The impact of age on the electroanatomical characteristics and outcome of catheter ablation in patients with atrial fibrillation.

BACKGROUND: Previous studies have indicated that atrial fibrillation (AF) in patients over the age of 60 at diagnosis is a risk factor for a substantial increase in cardiovascular events. However, information about the impact of age on the atrial substrate and clinical outcome after catheter ablation of AF is limited. METHODS: This study included 350 patients (53 ± 12 years, 254 males) who underwent circumferential pulmonary vein isolation (CPVI) of AF, guided by a NavX mapping system. The subjects were divided into three groups according to their age, as follows: Group I: age ≤50 (n = 141), Group II: age = 51-64 (n = 149) and Group III: age ≥65 years old (n = 60). The mean voltage and total activation time of the individual atria were obtained by using a NavX mapping system before ablation. Several parameters, including the gender, AF duration, and left atrial (LA) diameter were analyzed. RESULTS: The younger age group had a significantly smaller LA diameter (Group I vs Group II vs Group III, 36.89 ± 7.11 vs 39.16 ± 5.65 vs 40.77 ± 4.95 mm, P = 0.002) and higher LA bipolar voltage (2.09 ± 0.83 vs 1.73 ± 0.73 vs 1.86 ± 0.67 mV, respectively, P = 0.024), compared with the older AF patients. The LA bipolar voltage exhibited a significant reduction when the patients became older, however, that did not occur in the right atrium. The incidence of an AF recurrence was higher in the older age group than in the younger age groups. A subgroup of patients with lone AF was analyzed and age was found to be an independent predictor of the AF recurrence after receiving the first CPVI in the multivariable model (P < 0.05). CONCLUSIONS: Age has a significant impact on the LA substrate properties and outcome of the catheter ablation of AF.

Prognostic implications of the high-sensitive C-reactive protein in the catheter ablation of atrial fibrillation.

Previous studies have reported that increased high-sensitive C-reactive protein (hs-CRP) levels are associated with an inflammatory state. This study investigated the association among hs-CRP, substrate properties, and long-term clinical outcomes after catheter ablation of atrial fibrillation (AF). A total of 137 patients with AF (54 +/- 13 years) who underwent mapping and catheter ablation were included. The hs-CRP was measured before the first ablation procedure. The substrate properties (initiating triggers, biatrial mean voltage, and high-frequency sites) of the 2 atria and long-term outcome were investigated in patients in the low hs-CRP group (<75%, 2.92 mg/L) and high hs-CRP group (>75%, 2.92 mg/L). Patients with a higher hs-CRP were associated with an increased number of identified nonpulmonary vein ectopies (34.4% vs 17%, p = 0.034), lower mean left atrial (LA) voltage (1.72 +/- 0.73 vs 1.92 +/- 0.72 Hz, p = 0.045), and higher-frequency sites in the left atrium (71% vs 37%, p = 0.027). After a median follow-up period of 15 months, the single-procedure success rate (72% vs 53%, p = 0.008) and final success rate after multiple procedures (94% vs 81%, p = 0.02) were higher in the low hs-CRP group. In a multivariable regression model adjusted for other potential covariates, hs-CRP level (p = 0.021) and LA diameter (p = 0.032) were independent predictors of recurrence. In conclusion, baseline CRP levels before the first AF ablation procedure had an independent prognostic value in predicting long-term recurrence. Patients with a high hs-CRP level were associated with an abnormal LA substrate and high incidence of nonpulmonary vein AF sources.

The optimal automatic algorithm for the mapping of complex fractionated atrial electrograms in patients with atrial fibrillation.

