Prolonged Atrium Electromechanical Interval Is Associated with Stroke in Patients with Atrial Fibrillation After Catheter Ablation

Electromechanical Interval and Strokes After Ablations of AF . Introduction: Atrial fibrillation (AF) is associated with increased risk of embolic stroke. Catheter ablation of AF provides an effective therapy for patients with symptomatic and drug‐refractory AF. The aim of this study was to evaluate whether the atrial electromechanical interval is useful in identifying patients at risk of stroke after successful catheter ablation. Methods and Results: A total of 279 AF patients who received catheter ablation and showed no evidence of recurrences were enrolled. Electromechanical interval (PA–PDI) was determined as the time interval from the initiation of P wave deflection to the peak of mitral inflow A wave on pulse wave Doppler imaging. The PA–PDI interval was measured for each patient after the 3‐month blanking period of catheter ablation. The clinical endpoint was the occurrence of ischemic stroke. During the follow‐up of 46.5 ± 17.2 months, 6 patients suffered from ischemic strokes. Patients with strokes had higher CHA₂DS₂–VASc scores and longer PA–PDI intervals (138.7 ± 12.4 ms vs 161.2 ± 7.7 ms, P value < 0.001) compared to those without strokes. At a cutoff point of 150 ms identified by ROC curve, the positive and negative predictive values of the PA–PDI interval to predict stroke were 86.7% and 100%, respectively. The PA–PDI interval improved the predictive performance of the CHA₂DS₂–VASc score, and the area under the ROC curve increased from 0.75 to 0.85. Conclusions: Our results suggest that the PA–PDI interval is a useful tool to identify patients with high risk of stroke after successful catheter ablation of AF. (J Cardiovasc Electrophysiol, Vol. 24, pp. 375‐380, April 2013)     

Detection of atrial electrical and mechanical dysfunction in non-dipper pre-hypertensive subjects

Introduction: A relationship between atrial conduction time and hypertension was shown in previous studies. Increased atrial electromechanical intervals used to predict atrial fibrillation by measured tissue Doppler imaging (TDI). So we aimed to search if there was any association between the non-dipping status and atrial electromechanical intervals in pre-hypertensive patients.

Methods: Forty-one non-dipper and 33 dipper pre-hypertensive subjects enrolled in the study. Systolic and diastolic blood pressures were measured with a mercury sphygmomanometer. Twenty-four hours blood pressure was measured with cuff-oscillometric method. All patients were evaluated by transthoracic echocardiography. Using tissue Doppler imaging (TDI), atrial electromechanical coupling (PA) was measured from the lateral mitral annulus (PA lateral), septal mitral annulus (PA septum) and right ventricular tricuspid annulus (PA tricuspid).

Results: Systolic and diastolic blood pressures were significantly higher in subjects with non-dipper phenomenon than dipper ones at night. Twenty-four hours average systolic and diastolic blood pressures were higher in non-dipper pre-hypertensive subjects, but this elevation was not significant. Left and right intraatrial (PA lateral-PA septum and PA septum-PA tricuspid) and interatrial (PA lateral-PA tricuspid) electromechanical coupling intervals were measured significantly higher in non-dipper pre-hypertensive patients (31.3?±?3.9 versus 24.1?±?2.3, p?=?0.001; 19.5?±?4.3 versus 13.8?±?2.1, p?=?0.001; and 11.4?±?2.8 versus 8.8?±?1.5, p?=?0.001). Also, interatrial electromechanical delay was negatively correlated with dipping levels.

Conclusion: This study showed that prolonged atrial electromechanical intervals were related non-dipper pattern in pre-hypertensive patients. Prolonged electromechanical intervals may be an early sign of subclinical atrial dysfunction and arrhythmias’ in non-dipper pre-hypertensive patients.     

Direct conversion of atrial flutter to sinus rhythm with low-output,short-duration transesophageal atrial pacing

