Left Atrial and Pulmonary Vein Ostial Ablation as a New Treatment for Curing Persistent Atrial Fibrillation Initial Experience and Results

Left atrial reservoir and pump function after catheter ablation with persistent atrial fibrillation: a two-dimensional speckle tracking imaging study

OBJECTIVE

By using ultrasound strain rate (SR) imaging to evaluate the left atrial (LA) reservoir and pump function after catheter ablation (CA) with persistent atrial fibrillation (PAF).

METHODS

A total of 45 patients with PAF underwent echocardiography examination before and after ablation as well as during 6 months of follow-up. Peak SR was measured at each LA segment (septal, lateral, anterior, inferior and posterior) during systole (LAs) and late diastole (LAa).

RESULTS

During 6 months after CA, 30 patients were free of atrial fibrillation recurrence (AFR). left atrial area index (LAAI), left atrial maximum volume index (LAVImax), and E/Ea were obviously higher in patients with before CA, left atrial ejection fraction (LAEF), SR-LAs were lower than in normal cases, the SR-LAa was disappeared. Shortly after ablation, SR-LAa was recovered, and SR-LAs was reduced compared to those at baseline. At midterm follow-up, LAEF and SR-LAs were still lower than the control group, and LAAI and LAVImax were higher. SR-LAa was recovered slowly over time, but still lower.

CONCLUSION

LA reservoir function was seriously damaged and LA pump function disappeared in patients with PAF. LA reservoir function impairment appeared shortly after ablation, it showed improvement at midterm follow-up, but some degree of damage to the LA reservoir and pump function was still present. Speckle tracking imaging is a feasible technique for the assessment of LA function in patients with PAF, which is a potentially valuable clinical tool to assist in the early detection of atrial remodelling and reverse remodelling.

The Effect of Discharge Mode on the Distribution of Myocardial Pulsed Electric Field—A Simulation Study for Pulsed Field Ablation of Atrial Fibrillation

Background: At present, the effects of discharge modes of multielectrode catheters on the distribution of pulsed electric fields have not been completely clarified. Therefore, the control of the distribution of the pulsed electric field by selecting the discharge mode remains one of the key technical problems to be solved. Methods: We constructed a model including myocardium, blood, and a flower catheter. Subsequently, by setting different positive and ground electrodes, we simulated the electric field distribution in the myocardium of four discharge modes (A, B, C, and D) before and after the catheter rotation and analyzed their mechanisms. Results: Modes B, C, and D formed a continuous circumferential ablation lesion without the rotation of the catheter, with depths of 1.6 mm, 2.7 mm, and 0.7 mm, respectively. After the catheter rotation, the four modes could form a continuous circumferential ablation lesion with widths of 10.8 mm, 10.6 mm, 11.8 mm, and 11.5 mm, respectively, and depths of 5.2 mm, 2.7 mm, 4.7 mm, and 4.0 mm, respectively. Conclusions: The discharge mode directly affects the electric field distribution in the myocardium. Our results can help improve PFA procedures and provide enlightenment for the design of the discharge mode with multielectrode catheters.

Aging-associated changes in L-type calcium channels in the left atria of dogs

Action potential (AP) contours vary considerably between the fibers of normal adult and aged left atria. The underlying ionic and molecular mechanisms that mediate these differences remain unknown. The aim of the present study was to investigate whether the L-type calcium current (I_Ca.L) and the L-type Ca²⁺ channel of the left atria may be altered with age to contribute to atrial fibrillation (AF). Two groups of mongrel dogs (normal adults, 2-2.5 years old and older dogs, >8 years old) were used in this study. The inducibility of AF was quantitated using the cumulative window of vulnerability (WOV). A whole-cell patch-clamp was used to record APs and I_Ca.L in left atrial (LA) cells obtained from the two groups of dogs. Protein and mRNA expression levels of the a1C (Cav1.2) subunit of the L-type calcium channel were assessed using western blotting and quantitative PCR (qPCR), respectively. Although the resting potential, AP amplitude and did not differ with age, the plateau potential was more negative and the APD₉₀ was longer in the aged cells compared with that in normal adult cells. Aged LA cells exhibited lower peak I_Ca.L current densities than normal adult LA cells (P<0.05). In addition, the Cav1.2 mRNA and protein expression levels in LA cells were decreased in the aged group compared with those in the normal adult group. The lower AP plateau potential and the decreased I_Ca.L of LA cells in aged dogs may contribute to the slow and discontinuous conduction of the left atria. Furthermore, the reduction of the expression levels of Cav1.2 with age may be the molecular mechanism that mediates the decline in I_Ca.L with increasing age.