CFAEs and the Voltage. Introduction: Catheter ablation of atrial fibrillation (AF) can be guided by the identification of complex fractionated atrial electrograms (CFAEs). We aimed to study the prediction of the CFAEs defined by an automatic algorithm in different atrial substrates (high voltage areas vs low voltage areas). Methods and Results: This study included 13 patients (age = 56 +/- 12 years, paroxysmal AF = 8 and persistent AF = 5), who underwent mapping and catheter ablation of AF with a NavX system. High-density voltage mapping of the left atrium (LA) was performed during sinus rhythm (SR) (248 +/- 75 sites per patient) followed by that during AF (88 +/- 24 sites per patient). The CFAE maps were based on the automatic-detection algorithm. "Operator-determined CFAEs" were defined according to Nademannee's criteria. A low-voltage zone (LVZ) was defined as a bipolar voltage of less than 0.5 mV during SR. Among a total of 1150 mapping sites, 459 (40%) were categorized as "operator-determined CFAE sites," whereas 691 (60%) were categorized as "operator-determined non-CFAE sites." The sensitivity and negative predictive value increased as the fractionated interval (FI) value of the automatic algorithm increased, but the specificity and positive predictive value decreased. The automatic CFAE algorithm exhibited the highest combined sensitivity and specificity with an FI of <60 ms for the sites inside the LVZ and FI < 70 ms for the sites outside the LVZ, when compared with a single threshold for both the high- and low-voltage groups combined (i.e., no regard for voltage) (ROC: 0.89 vs 0.86). Conclusions: The clinical relevance of the CFAE map would be improved if the calculated index values were accordingly scaled by the electrogram peak-to-peak amplitude.

The disparities in the electrogram voltage measurement during atrial fibrillation and sinus rhythm.

INTRODUCTION: The peak electrogram voltage is a typical metric applied at each site for voltage mapping. However, the peak amplitude depends on the direction and complexity of the wavefront propagation. The root-mean-square (RMS) measure of the amplitude is a temporal integral that represents the steady-state value. The objective of this study was to investigate the disparities between the electrogram voltage during SR and AF by using 2 recording modalities: the conventional peak voltage and an RMS measurement. METHODS AND RESULTS: This study enrolled 20 patients (age = 59 +/- 13) with paroxysmal AF undergoing catheter ablation guided by Ensite array. The unipolar electrogram voltage during SR and AF (7 seconds in duration) was obtained from the same sites, and labeled by the 3-dimensional (3D) geometry. Overall 1,200 electrograms were analyzed from equally distributed mapping sites in the left atrium. A point-by-point comparison of the unipolar peak negative voltage (PNV) showed less agreement (Bland and Altman test: 10.4% outside 2 standard deviations, and intraclass correlation coefficient [ICC]= 0.64). The RMS voltage demonstrated agreement between SR and AF for all sites (BA test: 5.9% of the sites, and the ICC = 0.81). The probability of predicting a low-voltage during AF using the voltage during SR was significantly lower when using the PNV measurement compared to that when using the RMS voltage (15% vs 61%, P < 0.05). CONCLUSION: The peak electrogram unipolar voltage during AF did not represent the voltage during SR. The RMS amplitude may be an alternative metric for voltage mapping to characterize the myocardial substrate.

Spatiotemporal organization of the left atrial substrate after circumferential pulmonary vein isolation of atrial fibrillation.

BACKGROUND: There is a paucity of data regarding the mechanism of maintaining atrial fibrillation (AF) after pulmonary vein isolation (PVI) in patients with AF. The aim of this study was to examine the impact of circumferential PVI on the left atrial (LA) substrate characteristics. METHODS AND RESULTS: Seventy-two AF patients (age, 53+/-11 years) underwent mapping and catheter ablation using an NavX system. The biatrial characteristics such as the complex fractionated atrial electrograms (CFEs; based on fractionated intervals) and frequency analysis (based on dominant frequencies) were mapped before and after PVI. PVI with electric isolation was performed in all patients. In the 45 patients who did not respond to PVI, the continuous CFEs (>8 seconds, 18+/-18% and 12+/-17% of the LA sites, before and after PVI, respectively, P=0.02), degree of LA fractionation (mean fractionated interval: 75.6+/-14.3 msec versus 87.3+/-16.7 msec, P=0.001), and mean LA dominant frequencies (6.92+/-0.88 Hz versus 6.58+/-0.91 Hz, P=0.001) decreased after PVI. Complete PVI altered the distribution of the CFEs toward the LA anteroseptum, mitral annulus, and LA appendage regions. A persistent presence of continuous CFEs in the vicinity of the dominant frequencies sites (observed in 53% patients) correlated with a higher procedural AF termination rate for the CFE ablation (63% versus 23%, P<0.05). CONCLUSIONS: Complete PVI eliminated some CFEs in the LA and altered the distribution of the CFEs. The persistent presence of CFEs before and after PVI in the vicinity of the high frequency sites is important for AF maintenance after PVI.

