Rotational Activation Pattern During Functional Substrate Mapping: Novel Target for Catheter Ablation of Scar-Related Ventricular Tachycardia.

BACKGROUND: Recent advancements in a 3-dimensional mapping system allow for the assessment of detailed conduction properties during sinus rhythm and thus the establishment of a strategy targeting functionally abnormal regions in scar-related ventricular tachycardia (VT). We hypothesized that a rotational activation pattern (RAP) observed in maps during baseline rhythm was associated with the critical location of VT. METHODS: We retrospectively examined the pattern of wavefront propagation during sinus rhythm in patients with scar-related VT. The prevalence and features of the RAP on critical VT circuits were analyzed. RAP was defined as >90° of inward curvature directly above or at the edge of the slow conductive areas. RESULTS: Forty-five VTs in 37 patients (66±15 years old, 89% male, 27% ischemic heart disease) were evaluated. High-density substrate mapping during sinus rhythm (median, 2524 points) was performed using the CARTO3 system before VT induction. Critical sites for reentry were identified by direct termination by radiofrequency catheter ablation in 21 VTs or by pace mapping in 12 VTs. Among them, RAP was present in 70% of the 33 VTs. Four VTs had no RAP at the critical sites during sinus rhythm, but it became visible in the mappings with different wavefront directions. Six VTs, in which intramural or epicardial isthmus was suspected, were rendered noninducible by radiofrequency catheter ablation to the endocardial surface without RAP. RAP had a sensitivity and specificity of 70% and 89%, respectively, for predicting the elements in the critical zone for VT. CONCLUSIONS: The critical zone of VT appears to correspond to an area characterized by the RAP with slow conduction during sinus rhythm, which facilitates targeting areas specific for reentry. However, this may not be applicable to intramural VT substrates and might be affected by the direction of wavefront propagation to the scar during mapping. Graphic Abstract: A graphic abstract is available for this article.

Reverse-Type Left Posterior Fascicular Ventricular Tachycardia: A New Electrocardiographic Entity.

OBJECTIVES: This study sought to demonstrate a new type of verapamil-sensitive fascicular ventricular tachycardia (VT) with a reverse circuit. BACKGROUND: Left posterior fascicular ventricular tachycardia (LPFVT) is the most common form of verapamil-sensitive fascicular VT. Reverse-type LPFVT has not been reported. METHODS: We searched for a reverse-type LPFVT among 242 patients with verapamil-sensitive VT from February 2006 to September 2019. RESULTS: Three patients had a reverse-type LPFVT (cycle lengths: 340, 360, and 340 ms). QRS configuration during VT was narrow (140, 150, and 140 ms) and exhibited rSr' morphology in V1 with an early precordial transition and inferior axis. Two of 3 patients had common-type LPFVT. During reverse-type LPFVT, the earliest ventricular activation was the left superior middle septum. Fragmented Purkinje potentials (P1) buried within the local ventricular electrogram were recorded with an activation sequence from the apex to the base and were linked to the subsequent left ventricular septal activation. After radiofrequency catheter ablation at P1 during LPFVT, the reverse-type LPFVT also became noninducible. In 1 patient with only the reverse-type LPFVT, radiofrequency catheter ablation at the earliest LV activation site suppressed VT. These findings suggest that this new type of verapamil-sensitive fascicular VT shares a re-entrant circuit with a reverse direction of common LPFVT with an intramural exit site at the superior middle septum. CONCLUSIONS: Reverse-type LPFVT can occur. If common LPFVT exists, diastolic P1 during LPFVT can be a common target of ablation. If only reverse-LPFVT is inducible, the earliest ventricular activation site can be a target.

Chronic Kidney Disease as a Possible Predictor of Left Atrial Thrombogenic Milieu Among Patients with Nonvalvular Atrial Fibrillation.

