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.     

Abnormal right atrial electrograms predict the transition to chronic atrial fibrillation in paced patients with sick sinus syndrome

Although pacing therapy for sick sinus syndrome (SSS) is established, the risk of developing chronic atrial fibrillation (CAF) makes pacing therapy infeasible in some patients. We evaluated whether electrophysiological characteristics of atrial muscle can serve as predictors of the transition to CAF after pacemaker implantation in patients with SSS. Eighty-nine patients with SSS underwent electrophysiological study before pacing therapy. Catheter mapping of 12 right atrial sites was performed during sinus rhythm during electrophysiological. An abnormal atrial electrogram was defined as having a duration of 100 ms or longer, or eight or more fragmented deflections, or both. Right atrial extrastimulation was also performed for atrial vulnerability. After electrophysiological study, all patients underwent pacemaker implantation and were followed up. During the follow-up period of 85 +/- 50 months, development of CAF was observed in 12 patients (group A). The remaining 77 patients remained in sinus rhythm (group B). There were significantly more abnormal atrial electrograms in group A than group B (2.7 +/- 2.3 vs 0.8 +/- 1.2; P < 0.001). The distribution of abnormal atrial electrograms was also greater in group A; patients in group A had more abnormal atrial electrograms than patients in group B in both the high and middle right atrium (P < 0.005 and P < 0.01, respectively). Kaplan-Meier analysis showed that almost 50% of the paced patients with abnormal atrial electrograms (n = 42) developed CAF (P < 0.005). Our data suggest that the existence of abnormal atrial electrograms is predictive of the transition to CAF in paced patients with SSS.     

P wave dispersion on 12-lead electrocardiography in patients with paroxysmal atrial fibrillation

The prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses have been shown in patients with atrial fibrillation. Recently P wave dispersion (PWD), which is believed to reflect inhomogeneous atrial conduction, has been proposed as being useful for the prediction of paroxysmal atrial fibrillation (PAF). Ninety consecutive patients (46 men, 44 women; aged 55 +/- 13 years) with a history of idiopathic PAF and 70 healthy subjects (42 men, 28 women; mean age 53 +/- 14 years) were studied. The P wave duration was calculated in all 12 leads of the surface ECG. The difference between the maximum and minimum P wave duration was calculated and this difference was defined as P wave dispersion (PWD = Pmax-Pmin). All patients and controls were also evaluated by echocardiography to measure the left atrial diameter and left ventricular ejection fraction (LVEF). There was no difference between patients and controls in gender (P = 0.26), age (P = 0.12), LVEF (66 +/- 4% vs 67 +/- 5%, P = 0.8) and left atrial diameter (36 +/- 4 mm vs 34 +/- 6 mm, P = 0.13). P maximum duration was found to be significantly higher in patients with a history of PAF (116 +/- 17 ms) than controls (101 +/- 11 ms, P < 0.001). P wave dispersion was also significantly higher in patients than in controls (44 +/- 15 ms vs 27 +/- 10 ms, P < 0.001). There was a weak correlation between age and P wave dispersion (r = 0.27, P < 0.001). A P maximum value of 106 ms separated patients with PAF from control subjects with a sensitivity of 83%, a specificity of 72%, and a positive predictive accuracy of 79%. A P wave dispersion value of 36 ms separated patients from control subjects with a sensitivity of 77%, a specificity of 82%, and a positive predictive accuracy of 85%. In conclusion, P maximum duration and P wave dispersion calculated on a standard surface ECG are simple ECG markers that could be used to identify the patients with idiopathic paroxysmal atrial fibrillation.     

Pacemaker diagnostics to determine treatment and outcome in sick sinus syndrome with paroxysmal atrial fibrillation

Sequential analysis of pacemaker diagnostics has been used to help manage the treatment and pacemaker program in patients who have sick sinus syndrome with documented paroxysmal atrial fibrillation. One hundred consecutive patients were followed for an average of 18 months. Knowledge of the atrial fibrillation burden led to major changes in medical management for half of the patients and changes to pacemaker programming for all. At the end of the study, 48 patients were free of arrhythmia with pacing although 14 required antiarrhythmic medication. We advocate using pacemaker diagnostics to improve patient management.     