The impact of left atrial size on long-term outcome of catheter ablation of chronic atrial fibrillation.

BACKGROUND: The left atrial (LA) size is an important predictor of atrial fibrillation (AF) procedural termination and the long-term outcome. We sought to evaluate the long-term outcome in regard to the LA size and procedural termination. METHODS: Eighty-seven consecutive chronic AF patients (72 males, 53 +/- 10 years) underwent 3D mapping (NavX) and ablation. A stepwise approach including circumferential pulmonary vein (PV) isolation, linear ablation, and continuous complex-fractionated electrogram (CFE) ablation (targeting fractionation intervals of < 50 ms). Electrical cardioversion was applied to those without any procedural termination. The freedom from AF was defined as the maintenance of sinus rhythm without the use of any class I or III antiarrhythmic drugs after the blanking period. RESULTS: Among the 87 patients, all received a circumferential PV isolation, 93% a linear ablation, and 59% a continuous CFE ablation. Those with AF procedural termination (n = 30) had a better long-term outcome when compared with those without termination during a follow-up of 21 +/- 12 months. Moreover, a Kaplan-Meier analysis showed that in those with an LA diameter of less than 45 mm (n = 49), the freedom from AF rate was higher when procedural termination was achieved (P = 0.004). On the contrary, the outcome was comparable in those with an LA diameter of >or= 45 mm (n = 38), whether AF procedural termination occurred or not (P = 0.658). CONCLUSIONS: AF procedural termination was related to the long-term success during chronic AF ablation, especially in those with an LA diameter of less than 45 mm. The favorable effect of termination decreased when the LA diameter was >or= 45 mm.

Comparison of cooled-tip versus 4-mm-tip catheter in the efficacy of acute ablative tissue injury during circumferential pulmonary vein isolation.

INTRODUCTION: Although several studies have reported the benefits of cooled-tip ablation for circumferential pulmonary veins isolation (CPVI), the acute change of substrate property and acute PV reconnection have not been well demonstrated. The aim of this study was to compare the cooled-tip with regular 4-mm-tip catheter in acute substrate change after CPVI and long-term efficacy. METHODS AND RESULTS: One hundred and fifty-six patients (115 males, age 53 +/- 12 years) who underwent CPVI for treatment of atrial fibrillation (AF) were included. Group A consisted of 52 patients with cooled-tip ablation, and group B consisted of 104 patients with 4-mm-tip catheter ablation. The bipolar voltage of circumferential lesions was obtained using a 3-dimensional (3D) mapping system (NavX) before and after CPVI. The electrical reconnections of 4 PVs were evaluated 30 minutes after CPVI using a circular catheter. Cooled-tip catheter caused more reduction of the electrical voltage in PV antrum, lower incidence of acute PV reconnection, inducibility of AF, and gap-related atrial tachyarrhythmia (AT). Less number of left atrial (LA) ablation line and ablation applications and less procedure time were found in cooled-tip group compared to 4-mm-tip group. No significant difference in the incidence of pain sensation and complication was observed between the 2 groups. At a 14-month follow-up, the recurrence rate in the cooled-tip group was lower than in the 4-mm group (13.5% vs 33.7%, P = 0.009). CONCLUSION: Cooled-tip catheter has a superior long-term outcome than the 4-mm-tip catheter in CPVI, which may be associated with the efficacy of transmural block and electrical isolation in PV antrum.

Efficacy of additional ablation of complex fractionated atrial electrograms for catheter ablation of nonparoxysmal atrial fibrillation.

BACKGROUND: The efficacy of ablation of complex fractionated atrial electrograms (CFEs) in the single ablation procedure for nonparoxysmal atrial fibrillation (AF) patients is not well demonstrated. The aim of this study was to compare the ablation strategies of pulmonary vein isolation (PVI) plus linear ablation with and without additional ablation ofCFEs in these patients. METHODS: Consecutive 60 patients (49 +/- 11 years old, 50 male, 10 female) with nonparoxysmal AF underwent catheter ablation guided by a NavX mapping system. A stepwise approach included a circumferential PVI and left atrial (LA) linear ablation followed by either the additional ablation of continuous CFEs in the LA/coronary sinus (the first 30 patients) or not (the second 30 patients), detected by an automatic algorithm. RESULTS: There was no difference in the baseline characteristics between the two groups. Complete PVI eliminated some continuous CFEs and altered the distribution of CFEs. Following PVI and linear ablation,the remaining continuous CFEs were identified in 7.9 +/-10% mapping sites of the LA and CS, and were ablated successfully with a procedural AF termination rate of 53%. With a follow-up of 19 +/-11 months, a Kaplan-Meier analysis showed that the patients with additional ablation of the CFEs had a higher rate of sinus rhythm maintenance. Multivariate analysis showed the single procedure success could be predicted by the procedural AF termination and the additional ablation of continuous CFEs in the LA/CS. CONCLUSIONS: Ablation of continuous CFEs after PVI and LA linear ablation had a better long-term efficacy based on the results of single-ablation procedure.