Background and hypothesis: Transesophageal atrial pacing (TAP) is useful for terminating paroxysmal non-selfterminating atrial flutter (RAF); however, high output pacing of long stimulus duration causes severe symptoms such as chest pain. The objective of this study was to investigate the effect of low-output, short-duration TAP on the conversion of PAF. Methods: We applied low-output (within 15 mA with a pulse duration of 10 ms), short-duration (within 4 s) TAP in 31 patients (50±19 years) with PAF. Transesophageal pacing was delivered with 10 pulses of burst pacing at intervals that were 20 ms shorter than those of the flutter wave length. When the conversion was unsuccessful, we delivered 20 pulses of burst pacing. Results: Sixteen patients (52%) were converted directly to sinus rhythm and 12 (38%) to atrial fibrillation. Transesophageal pacing was ineffective in 3 (10%) patients. The duration of atrial flutter, maximum flutter wave amplitude, effective pacing intervals, underlying heart diseases, and cardiac function were not different between patients who had direct conversion to sinus rhythm and those converted to atrial fibrillation. The patients who had direct conversion to sinus rhythm had longer flutter wave cycle lengths than those converted to atrial fibrillation (248 vs. 221 ms, p<0.005). No patient had complications and complained of any symptoms. Conclusion: Low-output, short-duration TAP was useful to convert PAF directly to sinus rhythm without side effects.     

A novel finding of the atrial substrate properties and long-term results of catheter ablation in chronic atrial fibrillation patients with left atrial spontaneous echo contrast

Atrial Substrate Properties in Chronic AF Patients with LASEC. Background: The atrial substrate in chronic atrial fibrillation (AF) patients with a left atrial spontaneous echo contrast (LASEC) has not been previously reported. The aim of this study was to investigate the atrial substrate properties and long‐term follow‐up results in the patients who received catheter ablation of chronic AF. Methods: Of 36 consecutive patients with chronic AF who received a stepwise ablation approach, 18 patients with an LASEC (group I) were compared with 18 age‐gender‐left atrial volume matched patients without an LASEC (group II). The atrial substrate properties including the weighted peak‐to‐peak voltage, total activation time during sinus rhythm (SR), dominant frequency (DF), and complex fractionated electrograms (CFEs) during AF in the bi‐atria were evaluated. Result: The left atrial weighted bipolar peak‐to‐peak voltage (1.0 ± 0.6 vs 1.6 ± 0.7 mV, P = 0.04), total activation time (119 ± 20 vs 103 ± 13 ms, P < 0.001) and DF (7.3 ± 1.3 vs 6.6 ± 0.7 Hz, P < 0.001) differed between group I and group II, respectively. Those parameters did not differ in the right atrium. The bi‐atrial CFEs (left atrium: 89 ± 24 vs 92 ± 25, P = 0.8; right atrium: 92 ± 25 vs 102 ± 3, P = 0.9) did not differ between group I and group II, respectively. After a mean follow‐up of 30 ± 13 month, there were significant differences in the antiarrhythmic drugs (1.1 ± 0.3 vs 0.7 ± 0.5, P = 0.02) needed after ablation, and recurrence as persistent AF (92% vs 50%, P = 0.03) between group I and group II, respectively. After multiple procedures, there were more group II patients that remained in SR, when compared with group I (78% vs 44%, P = 0.04). Conclusion: There was a poorer atrial substrate, lesser SR maintenance after catheter ablation and need for more antiarrhythmic drugs in the chronic AF patients with an LASEC when compared with those without an LASEC. (J Cardiovasc Electrophysiol, Vol. pp. 1‐8)     

Pulmonary Vein Isolation Alone in Patients with Persistent Atrial Fibrillation: An Ablation Strategy Facilitated by Antiarrhythmic Drug Induced Reverse Remodeling

PVI Alone in Patients with Persistent AF . Introduction: Pulmonary vein isolation (PVI) alone has been thought to be insufficient in patients with persistent atrial fibrillation (PersAF). We hypothesized that preablation treatment of PersAF with a potent antiarrhythmic drug (AAD) would facilitate reverse atrial remodeling and result in high procedural efficacy after PVI alone. Methods and Results: Seventy‐one consecutive patients (59.4 ± 9.8 years) with PersAF and prior AAD failure were treated with oral dofetilide (768 ± 291 mcg/day) for a median of 85 days pre‐PVI. P‐wave duration (Pdur) on ECG was used to assess reverse atrial remodeling. Thirty‐five patients with paroxysmal (P) AF not treated with an AAD served as controls. All patients underwent PVI alone; dofetilide was discontinued 1–3 mos postablation. In the PersAF patients, the Pdur decreased from 136.3 ± 21.7 ms (assessed postcardioversion on dofetilide) to 118.6 ± 20.4 ms (assessed immediately prior to PVI) (P < 0.001). In contrast, no change in Pdur (122.6 ± 11.5 ms vs. 121.3 ± 13.7 ms, P = NS) was observed in PAF patients. The 6 and 12 mos AAD‐free response to ablation was 76% and 70%, respectively, in PersAF patients, similar to the 80% and 75%, response in PAF patients (P = NS). A decline in Pdur in response to dofetilide was the only predictor of long‐term clinical response to PVI in patients with PersAF. Conclusions: Pre‐treatment with AAD resulted in a decrease in Pdur suggesting reverse atrial electrical remodeling in PersAF patients. This may explain the excellent clinical outcomes using PVI alone, and may suggest an alternative ablation strategy for PersAF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 142‐148, February 2011)     