P波离散度对高血压病并发阵发性心房颤动患者的预测价值

目的　探讨P波离散度(Pd)对高血压病患者阵发性心房颤动的预测价值。方法　Ⅰ组38例,为有阵发 性心房颤动病史的高血压病患者;Ⅱ组54例,为无阵发性心房颤动病史的高血压病患者。同步记录窦性心律时12导 联心电图,分别测定12导联P波时限[Pd=最大P波时限(Pmax)-最小P波时限(Pmin)],超声心动图测定左心房内径 (LAD)、左心室舒张末期内径(LVD)和左心室射血分数(LVEF)。以Pd≥40ms为阳性标准,检测阵发性心房颤动的 阳性率、灵敏性、特异性。结果　Pmax:Ⅰ组显著高于Ⅱ组[Ⅰ组与Ⅱ组比较:(127±15)ms对(110±12)ms,P< 0.001];Pd:Ⅰ组显著高于Ⅱ组[Ⅰ组与Ⅱ组比较:(53±13)ms对(39±10)ms,P<0.01];LAD:Ⅰ组高于Ⅱ组[Ⅰ 组与Ⅱ组比较:(46±9)mm对(41±7)mm,P<0.05];LVEF:Ⅰ组低于Ⅱ组[Ⅰ组与Ⅱ组比较:(51±6)%对 (58±6)%,P<0.05];Pmin、LVD两组差别无统计学意义。单因素回归分析显示:除LVD外,Pmax、Pd、LAD和 LVEF均是阵发性心房颤动的预测因子。多因素回归分析显示:Pd是阵发性心房颤动的独立预测因子。以Pd≥40 ms为阳性标准,检测阵发性心房颤动的Ⅰ组阳性率显著高于Ⅱ组(P<0.01),灵敏性84.2%、特异性85.2%。结论　 Pd是高血压病患者发生阵发性心房颤动的独立预测因子,预测价值高。     

最大P波时限及P波离散度对预测特发性房颤的价值

目的：探讨最大Ｐ波时限及Ｐ波离散度（最大、最小Ｐ波时限之差）对特发性房颤的预测价值。方法：对２０例有特发性房颤病史者及２０例年龄、性别匹配的健康者,行１２导联同步体表心电图记录,测定最大Ｐ波时限及Ｐ波离散度。结果：在特发性房颤组,最大Ｐ波时限及Ｐ波离散度均较对照组增大（Ｐ〈０．０１）,最大Ｐ波时限〉１１０ｍｓ、Ｐ波离散度〉４０ｍｓ以及两者相结合对特发性房颤预测的敏感性和特异性分别为９０％、８５％和７５％及８０％、８５％和９０％。结论：最大Ｐ波时限及Ｐ波离散度可用于预测特发性房颤。     

Preprocedural ventricular rate predicts subsequent sick sinus syndrome after ablation for long-standing persistent atrial fibrillation

Background: Concealed sick sinus syndrome may become manifest after restoration of sinus rhythm by ablation in patients with long-standing persistent atrial fibrillation (AF). The purpose of this study was to investigate the association between the preprocedural ventricular rate during AF and sinus node function in patients with long-standing persistent AF. Methods: Consecutive patients (n = 102) who underwent ablation for long-standing persistent AF were enrolled. We measured the ventricular rate during AF before ablation in the absence of antiarrhythmic drugs. Sinus node function was assessed by electrophysiological study and serial Holter recordings after ablation. Results: Patients in the lowest quartile of ventricular rate during AF had longer corrected sinus node recovery time (1.06 ± 1.39 seconds) than those in the other quartiles (0.54 ± 0.31 seconds; P = 0.006) and lower mean heart rate on 24-hour Holter recording 3 months after ablation (68 ± 9 beats/min vs 75 ± 10 beats/min, P = 0.01). During a mean follow-up of 23 ± 10 months, sick sinus syndrome necessitating permanent pacemaker implantation developed in five (5%) patients, and multivariate analysis revealed that a low ventricular rate during AF rate was an independent risk factor for sick sinus syndrome (odds ratio = 0.90 for a 1 beat/min increase in AF rate, P = 0.04). Conclusions: A low preprocedural ventricular rate during AF indicates the existence of sinus node dysfunction after restoration of sinus rhythm by ablation in patients with long-standing persistent AF. (PACE 2012; 35:1074-1080).     