Cariporide (HOE642) attenuates lactic acidosis induced pulmonary vein arrhythmogenesis.

AIMS: Lactic acidosis causes atrial fibrillation (AF), and pulmonary veins (PVs) are the most important focus for the generation of AF. Cariporide (HOE642), a Na(+)/H(+) blocker, can prevent atrial tachycardia-induced electrical remodeling. The purpose of this study was to investigate whether cariporide can prevent lactic acidosis-induced PV arrhythmogenesis. MAIN METHODS: Conventional microelectrodes were used to record the action potentials (APs) before and after the administration of lactic acid (10 and 20 mM) in the absence and presence of cariporide (10 microM) pretreatment in isolated rabbit PV and atrial tissue preparations. KEY FINDINGS: Lactic acidosis of 10 mM (pH 7.0+/-0.1) and 20 mM (pH 6.7+/-0.1) reduced PV (n=6) spontaneous rates from 2.5+/-0.3 to 1.6+/-0.4 (by 36+/-1%) and 1.1+/-0.4 Hz (by 56+/-2%), respectively, but lactic acidosis (10 and 20 mM) induced 12 episodes (3.9+/-0.2 Hz) and 23 episodes (4.0+/-0.3 Hz) of non-sustained burst firings in 4 PV specimens. Lactic acidosis (10 and 20 mM) decreased the AP amplitude (APA) and velocity of depolarization (Vmax), but increased the resting membrane potential (RMP), AP duration, and strength-response interval (SRI) in the PV and atrium. In the presence of cariporide (10 microM), lactic acidosis (10 and 20 mM) only reduced PV spontaneous rates from 2.4+/-0.2 to 1.8+/-0.4 (by 25+/-1%) and 1.6+/-0.4 Hz (by 33+/-1%), respectively, and prevented lactic acidosis-induced PV burst firings. Cariporide also reduced the effects of lactic acidosis on the RMP, AP duration, APA, Vmax, and SRI. SIGNIFICANCE: Lactic acidosis has significant arrhythmogenic effects on PVs, which may be attenuated by Na(+)/H(+) blockers.

Predicting factors for atrial fibrillation acute termination during catheter ablation procedures: implications for catheter ablation strategy and long-term outcome.

BACKGROUND: Termination of atrial fibrillation (AF) can be achieved by catheter ablation. It has been used as one of the procedural endpoints for AF ablation. OBJECTIVE: The purpose of this study was to investigate the factors that predict AF termination and the association with long-term outcomes. METHODS: Eighty-five consecutive AF patients (33 paroxysmal, 52 nonparoxysmal) underwent three-dimensional mapping and catheter ablation. A stepwise ablation approach included circumferential pulmonary vein (PV) isolation and left atrial (LA) linear ablation, followed by LA and right atrial (RA) electrogram-based (complex fractionated atrial electrogram) ablation. Clinical and electrophysiologic characteristics were assessed to evaluate the predictors of acute AF termination. RESULTS: In univariate analysis, a diagnosis of paroxysmal AF, shorter AF history, absence of history of heart failure, smaller LA diameter, longer postablation coronary sinus cycle length, lower LA and RA mean dominant frequencies, lower RA max dominant frequency, and higher LA voltage were related to acute termination of AF during ablation. Multivariate analysis showed that smaller LA diameter and lower preablation mean RA dominant frequency were independent predictors of AF termination. Multivariate analysis also showed that larger LA diameter and the presence of RA non-PV ectopy during the index procedure could predict late recurrence during long-term (13 +/- 8 months) follow-up. CONCLUSION: LA size and RA non-PV drivers are important for acute termination of AF and for long-term success. Careful selection of patients, extensive RA mapping, and LA ablation may enhance long-term ablation efficacy.