Assessment of Atrial Electromechanical Coupling Characteristics in Patients with Ankylosing Spondylitis

Objective: The aim of this study was to evaluate atrial conduction abnormalities obtained by Doppler tissue imaging (DTI) and electrocardiogram analysis in ankylosing spondylitis (AS) patients. Methods: A total of 40 patients with AS (22 males /18 females, 37.82 ± 10.22 years), and 42 controls (22 males/20 females, 35.74 ± 9.98 years) were included. Systolic and diastolic left ventricular (LV) functions were measured by using conventional echocardiography and DTI. Interatrial and intraatrial electromechanical coupling (PA) intervals were measured with DTI. P-wave dispersion (PD) was calculated from the 12-lead electrocardiogram. Results: Atrial electromechanical coupling at the left lateral mitral annulus (PA lateral) was significantly delayed in AS patients (61.65 ± 7.81 vs 53.69 ± 6.75 ms, P < 0.0001). Interatrial (PA lateral – PA tricuspid), intraatrial electromechanical coupling intervals (PA septum – PA tricuspid), maximum P-wave (Pmax) duration, and PD were significantly longer in AS patients (23.50 ± 7.08 vs 14.76 ± 5.69 ms, P < 0.0001; 5.08 ± 5.24 vs 2.12 ± 2.09 ms, P = 0.001; 103.85 ± 6.10 vs 97.52 ± 6.79 ms, P < 0.0001; and 48.65 ± 6.17 vs 40.98 ± 5.37 ms, P < 0.0001, respectively). Reflecting LV diastolic function mitral A-wave and E/A, mitral E-wave deceleration time (DT), Am and Em/Am were significantly different between the groups (P < 0.05). We found a significant correlation between interatrial electromechanical coupling interval with PD (r = 0.536, P < 0.01). Interatrial electromechanical coupling interval was positively correlated with DT (r = 0.422, P < 0.01) and inversely correlated with E/A (r =−0.263, P < 0.05) and Em/Am (r =−0.263, P < 0.05). Conclusion: This study shows that atrial electromechanical coupling intervals and PD are delayed, and LV diastolic functions are impaired in AS patients.     

Interatrial Mechanical Dyssynchrony Worsened Atrial Mechanical Function in Sinus Node Disease With or Without Paroxysmal Atrial Fibrillation

Introduction: Atrial electromechanical dysfunction might contribute to the development of atrial fibrillation (AF) in patients with sinus node disease (SND). The aim of this study was to investigate the prevalence and impact of atrial mechanical dyssynchrony on atrial function in SND patients with or without paroxysmal AF. Methods: We performed echocardiographic examination with tissue Doppler imaging in 30 SND patients with (n = 11) or without (n = 19) paroxysmal AF who received dual‐chamber pacemakers. Tissue Doppler indexes included atrial contraction velocities (Va) and timing events (Ta) were measured at midleft atrial (LA) and right atrial (RA) wall. Intraatrial synchronicity was defined by the standard deviation and maximum time delay of Ta among 6 segments of LA (septal/lateral/inferior/anterior/posterior/anterospetal). Interatrial synchronicity was defined by time delay between Ta from RA and LA free wall. Results: There were no differences in age, P‐wave duration, left ventricular ejection fraction, LA volume, and ejection fraction between with or without AF. Patients with paroxysmal AF had lower mitral inflow A velocity (70 ± 19 vs 91 ± 17 cm/s, P = 0.005), LA active empting fraction (24 ± 14 vs 36 ± 13%, P = 0.027), mean Va of LA (2.6 ± 0.9 vs 3.4 ± 0.9 cm/s, P = 0.028), and greater interatrial synchronicity (33 ± 25 vs 12 ± 19 ms, P = 0.022) than those without AF. Furthermore, a lower mitral inflow A velocity (Odd ratio [OR]= 1.12, 95% Confidence interval [CI] 1.01–1.24, P = 0.025) and prolonged interatrial dyssynchrony (OR = 1.08, 95% CI 1.01–1.16, P = 0.020) were independent predictors for the presence of AF in SND patients. Conclusion: SND patients with paroxysmal AF had reduced regional and global active LA mechanical contraction and increased interatrial dyssychrony as compared with those without AF. These findings suggest that abnormal atrial electromechanical properties are associated with AF in SND patients.     

