Associations between the atrial electromechanical interval, atrial remodelling and outcome of catheter ablation in paroxysmal atrial fibrillation.

OBJECTIVE: The atrial electromechanical (PA-PDI) interval was reported to be a useful predictor of new-onset atrial fibrillation (AF) and the occurrence of AF after coronary artery bypass surgery. The aim of this study was to investigate the associations of the electromechanical interval with atrial substrate properties and the outcome of catheter ablation in paroxysmal AF patients. METHODS: 132 paroxysmal AF patients who had received catheter ablation were enrolled. The electromechanical interval was determined as the time interval from the initiation of P-wave deflection to the peak of the mitral inflow A-wave on pulse-wave Doppler imaging. The left atrial voltage and total activation time were collected before pulmonary vein isolation. Every patient underwent standard follow-up after catheter ablation. RESULTS: The PA-PDI interval was significantly correlated with the left atrial dimension (r=0.419, p=0.003), left atrial volume (r=0.827, p<0.001), left atrial voltage (r=-0.451, p<0.001) and left atrial activation time (r=0.547, p<0.001). During a follow-up of 23 ± 13 months, 36 patients (27% of the study population) had AF recurrence. The PA-PDI interval and left atrial volume were independent predictors of AF recurrence. At a cut-point of 160 ms, the Kaplan-Meier survival analysis showed that a long PA-PDI interval significantly predicted AF recurrence. CONCLUSIONS: The PA-PDI interval can reflect the process of left atrial remodelling, such as a left atrial enlargement, prolonged activation time and decreased voltage. It was a convenient parameter for predicting recurrence after catheter ablation of paroxysmal AF.

Atrial substrate properties and outcome of catheter ablation in patients with paroxysmal atrial fibrillation associated with diabetes mellitus or impaired fasting glucose.

Diabetes mellitus has been reported to be an independent risk factor of atrial fibrillation (AF). The present study investigated the atrial substrate properties and clinical outcome of catheter ablation in patients with paroxysmal AF and abnormal glucose metabolism. A total of 228 patients with paroxysmal AF who had undergone catheter ablation for the first time were enrolled. An abnormal glucose metabolism (n = 65) was defined as diabetes mellitus or an impaired fasting glucose. We analyzed the clinical and electrophysiologic characteristics in, and the clinical outcome of, patients with AF with and without an abnormal glucose metabolism. The right atrial (107.2 ± 15.4 vs 96.0 ± 16.5 ms, p < 0.001) and left atrial (108.4 ± 22.3 vs 94.0 ± 17.5 ms, p < 0.001) total activation times were significantly longer in the patients with AF and an abnormal glucose metabolism than in those without an abnormal metabolism. Furthermore, the right atrial (1.46 ± 0.61 vs 2.00 ± 0.70 mV, p < 0.001) and left atrial (1.48 ± 0.74 vs 2.05 ± 0.78 mV, p < 0.001) bipolar voltages were significantly lower in those with AF and an abnormal glucose metabolism than in those without. The AF recurrence rate was also greater in the patients with an abnormal glucose metabolism (18.5% vs 8.0%, p = 0.022) than in those without. The follow-up duration was 18.8 ± 6.4 months. In conclusion, an abnormal glucose metabolism affects the biatrial substrate properties with an intra-atrial conduction delay, decreased voltage, and greater recurrence rate after catheter ablation.

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.

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.

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.

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.