Acute effect of circumferential pulmonary vein isolation on left atrial substrate.

INTRODUCTION: The left atrial (LA) substrate plays an important role in the maintenance of atrial fibrillation (AF). However, little is known about the acute effect of circumferential pulmonary vein isolation (CPVI). This study was to investigate the acute change of LA activation, voltage and P wave in surface electrocardiogram (ECG) after CPVI. METHODS AND RESULTS: Electroanatomic mapping (NavX) was performed in 50 patients with AF (mean age = 54 +/- 10 years, 36 males) who underwent only CPVI. The mean peak-to-peak bipolar voltage and total activation time of LA were obtained during sinus rhythm before and immediately after CPVI. The average duration and amplitude of P waves in 12-lead ECG were also analyzed before and after CPVI. Change in the earliest LA breakthrough sites could cause decreased LA total activation time. Downward shift in the breakthrough site was inversely proportional to the proximity of the breakthrough site to the radiofrequency lesions. A shortening of P-wave duration and decrease in voltage after CPVI were observed after CPVI. Patients with recurrent AF had less voltage reduction in the atrial wall 1 cm from the circumferential PV lesions compared with those without recurrent AF (60.1 +/- 11.7% vs 74.1 +/- 6.6%, P = 0.002). Reduction of voltage < or = 64.4% in this area after CPVI is related with recurrent AF. CONCLUSION: CPVI could result in acute change of LA substrate, involving LA activation and voltage. Less reduction of voltage in the atrial wall adjacent to the circumferential PV lesions after CPVI may be associated to the recurrence of AF.

Induced atrial tachycardia after circumferential pulmonary vein isolation of paroxysmal atrial fibrillation: electrophysiological characteristics and impact of catheter ablation on the follow-up results.

INTRODUCTION: Atrial tachycardia (AT), including focal and reentrant AT, can occur after circumferential pulmonary vein isolation (CPVI). The aim of this study was to investigate the electrophysiological characteristics of induced AT and its clinical outcome. METHODS AND RESULTS: In our series of 160 patients with paroxysmal atrial fibrillation (AF), 45 ATs were induced by high-current burst pacing after CPVI in 26 patients. All induced ATs were mapped using a three-dimensional (3D) mapping system. Noninducibility was the endpoint of the ablation of the AT. Gap-related AT was considered if the AT was related to the CPVI lesions. A 16-slice multidetector computed tomography scan was performed in all patients to correlate the anatomical structure with electroanatomical mapping. Thirty-five (78%) reentrant ATs and 10 (22%) focal ATs were identified. Of those, 34 were gap-related ATs (24 reentrant and 10 focal ATs). Reentrant AT had more gaps in the left atrial appendage ridge than did focal AT (39.6% vs 0%, P = 0.02). Focal AT had a higher incidence of gap in the PV carina compared with reentrant AT (80% vs 10%, P < 0.001). Reentrant ATs were mostly terminated during the ablation creating the mitral and roof lines with crossing of the gaps. During a mean follow-up of 21 +/- 8 months, only one patient (0.6%) with induced mitral reentry had a recurrent AT. CONCLUSION: The location of the AT gap may be related with the complex anatomy of the LA. The induced ATs after CPVI can be eliminated by catheter ablation.

Characteristics of the cavotricuspid isthmus in predicting recurrent conduction in the long-term follow-up.

BACKGROUND: The characteristics of cavotricuspid isthmus (CTI) in patients with atrial fibrillation (AF) and flutter that may predict recurrence of flutter is not known. We aimed to investigate the CTI characteristics in patients who underwent a second ablation procedure for recurrent AF after previous combined pulmonary vein (PV) and CTI ablation. METHODS: Among 196 consecutive patients with drug-refractory symptomatic AF who underwent PV isolation and CTI ablation with bidirectional isthmus block, 49 patients (age 50 +/- 12 years, 43 males) had recurrent AF and received a second procedure 291 +/- 241 days after the first procedure. Right atrial angiography for the evaluation of the CTI morphology, and the biatrial contact bipolar electrograms were obtained before both procedures. RESULTS: In the second procedure, 11 (group 1) of the 49 patients demonstrated recovered CTI conduction. Compared with the patients without CTI conduction (group 2, n = 38), group 1 patients had a higher frequency of a pouch-type anatomy (82% vs 13%, P < 0.001), longer CTI (34.0 +/- 8.6 vs 25.5 +/- 7.5 mm, P = 0.01), longer ablation time, and larger number of radiofrequency applications; furthermore, the preablation bipolar voltage decreased along both the CTI and ablation line in group 2, whereas it remained similar in group 1 in the second procedure. CONCLUSIONS: A high (22%) percentage of CTIs exhibited recurrent conduction in the long-term follow-up. The CTIs with recurrent conduction had a higher incidence of a pouch and longer length compared with those without recurrent conduction.

