Interatrial Block: The Pandemic Remains Poorly Perceived

Interatrial block (IAB; P duration ≥110 ms) is a common electrocardiogram abnormality, which in addition to reduced left atrial function predicts atrial fibrillation and other arrhythmias. P terminal force (Ptf) ± biphasic P in lead V₁≥ the area of one small square on the grid also indicates left atrial abnormality, particularly left atrial enlargement, which is a strong correlate of IAB. Among 482 consecutively recorded electrocardiograms, IAB and Ptf were strongly and significantly correlated (χ²= 68.041; P ≤ 0.001). In conclusion, interatrial block exists in pandemic proportions in unselected hospital patients. Because of its pathologic implications it requires widespread attention which, heretofore, has been lacking.     

Renin-angiotensin system blocker use may be associated with suppression of atrial fibrillation recurrence after pulmonary vein isolation

Introduction: An additional approach may be essential to reduce recurrences of atrial fibrillation (AF) after pulmonary vein isolation (PVI). We examined the efficacy of renin‐angiotensin system blockers (RAS‐B) in suppressing AF recurrences after PVI. Methods and Results: We retrospectively studied 264 consecutive patients (195 male, median age: 63 years) who underwent successful PVI of paroxysmal (n = 94) or persistent AF (n = 170). RAS‐B treatment was performed in 145 patients (angiotensin‐converting enzyme inhibitors; n = 13, angiotensin receptor blockers; n = 129, both; n = 3). Echocardiography was performed before and 3 months after the ablation to examine the occurrence of left atrial structural reverse remodeling (LA‐RR). After a median follow‐up of 195 (interquartile range: 95–316) days, AF recurred in 51 (19.3%) patients. A Cox regression analysis revealed that AF recurrence was significantly lower in the patients with RAS‐B than in those without (hazard ratio [HR] = 0.41 [95% confidence interval (CI): 0.23–0.71], P = 0.002). After a multivariate adjustment for potential confounders, the use of RAS‐B (HR = 0.39 [95% CI: 0.19–0.77], P = 0.007) and type of AF (HR = 0.30 [95% CI: 0.13–0.66], P = 0.003) were the independent predictors for AF recurrence during the entire follow‐up. Although effect of RAS‐B was not significant during the early follow‐up (<3 month), it was the only independent predictor during the late follow‐up (>3 months) (HR = 0.21 [95% CI: 0.08–0.53], P = 0.001). There were no significant differences in LA‐RR occurrence regarding RAS‐B medication. The use of RAS‐B was an independent predictor of late AF recurrences irrespective of an early LA‐RR occurrence. Conclusions: Treatment with RAS‐B significantly reduced the AF recurrence after PVI. This benefit became more prominent 3 months after the PVI. (PACE 2011; 34:296–303)     

High-sensitivity C-reactive protein as a predictor of atrial fibrillation recurrence after primary circumferential pulmonary vein isolation

Background: Atrial fibrillation (AF) recurrence after circumferential pulmonary vein isolation (CPVI) is difficult to predict. Inflammation is associated with the development of AF. Inflammatory markers, such as high sensitivity C‐reactive protein (hsCRP), are related to AF development via atrial remodeling. However, it is unknown whether plasma hsCRP concentration before CPVI can be used as a predictor for AF recurrence. Methods: A total of 121 patients without structural heart disease who underwent primary CPVI by a single operator were included in the study (paroxysmal/persistent AF: 77/44). Left atrial diameter was measured by transesophageal echocardiography. Plasma hsCRP concentration was determined by enzyme‐linked immunosorbent assay. Based on the follow‐up outcomes, patients were divided into two groups, a recurrence group and a nonrecurrence group. AF recurrence was defined as AF or atrial flutter or atrial tachycardia episodes lasting for ≥30 s during regular follow‐up (>12 months). Results: A total of 36 (29.8%) patients (paroxysmal/persistent AF: 19 [24.7%]/17 [38.6%]) had AF recurrence in a mean 23 (range, 12–44) month follow‐up period. The plasma hsCRP concentration in the recurrence group was significantly higher than that in the nonrecurrence group for all patients (median [quartile range] 2.22 [1.97] mg/L vs 0.89 [1.30] mg/L, P < 0.001), for patients with paroxysmal AF (2.12 [2.78] mg/L vs 0.84 [1.15] mg/L, P = 0.028), and for those with persistent AF (2.29 [1.08] mg/L vs 0.89 [1.53] mg/L, P = 0.005). Multiple logistic regression analyses showed that the higher level of the plasma hsCRP (P < 0.001) was a significant prognostic predictor of AF recurrence, both for patients with paroxysmal AF (P = 0.012) and those with persistent AF (P = 0.003). Conclusion: Plasma hsCRP concentration before CPVI was associated with AF recurrence after primary CPVI procedure for both paroxysmal and persistent AF patients. Plasma hsCRP concentration could play a role in prediction of AF recurrence after primary CPVI. (PACE 2011; 34:398–406)     