Patients with chronic kidney disease (CKD) experiencing atrial arrhythmia are hypothesized to have elevated CHADS2 and CHA2DS2-VASc scores, thereby predisposed to left atrial (LA) thrombus formation and subsequent thromboembolism. We examined possible association of LA thrombogenic milieu (TM) with CKD in patients with nonvalvular atrial fibrillation. A total of 581 patients (181 women; mean age, 67 years) who underwent transesophageal echocardiography were examined. Patients were divided into 4 groups based on the estimated glomerular filtration rate (eGFR) (ml/min/1.73 m2): eGFR ≥90 (n = 29), 60≤ eGFR <90 (n = 329), 30≤ eGFR <60 (n = 209), and eGFR <30 (n = 14). TM was defined as the presence of LA thrombus, dense spontaneous echo contrast, or LA appendage velocity ≤25 cm/s. Of 581 patients, 147 (25%) had TM. The prevalence of TM increased with decreasing eGFR (4%, 18%, 36%, and 86% for each group, p <0.001). Similar trends were observed for some of the clinical and echocardiographic variables including CHA2DS2-VASc score and LA size. Multivariate logistic regression analysis revealed that every 10 ml/min/1.73 m2 decrement in eGFR was a significant independent correlate of TM (odds ratio 0.80, p = 0.005), along with nonparoxysmal atrial fibrillation (AF) (odds ratio 0.45, p = 0.004), higher CHA2DS2-VASc score (odds ratio 1.24, p = 0.012), every 5 ml/m2 increment in LA volume index (odds ratio 1.57, p <0.001), and every 10% decrement in left ventricular ejection fraction (odds ratio 0.51, p <0.001). In conclusion, CKD may be a significant risk factor for LA thrombus formation in patients with nonvalvular atrial fibrillation.

Basal wall hypercontraction of Takotsubo cardiomyopathy in a patient who had been diagnosed with dilated cardiomyopathy: a case report.

BACKGROUND: Takotsubo cardiomyopathy is characterized by the basal hypercontractility and apical ballooning of the left ventriculum and T-wave inversion in the electrocardiogram. It has been suggested that Takotsubo cardiomyopathy might underlie the pathogenesis of persistent cardiac dysfunction; however, few reports are present demonstrating the advent of Takotsubo cardiomyopathy in patients with idiopathic cardiomyopathy. CASE PRESENTATION: A 64-year-old women was admitted due to dyspnea on effort and lower extremity edema. She had been diagnosed with idiopathic dilated cardiomyopathy 2.5 years before owing to the reduced left ventricular ejection fraction (24%), normal coronary artery, and interstitial fibrosis of the myocardial samples. On admission, her electrocardiogram showed giant negative T wave in II, III, aVF, and precordial leads. Echocardiography showed dyskinesis of the left ventricular apex and hypercontraction of the basal wall, which had not been observed in the previous examinations. Coronary angiography showed normal coronary arteries, and apical ballooning and basal hypercontractility was confirmed by left ventriculography. On day 15 of admission, contraction of apical wall was recovered, and basal hypercontraction was disappeared. CONCLUSION: The present case is the first report demonstrating appearance the transient basal wall hypercontraction along with the advent of Takotsubo cardiomyopathy in a patient diagnosed with dilated cardiomyopathy. Whether such findings are indicative of fair prognosis and have the utility of understanding the pathogenesis of dilated cardiomyopathy needs further investigation.

Association between serum soluble urokinase-type plasminogen activator receptor and atrial fibrillation.

BACKGROUND: Circulating soluble urokinase-type plasminogen activator receptor (suPAR), which can reflect immune activation and low-grade inflammation, may be a novel biomarker of cardiovascular disease. METHODS: We investigated the potential association between suPAR and the prevalence of atrial fibrillation (AF) by analyzing patients with either sinus rhythm, paroxysmal atrial fibrillation (PAF), or non-paroxysmal atrial fibrillation (NPAF), which indicates either permanent or persistent AF. RESULTS: Among 426 patients enrolled (mean age 71.4±9.2 years; 110 (25.8%) female), 310, 62, and 54 were diagnosed with sinus rhythm, PAF, and NPAF, respectively. NPAF was >10-fold more prevalent in the highest suPAR quartile (>3534 pg/mL; 32 (30.2%) of 106 patients) than in the lowest suPAR quartile (<1802 pg/mL; 3 (2.8%) of 107 patients). Logistic regression analysis showed that, as compared with the lowest suPAR quartile, the highest suPAR quartile was associated with NPAF with an odds ratio of 6.48 (95% confidence interval, 1.71-24.5) after adjustment for sex, age, log(eGFR), C-reactive protein, and systolic blood pressure. In multivariate receiver operating characteristic analysis to predict NPAF, the area under the curve (AUC) for the combination of age, sex, log(eGFR), and C-reactive protein was 0.777 (standard error [SE], 0.036); the addition of log(suPAR) slightly improved the prediction (AUC, 0.812; SE, 0.034, P=0.084). CONCLUSIONS: Serum suPAR was associated with AF, particularly NPAF, as demonstrated by multivariate logistic regression analysis. Whether suPAR promotes or maintains AF should be investigated in further studies.