Spectral analysis during sinus rhythm predicts an abnormal atrial substrate in patients with paroxysmal atrial fibrillation.

BACKGROUND: Regions of rapid and multiple deflections can be identified with high dominant frequency (DF) during sinus rhythm (SR). These areas may play a role in the perpetuation of atrial fibrillation (AF) and indicate an atrial substrate abnormality. OBJECTIVE: The purpose of this study was to investigate the atrial substrate properties of the high-frequency sites in patients with paroxysmal AF. METHODS: Forty patients (52 +/- 12 years of age) with paroxysmal AF were studied using a three-dimensional mapping system. Spectral analysis was performed on the bipolar electrograms in the left atrium (LA) during SR. Overall, 7708 electrograms were analyzed, and the DFs higher than 70 Hz were labeled as abnormal. RESULTS: The regional distribution of the high-DF sites in the LA could be divided into two types. Type 1 includes high-DF sites existing only in the pulmonary veins (PVs; n = 19, 6.6 +/- 3.4 sites/patient). Type 2 includes high-DF sites in the LA or LA plus the PVs (n = 21, 11 +/- 5.6 sites/patient). In type 1, PV isolation (PVI) could eliminate the AF with negative AF inducibility testing after the PVI in 89% of patients. In type 2, additional LA substrate modification was needed in 81% of patients because sustained AF was induced after the PVI (P<.001, compared with type 1). Multivariate analysis showed that the lower mean voltage of the LA and high-frequency sites distribution both independently predicted a positive AF inducibility after the PVI (P<.05). CONCLUSIONS: Spectral analysis during SR can detect an abnormal atrial substrate. A regional distribution of the high-DF sites predicts the efficacy of the PVI.

The important role of pulmonary vein carina ablation as an adjunct to circumferential pulmonary vein isolation.

OBJECTIVES AND BACKGROUND: The success rate of achieving electrical isolation by circumferential pulmonary vein ablation (CPVA) varies from 32% to 88%. We carried out ablation at the pulmonary vein carina to evaluate the elimination rates of the pulmonary vein potentials (PVPs) after one round of CPVA had failed to eliminate all the PVPs in the patients with atrial fibrillation (AF). METHODS: Ninety-seven patients (75 males; mean age: 50 +/- 12 years; 15 with persistent AF and 82 with paroxysmal AF) who underwent catheter ablation were analyzed. All patients underwent one round of CPVA with PVP elimination as the endpoint. The electrophysiology tracings were then analyzed to look for the presence of any gaps that were subsequently targeted by radiofrequency ablation. The patients in whom the PVPs still persisted underwent ablation at the pulmonary vein carina and the success rate of the PVP elimination was studied. The patients were followed up for a mean duration of 12.9 +/- 8.2 months. RESULTS: One hundred ninety-four ipsilateral pulmonary veins in 97 patients were subjected to CPVA with successful elimination of the PVPs in 110 ipsilateral pulmonary veins (success rate of 56.7%). A carina ablation was carried out in the remaining 84 ipsilateral pulmonary vein pairs harboring PVPs. Elimination of the PVPs was achieved in all the remaining ipsilateral pulmonary veins after the carina ablation. CONCLUSION: Considering the limited efficacy of CPVA in eliminating the PVPs, pulmonary vein carina ablation is advisable to substantially increase the PVP elimination rate.

Consistency of complex fractionated atrial electrograms during atrial fibrillation.