Relation of gender and interatrial dyssynchrony on tissue Doppler imaging to the prediction of the progression to chronic atrial fibrillation in patients with nonvalvular paroxysmal atrial fibrillation

This prospective study aimed to identify the relation of gender and interatrial dyssynchrony on tissue Doppler imaging (TDI) to the prediction of the progression to chronic atrial fibrillation (CAF) in nonvalvular paroxysmal AF (PAF) patients. Nineteen consecutive men and 19 women with nonvalvular PAF were prospectively followed after echocardiography. We measured the interval of time from initiation of the P wave on the electrocardiogram until the beginning of the late diastolic TDI signal at the lateral border of the mitral (P-A′(M)) and the tricuspid annulus (P-A′(T)). Interatrial dyssynchrony was defined as the difference between the P-A′(M) and P-A′(T) intervals (A′(M)-A′(T)). The study endpoint was the onset of CAF (>6 months). Six men developed CAF during a follow-up of 32 ± 26 months, and 3 women developed CAF during a follow-up of 25 ± 19 months. Compared to those without CAF, the patients with CAF had significantly longer A′(M)- A′(T) intervals (men: 41 ± 10 vs 27 ± 12 ms, women: 64 ± 4 vs 23 ± 9 ms; P < 0.01) in both genders. Kaplan-Meier analysis, using cutoff values determined by analysis of receiveroperating characteristics curves, revealed that the progression to CAF was significantly observed more often when A′(M)-A′(T) interval was >34 ms in men and >43 ms in women. This prospective study suggests that nonvalvular PAF men and women with a high risk of developing CAF have “interatrial dyssynchrony” on atrial TDI, whose cutoff values are shorter and may affect the vulnerability of AF in men.     

多普勒超声和心导管测量阵发性心房颤动患者左心房压力的研究

目的探讨多普勒超声能否有效地预测阵发性心房颤动(PAF)患者的左心房压力(LAP)。方法选择PAF患者31例,导管射频消融术前1d行经胸及经食管彩色多普勒超声检查,测左心房内径、LVEF、舒张期肺静脉血流衰减时间(DTD)、收缩期肺静脉血流衰减时间(STD)等相关参数;术中通过心导管测量LAP。对多普勒超声参数与LAP进行相关性分析。结果 31例患者LAP(14.45±7.60)mm Hg(1mm Hg=0.133kPa)、DTD(176.97±56.74)ms、STD(193.97±55.17)ms。DTD和STD与LAP呈负相关(r=-0.63,r=-0.81,P=0.00)。结论DTD和STD可能是简便、可靠、无创性预测PAF患者LAP的理想指标。     

The Normal Sequence of Right and Left Atrial Contraction

Objective: To study the sequence of atrial activation and the interatrial electromechanical delay (IEmD) noninvasively in healthy subjects during sinus rhythm (SR). Methods and Results: In 66 SR healthy subjects P‐wave activation was analyzed by means of vectorcardiography. The timing of atrial contractions was measured as the intervals between the P‐wave and the A‐wave of the Doppler right and left ventricular inflows (P‐A_t and P‐A_m), and IEmD was calculated as the algebraic difference PA_m P‐A_t. In the horizontal plane the vectorcardiographic P‐loop was anteroposterior (“typical”, 41 subjects), anterior (18), or posterior (7). IEmD (mean ±; SE 17 ±; 8 ms) was directly related to R‐R and P‐R intervals. IEmD was significantly shorter in anterior and posterior P loops than in the typical (6.5 ±; 5.3 and 8.1 ±; 10.1, respectively, vs 24.2 ±; 3.1 ms). In the posterior P‐loop group, who exhibited longer P‐A_t, mitral E‐wave velocity and E/A ratio were reduced, and left atrial booster function was increased. Conclusion: IEmD was widely variable in SR, reflecting the origin site of sinus impulse, which independently influenced ventricular filling dynamics. A.N.E. 2001;6(3):222–228     