P波离散度与原发性高血压病合并阵发性心房颤动关系的临床分析

目的:探讨P波离散度(Pd)与高血压病合并阵发性心房颤动(房颤)的临床关系。方法:测量57例高血压合并阵发性房颤患者(Ⅰ组)窦性心律时12导联心电图的P波离散度[Pd=最大P波时限(Pmax)-最小P波时限(Pmin)],超声心动图测定左心房内径(LAD)、左心室舒张末期内径(LVD)和左心室射血分数(LVEF),并与单纯高血压组(Ⅱ组)55例比较。检测阵发性房颤的敏感度、特异度、阳性预测值。结果:PmaxⅠ组显著高于Ⅱ组[(121.5±16.3)msvs(107.3±10.3)ms,P<0.05];PdⅠ组显著高于Ⅱ组(45.3±12.7)msvs(24.7±10.5)ms,P<0.05);两组间Pmin、LAD、LVEF差异无显著性。Pmax>100ms预测的敏感性为89.5/,特异性为80.0/;Pd≥40ms预测的敏感性为86.0/,特异性为75.9/;Pmax>100ms Pd≥40ms的敏感性为78.5/,特异性为88.9/。结论:P波离散度是高血压病患者合并阵发性房颤的敏感性和特异性较高的预测指标之一。     

AV block and changes in pacing mode during long-term follow-up of 399 consecutive patients with sick sinus syndrome treated with an AAI/AAIR pacemaker

This retrospective study included a large cohort of consecutive patients primarily implanted at Skejby University Hospital with an AAI/AAIR pacemaker because of sick sinus syndrome (SSS) from July 1981 to July 1999. The primary aim of the study was to analyze the risk of developing AV block during long-term follow-up. A secondary aim was to study the incidence and reasons for changes in pacing mode caused by other than AV block. A total of 399 patients (231 women, mean age 71 +/- 13.5 years) were identified. Mean follow-up was 4.6 +/- 3.4 years and occurred at death, reoperation with mode change, pacemaker explant, or end of study. During follow-up, 44 patients had a ventricular lead implanted with a mean delay of 2.8 +/- 3.1 years (range 1 day-10.4 years) after the primary implantation. A total of 30 patients received a ventricular lead because of AV block or AF with bradycardia (annual incidence 1.7%). Another 14 patients received a ventricular lead without having documented AV block or AF with pauses (annual incidence 0.8%). The present observational study documents that in patients with SSS treated with AAI/AAIR pacing, AV block requiring implantation of a ventricular lead occurs at a rate of 1.7% per year. It is considered that AAI/AAIR pacing is safe and reliable as treatment for patients with SSS and normal AV conduction.     

Dual-site right atrial pacing increases left atrial appendage flow in patients with sick sinus syndrome and paroxysmal atrial fibrillation

BACKGROUND: Dual-site right atrial pacing has been proposed as a promising concept for prevention of paroxysmal atrial fibrillation (PAF). Effects of this pacing configuration on left atrial appendage (LAA) flow and transmitral flow may be of prognostic and hemodynamic relevance. This study aims to characterize acute changes in left atrial flow depending on dual-site right atrial pacing. METHODS: In 12 patients (66 +/- 8.8 years, 4 women) with PAF and sinus bradycardia a pacemaker with a right atrial dual-site lead configuration (right atrial lateral and coronary sinus ostium) was implanted. Flow velocities in the left pulmonary vein (LPV), LAA, and across the mitral valve were assessed by transesophageal echocardiography and compared during sinus rhythm (SR) and dual-site (DS) pacing. RESULTS: Dual-site pacing resulted in higher maximum (SR: 0.57 m/s; pacing: 0.77 m/s; P < 0.02) and mean (SR: 0.33 m/s; DS: 0.47 m/s; P < 0.01) LAA emptying flow when compared with SR. The passive transmitral flow component (maximum E-wave velocity) was lower during dual-site pacing (SR: 0.53 m/s vs DS: 0.44 m/s, P < 0.02). The E/A ratio tended to be lower during dual-site pacing (SR: 1.21 vs DS: 1.01, P = 0,10). LPV flow velocities during SR and DS pacing did not differ. CONCLUSION: DS right atrial stimulation in patients with PAF increases the LAA emptying flow velocity and shifts the transmitral flow pattern towards a lower passive component when compared with sinus rhythm. The change in LAA flow may contribute to a lower incidence of thromboembolism and merits further investigation.     

