Usefulness of isoproterenol during atrial fibrillation in evaluation of asymptomatic Wolff-Parkinson-White pattern

The asymptomatic individual with a Wolff-Parkinson-White (WPW) pattern is considered at risk for ventricular fibrillation if a rapid ventricular response (shortest RR interval less than or equal to 250 ms) is observed during induced atrial fibrillation (AF) in the laboratory. It has been suggested that isoproterenol administration during AF may more accurately define the patient at risk. Consequently, the effect of isoproterenol on ventricular response during AF was studied in 21 asymptomatic individuals with WPW pattern to assess the potential of isoproterenol to identify patients at risk for sudden death. An electrophysiologic study that included elective induction of AF was performed. The shortest and mean RR intervals between 2 consecutive preexcited and normal QRS complexes, the average RR interval and the proportion of preexcited QRS complexes were measured in the control state and after bolus injections of isoproterenol (0.5, 1.0, 2.0 and 4.0 micrograms) during AF. Both atrioventricular nodal and accessory pathway conductions were enhanced proportional to isoproterenol dose. Isoproterenol had a greater effect on the atrioventricular node, as reflected by significantly greater changes in the shortest RR between normal complexes (339 +/- 70 vs 255 +/- 21 ms, mean +/- standard deviation, p less than 0.001) than the shortest RR between preexcited complexes (264 +/- 39 vs 219 +/- 34 ms, p less than 0.001) and a decrease in percentage of preexcited complexes (65 +/- 37 vs 50 +/- 33%, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrophysiologic profile of asymptomatic Wolff-Parkinson-White pattern

Electrophysiologic testing in patients with asymptomatic Wolff-Parkinson-White syndrome (WPW) may be useful in defining arrhythmic substrates and predictors of fatality. Forty-two patients with asymptomatic WPW, mean age 36 years, underwent electrophysiologic studies and were followed prospectively. They were compared with a matched control group of patients studied within the same period for documented tachycardia associated with the WPW syndrome. Asymptomatic patients had longer anterograde effective refractory periods of the accessory pathway, longer minimum cycle lengths maintaining 1:1 conduction over the accessory pathway, longer minimum RR intervals between consecutive preexcited beats during atrial fibrillation (AF) and longer mean RR intervals during AF than their symptomatic counterparts. Sustained reciprocating tachycardia could not be induced in most patients and induction of AF required rapid atrial pacing in all patients. Nine patients had an anterograde effective refractory period of less than 270 ms and 17% had minimum cycle length less than 250 ms during induced AF. Over a follow-up of 29 +/- 18 months, 1 patient died of noncardiac causes and the rest remained asymptomatic. Thus, patients with asymptomatic WPW have deficient electrophysiologic substrates to maintain orthodromic reciprocating tachycardia under baseline conditions and do not have atrial vulnerability. Seventeen percent of patients had potentially lethal ventricular rates during induced AF.     

Relation between clinical presentation and induced arrhythmias in the Wolff-Parkinson-White syndrome

Electrophysiologic testing is warranted in patients with the Wolff-Parkinson-White (WPW) syndrome presenting with rapid atrial fibrillation (AF) or ventricular fibrillation. Indications are less clear in patients presenting only with atrioventricular reentrant tachycardia (ART). A knowledge of propensity of this latter group to show a rapid ventricular response in the event of AF and the ability of electrophysiologic testing to reproduce the type and rate of clinical arrhythmias are relevant to this decision. The records of 126 symptomatic patients with manifest WPW syndrome were reviewed and separated into 4 groups according to presentation: group 1--AF; group 2--ART; group 3--palpitations suggesting ART; and group 4--AF and ART. All patients except those in group 3 had electrocardiographically documented clinical arrhythmias, and these arrhythmias were compared with those induced during electrophysiologic testing. The shortest RR interval during induced AF and the cycle length of induced ART correlated well with those occurring clinically (r = 0.72, p less than 0.00001), as did the cycle length of induced ART (r = 0.79, p less than 0.00001). Patients presenting with AF (65%) had a higher incidence of atrial vulnerability (48%) and sustained AF at electrophysiologic testing than those presenting with ART (16% and 5%) or undocumented palpitations (27% and 21%). Forty-one percent of patients with ART and 51% with undocumented palpitations had potentially lethal rates (shortest RR interval less than 250 ms) during induced AF. The ability to reproduce clinical arrhythmias and the frequency of rapid rates during AF induced in patients presenting with only ART or undocumented palpitations supports the recommendation for electrophysiologic testing in symptomatic patients with WPW.     