Atrial Flutter Ablation in Inducible Patients during Pulmonary Vein Atrum Isolation: A Randomized Comparison

Background: The incidence of atrial flutter (AFL) post pulmonary vein antrum isolation (PVAI) in patients with atrial fibrillation (AF) is reported to be between 8% and 20%. The need for right or left AFL ablation during the initial PVAI procedure remains controversial. We prospectively compared mapping and ablation versus no ablative treatment of inducible AFL during PVAI. Methods and Results: In 220 patients (167 men, mean age 56 ± 15 years) with symptomatic AF presenting for PVAI, burst pacing from the high right atrium and coronary sinus was performed to determine AFL inducibility. A total of 25 patients with sustained (17 patients) or reproducible (eight patients) AFL were included in this study. Patients were randomized to mapping and ablation of AFL using the CARTO 3D mapping system (Biosense Webster, Diamond Bar, CA, USA) versus no further ablation. Typical AFL was induced in 48% of the patients. During a follow‐up of 12 ± 4 months, recurrences were determined by serial 48‐h Holter and event monitors. Recurrence rates, time to recurrence, and AFL cycle length differences between both groups were not statistically significant. Conclusion: These data suggest that inducibility of AFL post PVAI does not predict long‐term incidence of AFL. Moreover, this study demonstrates little benefit to mapping and ablation of these arrhythmias during the PVAI procedures.     

Atrial fibrillation ablation using a closed irrigation radiofrequency ablation catheter

Background: Catheter ablation is an effective therapy for symptomatic, medically refractory atrial fibrillation (AF). Open‐irrigated radiofrequency (RF) ablation catheters produce transmural lesions at the cost of increased fluid delivery. In vivo models suggest closed‐irrigated RF catheters create equivalent lesions, but clinical outcomes are limited. Methods: A cohort of 195 sequential patients with symptomatic AF underwent stepwise AF ablation (AFA) using a closed‐irrigation ablation catheter. Recurrence of AF was monitored and outcomes were evaluated using Kaplan–Meier survival analysis and Cox proportional hazards models. Results: Mean age was 59.0 years, 74.9% were male, 56.4% of patients were paroxysmal and mean duration of AF was 5.4 years. Patients had multiple comorbidities including hypertension (76.4%), tobacco abuse (42.1%), diabetes (17.4%), and obesity (mean body mass index 30.8). The median follow‐up was 55.8 weeks. Overall event‐free survival was 73.6% with one ablation and 77.4% after reablation (reablation rate was 8.7%). Median time to recurrence was 26.9 weeks. AF was more likely to recur in patients being treated with antiarrhythmic therapy at the time of last follow‐up (recurrence rate 30.3% with antiarrhythmic drugs, 13.2% without antiarrhythmic drugs; hazard ratio [HR] 2.2, 95% confidence interval [CI] 1.1–4.4, P = 0.024) and in those with a history of AF greater than 2 years duration (HR 2.7, 95% CI 1.1–6.9, P = 0.038). Conclusions: Our study represents the largest cohort of patients receiving AFA with closed‐irrigation ablation catheters. We demonstrate comparable outcomes to those previously reported in studies of open‐irrigation ablation catheters. Given the theoretical benefits of a closed‐irrigation system, a large head‐to‐head comparison using this catheter is warranted. (PACE 2012; 35:506–513)     

Noninvasive Evidence of Shortened Atrial Refractoriness during Sinus Rhythm in Patients with Paroxysmal Atrial Fibrillation

