Comparison of the electrophysiological properties of the pulmonary veins between paroxysmal and persistent atrial fibrillation.

Background: The role of the pulmonary veins (PVs) as triggers in atrial fibrillation (AF) is well-known; however, their detailed electrophysiological properties have not been thoroughly examined. Objective: This study aimed to investigate the electrophysiological properties of the PVs between paroxysmal AF (pAF) and persistent AF (perAF). Methods: Prior to catheter ablation in patients with pAF (n = 51) and perAF (n = 41), a voltage map of the left atrium and PVs was created under sinus rhythm, and the area of the myocardial sleeves in the PVs and their electrophysiological characteristics, including the pacing threshold and effective refractory period (ERP), were compared between the two groups. Results: Compared with perAF, the myocardial sleeves of PVs for pAF were significantly larger for all PVs. The ERP for perAF was significantly shorter than that for pAF for all PVs. The pacing threshold for perAF was significantly higher than that for pAF for the right and left superior PVs. Conclusion: In patients with perAF, a decrease in the normal myocardial sleeves and a shortening of the ERP were observed for all PVs. Those changes in the electrophysiological properties of the PVs might be related to the persistence of AF.

Atrial Structural Remodeling in Patients With Atrial Fibrillation Is a Diffuse Fibrotic Process: Evidence From High-Density Voltage Mapping and Atrial Biopsy.

Background Low-voltage areas (LVAs) in the atria of patients with atrial fibrillation are considered local fibrosis. We hypothesized that voltage reduction in the atria is a diffuse process associated with fibrosis and that the presence of LVAs reflects a global voltage reduction. Methods and Results We examined 140 patients with atrial fibrillation and 13 patients with a left accessory pathway (controls). High-density bipolar voltage mapping was performed using a grid-mapping catheter during high right atrial pacing. Global left atrial (LA) voltage (VGLA) in the whole LA and regional LA voltage (VRLA) in 6 anatomic regions were evaluated with the mean of the highest voltage at a sampling density of 1 cm2. Patients with atrial fibrillation were categorized into quartiles by VGLA. LVAs were evaluated at voltage cutoffs of 0.1, 0.5, 1.0, and 1.5 mV. Twenty-eight patients with atrial fibrillation also underwent right atrial septum biopsy, and the fibrosis extent was quantified. Voltage at the biopsy site (Vbiopsy) was recorded. VGLA results by category were Q1 (<4.2 mV), Q2 (4.2-5.6 mV), Q3 (5.7-7.0 mV), and Q4 (≥7.1 mV). VRLA at any region was reduced as VGLA decreased. VGLA and VRLA did not differ between Q4 and controls. The presence of LVAs increased as VGLA decreased at any voltage cutoff. Biopsies revealed 11±6% fibrosis, which was inversely correlated with both Vbiopsy and VGLA (r=-0.71 and -0.72, respectively). Vbiopsy was correlated with VGLA (r=0.82). Conclusions Voltage reduction in the LA is a diffuse process associated with fibrosis. Presence of LVAs reflects diffuse voltage reduction of the LA.

Erratum: Differential Atrial Pacing to Detect Reconnection Gaps After Pulmonary Vein Isolation in Atrial Fibrillation.

The errors in the following list appeared in the article entitled "Differential Atrial Pacing to Detect Reconnection Gaps After Pulmonary Vein Isolation in Atrial Fibrillation" by Mai Tahara, Ritsushi Kato, Yoshifumi Ikeda, Koji Goto, So Asano, Hitoshi Mori, Shiro Iwanaga, Toshihiro Muramatsu, and Kazuo Matsumoto (Vol. 61, No. 3, 503-509, 2020).

Impact of Renal Dysfunction on Left Atrial Structural Remodeling and Recurrence After Catheter Ablation for Atrial Fibrillation　- A Propensity Score Matching Analysis.