Effects of exercise and isoproterenol during atrial fibrillation in patients with wolff-parkinson-white syndrome

The effects of exercise and isoproterenol on atrial fibrillation (AF) were studied in 17 patients with Wolff-Parkinson-White syndrome (WPW) to assess the risk of developing a rapid ventricular response. Mean cycle length (R-R interval) and shortest R-R interval between both preexcited and nonpreexcited QRS complexes were recorded, as well as the percentage of preexcited complexes during control periods, during bicycle exercise, and during isoproterenol infusion. Exercise resulted in significantly shorter mean cycle length and the shortest R-R interval between nonpreexcited complexes. Exercise also resulted in a significantly lower percentage of preexcited complexes during AF, but had no effect on the R-R intervals between preexcited complexes. Isoproterenol had a variable effect on the percentage of preexcited QRS complexes, but resulted in significant shortening of mean cycle length and the shortest R-R interval between both normal and preexcited complexes. With isoproterenol, 12 of 17 patients had shortest preexcited R-R intervals ≤215 ms, compared with 6 of 17 in the control state. Isoproterenol infusion increased the rate of conduction over the accessory pathway during AF and allowed better assessment of the risk of excessively rapid rates occurring during AF. Exercise is not an adequate test for this purpose.     

Sudden death in the Wolff-Parkinson-White syndrome

Clinical electrophysiologic studies in patients with Wolff-Parkinson-White syndrome (WPW) suffering from ventricular fibrillation have shown a high prevalence of short anterograde refractory period of the accessory pathway (less than or equal to 250 ms), short preexcited RR intervals during atrial fibrillation (less than or equal to 250 ms), and multiple accessory pathways. Unfortunately the specificity of these findings is low, as they are present in almost 50% of patients with WPW without a history of ventricular fibrillation, and in 17% of patients with asymptomatic WPW. Pharmacologic and exercise testing detect a population of WPW with a low probability of having a short anterograde refractory period of the accessory pathway, but don't rule-out the ability of these patients to develop very short RR intervals during atrial fibrillation. Natural history studies show that sudden death in WPW occurs with an incidence less than or equal to 1:1,000 per year. The low predictive value of electrophysiologic and noninvasive studies for sudden death, makes then a poor means for screening patients at risk. Some clinical factors, such as the frequency of tachycardias and/or the detection of episodes of atrial flutter or fibrillation are markers of higher sudden death risk, and indications for aggressive electrophysiologic evaluation.     

Electrophysiologic testing in the management of patients with the Wolff-Parkinson-White syndrome and atrial fibrillation

Twenty patients with the Wolff-Parkinson-White (WPW) syndrome and 1 or more episodes of symptomatic atrial fibrillation (AF) due to rapid anterograde bypass tract conduction underwent electrophysiologic testing. The mean ventricular rate during spontaneous AF was 242 ± 56 beats/min (± standard deviation) and the shortest preexcited R-R interval was 194 ± 40 ms. Six patients underwent surgical bypass tract ablation and 14 were treated medically, based on the results of electropharmacologic testing. Over a mean follow-up period of 35 ± 19 months (± standard deviation), only 1 patient treated medically had a recurrence of minimally symptomatic AF. The successful chemoprophylaxis of symptomatic AF was associated with the inability to induce AF and atrioventricular reciprocating tachycardia during drug testing (7 patients) or with the induction of AF with a ventricular rate < 200 beats/min and a shortest preexcited R-R interval of > 250 ms (7 patients). Electrophysiologic testing can identify a subgroup of patients with WPW and AF in whom medical therapy is a suitable alternative to bypass tract ablation.     

Alternatives to Warfarin for Thromboembolism Prophylaxis in Nonrheumatic Atrial Fibrillation

A 45-year-old male with a preexcited QRS consistent with WPW syndrome was hospitalized for syncope. ECG monitoring revealed episodes of advanced atrioventricular block. An electrophysiologic study demonstrated right anteroseptal preexcitation and revealed an intermittent block in the accessory pathway and AV complete block causing long periods of spontaneous asystole. A DDD pacemaker was implanted without ablation of the accessory pathway.     

Effect of flestolol on ventricular rate during atrial fibrillation in Wolff-Parkinson-White syndrome