预激综合征患者发生阵发性心房颤动机制的探讨

目的通过分析预激综合征患者旁道的电生理特性以及消融旁道后P波离散度(Pd)的计算,探讨预激综合征发生阵发性心房颤动(简称房颤)的机制。方法分析预激综合征合并旁道介导的阵发性心动过速患者127例。根据既往有无阵发性房颤(PAF)发作将患者分为PAF组(23例)和无PAF组(NPAF,104例)2组进行分析。电生理检查测定旁道的前传和逆传不应期。消融成功术后24h描记12导联心电图测量P波最大时限(Pmax)、P波最小时限(Pmin),计算Pd。结果消融前PAF组旁道前传和逆传不应期较NPAF组短(前传:265.3±42.5msvs331.4±38.7ms;逆传:255.8±46.7msvs317.5±31.7ms;P均<0.05)。消融术后心电图Pmax和PdPAF组显著长于NPAF组(Pmax:135.2±12.5msvs120.4±8.7ms;Pd:51.6±10.3msvs32.7±6.7ms;P均<0.05)。结论旁道有效不应期缩短和窦性激动在心房内的非均质传导在预激综合征患者房颤发生中可能起重要作用。     

Assessment of atrial electromechanical coupling and influential factors in nonrheumatic paroxysmal atrial fibrillation

BACKGROUND: Sequential analysis of atrial electromechanical coupling (P-A) by Doppler tissue imaging (DTI) might provide important insight into the mechanisms of paroxysmal atrial fibrillation (PAF). HYPOTHESIS: The purpose of this study was to evaluate P-A and the dispersion of P-A, and to analyze the influential factors of P-A. METHODS: One hundred and ten patients with PAF and 87 normal controls were enrolled. Using DTI, the time intervals from the beginning of P-wave to the onset of atrioventricular ring motion related to atrial contraction were measured. RESULTS: Atrial electromechanical coupling at the interventricular septum atrioventricular annulus (P-A1), left lateral mitral annulus (P-A2) and right lateral tricuspid annulus (P-A3) in PAF group were significantly longer than those in control (p < 0.001). The difference between P-A2 and P-A1 (T1), P-A2 and P-A3 (T3) in PAF group were greater than those in control before age correction (p < 0.05). The linear regression analysis showed that the duration of PAF episodes and age were the greatest influential factors of P-A1 (r = 0.564). Left atrial anterior-posterior dimension (LAD) and age were the greatest influential factors of P-A2 (r = 0.459). The LAD was the greatest influential factors of T1 and T3 (r = 0.408, 0.542). CONCLUSIONS: The atrial electromechanical coupling was significantly longer and the dispersion of P-A at left lateral mitral annulus was greater in PAF patients. The prolongation of P-A may be related to left atrial enlargement, long episodes of PAF and aging and the dispersion of P-A at left lateral mitral annulus to LAD.     

Atrial conduction abnormalities in patients with systemic progressive sclerosis

BACKGROUND: Atrial abnormalities in patients with progressive systemic sclerosishave not been evaluated in terms of intra-artrial conduction.We hypothesized that a delay in atrial conduction in these patientsmight produce diastolic abnormalities as well as atrial arrhythmias. OBJECTIVE: To evaluate the atrial function of patients with progressivesystemic sclerosis by using echocardiography to measure theintra-atrial electromechanical activation coupling interval. METHODS: Twenty patients with progressive systemic sclerosis were assessedby Doppler echocardiography. Twenty age-matched healthy controlswere also evaluated. Two-dimensional guided M-modes of ventricularlong axes were recorded using simultaneous phono- and electrocardiogramsof the apical four chamber view at the right lateral, septaland left lateral sites of the atrioventricular rings. Transmitraland tricuspid pulsed Doppler flow velocities were also recorded.Filtered P wave duration was measured on the signal averagedECG to determine the duration of atrial electrical activation. RESULTS: There was a delay in P on the electrocardiogram (P) at the onsetof atrial contraction on long axis M-modes at all three atrioventricularring sites in patients with progressive systemic sclerosis ascompared with controls (P-right; 56±13 vs 47±10ms, P-septal; 74±14 vs 55±10 ms, and P-lateral;93±16 vs 72±11 ms, P<0·01). Inter-atrialconduction time [(P-lateral) — (P-right)] was delayedin patients with progressive systemic sclerosis, compared withhealthy controls (37±15 vs 25±6 ms, P<0·01).Mitral A waves acceleration and deceleration times were alsodecreased in the patients. The interval was prolonged betweenP to the onset and the peak of the A wave in transmitral flow.Duration of the filtered P wave was significantly prolongedin progressive systemic sclerosis as compared with controls(124±12 ms vs 106±8 ms, P<0·01). PQintervals, E waves and acceleration and deceleration times didnot differ significantly in progressive systemic sclerosis vs,controls. The A wave acceleration rate on transmitral flow (peakA wave velocity/acceleration time) showed a significant correlationwith inter-atrial conduction delay (r=0·55, P<0·01). CONCLUSIONS: Intra-atrial electromechanical coupling intervals were delayedin patients with progressive systemic sclerosis. Thus, the mechanicallate diastolic filling time due to atrial contraction in thetotal diastolic phase was severely limited, and this resultedin a restricted mitral A wave. We should therefore evaluatepatients with progressive systemic sclerosis for significantatrial abnormalities.     