Acute coronary syndrome: Short-term effects of early intravenous metoprolol on maximum P wave duration and P wave dispersion

In patients with acute coronary syndrome (ACS), the presence of atrial fibrillation (AF) results in worse inpatient outcomes than in those without AF. Two electrocardiographic markers, maximum P wave duration (P_maximum) and P wave dispersion (P_dispersion), have been assessed because they reflect conduction abnormalities in patients with paroxysmal AF. β blockers are known to have beneficial effects in patients with ACS. This prospective study was conducted to investigate whether early intravenous (IV) metoprolol injection acutely decreases P_maximum and P_dispersion in patients with ACS. This study involved 100 consecutive patients with ACS who were divided into 2 groups according to whether or not they received early IV metoprolol. Group 1 consisted of 19 patients who received IV metoprolol within 3 h after onset of symptoms, and group 2 consisted of 81 patients who did not receive IV metoprolol within 3 h after symptom onset because of late admission. P_maximum and P_dispersion were measured on admission and again at 2 h after admission. Two-dimensional echocardiographic examination was also performed. For patients who received early IV metoprolol, P_maximum and P_dispersion, measured 2 h after admission, were shorter than values at admission (P<.001). Conversely, P_maximum and P_dispersion, measured 2 h after admission, did not differ significantly from values at admission in patients who did not receive early IV metoprolol (P=.292 andP=.236, respectively). IV administration of metoprolol reduced values for P_maximum and P_dispersion, measured 2 h after admission, among patients with ACS who were admitted within 3 h after onset of symptoms.     

P wave separation after atrial compartment operation for atrial fibrillation

Surgically induced abnormalities in atrial conduction could result in unusual P wave changes. A 31-year-old woman underwent concomitant mitral valve surgery and atrial compartment operation for mitral stenosis and atrial fibrillation (AF). After operation, the AF was successfully converted to sinus rhythm, whereas an unusual electrocardiogram (ECG) with a discrete negative deflection before the T wave in V1 was noted. Electrophysiological study showed a marked conduction delay from the high right atrium (HRA) to the right atrial appendage (RAA) compartment, which resulted in a separation of P waves. The P wave preceding the QRS complex represented the activation of sinus node and the left atrial compartments, and the P at the vicinity of T wave represented the activation of RAA compartment. The conduction from HRA to RAA was worsened on HRA pacing at a faster rate, and improved after isoproterenol infusion. This report demonstrated that conduction across a surgically created isthmus in the atrium could be severely impaired and result in unusual P wave separation.     

经皮球囊二尖瓣成形术对风湿性心脏病二尖瓣狭窄伴阵发性房颤患者P波离散度的影响

目的　探讨经皮球囊二尖瓣成形术 (PBMV)对风湿性心脏病二尖瓣狭窄伴阵发性房颤患者P波离散度的影响。方法　风湿性心脏病二尖瓣狭窄患者 90例。依据患者是否伴阵发性房颤分为两组。不伴阵发性房颤 (A组 ) 6 0例 ,伴阵发性房颤 (B组 ) 30例 ,均接受PBMV术 ,分别测量两组患者术前及术后 3个月P波最大时限 (Pmax)和P波离散度 (Pd)。结果　术前B组患者Pmax及Pd显著高于A组 (P <0 .0 1) ,术后 3个月B组患者Pmax及Pd较术前显著减低 (P <0 .0 1)。结论　Pmax及Pd可预测风湿性心脏病二尖瓣狭窄患者伴阵发性房颤的发生 ;PBMV术可改善心房电传导。降低风湿性心脏病二尖瓣狭窄伴阵发性房颤患者的Pmax及Pd。     