Prospective Evaluation of Electromyography-Guided Phrenic Nerve Monitoring During Superior Vena Cava Isolation to Anticipate Phrenic Nerve Injury.

BACKGROUND: Right phrenic nerve injury (PNI) is a major concern during superior vena cava (SVC) isolation due to the anatomical close proximity. The functional and histological severity of PNI parallels the degree of the reduction in the compound motor action potential (CMAP) amplitude. This study aimed to evaluate the feasibility of monitoring CMAPs during SVC isolation to anticipate PNI during atrial fibrillation (AF) ablation. METHODS: Thirty-nine paroxysmal AF patients were prospectively enrolled. Radiofrequency energy was delivered point-by-point for 30 seconds with 20 W until eliminating all SVC potentials after the pulmonary vein isolation. Right diaphragmatic CMAPs were obtained from modified surface electrodes by pacing from the right subclavian vein. Radiofrequency applications were applied without fluoroscopy under CMAP monitoring at sites with phrenic nerve capture by high output pacing. RESULTS: Electrical SVC isolation was successfully achieved with a mean of 9.4 ± 3.3 applications in all patients. In 3 (7.5%) patients, the SVC was isolated without radiofrequency delivery at phrenic nerve capture sites. Among a total of 346 applications in the remaining 36 patients, 71 (20.5%) were delivered while monitoring CMAPs. In 1 (1.4%) application, the RF application was interrupted due to a decrease in the CMAP amplitude. However, no PNI was detected on fluoroscopy, and the decreased amplitude recovered spontaneously. The remaining 70 (98.6%) applications exhibited no significant changes in the CMAP amplitude throughout the applications (from 1.01 ± 0.47 to 0.98 ± 0.45 mV, P = 0.383). CONCLUSIONS: Stable right diaphragmatic CMAPs could be obtained, and monitoring CMAPs might be useful for anticipating right PNI during SVC isolation.

Impact of Catheter Contact Force on Superior Vena Cava Mapping and Localization of the Right Phrenic Nerve by High Output Pacing.

BACKGROUND: Right phrenic nerve injury (PNI) is a major concern during superior vena cava (SVC) isolation. Phrenic nerve (PN) localization by high-output pacing is a standard technique for anticipating PNI. This study evaluated the impact of catheter contact force (CF) on SVC mapping and PN localization. METHODS: Twenty-one atrial fibrillation patients undergoing cardiac enhanced computed tomography (CT) were prospectively enrolled. SVC geometries were created at the SVC-right atrium junction level with low (<10 × g) and high (>10 × g) CFs. The PN was localized by high-output pacing (10 V, 2 milliseconds) at the SVC and anterior right superior pulmonary vein (RSPV) with different CFs. RESULTS: The SVC cross-sectional area was significantly greater when created with high (22.1 ± 4.9 × g) compared with low CFs (4.2 ± 1.3 × g) (5.3 ± 1.4 cm2 vs. 2.3 ± 0.7 cm2 , P < 0.0001). High CFs distorted the SVC and anterior RSPV by a mean of 4.8 ± 2.5 and 4.4 ± 1.7 mm, with minimal distortion at the anteroseptal SVC. The PN was more frequently captured with a high compared with low CF at the SVC (95.2% vs. 71.4%, P = 0.038) and RSPV (66.7% vs. 14.3%, P = 0.0005). The PN capture area was also wider with a high compared with low CF at the SVC (9.0 ± 4.1 mm vs. 4.5 ± 2.8 mm, P = 0.001). The PN location was at the anterolateral, lateral, and posterolateral SVC in 3 (14.3%), 13 (61.9%), and 5 (23.8%) patients, respectively, which was identical to that identified on CT. No PNs located >1.98 mm from the RSPV were captured by RSPV pacing. CONCLUSIONS: CF impacted the SVC mapping and PN localization. Cardiac CT identified the PN location, and the distance from the pacing site influenced PN capture.