Background: Shortening of the atrial refractory period is the key feature of atrial electrical remodeling during atrial fibrillation (AF). During sinus rhythm (SR), assessment of the atrial refractoriness is hampered by the fact that the atrial repolarization wave (Ta wave) is largely obscured by the following QRST complex. The purpose of this study was to study the Ta wave in subjects with paroxysmal AF during SR with third‐degree atrioventricular (AV) block, and in matched controls. Methods: Fifteen patients (mean age 70 ± 10 years, five males) with paroxysmal AF undergoing AV‐nodal ablation were studied. Fifteen age‐ and gender‐matched subjects (mean age 71 ± 9 years, five males) with third‐degree AV block, without a history of heart disease, were used as controls. Standard 12‐lead electrocardiograms (ECGs) were recorded and transformed to orthogonal leads and studied using P‐wave signal averaging technique. Results: The P to Ta interval was shorter (408 ± 47 ms vs 451 ± 53 ms, P = 0.017) and in Lead Y the Ta peak location was earlier (156 ± 31 ms vs 187 ± 34 ms, P = 0.002) in subjects with paroxysmal AF than in the controls. The P‐wave duration (126 ± 15 ms vs 129 ± 17 ms, P = 0.59) and morphology was similar in AF patients and controls. Conclusions: In this study, the ECG signs of shorter atrial refractoriness associated with a history of AF are visualized for the first time during SR. The finding of the earlier location of the PTa peak in AF subjects implies that a possible indicator of increased arrhythmia susceptibility may be visible already in the unprocessed ECG.     

Long‐term Follow‐up of P‐wave Duration and Dispersion in Patients with Mitral Stenosis

Background: Patients with mitral stenosis have prolonged P‐wave duration and increased P‐wave dispersion (PWD) that have been associated with increased risk for atrial fibrillation. Methods: Thirty mild‐to‐moderate mitral stenosis patients were followed for 38.4 ± 10.7 (23–48) months. Baseline and last 12‐lead electrocardiographic and transthoracic echocardiographic measurements were evaluated. Maximum and minimum P‐wave durations (P_max and P_min) and PWD were calculated. Results: P_max and PWD were significantly higher in patients compared to control group. Left atrial (LA) size, mitral gradient, and pulmonary artery systolic pressure (PASP) were significantly increased and mitral valve area (MVA) was decreased during follow‐up. There were significant increases in P_max and PWD and significant decrease in P_min (P_max: 101.0 ± 12.5 ms vs 105.0 ± 16.5 ms, P = 0.005; P_min: 59.3 ± 8.5 ms vs 55.0 ± 12.3 ms P = 0.004; PWD: 41.7 ± 5.5 ms vs 50.0 ± 6.2 ms, P < 0.001). Baseline P_max, P_min, and PWD were significantly correlated with MVA (P_max: r = ? 0.605, P < 0.001, P_min: r =?0.632, P < 0.001, PWD: r =?0.402, P = 0.0028) and mean mitral gradient (P_max: r = 0.412, P = 0.024, P_min: r = 0.632, P = 0.049, PWD: r = 0.378, P = 0.039). In addition to MVA and mean mitral gradient follow‐up P‐wave variables were significantly correlated with LA size (P_max: r = 0.573, P = 0.001, P_min: r = 0.636, P = 0.001, PWD: r = 0.265, P = 0.046) and PASP (P_max: r = 0.462, P = 0.011, P_min: r = 0.472, P = 0.008 PWD: r = 0.295, P = 0.047). Conclusions: P‐wave duration and PWD increase progressively in accordance with the progression of mitral stenosis.     

Increased intraatrial conduction abnormality assessed by P-wave signal-averaged electrocardiogram in patients with Brugada syndrome

Background: Atrial fibrillation (AF) is observed in patients with Brugada syndrome (BS), especially those showing coved‐type electrocardiogram (ECG) pattern. Using P‐wave signal‐averaged ECG (P‐SAE), we investigated whether increased intraatrial conduction abnormality contributed to AF generation in BS patients. Methods: Twenty BS patients and 20 age‐ and gender‐matched healthy controls were enrolled. At the P‐SAE recording, 12 of the 20 BS patients showed coved‐type (C‐BS) and eight showed saddleback‐type (S‐BS). The total duration (Ad) and root mean square voltage for the terminal 20 ms (LP₂₀) of the filtered P wave were measured. P‐wave dispersion (P‐disp) was defined as the difference between the maximum and minimum, measured from 16 precordial recording sites. Results: BS patients had a significantly longer Ad (128.2 ± 7.6 vs 116.3 ± 8.2 ms, P < 0.0001), lower LP₂₀ (2.6 ± 0.9 vs 3.4 ± 0.8 μV, P < 0.01), and greater P‐disp (15.5 ± 7.0 vs 7.4 ± 3.2 ms, P < 0.0001) than the controls. C‐BS patients had significantly longer Ad (131.0 ± 7.2 vs 124.1 ± 6.8 ms, P < 0.05) and lower LP₂₀ (2.2 ± 0.6 vs 3.2 ± 1.0 μV, P < 0.05) than S‐BS patients. All C‐BS patients and only three S‐BS patients had atrial late potential (100% vs 38%, P < 0.01). Conclusion: Intraatrial conduction delay and its heterogeneity may exist in BS patients, especially those showing coved‐type ECG patterns. These atrial electrical abnormalities could be a substrate for atrial reentrant tachycardia such as AF. (PACE 2011; 34:1138–1146)     