BACKGROUND: Renal dysfunction coexists with other known risk factors of left atrial (LA) structural remodeling, expressed as low-voltage zones (LVZs), and the recurrence of atrial fibrillation (AF) after ablation. This study aimed to determine whether renal dysfunction had an independent effect on the presence of LVZs and recurrence after AF ablation, using propensity score (PS) matching analysis.Methods and Results:448 consecutive patients who underwent their initial AF ablation were enrolled. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2, with 126 (28%) patients having CKD. Using PS matching analysis, new subsets (CKD and non-CKD group, n=103 each) were obtained, matched for age, sex, AF type, and LA volume. The presence of LVZs defined as bipolar voltage <0.5 mV was higher in the CKD group than in the non-CKD group (31% vs. 17%, P=0.034). Multivariate analysis showed eGFR was an independent predictor of the presence of LVZs (odds ratio 1.31 per 10-mL/min/1.73 m2decrease, P=0.029). AF-free survival rate was significantly lower in the CKD patients during 20±9 months of follow-up (63% vs. 82%, P=0.019), and eGFR was shown to be an independent predictor of recurrence (hazard ratio 1.29 per 10-mL/min/1.73 m2decrease, P=0.006), but the presence of LVZs did not predict recurrence. CONCLUSIONS: Renal dysfunction independently predicted not only the recurrence of AF after ablation but also the presence of LVZs.

Differential Atrial Pacing to Detect Reconnection Gaps After Pulmonary Vein Isolation in Atrial Fibrillation.

High-resolution mapping is useful to identify reconnection gaps in the pulmonary vein after pulmonary vein isolation for atrial fibrillation. However, it is sometimes difficult to differentiate pulmonary vein potentials from far-field potentials because of very low amplitudes. Our purpose was to evaluate the usefulness of a novel differential atrial pacing method to differentiate reconnected pulmonary vein potentials from isolated pulmonary vein potentials. This retrospective observational study included 34 patients with atrial fibrillation (22 men; mean age, 64 ± 14 years; 28 with paroxysmal atrial fibrillation) who underwent radiofrequency or cryoballoon ablation. Following pulmonary vein isolation, we created a high-resolution activation map during pacing from both the coronary sinus and left atrial appendage. We compared the characteristics of the pulmonary vein potentials and the pattern of activation between the reconnected and isolated pulmonary veins. We analyzed 131 pulmonary veins and found reconnections in 41 pulmonary veins (R group); 90 pulmonary veins had no reconnection (NR group). The R group had a significantly shorter distance between the earliest pulmonary vein activation sites in both activation maps, compared with the NR group (5.22 ± 0.53 mm versus 17.08 ± 0.36 mm, respectively; P < 0.0001). The amplitude of the pulmonary vein potentials was higher in the R group versus the NR group (0.61 ± 0.05 mV versus 0.04 ± 0.03 mV, respectively; P < 0.0001). Six gaps (14%) in the R group that were unrecognized using a conventional method were identified using our novel method. In conclusion, differential atrial pacing was useful to identify pulmonary vein reconnection gaps during ablation using a novel high-resolution mapping system.

Relationship between the ablation index, lesion formation, and incidence of steam pops.

BACKGROUND: The ablation index (AI) is reported to be useful for a durable pulmonary vein isolation (PVI). However, there have been no studies investigating the relationship between the power, contact force (CF), AI, and steam pops. METHODS: Using an in vitro model, ablation energy was delivered until a steam pop occurred and the time to the steam pop and AI when the steam pop occurred were measured. The experiment was performed with a combination of various powers (20, 30, 40, and 50 W) and contact forces (CFs) (10, 30, and 50 g) 20 times for each setting. The analysis consisted of two protocols. The first protocol was a comparison between the ablation power and several parameters under the same CF (10, 30, and 50 g). The second protocol was a comparison between the CF and several parameters under the same power (20, 30, 40, and 50 W). The correlation between the lesion formation and ablation parameters was evaluated. RESULTS: The AI value when steam pops occurred varied depending on the ablation settings. All AI median values were <500 under an ablation power of 50 W. On other hand, the median ablation time up to the steam pop was more than 46 seconds, but all median values of the AI were more than 550 under an ablation with 20 W. CONCLUSIONS: The AI cannot predict steam pops. A low power and long duration ablation could obtain a high AI value. However, high-power ablation could not obtain a high AI value because of an early occurrence of steam pops.