Increased variance of P wave duration on the electrocardiogram distinguishes patients with idiopathic paroxysmal atrial fibrillation

We hypothesized that the variance of P wave duration (P variance) in the 12-lead ECG could reflect the spatial dispersion of P wave duration due to inhomogeneous and delayed propagation of sinus impulses in the atria, and moreover could present better reproducibility than maximum P wave duration and P wave dispersion that have already been used for the prediction of idiopathic paroxysmal AF. We also tested a semiautomated PC-based method to improve the accuracy and reproducibility of P wave measurements. A 12-lead ECG was obtained from 60 patients with idiopathic paroxysmal AF and from 50 healthy controls. All ECGs were analyzed manually using magnifying lens and calipers, while 20 randomly selected ones were scanned and analyzed on screen using common commercial software. P maximum, P dispersion, and P variance were all significantly higher in patients with paroxysmal AF than in controls. A P maximum value of 110 ms, a P dispersion value of 40 ms, and a P variance value of 120 ms2 separated patients from controls with a sensitivity of 88%, 83%, and 80%, respectively and a specificity of 75%, 85%, and 74%, respectively. The reproducibility of P variance was higher compared to P dispersion and P maximum. Finally, the PC-based method significantly increased accuracy and reproducibility of P wave measurements. Thus, the variance of P wave duration could be a useful ECG marker for the prediction of paroxysmal idiopathic AF and the use of PC-based methods may enhance the accurate measuring of P wave duration on the ECG.     

二维斑点追踪技术评价心房同步性与病态窦房结综合征伴发阵发性心房颤动的关系

目的采用二维斑点追踪技术评价心房同步性与病态窦房结综合征伴发阵发性心房颤动的关系。 方法收集2015年1月至2016年8月在浙江省宁波市鄞州第二医院超声科行超声心动图检查的病态窦房结综合征患者。选择病态窦房结综合征不伴发阵发性心房颤动患者25例（病态窦房结综合征A组）,病态窦房结综合征伴发阵发性心房颤动患者19例（病态窦房结综合征B组）。选择同期本科行超声心动图检查的健康志愿者28名作为健康对照组。采用超声心动图评价所有受检者左心室结构和功能参数,在获取右心房游离壁、房间隔和左心房游离壁二维斑点追踪图像后,测量心电图P波起始点至图像上舒张期第二个负向波的时间间期,代表右心房游离壁电-机械运动时间（P-RA）、房间隔电-机械运动时间（P-IAS）和左心房游离壁电-机械运动时间（P-LA）,计算心房同步性参数。采用单因素方差分析比较3组受检者常规超声心动图参数、P-RA、P-IAS、P-LA及心房同步性参数差异,进一步组间两两比较采用SNK-q检验;采用Spearman相关分析法分析心房电-机械运动时间参数、心房同步性参数与阵发性心房颤动的相关性;绘制应用心房电-机械运动时间参数、心房同步性参数预测病态窦房结综合征伴发阵发性心房颤动的受试者工作特征（ROC）曲线。 结果病态窦房结综合征A组、病态窦房结综合征B组患者左心房前后径（LAD）均大于健康对照组受检者,且差异均有统计学意义（q=4.18、5.37,P均<0.05）;而病态窦房结综合征A组与病态窦房结综合征B组患者LAD差异无统计学意义。病态窦房结综合征A组、病态窦房结综合征B组患者P-RA、P-IAS均大于健康对照组受检者,且差异均有统计学意义（q=4.03、4.10;q=4.16、4.31,P均<0.05）,但病态窦房结综合征A组与病态窦房结综合征B组患者P-RA、P-IAS差异均无统计学意义;P-LA、右心房内同步性、左心房内同步性和左右心房间同步性均为健康对照组<病态窦房结综合征A组<病态窦房结综合征B组,且任意两组间差异均有统计学意义（q=5.18、11.23、4.43;q=5.25、11.74、4.63;q=7.38、14.67、4.73;q=8.01、16.37、6.39,P均<0.05）。Spearman相关分析结果显示,P-LA、右心房内同步性、左心房内同步性和左右心房间同步性与病态窦房结综合征伴发阵发性心房颤动均呈正相关（r=0.61、0.55、0.75、0.78,P均<0.01）,其中,左右心房间同步性与与病态窦房结综合征伴发阵发性心房颤动的相关性最佳。ROC曲线显示,P-LA预测病态窦房结综合征伴发阵发性心房颤动的最佳阈值为94 ms,敏感度和特异度分别为68.42%和76.00%,曲线下面积为0.764（95% CI 0.612~0.879）;右心房内同步性预测病态窦房结综合征伴发阵发性心房颤动的阈值为19 ms,敏感度和特异度分别为57.89%和76.00%,曲线下面积为0.714（95% CI 0.558~0.840）;左心房同步性预测病态窦房结综合征伴发阵发性心房颤动的阈值为42 ms,敏感度和特异度分别为78.95%和76.00%,曲线下面积为0.860（95% CI 0.722~0.946）;左右心房间同步性预测病态窦房结综合征伴发阵发性心房颤动的阈值为68 ms,敏感度和特异度分别为84.21%和84.00%,曲线下面积为0.859（95% CI 0.721~0.945）;ROC曲线下面积显示,左心房内同步性和左右心房间同步性预测病态窦房结综合征伴发阵发性心房颤动的效能优于右心房内同步性。 结论心房电-机械运动时间参数和同步性参数与病态窦房结综合征伴发阵发性心房颤动关系密切。左心房内同步性和左右心房间同步性预测病态窦房结综合征伴发阵发性心房颤动的价值最佳。     