Impact of the Preprocedural Frequency of Paroxysmal Atrial Fibrillation on the Clinical Outcome after Catheter Ablation

Background: Pulmonary vein antral isolation (PVAI) is a recommended treatment for symptomatic drug‐refractory paroxysmal atrial fibrillation (PAF). PAF naturally progresses toward persistent AF with an increase in the frequency and duration of AF. The objective of this study was to evaluate whether the preprocedural AF frequency had an impact on the AF recurrence after PVAI in patients with symptomatic PAF. Methods and Results: A total of 362 consecutive patients (61.0 ± 9.8 years; 274 males) with drug‐refractory PAF who underwent PVAI were included. The preprocedural frequency of PAF was daily, weekly, monthly, and yearly in 145 (40.1%), 112 (30.9%), 90 (24.9%), and 15 (4.1%) patients, respectively. There were no significant differences in any of the preprocedural variables between the four groups, except for the number of ineffective antiarrhythmic drugs (AADs). PVAI was successfully performed in all patients. At 12 months after the initial procedure, 63.5% of the entire group of patients were free of AF recurrences without any AADs, respectively. A Cox regression multivariate analysis of the variables including the AF frequency, age, gender, duration of AF, presence of hypertension or structural heart disease, left atrial size, left ventricular ejection fraction, and body mass index demonstrated that the AF frequency was not an independent predictor of AF recurrence after a single ablation procedure (P = 0.194). Conclusions: This study demonstrated that the preprocedural AF frequency did not predict AF recurrence after PVAI in patients with PAF. From the clinical point of view, an additional AF classification based on the preprocedural AF frequency might not be valuable in patients undergoing PVAI. (PACE 2012; 35:1236–1241)     

P波离散度预测阵发性心房颤动射频消融术后复发的价值

【目的】探讨阵发性房颤射频消融术后复发的预测因素。【方法】145例行环肺静脉导管射频消融术的阵发性房颤患者,记录术前及术后心电图,测量最大、最小P波时限,计算P波离散度。【结果】术后平均随访（6．1±0．2）个月,根据是否复发房颤分为复发组51例和未复发组94例。复发组较未复发组的术前最大P渡时限增大[（120．2±11．0）ms比（105．6±7．8）ms,P〈0．001];P波离散度明显增大[（53．6±6．2）ms比（39．9±4．7）ms,P〈0．001];两组P波最小时限及其他临床指标均无统计学差异。多因素分析示术前P波离散度≥46ms（P=0．04）和发作频率≥5次／月（P=0．01）是房颤复发的预测因素,二者预测复发的灵敏度分别是87％和86％;特异度92％和85％。【结论】术前P波离散度及房颤发作频率一定程度上可预测阵发性房颤射频消融术后的复发。     

Impact of Atrial Fibrillation Termination on Clinical Outcome after Ablation in Relation to the Duration of Persistent Atrial Fibrillation

Background: Whether procedural termination of persistent atrial fibrillation (AF) is necessary for optimal clinical efficacy still remains controversial. We sought to characterize the patients with persistent AF in whom procedural AF termination impacted an improved clinical outcome after ablation. Methods: We retrospectively assessed 132 patients (61.0 ± 9.3 years, 114 males) undergoing catheter ablation of persistent AF (duration 3 years, median). A stepwise ablation approach including pulmonary vein isolation and atrial substrate ablation targeting complex fractionated and high‐frequency electrograms was performed with desired endpoint of AF termination. Results: Overall, 90 patients (68%) were free from recurrent arrhythmias at 20 ± 11 months of follow‐up after one or two procedures. The left atrial diameter and continuous AF duration according to medical history were associated with the outcome (P = 0.002 and P< 0.001, respectively). In multivariate Cox regression analysis, the continuous AF duration was the only independent predictor of recurrent arrhythmias (hazard ratio 1.17, 95% confidence interval 1.10–1.23, P < 0.001). In patients with AF duration of ≥3 years, the clinical success was comparable regardless of whether AF termination was achieved or not (log‐rank, P = 0.27). In the remaining patients with AF duration of <3 years, procedural AF termination was associated with a higher arrhythmia‐free rate than when AF was sustained after ablation (log‐rank, P = 0.023). Conclusion: Extensive ablation to terminate AF might not be warranted in patients with a longer AF duration. On the contrary, procedural AF termination could be associated with maintenance of sinus rhythm in patients with a shorter AF duration with a less proarrhythmic substrate. (PACE 2012;35:1436–1443)     