Hybrid therapy of radiofrequency catheter ablation and percutaneous transvenous mitral commissurotomy in patients with atrial fibrillation and mitral stenosis

BACKGROUND

The rhythm control of atrial fibrillation (AF) associated with mitral stenosis (MS) is often difficult using antiarrhythmic drugs (AADs), even after a percutaneous transvenous mitral commissurotomy (PTMC). Few studies have examined the efficacy and safety of simultaneously performing radiofrequency catheter ablation (RFCA) and a PTMC in patients with MS and AF.

METHODS

Twenty consecutive patients with drug-resistant AF and rheumatic MS underwent RFCA combined with a PTMC (n = 10; persistent AF-8, long-lasting [>1 year] persistent AF-2; RFCA group) or transthoracic direct cardioversion (DC) following a PTMC (n = 10; persistent AF-7, long-lasting persistent AF-3; DC group). In all patients, the mitral valve morphology was amenable to a PTMC, and more than 2 AADs had been ineffective in maintaining sinus rhythm (SR). In the RFCA group, a segmental pulmonary vein isolation (PVI) was performed in the initial 5 patients, and an extensive PVI was performed in the remaining 5.

RESULTS

During a mean follow-up period of 4.0 +/- 2.7 years, 8 patients (80%) in the RFCA group were maintained in SR, as compared to 1 (10%) in the DC group (hazard ratio, 0.16; 95% confidence interval, 0.03 to 0.75; P = 0.008 by the log-rank test). The prevalence of the concomitant use of class I and/or class III AADs was comparable between the 2 groups (P = 0.70). No complications occurred during the procedure or follow-up period in either group.

CONCLUSIONS

The hybrid therapy using RFCA and a PTMC was safe and feasible, and significantly improved the AF free survival rate compared to DC following a PTMC.

Left atrial strain as predictor of successful outcomes in catheter ablation for atrial fibrillation: a two-dimensional myocardial imaging study

BACKGROUND

The objective of this study was to investigate atrial myocardial properties through two-dimensional (2D) myocardial imaging in patients with atrial fibrillation (AF) and its predictive role for recurrence after catheter ablation.

METHODS AND RESULTS

Echocardiographic examinations were performed in 40 patients with paroxysmal AF before catheter ablation and 40 age- and gender-matched healthy control subjects. Using a software package, bidimensional acquisitions were analyzed to measure longitudinal strain and strain rate for the left atrium (LA). Systolic strain and strain rate in all eight segments, and its average values, were significantly reduced in AF patients compared to controls. During 9 months of follow-up after catheter ablation for AF, 11 of 40 AF patients had AF recurrence. AF recurrence was associated with gender, LA volume index, and average values of systolic strain and strain rate. By multivariate analysis, only average strain was an independent predictor of AF recurrence (OR = 0.88, 95% CI 0.79-0.98, p = 0.018).

CONCLUSIONS

Lower systolic strain of LA was strongly associated with recurrence after catheter ablation. Thus, diverse adjunctive ablation strategies should be considered to reduce recurrence in patients with lower systolic strain.