Early Recurrence After Pulmonary Vein Isolation of Paroxysmal Atrial Fibrillation With Different Ablation Technologies - Prospective Comparison of Radiofrequency vs. Second-Generation Cryoballoon Ablation.

BACKGROUND: Inflammation plays a prominent role in the etiology of the early recurrence of atrial fibrillation (ERAF). We prospectively compared the proportion of ERAF and time-course patterns of biomarkers between radiofrequency (RF) and cryoballoon (CB) ablation. METHODS AND RESULTS: We enrolled 82 consecutive paroxysmal AF patients undergoing pulmonary vein (PV) isolation, performed with either a 28-mm 2nd-generation CB and 3-min freeze technique or point-by-point RF ablation. Each group had 41 patients. In the RF group, all PVs were successfully isolated with 28.9 ± 6.5 min of RF delivery. In the CB group, a mean of 5.3 ± 1.4 applications/patient was delivered. The proportion of ERAF was similar between the groups. The time-course patterns significantly differed between the groups for high-sensitivity C-reactive protein (hs-CRP) value (P=0.006) and myocardial injury markers (P<0.0001). Greater myocardial injury was observed in the CB than in the RF group (P<0.0001), whereas the peak hs-CRP value was comparable between the groups. The 2-day post-procedure hs-CRP value was the sole factor correlating with ERAF as identified by the multivariable analysis (hazard ratio 1.697; 95% confidence interval, 1.005-2.865; P=0.048) in the RF, but not the CB group. CONCLUSIONS: The proportion of ERAF was comparable after RF and 2nd-generation CB ablation. Despite CB ablation exhibiting greater myocardial injury than RF ablation, the inflammatory responses were comparable between the groups. The inflammatory response extent predicted ERAF post-RF ablation but not post-CB ablation.

Impact of the order of the targeted pulmonary vein on the vagal response during second-generation cryoballoon ablation.

BACKGROUND: Radiofrequency applications around pulmonary vein (PV) ostia often induce vagal reflexes. OBJECTIVE: This study aimed to evaluate the impact of the order of the targeted PV on the vagal response during second-generation cryoballoon ablation. METHODS: Eighty-one consecutive paroxysmal atrial fibrillation (AF) patients undergoing cryoballoon ablation were prospectively enrolled. PV isolation was performed with one 28-mm second-generation balloon using a 3-minute freeze technique. In the first 39 patients, the left superior PV (LSPV) was initially targeted. In the second 42, the LSPV was targeted following the right PVs. RESULTS: Baseline rhythms were sinus rhythm and AF in 34 and 5 patients in the first group, and 34 and 8 in the second group, respectively. In the first group, sinus bradycardia/arrest requiring back-up pacing occurred in 13 patients (38.2%) at a median of 41.0 (10.0-55.5) seconds after balloon deflation (90 [60-100] seconds post freezing), and pauses requiring pacing in 1 (20.0%) with AF. In the second group, no sinus bradycardia/arrest occurred throughout the procedure; however, atrioventricular block requiring back-up pacing occurred 21 seconds after balloon deflation in 1 patient in whom right superior PV (RSPV) ablation was performed for only 60 seconds owing to right phrenic nerve injury. The cycle length was similar at baseline and post PV isolation between the 2 groups, and significantly shorter during RSPV ablation (P < .0001) in both. In total, marked vagal responses were significantly higher in the first than second group (14/39 vs 1/42, P < .0001). CONCLUSIONS: LSPV cryoballoon ablation often provoked marked vagal responses; however, preceding RSPV ablation markedly suppressed this response.

Pre-procedural evaluation of the left atrial anatomy in patients referred for catheter ablation of atrial fibrillation.