P‐wave Measurements and Electrical Reconnection of the Posterior Left Atrium after Catheter Ablation for Atrial Fibrillation

Background: Recurrent atrial arrhythmias (RAAs) following posterior left atrial isolation (PLAI) for atrial fibrillation are common and are associated with reconnection of the PLA and pulmonary veins. We aimed to show that P‐wave duration (PWD) and P‐wave area under the curve (PWAUC) changes in patients undergoing PLAI can be measured using signal‐averaged electrocardiogram (SAECG), and that reversal of these changes in patients with RAAs can be used to noninvasively detect reconnection. Methods: SAECG recordings before and after PLAI in 52 patients were analyzed for changes in PWD and PWAUC and also in 26 of these patients who had a repeat procedure for RAA. Results: PWD and PWAUC reduced significantly in most leads following PLAI (mean 104 ± 11 ms to 93 ± 15 ms [P < 0.001] and 3.53 ± 1.23 microvolt seconds (μVs) to 2.87 ± 1.23 μVs [P = 0.001], respectively). Reconnection was observed in 20 of 26 patients at the repeat procedure. Compared to after the first procedure, reconnected patients had increased PWD and PWAUC (e.g., the increase in V4 was 14.1 ± 20.9 ms [P = 0.01] and 0.98 ± 1.17 μVs [P = 003], respectively) at the repeat procedure, while nonreconnected patients had decreased PWD and PWAUC (in V4, it was decreased by 11.5 ± 7.0 ms [P = 0.05] and 0.97 ± 0.33 μVs [P = 0.001]). A change in lead V4 PWAUC > ?0.29 μVs for detecting reconnection had a sensitivity of 94% and specificity of 100% (receiver operator characteristic area under the curve 0.97, P = 0.005). Conclusions: PLAI reduces PWD and PWAUC while reconnection increases them both. SAECG may be able to detect reconnection of the PLA noninvasively. (PACE 2010; 1324–1334)     

Long-Term Sinus Rhythm Stability after Intraoperative Ablation of Permanent Atrial Fibrillation

Introduction: Short‐ and medium‐term sinus rhythm (SR) rates after intraoperative radiofrequency ablation to treat permanent atrial fibrillation (AF) are well documented. Is rhythm success stable during a long‐term follow‐up? Methods and Results: A total of 130 patients who had undergone intraoperative radiofrequency cooled‐tip endocardial ablation (SICTRA) of permanent AF (mean AF duration 6±5 years) concomitant to open heart surgery more than 3 years ago were followed up using electrocardiogram (ECG), Holter‐ECG, and echocardiography and compared with 12‐month follow‐up data. In 55% of patients, only the left atrium and in 45%, both atria were treated using SICTRA. Mitral valve replacement was performed in 21, mitral valve reconstruction in 25, aortic valve replacement in 13, CABG procedures in 51 (including 11 patients with additional mitral valve surgery), and complex procedures in 20 patients. Sixty‐nine percent of patients (90/130) were in stable SR after a median period of 48 months, whereas 28% (36/130) were in AF and 3% (4/130) were in atrial flutter. In between the 12‐month follow‐up and the long‐term follow‐up, seven patients converted to AF after having documented SR, two patients converted to typical right atrial flutter after being in SR, and two patients from AF to left atrial macroreentry. After left and biatrial SICTRA, SR rates were comparable (73% vs 66%, P = 0.45). Echocardiography revealed 73% of patients in SR to have effective left atrial contraction. Conclusions: SICTRA restores long‐term stable SR in 69% of all patients. Nine percent of patients reconverted back to atrial arrhythmia after having documented SR at 12 months.     