BACKGROUND: Temporal variation in complex fractionated atrial electrograms (CFAEs) exists during atrial fibrillation (AF). OBJECTIVE: This study sought to quantify the variation in CFAEs using a fractionation interval (FI) algorithm and to define the shortest optimal recording duration required to consistently characterize the magnitude of the fractionation. METHODS: Twenty-seven patients undergoing AF mapping in the left atrium were studied. The FI and frequency analysis were performed at each mapped site for recording durations of 1 to 8 seconds. The magnitude of the fractionation was quantified by the FI algorithm, which calculated the mean interval between multiple, discrete deflections during AF. The results from each duration were statistically compared with the maximal-duration recording, as a standard. The FI values were compared with the dominant frequency values obtained from the associated frequency spectra. RESULTS: The FIs obtained from recording durations between 5 and 8 seconds had a smaller variation in the FI (P < .05) and, for those sites with a FI < 50 ms, the fractionation was typically continuous. The fast-Fourier Transform spectra obtained from the CFAE sites with recording durations of >5 seconds harbored higher dominant frequency values than those with shorter recording durations (8.1 +/- 2.5 Hz vs. 6.8 +/- 0.98 Hz, P < .05). The CFAE sites with continuous fractionation were located within the pulmonary veins and their ostia in 77% of patients with paroxysmal AF, and in only 29% of patients with nonparoxysmal AF (P < .05). CONCLUSION: The assessment of fractionated electrograms requires a recording duration of > or =5 seconds at each site to obtain a consistent fractionation. Sites with the shortest FIs consistently identified sites with the fastest electrogram activity throughout the entire left atrium and pulmonary veins.

Frequency analysis of the fibrillatory activity from surface ECG lead V1 and intracardiac recordings: implications for mapping of AF.

AIMS: Fibrillatory waves observed in the surface electrograms may be a direct reflection of the electrophysiologic mechanism of the atrial fibrillation (AF). This study compared the fibrillatory waves in the surface ECG and the individual intracardiac mapping sites in different types of paroxysmal AF. METHODS AND RESULTS: Thirty patients with paroxysmal AF originating from the pulmonary veins (PVs) or superior vena cava (SVC) were enrolled. Frequency analysis was performed on the intracardiac electrograms recorded from various mapping sites in both atria sequentially with simultaneous surface electrogram recordings. The SVC-AF patients had a trend toward a higher DF in ECG lead V1 when compared with the PV-AF patients (7.35 +/- 2.09 vs. 5.89 +/- 0.79 Hz, P = 0.018). The mean dominant frequency (DF) of the LA mapping sites in the PV-AF patients was higher than that in the SVC-AF patients (7.06 +/- 0.66 vs. 6.13 +/- 0.96 Hz, P = 0.009), whereas the mean DF of the RA mapping sites was similar between the two groups (5.84 +/- 0.80 vs. 6.26 +/- 1.11 Hz, P = NS). The intra-class correlation coefficient (ICC) between the mean DF of the RA sites and V1 was higher (r = 0.21, P = 0.02) when compared with the mean DF of the LA sites (r = -0.007, P > 0.05). Furthermore, the maximal ICC was observed in the anterolateral RA free wall (r = 0.84, P < 0.001) and not the other anatomic sites of the RA and LA. CONCLUSION: The fibrillatory activity observed in ECG lead V1 correlated primarily with the activity of the anterolateral RA free wall and thus may be useful for detecting the AF source if it is close to that area.

The change in the fluoroscopy-guided transseptal puncture site and difficult punctures in catheter ablation of recurrent atrial fibrillation.

AIMS: A second procedure for recurrent atrial fibrillation (AF) may be associated with the need for a different positioning of the puncture site and may increase the difficulty and complications. This study investigated whether the transseptal puncture site changed and whether the difficult punctures increased in the patients who received a repeat ablation procedure for recurrent AF. METHODS AND RESULTS: Twenty-nine AF patients (52 +/- 12 years old, 20 males) underwent catheter ablation for a recurrence of AF. Compared with the first procedure, the height between the transseptal puncture site and coronary sinus ostium was higher in the second procedure during both the atrial end-systolic phase (38.0 +/- 4.7 vs. 34.8 +/- 5.3 mm, P = 0.036), and end-diastolic phase (43.0 +/- 4.8 vs. 39.1 +/- 5.4 mm, P = 0.004) in the 30 degrees right anterior oblique view. No significant change in the vertical atrial diameter was noted between the first and second procedures. A higher incidence of a difficult puncture was noted during the second procedure than in the first procedure (28 vs. 7%, P = 0.014). All those difficult punctures were overcome by using a large-curved transseptal needle. No differences of age, gender, AF duration, interval between first and second procedures, procedure time of the first procedure, and left atrial anteroposterior diameter were noted between easy and difficult transseptal punctures during the second procedure. CONCLUSION: The incidence of a difficult puncture was higher in the second procedure compared with the first procedure. The transseptal puncture site moved higher in the second procedure. Chronic scarring over the previous transseptal site is a reasonable hypothesis to explain the observations. The difficult punctures experienced during the second procedure might be overcome by changing the needle curve from a small curve to a large curve design.