The influence of the electrodes spacing of a mapping catheter on the atrial voltage substrate map.

BACKGROUND: Detailed substrate mapping is important for catheter ablation. However, the influence of the electrode spacing of the mapping catheter on the substrate map has not been well clarified. The aim of this study was to investigate the influence of the electrode spacing of the mapping catheter on the voltage of the substrate map. METHODS: Protocol 1: We recorded the local atrial potentials of the left atrium (LA) using the ablation catheter during sinus rhythm in six atrial fibrillation (AF) patients. The voltage of each atrial potential was compared between a close-bipolar (1-2 electrode) recording and wide-bipolar (1-4 electrode) recording. Protocol 2: Two voltage-maps of the LA were constructed separately using a 20-pole circular catheter and 10-pole circular catheter during sinus rhythm in 42 AF patients. The low voltage zone (LVZ) (<0.5mV) areas obtained by 2 voltage maps using the 10-pole and 20-pole circular catheters were compared. RESULTS: Protocol 1: The close-bipolar voltage of the local potentials was significantly smaller than that of the wide-bipolar voltages (0.76±0.39mV vs. 0.63±0.41mV, p<0.0001). Protocol 2: The size of the LVZ areas identified by the 10-pole and 20-pole catheters was 1.12±1.92cm2 (1.47±2.78%) and 8.30±7.80cm2 (8.83±8.32%), respectively (p<0.0001). CONCLUSIONS: The voltage of the local atrial potential using the close-bipolar catheter was significantly smaller than that using the wide-bipolar catheter. Care should be given to the electrode spacing of mapping catheters when analyzing the voltage of the atrial myocardial potentials.

Primary Mural Endocarditis Without Valvular Involvement.

Primary mural endocarditis is an extremely rare infection in which nonvalvular endocardial involvement is seen without any cardiac structural abnormalities such as ventricular septal defects. The rapid and precise diagnosis of this disease remains challenging. We present 2 cases (67- and 47-year-old male patients) of pathologically confirmed primary mural endocarditis that could have been detected by initial transthoracic echocardiography in the emergency department. Transthoracic echocardiography and transesophageal echocardiography play critical roles in the early recognition and confirmation of primary mural endocarditis.

Visualization of Recanalized Coronary Occlusion with Dissection by Optical Frequency Domain Imaging.

A 43-year-old asymptomatic male patient with a positive stress myocardial perfusion imaging result was admitted to our institution. Although no organic lesion was detected by 64-row coronary computed tomography angiography (CCTA), invasive coronary angiography revealed a unique anatomy with a long lesion in the middle of the left anterior descending artery. Optical frequency domain imaging (OFDI) demonstrated the details of the recanalized occlusion with coronary dissection. OFDI provides in vivo coronary images with high spatial resolution and better three-dimensional reconstructions and supports invasive coronary angiography to elucidate infinitesimal and complicated intraluminal morphology that might be missed by CCTA alone.

Cardiac Asystole Triggered by Temporal Lobe Epilepsy with Amygdala Enlargement.

A 25-year-old previously healthy man was hospitalized for syncope. While standing, he suddenly lost consciousness, followed by a generalized tonic clonic seizure. An electrocardiogram demonstrated asystole. No cardiac abnormalities were detected on the echocardiogram, cardiac magnetic resonance imaging (MRI), positron emission tomography, or a coronary angiogram. An electrophysiological study showed normal sinus node and atrioventricular node function. An electroencephalogram revealed small spike waves in the fronto-temporal region. Brain MRI demonstrated a left-sided amygdala enlargement. To the best of our knowledge, this is the first case of temporal lobe epilepsy with an amygdala enlargement that induced cardiac asystole.