolar catheters positioned in the posterolateral right atrium (along the crista terminalis with the distal bipole pair in the superior vena cava) and in the proximal coronary sinus (CS).

METHODS

After pulmonary vein isolation in 42 patients with AF, pacing from 15 typical anatomic NPVT sites was conducted. For each pacing site, the electrogram activation sequence was analyzed from the CS catheter (simultaneous/chevron/inverse chevron/distal-proximal/proximal-distal) and activation time (ie, CSCTAT) between the earliest electrograms from the 2 decapolar catheters was measured referencing the earliest CS electrogram; a negative CSCTAT value indicates the crista terminalis catheter electrogram was earlier, and a positive CSCTAT value indicates the CS catheter electrogram was earlier. A regionalization algorithm with high predictive value was defined and tested in a validation cohort with AF NPVTs localized with electroanatomic mapping.

RESULTS

In the study patient cohort (71% male; 43% with persistent AF, 52% with left atrial dilation), the algorithm grouped with high precision (positive predictive value 81%-99%, specificity 94%-100%, and sensitivity 30%-94%) the 15 distinct pacing sites into 9 clinically useful regions. Algorithm testing in a 98 patient validation cohort showed predictive accuracy of 91%.

CONCLUSIONS

An algorithm defined by the activation sequence and timing of electrograms from 2 linear multipolar catheters provided accurate regionalization of AF NPVTs to guide focused detailed mapping.

Intra-atrial activation pattern is useful to localize the areas of non-pulmonary vein triggers of atrial fibrillation

Background

Pulmonary vein isolation (PVI) is an established ablation procedure for atrial fibrillation (AF), however, PVI alone is insufficient to suppress AF recurrence. Non-pulmonary vein (non-PV) trigger ablation is one of the promising strategies beyond PVI and has been shown to be effective in refractory/persistent AF cases. To make non-PV trigger ablation more standardized, it is essential to develop a simple method to localize the origin of non-PV triggers.

Methods

We retrospectively analyzed 37 non-PV triggers in 751 ablation sessions for symptomatic AF from January 2017 to December 2020. Regarding non-PV triggers, intra-atrial activation interval from the earliest in right atrium (RA) to proximal coronary sinus (CS) (RA-CSp) and that from the earliest in RA to distal CS (RA-CSd) obtained by a basically-positioned duodecapolar RA-CS catheter were compared among 3 originating non-PV areas [RA, atrial septum (SEP) and left atrium (LA)].

Results

RA-CSp of RA non-PV trigger (56.4 ± 23.4 ms) was significantly longer than that of SEP non-PV (14.8 ± 25.6 ms, p = 0.019) and LA non-PV (-24.9 ± 27.9 ms, p = 0.0004). RA-CSd of RA non-PV (75.9 ± 32.1 ms) was significantly longer than that of SEP non-PV (34.2 ± 32.6 ms, p = 0.040) and LA non-PV (-13.3 ± 41.2 ms, p = 0.0008). RA-CSp and RA-CSd of SEP non-PV were significantly longer than those of LA non-PV (p = 0.022 and p = 0.016, respectively). Sensitivity and specificity of an algorithm to differentiate the area of non-PV trigger using RA-CSp (cut-off value: 50 ms) and RA-CSd (cut-off value: 0 ms) were 88% and 97% for RA non-PV, 81% and 73% for SEP non-PV, 65% and 95% for LA non-PV, respectively.

Conclusions

The analysis of intra-atrial activation sequences was useful to differentiate non-PV trigger areas. A simple algorithm to localize the area of non-PV trigger would be helpful to identify non-PV trigger sites in AF ablation.

Ablation Therapy for Persistent Atrial Fibrillation

Atrial Fibrillation (AF) is the most common form of electrical disturbance of the heart and contributes to significant patient morbidity and mortality. With a better understanding of the mechanisms of atrial fibrillation and improvements in mapping and ablation technologies, ablation has become a preferred therapy for patients with symptomatic AF. Pulmonary Vein Isolation (PVI) is the cornerstone for AF ablation therapy, but particularly in patients with AF occurring for longer than 7 days (persistent AF), identifying clinically significant nonpulmonary vein targets and achieving durability of ablation lesions remains an important challenge.

Prevalence and Characteristics of Atrial Tachycardia From Noncoronary Aortic Cusp During Atrial Fibrillation Catheter Ablation

The prevalence of the uncommon atrial tachycardia (AT) originating from the non-coronary cusp (NCC) in patients undergoing atrial fibrillation (AF) ablation were overall 0.08% (0.07% in initial AF ablation cases, and 0.15% in redo cases). The characteristics of NCC ATs uncovered during AF ablation presented shorter tachycardia cycle length and increased P-wave duration compared to that of de novo NCC AT without AF. The AF recurrence rate after pulmonary vein isolation and NCC AT ablation was low without significant procedure related complication such as atrioventricular conduction block.