BACKGROUND: Cardiac computed tomography (CT) provides accurate imaging of the pulmonary vein (PV) and left atrial (LA) anatomy. This study aimed to evaluate the prevalence and morphological characteristics of anatomical variants that could influence atrial fibrillation (AF) ablation procedures. METHODS AND RESULTS: One thousand forty consecutive patients (62±10 years, 243 female, 644 paroxysmal AF) undergoing pre-procedural imaging with a 320-row CT and their first AF ablation procedure were analyzed. A total of 194 (18.7%) patients had anatomical variants. Left, right, and inferior common PVs were observed in 118, 5, and 6 patients, respectively. Three right and left PVs were observed in 44 and 4 patients, respectively. Three patients had remnants of PVs after lobectomies, and significant PV stenosis was observed in one. Supernumerary PVs that drained into the LA and diverticula were observed in eight patients. One patient had a string-like structure connecting the LA septum and posterior LA, and the others had membranous structures incompletely compartmentalizing the LA. Three patients had persistent left superior vena cavae, two strong deviations of the LA and PVs, and one dexiocardia. All patients underwent successful PV isolation during the index procedure. CONCLUSIONS: Patients referred for AF ablation often have anatomical variants, which could influence the procedure. This information might aid in planning procedural strategies, and reducing unexpected procedural complications in AF ablation.

Prevalence and Pre-Procedural Predictors Associated With Right Phrenic Nerve Injury in Electromyography-Guided, Second-Generation Cryoballoon Ablation: Single Large Balloon and Single 3-Minute Freeze Techniques.

OBJECTIVES: This study aimed to evaluate the incidence and pre-procedural predictors of right phrenic nerve injury (PNI) in electromyography-guided, second-generation cryoballoon (CB) ablation. BACKGROUND: Second-generation CBs perform better pulmonary vein isolation (PVI) than first-generation CBs; however, right PNI remains a concern. METHODS: One hundred consecutive patients with paroxysmal atrial fibrillation who underwent cryoablation were prospectively enrolled. Contrast-enhanced cardiac multidetector computed tomography (MDCT) was obtained pre-procedurally. PVI was performed with one 28-mm second-generation balloon using a 3-min freeze technique under electromyography guidance. RESULTS: In all, 377 of 392 (96.2%) PVs were isolated using a CB. In 9 (9.0%) patients, right PNI was observed during the ablation of the right superior PV (RSPV). All events occurred during freezing, except for 1 that occurred during thawing. Right peri-cardiophrenic bundles (RPCBs) were identified at the level of the RSPV on MDCT in 97 patients. In the logistic regression analysis, the distance from the RSPV ostium to the RPCBs (hazard ratio: 0.263; 95% confidence interval [CI]: 0.110 to 0.630; p = 0.003) was the sole predictor of PNI. The optimal cutoff point for the distance for predicting right PNI was 12.4 mm (sensitivity 96.6%, specificity 88.9%) with an area under the curve of 0.968 (95% CI: 0.922 to 1.000). The PNI resolved spontaneously within 1 day and 2 months in 6 and 2 patients, respectively, and at 8 months in the remaining patient, with delayed recognition of an electromyography decrease. CONCLUSIONS: Persistent right PNI is a rare complication during electromyography-guided, second-generation CB ablation. Electromyography should be monitored even during the thawing time. Pre-procedural MDCT might be useful for risk stratification of right PNI.

Electrocardiographic characteristics differentiating epicardial outflow tract-ventricular arrhythmias originating from the anterior interventricular vein and distal great cardiac vein.

BACKGROUND: The aim of this study was to identify the ECG features that might differentiate between anterior interventricular vein (AIV) and distal great cardiac vein (d-GCV) outflow tract-ventricular arrhythmias (OT-VAs). METHODS AND RESULTS: Radiofrequency catheter ablation was performed in 13 of 375 patients (3.5%) for AIV or d-GCV OT-VAs. We grouped the 13 patients by the origin, d-GCV (n=9) or AIV (n=4), and compared their ECGs and electrophysiological data. The OT-VA ECGs had S waves in lead I in all 13 patients. The voltage in the inferior lead III and peak deflection index showed no significant between-group differences (2.3±0.7 vs. 2.5±0.3 mV and 0.65±0.04 vs. 0.68±0.04 mV, respectively) for the d-GCV and AIV groups. There were also no significant between-group differences in the QaVL/QaVR, where Q denotes the amplitude of the Q wave in the suffix lead. However, the R/S ratio in V1 (1.7±1.0 [n=5] vs. 0.2±0.05, P=0.04), and QRS duration (149±16.6 vs. 123±3.8 ms, P=0.012) were greater in the d-GCG group than in the AIV group. There were no significant between-group differences in the activation time or pace mapping score at the optimal ablation sites. CONCLUSIONS: A low R/S ratio in V1 and shorter QRS duration may help identify AIV sites of epicardial OT-VA origin.