P wave duration and morphology predict atrial fibrillation recurrence in patients with sinus node dysfunction and atrial-based pacemaker

P wave duration and morphology have never been systematically evaluated as markers of AF in patients with a conventional indication to pacing. This study correlated sinus P wave duration and morphology and the incidence of AF in patients with sinus node dysfunction (SND), previous history of AF before implant, and atrial-based pacemaker. Included were 140 patients (86 men, 54 women; mean age 71.8 +/- 10.4 years) with recurrent paroxysmal AF and who received a DDD (128 patients) or AAI (12 patients) pacemaker for SND. Forty-nine patients had structural heart disease. Sinus P wave duration and morphology was evaluated in leads II, III. Twenty-two patients had an abnormal P wave morphology, diphasic (+/-) in 5 and notched (+/+) in 17. The basic pacemaker rate was programmed between 60 and 70 beats/min. Rate responsive function was activated in 65 patients. During a follow-up of 27.6 +/- 17.8 months, AF was documented in 87 patients. Forty-four patients developed permanent AF, following at least one episode of paroxysmal AF in 26 cases. Statistical analysis used Cox model regression. Univariate predictors of AF (P < 0.10) were drugs (mean: 2 +/- 1.4) and DC shock before pacing (16/140 patients), P wave duration (mean 112.5 +/- 24.6 ms), basic pacemaker rate (mean 68 +/- 5 beats/min), and drugs in the follow-up (mean 1.2 +/- 0.94). Multivariate analysis showed that P wave duration (b = 0.013, s.e. = 0.004; P = 0.003), and drugs before pacing (b = 0.2; s.e. = 0.08; P < 0.01) resulted in a significant independent predictor of AF. Actuarial incidence of patients free of AF at 30 months was 35%: 56% in patients with a P wave < 120 ms, and 13% in those with P wave > or = 120 ms (P < 0.01 by Score test). Univariate predictors of permanent AF were drugs and DC shock before pacing, left atrial size (mean 39 +/- 6 mm), P wave duration, abnormal P wave morphology (22/140 patients), and drugs in the follow-up. Multivariate analysis showed that P wave morphology was the most important predictor of permanent AF (b = -0.56, s.e. = 0.2; P = 0.008). Incidence of patients free of permanent AF at 30 months was 69%: 74% in patients with normal P wave, compared to 28% in the case of abnormal P wave morphology (P < 0.01). P wave duration and morphology are good markers of postpacing AF recurrence in patients with SND and an atrial-based pacemaker. This observation suggests that intra- and interatrial conduction disturbances be extensively evaluated before implantation, and the indication for atrial resynchronization procedures be reevaluated.     

Relationship between P-wave duration and atrial electromechanical delay assessed by tissue Doppler echocardiography

Background: The aim of the study was to assess the relationship between P‐wave duration on the surface electrocardiogram (ECG) and echocardiographic parameters of atrial electromechanical delay (EMD), as well as contraction synchrony during different atrial pacing modalities. Methods: In 57 patients with sinus node disease and prolonged sinus P‐wave duration treated with multisite atrial pacing (MSAp), the EMD was measured by tissue Doppler in several left and right atrial sites during sinus rhythm, MSAp, and single‐site pacing at right atrial appendage (RAAp), Bachmann's bundle (BBp) region, and coronary sinus (CSp) ostium. Regional atrial synchrony was calculated on the basis of EMD. Results: P‐wave duration was 141 ± 16, 120 ± 17, 138 ± 17, 144 ± 16, and 160 ± 19 ms during sinus rhythm, MSAp, BBp, CSp, and RAAp, respectively (P < 0.001 RAAp and MSAp vs other). P‐wave duration correlated with all atrial EMDs as well as interatrial and intraleft atrial parameters of dyssynchrony. In multivariate analysis, the EMD in lateral left atrial wall was the strongest predictor of P‐wave duration (β 0.41; P < 0.001). The relationship between P‐wave duration and the atrial EMDs was most prominent during RAAp (all left atrial walls r > 0.51; P < 0.01) and BBp (all atrial walls r > 0.42; P < 0.05), while during sinus rhythm and CSp, only weak correlation between echo and ECG was found. Neither of the tissue Doppler parameters correlated with P‐wave duration during MSAp. Interatrial dyssynchrony correlated with P‐wave duration during sinus rhythm and RAAp and intraleft atrial dyssynchrony only during sinus rhythm. Conclusions: P‐wave duration of the surface ECG is highly correlated with the atrial EMD, the relationship is specific for each pacing modality. (PACE 2011; 23–31)     