Background and Objectives

Atrial tachycardias (ATs) from noncoronary aortic cusp (NCC) uncovered after radiofrequency ablation for atrial fibrillation (AF) are rarely reported. This study was conducted to investigate the prevalence and clinical characteristics of NCC ATs detected during AF ablation and compare their characteristics with de novo NCC ATs without AF.

Methods

Consecutive patients who underwent radiofrequency catheter ablation for AF were reviewed from the multicenter AF ablation registry of 11 tertiary hospitals. The clinical and electrophysiological characteristics of NCC AT newly detected during AF ablation were compared with its comparators (de novo NCC AT ablation cases without AF).

Results

Among 10,178 AF cases, including 1,301 redo ablation cases, 8 (0.08%) NCC AT cases were discovered after pulmonary vein isolation (PVI; 0.07% in first ablation and 0.15% in redo ablation cases). All ATs were reproducibly inducible spontaneously or with programmed atrial stimulation without isoproterenol infusion. The P-wave morphological features of tachycardia were variable depending on the case, and most cases exhibited 1:1 atrioventricular conduction. AF recurrence rate after PVI and NCC AT successful ablation was 12.5% (1 of 8). Tachycardia cycle length was shorter than that of 17 de novo ATs from NCC (303 versus 378, p=0.012). No AV block occurred during and after successful AT ablation.

Conclusions

Uncommon NCC ATs (0.08% in AF ablation cases) uncovered after PVI, showing different characteristics compared to de-novo NCC ATs, should be suspected irrespective of P-wave morphologies when AT shows broad propagation from the anterior interatrial septum.

Long P-wave duration immediately after pulmonary vein isolation on radiofrequency catheter ablation for atrial fibrillation predicts clinical recurrence: correlation with atrial remodeling in persistent atrial fibrillation

P-wave morphology reflects atrial remodeling and indicates prognosis after radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF). The impact of p-wave morphology after excluding the effect of pulmonary vein (PV) substrate on outcomes is unknown. We evaluated the p-wave morphology on electrocardiography immediately after PV isolation for clinical outcomes. Eighty-four consecutive patients (47 with paroxysmal AF and 37 with persistent AF) who underwent RFCA were included. P-wave duration (PWD) and amplitude in all leads were examined during sinus rhythm immediately after PV isolation. We evaluated the relationship between electrocardiogram parameters and AF recurrence, according to the type of AF and following ablation, and the correlation with left atrial (LA) volume, low voltage ratio, and fixed conduction time. During 12 months of follow-up, 20 patients experienced recurrence. The cut-off value of PWD > 120 ms in lead I showed a sensitivity of 75% and specificity of 69% for predicting recurrence. PWD was significantly correlated with LA volume, low voltage, and conduction velocity. Significantly higher recurrence rates were observed in patients with PWD > 120 ms than in those with PWD ≤ 120 ms (p < 0.001), and the difference was more pronounced in patients with persistent AF. Multivariate analysis demonstrated that PWD > 120 ms was independently associated with recurrence in the total population (hazard ratio 2.00; 95% confidence interval 1.27-3.22; p = 0.003) and in patients with persistent AF. In conclusion, long PWD after PV isolation predicts AF recurrence, which might be associated with the extent of the LA substrate in persistent AF.

Low-Voltage Areas as Alternative Targets for the Ablation of Unmappable Atrial Tachycardia in Patients Undergoing Atrial Fibrillation Ablation

Aims

Unmappable regular atrial tachycarrhythmias (ATs) occasionally develop during atrial fibrillation (AF) ablation, and are difficult to treat by conventional ablation. Recently, low-voltage areas (LVAs) have been reported to represent AT substrate. The purpose of this study was to elucidate the efficacy of LVA ablation for unmappable AT.

Methods

This observational study included 32 consecutive patients who developed unmappable ATs during and after AF ablation. Unmappable AT was defined as AT lasting for >5 s, but that terminated or changed the activation sequence over too short a time to create a sufficient activation map. We used conventional ablation to target undetermined AT circuits estimated from activation timings of electrograms recorded on the placed electrode catheter, the response to entrainment mappings, and/or diastolic potentials during AT. Subsequently, in cases without successful elimination of unmappable ATs by conventional ablation, LVA (≤ 0.5 mV) ablation was performed at the discretion of the operators.

Results

Conventional ablation failed to eliminate at least one unmappable AT in 29 patients. Among them, LVA ablation was performed in 16 patients. LVA ablation eliminated all the unmappable ATs in 8 of 16 patients. The LVA size did not differ between patients with and without the acute elimination of unmappable ATs (17±11 vs. 21±12 cm2, p = 0.39), and AT/AF recurrence rates were comparable between the two groups (38% vs. 63%, p = 0.62) during a mean follow-up period of 14±8 months.

Conclusions

LVA ablation was efficacious to some extent for the elimination of unmappable ATs refractory to conventional ablation.