Clinical and electrocardiographic predictors of recurrent atrial fibrillation

Patients with frequent episodes of paroxysmal atrial fibrillation (AF) are prone to develop permanent AF and have an increased thromboembolic risk. We have previously shown that P wave dispersion (P dispersion), defined as the difference between the maximum and the minimum P wave duration, and maximum P wave duration (P maximum) can distinguish patients with paroxysmal lone AF. The ability of those ECG markers and of other clinical and ECG variables to detect patients at risk for recurrent AF was tested in 88 patients, aged 64 +/- 12 years. All patients had a history of symptomatic episodes of AF during the last 2 years and had not previously received any antiarrhythmic prophylaxis. P maximum and P dispersion were calculated from a 12-lead surface ECG recorded in all patients during sinus rhythm. A computerized ECG system was used and P maximum and P dispersion were calculated on screen from the averaged complexes of all 12 leads. Age (P = 0.01), history of organic heart disease (P = 0.03), P maximum (P < 0.001), minimum P wave duration (P = 0.05), and P dispersion (P < 0.001) were found to be significant univariate predictors of recurrent AF, whereas only P maximum (P < 0.001) and age (P = 0.037) remained significant independent predictors of frequent AF paroxysms in the multivariate analysis. It is concluded that advanced age and prolonged P wave duration may be used as predictors of frequently relapsing AF. Therefore, simple AF predictors exist that could possibly distinguish the patients in whom prophylaxis with antiarrhythmic medicines should be instituted.     

Brugada-type ECG association with unexpected sick sinus syndrome

A 23-year-old man was referred to our center for atrial flutter ablation. After arrhythmia termination sinus node dysfunction unmasked and persisted after 2 months drug-free follow-up. Secondary causes such as antiarrhythmic drug consumption, organic heart disease, or electrolyte disturbance could be excluded. Standard 12-lead ECG showed a coved-type ST elevation in V1-V3, which increased after flecainide provocative test. Following an unexpected sick sinus syndrome, a Brugada-type ECG should be noted.     