Endothelin-1 modulates the arrhythmogenic activity of pulmonary veins.

OBJECTIVE: Endothelin-1 has important cardiovascular effects and is activated during atrial fibrillation. Pulmonary veins (PVs) play a critical role in the pathophysiology of atrial fibrillation. The aim of this study was to evaluate whether endothelin-1 affects PV arrhythmogenic activity. METHODS: Conventional microelectrodes were used to record the action potentials (APs) and contractility in isolated rabbit PV tissue specimens before and after the administration of endothelin-1 (0.1, 1, 10 nM). The ionic currents of isolated PV cardiomyocytes were investigated before and after the administration of endothelin-1 (10 nM) through whole-cell patch clamps. RESULTS: In the tissue preparation, endothelin-1 (1, 10 nM) concentration dependently shortened the AP duration and decreased the PV firing rates. Endothelin-1 (10 nM) decreased the resting membrane potential. Endothelin-1 (0.1, 1, 10 nM) decreased the contractility and increased the resting diastolic tension. In single PV cardiomyocytes, endothelin-1 (10 nM) decreased the PV firing rates from 2.7 +/- 1.0 Hz to 0.8 +/- 0.5 Hz (n = 16). BQ-485 (100 microM, endothelin-1 type A receptor blocker) reversed and prevented the chrono-inhibitory effects of endothelin-1 (10 nM). Endothelin-1 (10 nM) reduced the L-type calcium currents, transient outward currents, delayed rectifier currents, transient inward currents, and sodium-calcium exchanger currents in the PV cardiomyocytes with and without pacemaker activity. Endothelin-1 (10 nM) increased the inward rectifier potassium current, hyperpolarization-induced pacemaker current, and the sustained outward potassium current in PV cardiomyocytes with and without pacemaker activity. CONCLUSION: Endothelin-1 may have an antiarrhythmic potential through its direct electrophysiological effects on the PV cardiomyocytes and its action on multiple ionic currents.

Electrophysiological characteristics and catheter ablation in patients with paroxysmal supraventricular tachycardia and paroxysmal atrial fibrillation.

INTRODUCTION: Paroxysmal supraventricular tachycardia (PSVT) is often associated with paroxysmal atrial fibrillation (AF). However, the relationship between PSVT and AF is still unclear. The aim of this study was to investigate the clinical and electrophysiological characteristics in patients with PSVT and AF, and to demonstrate the origin of the AF before the radiofrequency (RF) ablation of AF. METHODS AND RESULTS: Four hundred and two consecutive patients with paroxysmal AF (338 had a pure PV foci and 64 had a non-PV foci) that underwent RF ablation were included. Twenty-one patients (10 females; mean age 47 +/- 18 years) with both PSVT and AF were divided into two groups. Group 1 consisted of 14 patients with inducible atrioventricular nodal reentrant tachycardia (AVNRT) and AF. Group 2 consisted of seven patients with Wolff-Parkinson-White (WPW) syndrome and AF. Patients with non-PV foci of AF had a higher incidence of AVNRT than those with PV foci (11% vs. 2%, P = 0.003). Patients with AF and atypical AVNRT had a higher incidence of AF ectopy from the superior vena cava (SVC) than those with AF and typical AVNRT (86% vs. 14%, P = 0.03). Group 1 patients had smaller left atrial (LA) diameter (36 +/- 3 vs. 41 +/- 3 mm, P = 0.004) and higher incidence of an SVC origin of AF (50% vs. 0%, P = 0.047) than did those in Group 2. CONCLUSION: The SVC AF has a close relationship with AVNRT. The effect of atrial vulnerability and remodeling may differ between AVNRT and WPW syndrome.