Incremental predictive value of pre-procedural N-terminal pro-B-type natriuretic peptide for short-term recurrence in atrial fibrillation ablation

The objective of this work was to assess the predictive value of pre-procedural N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in patients undergoing atrial fibrillation (AF) ablation. Seventy-three consecutive patients with AF (paroxysmal n = 49, persistent n = 24) and preserved left ventricular (LV) systolic function (LV ejection fraction > 45%) were prospectively enrolled in this study. All of the enrolled patients underwent catheter ablation after a measurement of their plasma NT-proBNP levels, and an echocardiographic examination with assessment of their LV diastolic function and left atrial(LA) volume. Patients with AF recurrence at 3 months had more persistent AF (P = 0.001), a higher LA volume index (P = 0.002), lesser decelerating times (DT) of mitral inflow (P = 0.014), and higher NT-proBNP levels (P < 0.001), when compared with patients with sinus rhythm restoration. The baseline log NT-proBNP correlated significantly with age (r = 0.26, P = 0.025), LA volume index (r = 0.41, P = 0.001), E/E' (r = 0.34, P = 0.007), DT (r = -0.34, P = 0.007), and E (r = 0.25, P = 0.04). The log NT-proBNP (HR 7.76, 95% CI 2.95-20.39, P < 0.001) was an independent predictor of AF recurrence. The measurement of NT-proBNP added incremental predictive value to standard indexes of LA size or diastolic function, including LA volume index and DT (P = 0.02). This study suggests the clinical utility of the level of NT-proBNP as an integrating marker of various risk factors, and as an incremental predictive marker for AF catheter ablation.

Swallowing-Induced Atrial Tachyarrhythmias: Prevalence, Characteristics, and the Results of the Radiofrequency Catheter Ablation

BACKGROUND

Detailed information on swallowing-induced tachyarrhythmias has been lacking.

METHODS

The prevalence, characteristics, and results of the radiofrequency catheter ablation (RFCA) of swallowing-induced tachyarrhythmias were examined in 544 patients with symptomatic premature atrial contractions (PACs), paroxysmal atrial tachycardia (AT), and/or paroxysmal atrial fibrillation (AF). We also conducted a search of the medical literature on swallowing-induced tachyarrhythmias. Further, we presented an in-depth review of the literature and investigated the published data on swallowing-induced tachyarrhythmias.

RESULTS

The prevalence of swallowing-induced tachyarrhythmias was 0.6% (three patients). An analysis of the published literature and our three cases demonstrated that (1) males predominated 9:1 over females, (2) most cases occurred over 35 years of age, (3) tachyarrhythmias occurred consistently and reproducibly shortly after each swallow, (4) 90% of the patients had PACs and/or AT as the manifesting arrhythmia, (5) the PACs provoked by swallowing usually had the same P-wave morphology as the first beat of the AT and AF, and (6) RFCA procedures performed in five cases resulted in success with no recurrence or complications.

CONCLUSIONS

Swallowing-induced tachyarrhythmias are rare, but have several distinct characteristics. RFCA should be considered in appropriately selected patients with reliable inducibility because such an ablation may offer a permanent cure.

Radiofrequency catheter ablation within the coronary sinus eliminates a macro-reentrant atrial tachycardia: importance of mapping in the coronary sinus

We describe a patient who underwent radiofrequency (RF) catheter ablation of symptomatic atrial fibrillation. After left atrial (LA) catheter ablation and pulmonary vein isolation, a macro-reentrant atrial tachycardia (AT) with a critical isthmus at the mitral isthmus was induced by incremental atrial pacing from the coronary sinus. Extensive RF energy applications from endocardial sites using ablation catheters with 4 mm- and 8 mm- tips resulted in no discrete potentials being recorded from the endocardial sites of the isthmus, but the tachycardia could not be terminated. However, discrete potentials were recorded within the CS, and epicardial RF energy applications from the CS eliminated the tachycardia. Thus, mapping in the CS is useful for detecting residual conduction at epicardial sites along the mitral isthmus. RF catheter ablation within the CS should be considered when no distinct electrograms are recorded after extensive ablation from the endocardial sites and when distinct electrograms are recorded within the CS.