Noncontact electroanatomic mapping to characterize typical atrial flutter: participation of right atrial posterior wall in the reentrant circuit

Reentrant Circuit of Typical Atrial Flutter . Background: Reentry utilizing cavotricuspid isthmus (CTI) is accepted as the mechanism underlying typical atrial flutter (AFLT). However, it is unclear how the right atrial (RA) posterior wall (PW) participates in AFLT circuit. We sought to investigate this by using noncontact electroanatomic mapping. Methods: Fifteen patients (pts) undergoing ablation for typical AFLT participated. Multipolar catheters were deployed in RA and coronary sinus. RA shell was created during AFLT. Entrainment was performed to confirm CTI dependence and assess participation of various RA regions (septum‐Sep, PW, lateral wall‐LW). Data were analyzed for (1) RA activation patterns and (2) conduction time (CT) through various RA regions. Results: Mean pt age was 70 ± 13 years (all males; CCW = 10; CW = 5). Mean AFLT cycle length was 255 ± 15 ms. Single activation wave front traversing sequentially CTI, Sep, and LW was seen in all pts and in 12 (80%; 9 CCW, 3 CW) this also traversed PW. Entrainment confirmed PW participation in 7 of these. Mean CT (in ms) through various RA regions was as follows: CTI = 69 ± 27, Sep = 50 ± 39, PW = 65 ± 35, and LW = 76 ± 35; P = NS. Conclusion: These observations offer new insights regarding the participation of PW in the reentrant circuit of typical AFLT in some patients. (J Cardiovasc Electrophysiol, Vol. 22, pp. 422‐430)     

Usefulness of interatrial conduction time to distinguish between focal atrial tachyarrhythmias originating from the superior vena cava and the right superior pulmonary vein

Objective: Differentiation of the tachycardia originating from the superior vena cava (SVC) or the right superior pulmonary vein (RSPV) is limited by the similar surface P‐wave morphology and intraatrial activation pattern during tachycardia. We sought to find a simple method to distinguish between the two tachycardias by analyzing the interatrial conduction time. Methods: Sixteen consecutive patients consisting of 8 with SVC tachycardia and the other 8 with RSPV tachycardia were studied. The interatrial conduction time from the high right atrium (HRA) to the distal coronary sinus (DCS) and the intraatrial conduction time from the HRA to the atrial electrogram at the His bundle region (HIS) were measured during the sinus beat (SR) and during the tachycardia‐triggering ectopic atrial premature beat (APB). The differences of interatrial (Δ[HRA‐DCS]_SR‐APB) and intraatrial (Δ[HRA‐HIS]_SR‐APB) conduction time between SR and APB were then obtained. Results: The mean Δ[HRA‐DCS]_SR‐APB was 1.0 ± 5.2 ms (95% confident interval [CI]–3.3–5.3 ms) in SVC tachycardia and 38.5 ± 8.8 ms (95% CI 31.1–45.9 ms) in RSPV tachycardia. The mean Δ[HRA‐HIS]_SR‐APB was 1.5 ± 5.3 ms (95% CI –2.9–5.9 ms) in SVC tachycardia and 19.9 ± 12.0 ms (95% CI 9.9–29.9 ms) in RSPV tachycardia. The difference of Δ[HRA‐DCS]_SR‐APB between SVC and RSPV tachycardias was wider than that of Δ[HRA‐HIS]_SR‐APB (37.5 ± 9.3 ms vs. 18.4 ± 15.4 ms, P < 0.01). Conclusions: The wide difference of the interatrial conduction time Δ[HRA‐DCS]_SR‐APB between SVC and RSPV tachycardias is a useful parameter to distinguish the two tachycardias and may avoid unnecessary atrial transseptal puncture.     