Impact of Pulmonary Vein Isolation on Superior Vena Cava Potentials With a Second-Generation Cryoballoon.

BACKGROUND: Radiofrequency ablation of the right superior pulmonary vein (RSPV) can lead to inadvertent superior vena cava (SVC) isolation due to the close anatomical proximity. This study aimed to evaluate the impact of PV isolation on SVC potentials with a second-generation cryoballoon. METHODS: Thirty-one consecutive paroxysmal atrial fibrillation patients who underwent PV isolation exclusively with a 28 mm second-generation cryoballoon and single 3-minute freeze technique were prospectively enrolled. The produced SVC potential conduction delay during the RSPV isolation was prospectively evaluated using circular mapping catheters placed in the SVC throughout the cryoballoon procedure. RESULTS: Stable SVC potentials were recorded in 28 (90.3%) patients. The produced SVC potential conduction delay during the RSPV isolation was a median of 6.0 (0.5-7.6) milliseconds, and >5.0 milliseconds in 16 (57.1%) patients. Among them, the delay had shortened by >5.0 milliseconds in 7 (43.8%) patients within 5 minutes after the RSPV application. The distance between the RSPV ostium and SVC was the sole parameter correlated with the produced delay (R = 0.77, P < 0.0001). For the association between the distance and a produced delay of >5 milliseconds, the area under the curve was 0.896 (95% confidential interval = 0.775-1.000). The optimal cutoff point for the distance predicting the occurrence of the conduction delay (>5 milliseconds) was 2.5 mm (sensitivity 83.3%, specificity 81.2%). CONCLUSIONS: RSPV isolation with a second-generation cryoballoon could produce an SVC potential conduction delay. The anatomical distance between the RSPV and SVC significantly correlated with the impact.

Adenosine Triphosphate Test After Cryothermal Pulmonary Vein Isolation: Creating Contiguous Lesions Is Essential for Eliminating Dormant Conduction.

BACKGROUND: Adenosine triphosphate (ATP) testing reveals dormant pulmonary vein (PV) conduction after electrical PV isolation (PVI). This study aimed to evaluate the incidence of latent PV conduction after cryothermal PVI. METHODS: Fifty-four consecutive paroxysmal atrial fibrillation patients undergoing cryothermal PVI were prospectively enrolled. PVI was performed with one 28-mm second-generation balloon using a 3-minute freeze technique, and touch-up lesions were created by focal cryothermal applications. ATP testing was performed following PVI with a 20-mm circular mapping catheter placed in each PV. RESULTS: Of 217 PVs, 205 (94.5%) were isolated using a cryoballoon, and 12 required additional focal ablation. ATP testing was performed in 46 patients for 173 and 8 PVs, which were isolated by cryoballoons and focal ablation, respectively. No dormant PV conduction was provoked in any PVs, which were isolated by cryoballoons, whereas 4 (50.0%) out of 8 PVs requiring focal ablation had transient ATP-provoked reconnections (0 vs. 50.0%, P < 0.0001) with a median duration of 11.3 (10.7-17.1) seconds. The latent PV conduction site was identical to the residual conduction gap site after cryoballoon ablation in all. All latent conduction was successfully eliminated by 2 (2.0-9.5) additional focal applications. At a mean follow-up of 7.7 ± 1.6 months, 81.5% of the patients were arrhythmia free after a single procedure. CONCLUSIONS: No dormant PV conduction was provoked in PVs, which were isolated by 28-mm second-generation cryoballoons, but was provoked in 50% of PVs, which were isolated by focal cryoablation. These findings suggest that creating contiguous lesions is essential for eliminating dormant conduction in cryothermal ablation.

Ventricular arrhythmias with superior axis originating from the left ventricular septum: electrocardiographic characteristics predicting successful ablation and insights into their mechanism-observations from a small series of patients.