Plasma Natriuretic Peptide Concentrations as a Predictor for Successful Catheter Ablation in Patients With Drug-Refractory Atrial Fibrillation

BACKGROUND

The concentrations of atrial and brain natriuretic peptides (ANP and BNP) are elevated in patients with atrial fibrillation (AF), but the usefulness of their measurement before and after AF ablation has not been reported.

METHODS AND RESULTS

The concentrations of the natriuretic peptides were evaluated in 54 patients undergoing catheter ablation for drug-resistant paroxysmal and persistent AF without heart failure. Based on the outcome, the patients were divided into 2 groups: successful (n=42) or failure (n=12). All patients were asked to keep a log of the duration and frequency of their symptoms and underwent 24-h ECG monitoring at least once after the ablation. The plasma BNP and ANP concentrations, most of which were well below the heart failure range, exceeded the normal range in 69% and 26% of the patients, respectively. The BNP concentration decreased after ablation in the success group (49+/-43 to 27+/-28 pg/ml; p<0.05), however, it was unchanged in the failure group (46+/-35 to 70+/-37 pg/ml; p=0.46). A value of the DeltaBNP (BNP after ablation - BNP before ablation) of </=0 pg/ml identified a successful ablation with a sensitivity of 83% and specificity of 83%. The plasma ANP concentration did not differ statistically between the 2 groups before and after the ablation.

CONCLUSION

A moderate elevation in the BNP concentration is often found in patients with symptomatic paroxysmal and persistent AF, and a reduction in the plasma BNP concentration shortly after the ablation may indicate a successful outcome.

Pulmonary Vein Isolation for Atrial Fibrillation in Patients With Paroxysmal Atrial Fibrillation and Prolonged Sinus Pause

BACKGROUND

Symptomatic prolonged sinus pauses upon termination of atrial fibrillation (AF) are an indication for pacemaker implantation.

METHODS AND RESULTS

We evaluated the clinical outcomes of 4 patients who showed prolonged sinus pauses (> 2 seconds) upon termination of AF and thus underwent ablation. The ablative procedure included pulmonary vein isolation, superior vena cava isolation, and cavo-tricuspid isthmus ablation. Twenty-four-hour ambulatory electro-cardiogram monitoring was performed before and 1 month after ablation. The maximum sinus pause decreased from 4.5 +/- 2.1 seconds before ablation to 1.7 +/- 0.2 seconds after ablation. Sinus pauses > 2.0 seconds disappeared after ablation in all 4 patients. Minimum heart rate increased from 35.0 +/- 8.1 beats/minute before ablation to 52 +/- 6.7 beats/minute after ablation. The number of heart beats in 24 hours did not change significantly after ablation.

CONCLUSION

Prolonged sinus pauses after paroxysmal AF may result from depressed sinus node function, which can be eliminated by curative ablation of AF.

Is circumferential pulmonary vein isolation preferable to stepwise segmental pulmonary vein isolation for patients with paroxysmal atrial fibrillation?

BACKGROUND

Stepwise segmental pulmonary vein isolation (SPVI) and circumferential pulmonary vein isolation (CPVI) have been developed to treat patients with atrial fibrillation (AF), but the preferable approach for paroxysmal AF (PAF) has not been established.

METHODS AND RESULTS

One hundred and ten patients with symptomatic PAF were randomized into a stepwise SPVI group (n=55) or CPVI group (n=55). Systemic SPVI combined with left atrial linear ablation tailored by inducibility of AF was performed in the stepwise SPVI group. Circumferential linear ablation around the left and right-sided pulmonary veins (PVs) guided by 3-dimensional electroanatomic mapping was performed in the CPVI group. The endpoints of ablation are non-induciblity of AF in the stepwise SPVI group and continuity of circular lesions combined with PV isolation in the CPVI group. After the initial procedures, atrial tachyarrhythmis (ATa) recurred within the first 3 months in 23 of the 55 patients (41.8%) who underwent stepwise SPVI and in 20 of the 55 patients (36.4%) who had CPVI (p=0.69). Repeat procedures were performed in 7 patients from the stepwise SPVI group and 5 from the CPVI group (p=0.76). During the 3-9 months after the last procedure, 46 patients (83.6%) from the CPVI group and 43 (78.2%) from the stepwise SPVI group did not have symptomatic ATa while not taking anti-arrhythmic drugs (p=0.63). Severe subcutaneous hematoma or PV stenosis occurred in 3 patients.