Atrial fibrillation in patients with Wolff-Parkinson-White syndrome: role of pulmonary veins

AF in WPW Syndrome. Aim: We aimed to characterize electrophysiological properties of pulmonary veins (PVs) in patients with Wolff–Parkinson–White (WPW) syndrome and atrial fibrillation (AF), and to compare them to those in patients with WPW without AF. Methods and Results: A total of 31 patients (mean age 40 ± 15 years, 23 males) with WPW were recruited: 16 patients with (AF group) and 15 without (controls) a history of AF. The basic electrophysiological (EPS) and echocardiographic data were not different between the 2 groups. Effective refractory periods (ERPs) of PVs were significantly shorter in the AF group compared to controls: left superior (LS) PV ERP 185±29 versus 230 ± 24 ms, P = 0.001; left inferior PV ERP 198 ± 25 versus 219 ± 26 ms, P = 0.04; right superior (RS) PV ERP 207 ± 25 versus 236 ± 19 ms, P = 0.001; right inferior PV ERP 208 ± 30 versus 240 ± 19 ms, P = 0.003. Maximal veno‐atrial conduction delay (i.e., the maximal prolongation of interval from stimulus delivered at PV ostia to proximal coronary sinus after extrastimulus compared to the basic drive cycle) was longer in the AF group when pacing from LSPV (69.3 ± 37.9 vs 32.6 ± 16.1 ms, P = 0.01) and RSPV (74.1 ± 25.9 vs 50.2 ± 26.5 ms, P = 0.04). During EPS, AF was induced more often in the AF group (n = 7) compared to controls (n = 1; P = 0.04). Follow‐up revealed that AF recurred in 3 patients in the AF group and none of the controls. Conclusion: Patients with WPW syndrome and AF have shorter ERPs of PVs and greater maximal veno‐atrial conduction delay compared to patients with WPW without AF. These findings suggest a potential role of PVs in the development of AF in patients with WPW. (J Cardiovasc Electrophysiol, Vol. 23 p. 280‐286, March 2012.)     

The Effect of Exercise to P Wave Dispersion and Its Evaluation as a Predictor of Atrial Fibrillation

Aim: Prolongation of P wave time and increase of its dispersion as an independent predictor of atrial fibrillation. In patients with paroxysmal atrial fibrillation (PAF) as in healthy people, exercise augments sympathetic activity and therefore can cause the development of atrial fibrillation. The aim of this study is to evaluate the effect of exercise on P wave dispersion and to predict the development of atrial fibrillation. Methods: One hundred and ninety‐eight patients (93 women, 105 men, mean age: 59.05 ± 11.01 years ) having the diagnosis of PAF were included in the study. The left atrial diameter of all these patients was more than 4.0 cm. One hundred and fifty‐five patients (72 females, 83 males, mean age: 58.41 ± 10.79 years ), with left atrial diameter more than 4.0 cm and without PAF were taken as control group. Symptom limited exercise test with modified Bruce protocol was performed on all patients. Rest, maximum exercise and recovery, and first, third, and fifth‐minute 12‐derivation ECG was taken in all patients. The velocity of ECG was adjusted to 50 mm/s; shortest and largest P wave durations were measured and P wave dispersion was calculated. Results: The mean left atrial diameter was 4.41 ± 0.58 cm in PAF patients and 4.38 ± 0.48 cm in control group. No differences were found between PAF patients with the controls in exercise time (10.38 ± 2.93 vs 10.81 ± 2.75 minutes ); METs (6.98 ± 1.72 vs 7.28 ± 1.75 minutes ); resting heart rate (79.13 ± 14.86 vs 79.69 ± 10.43 bpm ); peak heart rate (146.83 ± 23.21 vs 146.94 ± 16.13 bpm ). Maximum exercise P wave duration and P wave dispersion were greater than the rest measurements in PAF group (respectively P < 0.0001 and P = 0.0004 ). Conclusion: In PAF patients, P wave dispersion is significantly longer at rest, maximum exercise and recovery time than in a control group without PAF.     

Transthoracic tissue Doppler imaging of the atria: a novel method to determine the atrial fibrillation cycle length