AIMS: This study aimed to evaluate the electrocardiographic characteristics and predictors of successful ablation for ventricular arrhythmias (VAs) with superior axis originating in the ventricular septum. METHODS AND RESULTS: This study included 385 consecutive patients with VAs undergoing radiofrequency ablation (RFA). Of these, 14 patients (3.7%) were identified who had VAs with superior axis that were mapped to and ablated at the left ventricular (LV) septum. These patients were classified into two groups, successful (n = 9, Success-RFA) and failed (n = 5, Fail-RFA) ablation. The QRS duration of the VAs was longer in the Success-RFA than the Fail-RFA [median (25%, 75% quartile), 140 (134, 149) vs. 128 (116, 132) ms; P = 0.007]. In the Success-RFA, the QRS morphology in lead V1 exhibited qR or rSR (r < 0.2 mV) pattern. In the Fail-RFA, QRS in lead V1 demonstrated an initial R-wave of ≥0.2 mV except for one patient who demonstrated a qR pattern. The initial R-wave amplitude of <0.2 mV in lead V1 identified successful ablation cases with 100% sensitivity and 80% specificity. The magnitude of the initial R-wave amplitude in lead V1 could be related to the originating site's depth within the septal tissue, which could also explain the RFA results. CONCLUSION: Four percent of VA patients had superior axis on electrocardiogram and foci that mapped to the LV septum, two-thirds of which were successfully ablated. The initial R-wave amplitude of <0.2 mV in lead V1 identified RFA success with high sensitivity and specificity.

Prospective Evaluation of Bilateral Diaphragmatic Electromyograms During Cryoballoon Ablation of Atrial Fibrillation.

BACKGROUND: Left phrenic nerve injury (PNI) can occur during cryoballoon ablation of the left pulmonary veins (PVs). This study aimed to evaluate the feasibility of monitoring the bilateral phrenic nerve function during cryoballoon ablation of atrial fibrillation (AF). METHODS: Fifty consecutive paroxysmal AF patients undergoing cryoballoon ablation using one 28-mm second-generation balloon were prospectively enrolled. Bilateral diaphragmatic compound motor action potentials (CMAPs) were obtained from modified surface electrodes by pacing from the bilateral subclavian veins, and monitored during 3-minute cryoballoon applications at the ipsilateral PVs. RESULTS: One hundred ninety of 202 PVs were successfully isolated exclusively using 28-mm cryoballoons. CMAPs could be obtained in all except 3 cases with catheter inaccessibility in the left subclavian vein. The left and right CMAP amplitudes were similar at baseline (1.04 ± 0.41 mV vs. 1.01 ± 0.43 mV, P = 0.49). Among 105 left and 132 right PV applications while monitoring CMAPs, 2 (1.9%) and 13 (9.8%) applications were interrupted for a decreased CMAP amplitude (P = 0.01). Among them, CMAPs decreased due to right PNI in 4 applications/patients and to catheter dislodgement in the remaining applications. PNI remained in 1 and recovered in the remaining 3 patients one day after the procedure. Applications without requiring interruptions exhibited no significant CMAP amplitude changes throughout the applications, and the time-course pattern was similar between the bilateral CMAPs (P = 0.292). CONCLUSIONS: A stable bilateral diaphragmatic CMAP could be similarly obtained during cryoballoon applications in the vast majority of patients. Monitoring CMAPs might be useful to anticipate not only right but also left PNI during cryoballoon ablation.

Recurrence after "long-term success" in catheter ablation of paroxysmal atrial fibrillation.

BACKGROUND: The latest guidelines define "long-term success" as freedom from atrial arrhythmia recurrence more than 36 months after procedures without any antiarrhythmic drug therapy. OBJECTIVE: The purpose of this study was to investigate the clinical outcomes and procedural findings in patients with recurrence beyond "long-term success." METHODS: Among patients who underwent pulmonary vein (PV) antrum isolation for drug-refractory symptomatic paroxysmal atrial fibrillation (AF), 37 in whom recurrent arrhythmias were observed during annual follow-up after "long-term success" and who underwent repeat procedures for recurrent arrhythmias were included in the study. RESULTS: The time from the latest procedure to recurrence was a median of 61 ([25th, 75th percentiles]: [51-77.5]) months. Recurrent arrhythmia type was paroxysmal in 22 patients (59.5%) and persistent in 15 (40.5%). Recurrent arrhythmias were atrial tachycardia (AT) in 13 patients (35.1%), including 8 with AT unrelated to PVs. Repeat procedures were performed a median of 2.0 [1.0-4.0] months after identifying recurrent episodes. Recovered PV conduction was found in 29 patients (78.4%) and non-PV foci in 4 (10.8%). Freedom from recurrence 1 year after repeat procedures was 63.3%. Seven patients (18.9%) underwent further repeat procedures a median of 7.0 [2.0-28.0] months after repeat procedures and had no PV reconnections. In total, AF/AT unrelated to PVs was present in 24 patients (64.9%). In contrast, arrhythmias related to PVs were observed in 2 patients (5.4%) during a total of 46 repeat procedures after "long-term success." CONCLUSION: Although PV reconnections were commonly found even after "long-term success," AF/AT unrelated to PVs was assumed to be present in the majority of this population.