非瓣膜性心脏病患者心房颤动发作持续时间不同对P波离散度的影响

目的　分析非瓣膜性心脏病患者心房颤动发作持续时间不同对P波离散度的影响。方法　根据房颤发作持续时间不同将 6 7例非瓣膜性心脏病患者分为两组 :短时房颤组 (≤ 4 8小时 ) 35例和长时房颤组 (>4 8小时 ,<3个月 ) 32例。同步体表 12导联心电图 ,计算P波最大时限和P波离散度 ;超声心动图测定左心房内径 ;分析P波最大时限和P波离散度与临床、超声参数之间的相关关系。结果　两组在年龄、性别和基础疾病组成方面无差别。长时房颤组左心房内径显著高于短时房颤组 [(40 .5 9± 2 .5 8)mmvs (38.6 0± 3.4 3)mm ,t =2 .70 4 ,P =0 .0 0 9]、P波最大时限长 [(12 2 .91± 11.74 )msvs(114 .6 9± 9.2 2 )ms,t =3.16 8,P =0 .0 0 2 ]、P波离散度大 [(6 0 .5 3± 11.14 )msvs(5 1.6 6± 10 .6 1)ms ,t =3.331,P =0 .0 0 1]。相关分析显示P波最大时限和P波离散度均与房颤发作持续时间 (r值分别为 0 .6 88,0 .5 4 6 ;P 均 <0 .0 0 1)和左心房内径相关 (r值分别为 0 .716 ,0 .6 0 3;P 均 <0 .0 0 1) ,与年龄无关。结论　长时房颤组较短时房颤组P波最大时限长和P波离散度大 ,与左心房扩大有关。     

Pacing of the Atria in Sick Sinus Syndrome Trial: Preventive Strategies for Atrial Fibrillation

SPITZER, S.G., et al .: Pacing of the Atria in Sick Sinus Syndrome Trial: Preventive Strategies for Atrial Fibrillation. This study examines the effects of various atrial lead positions in physiological pacing on the incidence of AF in patients with sick sinus syndrome. The lead is implanted in the RA free wall, in the RA appendage, near the coronary sinus ostium (CSO) or, in dual site RA pacing, in the appendage and the CSO. Since CSO and dual site right atrial pacing aim at modifying the pathological substrate, pacing of two-thirds of all cardiac cycles is attempted by adapting the basic rate and the rate response option. The results of this study are expected to assist in the development of guidelines for the placement of atrial pacing leads in sick sinus syndrome. (PACE 2003; 26[Pt. II]:268–271)     

Electrophysiological properties of the left atrium evaluated by coronary sinus pacing in patients with atrial fibrillation

Repetitive atrial firing (RAF), marked fragmentation of atrial activity (FAA), and interatrial conduction delay (CD) have been shown to be electrophysiological features of the atrium in patients with atrial fibrillation (AF). Moreover, it has been observed that atrial extrastimuli are more likely to induce AF when delivered from the right atrial appendage (RAA) than from the distal coronary sinus (CSd). We examined the electrophysiological properties of the atrial muscle by CS and RAA stimulation in patients with paroxysmal AF. Patients were divided into two groups: group I, consisting of 18 patients with clinical paroxysmal AF; and group II, consisting of 22 patients with various cardiac arrhythmias in which the substrate does not exist in the atrium. In group I, the following values of electrophysiological parameters of the atrium indicated that AF was more likely to be induced during RAA pacing than CSd pacing: atrial effective refractory period (RAA vs CSd: 201 +/- 28 ms vs 240 +/- 35 ms, P < 0.001), RAF zone (16 +/- 25 ms vs 0 +/- 0 ms, P < 0.03), FAA zone (38 +/- 37 ms vs 5 +/- 19 ms, P < 0.01), maximum interatrial conduction time (144 +/- 19 ms vs 93 +/- 19 ms, P < 0.0001) and CD zone (53 +/- 21 ms vs 9 +/- 18 ms, P < 0.0001). The values of the electrophysiological parameters of the atrium evaluated by CSd pacing in group I patients were not significantly different from those in group II patients. In conclusion, when coronary sinus stimulation is performed, electrophysiological properties of the atrium in patients with AF show a significant decrease in atrial vulnerability compared to stimulation from RAA and also show similar values to those in patients without AF. It might be suggested that the left posterior or posterolateral atrium is electrophysiologically stable even in patients with paroxysmal AF.