CONCLUSIONS

The efficacy of stepwise SPVI is comparable to that of CPVI for patients with PAF.

Differences in the aging-associated trends of the monophasic action potential duration and effective refractory period of the right and left atria of the rat

BACKGROUND

The incidence of atrial fibrillation (AF) increases with aging, but the aging-associated electrophysiological changes of atrial myocardium are poorly understood.

METHODS AND RESULTS

Based on the hypothesis that aging of the atrium enhances AF susceptibility, 30 Wistar rats were divided into 3 age groups: adult, middle-aged, and aged (n=20 per group). Their hearts were isolated and perfused by Langendorff apparatus. Monophasic action potential duration at 90% repolarization (MAPD(90)) and effective refractory period (ERP) at the basic stimulation cycle length (BCL: 400 ms), and MAPD(90) at other different stimulation cycle lengths in each age group were measured. At the BCL, the MAPD (90) of the right atrial myocardium was prolonged from the adult to the aged group, that of the left atrial myocardium was prolonged from the adult to middle-aged group, and the MAPD(90) of the left atrial myocardium in the aged group were shorter than that in the adult and middle-aged groups. The ERP of the atrial myocardium showed the same age-associated trend as MAPD(90). As the stimulation frequency increased, the MAPD(90) of both the left and right atrial myocardium shortened correspondingly in the adult and middle-aged groups, but in the aged group the MAPD(90) of the right atrial myocardium shortened markedly more than that of the left atrial myocardium.

CONCLUSIONS

There are different aging-associated electrophysiological changes in the right and left atrium, and the older heart is more vulnerable to developing the substrate for AF.

Prediction of Paroxysmal Atrial Fibrillation Using Nonlinear Analysis of the R-R Interval Dynamics Before the Spontaneous Onset of Atrial Fibrillation

BACKGROUND

New methods based on nonlinear theory have been developed to give more insight into complex heart rate (HR) dynamics. This study was designed to test the hypothesis that altered HR dynamics, as analyzed with complexity and fractal measures, may precede the spontaneous onset of paroxysmal atrial fibrillation (PAF). Secondly, the difference in the temporal change of these measurements between the different types of atrial fibrillation (AF) was assessed.

METHODS AND RESULTS

From 105 Holter tapes in which PAF was recorded, 44 PAF (>or=5 min) episodes in 33 patients (22 men, 58 +/- 12 years), preceded by sinus rhythm for more than 1 h, were selected and submitted to time-and frequency-domain HR variability analyses, along with detrended fluctuation analysis, approximate entropy (ApEn) and sample entropy (SampEn). The 60 min before the onset of AF were divided into 6 10-min periods and studied using repeated measures ANOVA. PAF episodes were divided into 3 subgroups: an increased HF component and decreased L/H ratio (vagal type, n=20); increased L/H ratio and decreased HF component (sympathetic type, n=14); and non-related type (n=10). None of the time- or frequency-domain parameters showed any significant change before AF in any type of AF. The alpha(1) showed a tendency to decrease before the onset of AF and the change in alpha(1) was divergent according to the AF type. The ApEn decreased before the onset of AF (1.005+/-0.046, 60-50 min before AF to 0.894+/-0.052, 10-0 min before AF; p=0.032). The SampEn also decreased progressively before the start of AF (1.165 +/- 0.085, 60-50 min before AF to 0.887 +/- 0.077, 10-0 min before AF, p=0.003). The decrease in both the ApEn and SampEn was irrespective of the AF type.

CONCLUSIONS

A reduction in the ApEn and SampEn, which reflects the nonlinear complexity of HR variability, is a hallmark of altered HR dynamics preceding the spontaneous onset of AF.