Significant Reduction of Atrial Defibrillation Threshold and Inducibility by Catheter Ablation of Atrial Fibrillation

Background: Radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) has antiarrhythmic effects by multiple mechanisms. We hypothesized that RFCA curtails atrial defibrillation threshold (A‐DFT) and postablation induction pacing cycle length (iPCL), making critical mass reduction one potential mechanism by which antiarrhythmic effect is achieved. Methods: We included 289 patients with AF (male 77.9%, 55.7 ± 10.8 years old; 197 paroxysmal AF: 92 persistent AF) who underwent RFCA. A‐DFT (serial internal cardioversion 2, 3, 5, 7, and 10 J) and iPCL (serial 10 mA 10‐second atrial pacing with pacing cycle length 250, 200, 190, 180, 170, 160, and 150 ms) were evaluated before and after RFCA. Results: (1) RFCA of AF reduced the A‐DFT from 6.7 ± 3.7 J to 3.0 ± 3.0 J (P < 0.001). (2) AF ablation reduced AF inducibility from 95.4% before the procedure to 56.3% after the procedure (P < 0.001), and the iPCL from 194.8 ± 32.6 to 160.9 ± 26.2 ms (P < 0.001). (3) In patients who underwent a greater number of ablation lines, the post‐RFCA A‐DFT (P < 0.001) was lower, and %ΔA‐DFT (P = 0.003) and proportion of atrial tachycardia (P = 0.022) were higher than those with a lower number of ablation lines. Conclusion: AF ablation significantly reduced A‐DFT, AF inducibility, and iPCL, and the degree of their reduction was related to the number of ablation lines. (PACE 2012;35:1428–1435)     

Left Atrial Ablation at the Anatomic Areas of Ganglionated Plexi for Paroxysmal Atrial Fibrillation

Background: Modification of left atrial ganglionated plexi (GP) is a promising technique for the treatment of paroxysmal atrial fibrillation (AF) but its therapeutic efficacy is not established. This study aimed at evaluating the effectiveness of anatomic GP modification by means of an implantable arrhythmia monitoring device. Methods: In 56 patients with paroxysmal AF, radiofrequency ablation at anatomic sites, where the main clusters of GP have been identified in the left atrium, was performed. In all patients, an electrocardiogram monitor (Reveal XT, Medtronic Inc., Minneapolis, MN, USA) was implanted before (n = 7) or immediately after (n = 49) AF ablation. Results: Average duration of the procedure was 142 ± 18 min and average fluoroscopy time 20 ± 7 min. In total, 53–81 applications of RF energy were delivered (mean of 18.2 ± 3.8 at each of the four areas of GP ablation). Heart rate variability was assessed in 31 patients. Standard deviation of RR intervals over the entire analyzed period, the root mean square of differences between successive RR intervals, and high frequencies decreased, while HRmin, HRmean, and LF to HF ratio increased immediately postablation; these values returned to baseline 6 months after the procedure. At end of 12‐month follow‐up, 40 (71%) patients were free of arrhythmia recurrence. Ten patients had AF recurrence, two patients had left atrial flutter, and four patients had episodes of flutter as well as AF recurrence. Duration of episodes of AF after ablation gradually decreased over the follow‐up period. Conclusions: Regional ablation at the anatomic sites of the left atrial GP can be safely performed and enables maintenance of sinus rhythm in 71% of patients with paroxysmal AF for a 12‐month period. (PACE 2010; 33:1231–1238)     

Impact of impaired renal function and metabolic syndrome on the recurrence of atrial fibrillation after catheter ablation: a long term follow-up

Background: The goal of this study was to analyze impact of metabolic syndrome (MetS) and impaired renal function on long‐term follow‐up after catheter ablation of atrial fibrillation (AF). Methods and Results: A total of 702 consecutive patients with AF (age = 58 year, history of AF = 5 year, male = 478, paroxysmal atrial fibrillation = 416, coronary artery disease = 62, hypertension = 487) considered for catheter ablation were enrolled in the study. The MetS was diagnosed at admission in 276 patients. The renal function was estimated by glomerular filtration rate (eGFR). Pulmonary vein isolation (PVI) was performed either with cryoballoon technique (n = 260) or circumferential PVI (n = 442) with a 3.5‐mm irrigated tip catheter. A 7‐day‐Holter electrocardiogram was performed at each follow‐up visit. Any episode of documented AF after an initial 3‐month blanking period was considered as clinical endpoint. Out of 702 patients, 370 (52.7%) were free of AF recurrences at median follow‐up of 15 six interquartile range (12.7–42.3) months. The patients with MetS had significantly lower success rate than those without (128/276 (46.4%) vs 242/426 (56.8%), P = 0.006). Among 103 patients with eGFR < 68 mL/min only 35 (34%) were free of recurrences compared with 335/599 (55.9%) in patients with GFR ≥ 68 mL/min (P = 0.001). Both parameters were revealed in multivariate analysis to be independent predictors for outcome after catheter ablation. Conclusion: The results of our study clearly demonstrated that outcome after 1st catheter ablation of AF is poor in patients with MetS and/or impaired renal function. This observation has a potential clinical impact for the follow up management of these patients. (PACE 2012;1–12)     