Background: The atrial fibrillation cycle length (AFCL) is a critical parameter for the perpetuation and termination of AF. In the present study, we evaluated a new method to measure the AFCL based on transthoracic tissue Doppler imaging (TDI) of the right atrium (RA) and left atrium (LA). Methods: Twenty patients with AF (6 acute AF, 14 persistent or permanent AF) were studied. A quadripolar catheter was positioned at RA or LA to measure AFCL (AFCL_EGM, gold standard). Transthoracic echocardiography (apical 4‐chamber view) was used to perform pulsed wave TDI at the free wall of RA or LA. AFCL_TDI was defined as the time interval between two consecutive positive to negative crossings of the baseline of the atrial time velocity curves. AFCL_EGM and AFCL_TDI were measured at baseline and during a 10‐minute infusion of flecainide (1.5 mg/kg). Results: Measurement of AFCL_TDI was feasible in all but one patient. At baseline, AFCL_EGM was 170 ± 22 ms, AFCL_TDI 172 ± 22 ms (difference 2 ± 5 ms). AFCL_TDI correlated significantly with AFCL_EGM (R = 0.91, P < 0.0001). Bland‐Altman analysis showed a bias of ?2 ms with a 95% limit of agreement between ?26 ms and +22 ms. During flecainide, the AFCL_TDI method yielded an AFCL prolongation from 176 ± 23 ms at baseline to 279 ± 68 ms (P < 0.01) after 10 minutes of infusion (57 ± 26%). Conclusions: (1) Tissue Doppler imaging of the atria during transthoracic echocardiography can be used to reliably determine the AFCL during both acute and persistent or permanent AF. (2) Continuous measurement of AFCL with TDI can be used to monitor the effect of antiarrhythmic drugs on atrial rate during AF. (3) This novel method is attractive because of the ease of acquiring the data and its noninvasive character.     

Relationship between arrhythmogenic pulmonary veins and the surrounding atrial substrate in patients with paroxysmal atrial fibrillation

Arrhythmogenic PVs and the Fibrillatory Activities . Introduction: The relationship between pulmonary veins (PVs) with atrial fibrillation (AF) initiating triggers and their surrounding atrial substrate has not been elucidated. We aimed to clarify the atrial substrate properties around the PVs. Methods and Results: Twenty‐three paroxysmal AF patients were studied with the identification of PV initiating triggers. High‐density mapping of the dominant frequency (DF, 1200 Hz) and the mean degree of the complex fractionated electrograms (CFE mean interval over 6 seconds) was evaluated in 2 zones (zone 1: < 5 mm, zone 2: 5–15 mm from the PVs) and the left atrial (LA) using a NavX system prior to the PV isolation. High‐DFs (>8 Hz) and continuous CFEs (<50 ms) were identified in 1.5 ± 0.9 and 2.3 ± 1.1 regions per patient, respectively. Most of the high‐DF regions (86%) and continuous CFE regions (77%) were located within 15 mm of the PV ostia. Of those, 75% of the high‐DF regions and 54% of the continuous CFE regions were related to arrhythmogenic PVs. There was a significant DF gradient from arrhythmogenic PV zone 1 to zone 2, while the mean CFE exhibited a significant gradient between arrhythmogenic PV zone 2 and the rest of the LA. Additionally, 69% of the procedural AF termination sites were at arrhythmogenic PV zone 2. Conclusion: Evaluation of the atrial substrate properties may be useful for locating arrhythmogenic PVs during AF and defining the extent of the circumferential PV isolation. (J Cardiovasc Electrophysiol, Vol. 22, pp. 405‐410)     

Relation of atrial electromechanical delay to P-wave dispersion on surface ECG using vector velocity imaging in patients with hypertrophic cardiomyopathy

Objectives

Heterogeneity of structural and electrophysiologic properties of atrial myocardium is common characteristic in hypertrophic cardiomyopathy (HCM). We assessed the dispersion of atrial refractoriness on surface ECG using P-wave dispersion (PWD) and its relation to atrial electromechanical functions using vector velocity imaging (VVI) in HCM population.

Methods

Seventy-nine HCM patients (mean age: 43.7 ± 13 years, 67% male) were compared with 25 healthy individuals as control. P-wave durations, P_max and P_min, P-wave dispersion (PWD), and P terminal force (PTF) were measured from 12-lead ECG. LA segmental delay (TTP-d) and dispersion (TTP-SD) of electromechanical activation were derived from atrial strain rate curves.

Results

HCM patients had longer PR interval, PW duration, higher PWD, PTF, QT_c compared to control (p < .001). HCM patients were classified according to presence of PWD into two groups, group I with PWD > 46 ms (n = 25) and group II PWD ≤ 46 ms (n = 54). Group I showed higher prevalence of female gender, higher PTF, QTc interval, left ventricular outflow tract (LVOT) obstruction, p < .01, LVOT gradient (p < .001), LV mass index (p < .01), E/E' (p < .01), and severe mitral regurgitation (p < .001). Moreover, PWD was associated with increased atrial electromechanical delay (TTP-d) and LA mechanical dyssynchrony (TTP-SD), p < .001. LA segmental delay and dispersion of electromechanical activation were distinctly higher among HCM patient.

Conclusion

PWD is simple ECG criterion, and it is associated with more severe HCM phenotype and LA electromechanical delay while PTF is linked only to atrial remodeling.