Adenosine-Provoked Atrial Fibrillation Originating From Non-Pulmonary Vein Foci: The Clinical Significance and Outcome After Catheter Ablation.

OBJECTIVES: The goal of this study was to systematically investigate the incidence and clinical significance of non-pulmonary vein (PV) foci revealed by adenosine/adenosine triphosphate (ATP) testing during atrial fibrillation (AF) ablation. BACKGROUND: ATP is reported to provoke AF. METHODS: A total of 464 patients with consecutive paroxysmal AF undergoing ATP testing after PV antrum isolation were included. RESULTS: AF originating from non-PV foci was provoked in 26 (5.6%) total patients during first (n = 20) or repeat (n = 8) ablation procedures. Dormant PV conduction was also revealed by ATP testing in 6 patients. Non-PV foci were located in the superior vena cava (SVC) (i.e., the SVC group) and atria (i.e., the atria group) in 10 and 18 (9 each in the right and left atria) patients, respectively. In the multivariable analysis, being female was the sole independent predictor of ATP-provoked AF originating from non-PV foci (hazard ratio [HR]: 2.52 [95% confidence interval (CI): 1.069 to 5.929]; p = 0.034). After additional ablation targeting non-PV foci, freedom from recurrent AF after the last procedure was similar between the SVC group and patients without ATP-provoked AF but was significantly lower in the atria group than in others (p = 0.0008). Atria group membership (HR: 3.725 [95% CI: 1.692 to 8.199]; p = 0.001) and being female (HR: 1.538 [95% CI: 1.189 to 1.989]; p = 0.001) were significant independent predictors associated with recurrence after the last procedure in the multivariable Cox regression model. CONCLUSIONS: ATP provoked AF originating from non-PV foci under isoproterenol in 5.6% of patients undergoing paroxysmal AF ablation. ATP testing might be useful for identifying and eliminating AF originating from the SVC. The atria group was associated with a poor outcome after the last procedure despite efforts to eliminate non-PV foci.

Catheter ablation of atrial tachyarrhythmias causing inappropriate implantable cardioverter-defibrillator shocks.

AIMS: Inappropriate shocks have been an important issue post-implantable cardioverter-defibrillator (ICD) implantation. Moreover, inappropriate ICD shocks are associated with increased mortality. The objective of this study was to evaluate the feasibility of catheter ablation therapy for atrial tachyarrhythmias (ATa) responsible for inappropriate ICD shocks. METHODS AND RESULTS: Among 108 consecutive patients who underwent ICD implantations, 22, 5, and 3 experienced inappropriate ICD shocks due to ATa, sinus tachycardia, and T-wave oversensing, respectively. Among the 22 patients with ATa, 18 patients (55 ± 10 years, 15 men, structural heart disease in 9) underwent catheter ablation of ATa causing inappropriate shocks. The median duration between the ICD implantation and first inappropriate shock was 10.0 (3.0-24.5) months. The ATa were atrial fibrillation (AF), atrial flutter (AFL), and atrioventricular nodal reentrant tachycardia in 14, 2, and 2 patients, respectively. One patient underwent an atrioventricular nodal ablation for persistent AF associated with a venous anomaly. Among 13 patients who underwent pulmonary vein antrum isolation, 10 (76.9%) were free from AF for a median of 21.0 (13-37.3) months after an average of 1.3 ± 0.5 procedures. In four patients with AFL or a supraventricular tachycardia, none had any arrhythmia recurrence for a median of 6.0 (3.3-93.5) months after a cavotricuspid isthmus or slow pathway ablation, respectively. There were no procedural complications. During the median follow-up of 19.0 (9.5-37.3) months after the last procedure, no patients experienced any inappropriate shocks. CONCLUSION: Catheter ablation is a feasible therapeutic option for treating ATa responsible for inappropriate shock(s) in patients with ICD.