The prevalence and prognostic significance of interatrial block in the general population

Abstract

Introduction: Partial and advanced interatrial block (IAB) in the electrocardiographic (ECG) represents inter-atrial conduction delay. IAB is associated with atrial fibrillation (AF) and stroke in the general population.

Material and methods: A representative sample of Finnish subjects (n?=?6354) aged over 30?years (mean: 52.2?years, standard deviation: 14.6) underwent a health examination including a 12-lead ECG. Five different IAB groups based on automatic measurements were compared to normal P waves using multivariate-adjusted Cox proportional hazard model. Follow-up lasted up to 15?years.

Results: The prevalence of advanced and partial IAB was 1.0% and 9.7%, respectively. In the multivariate model, both advanced (hazard ratio (HR): 1.63 (95% confidence interval (CI): 1.00?2.65)) and partial IAB (HR: 1.39 (1.09?1.77)) were associated with increased risk of AF. Advanced IAB was associated with increased risk of stroke or transient ischaemic attack (TIA) independently of associated AF (HR: 2.22 (1.20?4.13)). Partial IAB was also associated with increased risk of being diagnosed with coronary heart disease (HR: 1.26 (1.01?1.58)).

Discussion: IAB is a rather frequent finding in the general population. IAB is a risk factor for AF and is associated with an increased risk of stroke or TIA independently of associated AF.

• Key messages

• Both partial and advanced interatrial block are associated with increased risk of atrial fibrillation in the general population.

• Advanced interatrial block is an independent risk factor for stroke and transient ischaemic attack.

• The clinical significance of interatrial block is dependent on the subtype classification.

     

Immediate and Short-Term Reproducibility of the P Wave Signal-Averaged Electrocardiogram

While abnormalities in the P wave SAECG have been associated with the occurrence of AF, its reproducibility has never been documented. The purpose of this study was to evaluate the immediate and short-term reproducibility of measurements from the P wave SAECG. P wave SAECGs were obtained using well-described techniques that utilize the QHS complex as the trigger and the P wave as template for averaging. In 28 subjects (8 controls, 11 with cardiac disease, 9 with prior AF), 3 P wave SAECGs were obtained: an initial study; an immediate reacquisition; and reacquisition after 4–5 days. Vector duration and RMS voltage of the terminal 20 ms of the P wave SAECG were measured and compared. The mean P wave duration was 152 ± 14 ms on initial SAECG, 152 ± 14 ms and 152 ± 15 ms at immediate and short-term reacquisitions, respectively (both P = NS vs initial). The mean terminal BMS voltage was 6.4 ± 6.0 mcV on initial SAECG, 6.4 ± 5.9 mcV and 6.5 ± 5.8 meV at immediate and short-term reacquisitions, respectively (both P = NS vs initial). Linear regression analysis showed high reproducibility for both P wave duration (r = 0.94 for immediate and r = 0.96 for short-term reacquisition vs initial) but slightly less for terminal RMS voltage (r = 0.92 for immediate and r = 0.84 for short-term reacquisition vs initial). In subgroup analysis, P wave duration measurements were highly reproducible in controls, in subjects with cardiac disease, and in those with a history of AF. P wave duration was also reproducible for both males and females, as well as for subjects age > 65 years (r = 0.96 and 0.89 for immediate and short-term reacquisition, respectively). Terminal RMS voltage measurements were reproducible for controls, but less reproducible in other subgroups. In conclusion, P wave duration measurements on SAEGG are reproducible when evaluated at immediate and short-term reacquisition regardless of age, sex, cardiac disease, or prior AF. Terminal RMS voltages were less reproducible, especially in patients with cardiac disease and/or prior AF. These findings may explain conflicting observations regarding the clinical utility of terminal P wave measurements.