The ultrashort-acting beta blocker flestolol was studied during atrial pacing and atrial fibrillation (AF) in 10 patients with Wolff-Parkinson-White syndrome. Flestolol was given as a 100-micrograms/kg bolus followed by a 10-micrograms/kg/min infusion for 15 minutes. The drug did not alter the antegrade effective refractory period of the accessory pathway or the atrial paced cycle length at which block occurred in the accessory pathway. After flestolol, the percent of preexcited QRS complexes during AF increased (60 +/- 10 vs 87 +/- 5%, p = 0.01). Despite this, the ventricular rate slowed, with increases in mean RR interval (382 +/- 20 vs 416 +/- 22 ms, p = 0.02) and in the shortest interval between preexcited QRS complexes (251 +/- 18 vs 270 +/- 17 ms, p less than 0.01). The effect of isoproterenol 3 to 5 micrograms/min was studied in 5 patients. During atrial pacing, isoproterenol decreased the antegrade refractory period and the atrial paced cycle length of block in the accessory pathway (p less than or equal to 0.05). During AF, it decreased the percent of preexcited QRS complexes, mean RR interval and shortest interval between preexcited QRS complexes (p less than 0.05). Flestolol reversed the effects of isoproterenol both during atrial pacing and AF. Thus, flestolol does not alter conduction over the accessory pathway during atrial pacing, but during AF it slows conduction over the accessory pathway and prevents isoproterenol-mediated increases in ventricular rate. This suggests that in patients with Wolff-Parkinson-White syndrome sympathetic stimulation after the onset of AF enhances conduction over the accessory pathway and is an important determinant of ventricular rate.     

Risk factors of atrial fibrillation in patients with Wolff-Parkinson-White syndrome

BACKGROUND: Atrial fibrillation (AF) in patients with WPW syndrome may be a life-threatening arrhythmia. AIM: To identify risk factors of AF and their prognostic significance in patients with WPW syndrome. METHODS: Clinical and electrophysiological parameters of 239 patients with WPW syndrome, who underwent successful RF ablation, were analysed using logistic regression and multivariate analysis. One hundred eight patients had no history of AF whereas the remaining 81 patients had previous spontaneous AF episodes. Long-term follow-up data (mean 29+/-23 months, range 1-99 months) were available in 136 patients (87 without AF and 49 with AF). RESULTS: Patients with AF were significantly older, more frequently of male gender and had more often a history of syncope than patients without AF. There were two peaks of AF occurrence - in the third and in the fifth decade of life. Fourteen patients had a history of ventricular fibrillation - 11 patients with AF vs 3 patients without AF (p=0.0016). Patients with a history of AF were more prone to AF induced during electrophysiological study and had less frequently concealed accessory pathways. CONCLUSIONS: Age, gender and a history of syncope are the independent risk factors of AF in patients with WPW syndrome. Anterograde conduction via accessory pathway is of major importance in the development of AF. RF ablation of an accessory pathway should be performed early because the risk of the procedure is small and there is an increasing risk of AF with ageing.     

Atrial fibrillation in the Wolff-Parkinson-White syndrome.

Atrial fibrillation in patients with Wolff-Parkinson-White (WPW) syndrome may lead to syncope, ventricular fibrillation, and sudden death. In a follow-up study of 241 patients with WPW syndrome in a relatively unselected population, 26 patients had documented atrial fibrillation (11%). These patients were followed up after 1-37 years (median 11 years; mean 15 years). During this period, 2 of 26 died suddenly. These 2 patients had the shortest RR interval during spontaneous atrial fibrillation (less than or equal to 220 msec), greater than or equal to 1 episodes of syncope, and a persistent delta wave in all available electrocardiograms. In comparison, sudden or tachycardia-related death was seen in 4 of the 241 patients. This difference is not statistically significant. Thus, atrial fibrillation of 26 patients with WPW syndrome was surprisingly well tolerated in our follow-up study with only 2 sudden deaths.     

Atrial electrophysiologic abnormalities in patients with Wolff-Parkinson-White syndrome but without paroxysmal atrial fibrillation

BACKGROUND: Paroxysmal atrial fibrillation (PAF) frequently occurs in patients with Wolff-Parkinson-White (WPW) syndrome. HYPOTHESIS: The purpose of this study was to analyze the atrial electrophysiologic abnormalities and vulnerability to develop atrial fibrillation (AF) in patients with WPW syndrome but with no previous history of PAF. METHODS: We investigated atrial electrophysiologic abnormalities and vulnerability to AF in patients with WPW syndrome but without PAF. An electrophysiologic study was performed in 28 patients with WPW syndrome, 23 with atrioventricular nodal reentrant tachycardia (AVNRT) and 25 with other arrhythmias (control), all of whom had no history of PAF. The following atrial excitability parameters were assessed: effective refractory period (ERP), spontaneous or paced (A1) and extrastimulated (A2) atrial electrogram widths, percent maximum atrial fragmentation (%MAF; A2/A1 x 100), wavelength index (WLI; ERP/A2), and inducibility of AF. RESULTS: The ERP tended to be shorter in patients with WPW syndrome and in those with AVNRT than in the control group. The %MAF increased (154 +/- 33 vs. 137 +/- 23%, p < 0.05) and WLI decreased (2.7 +/- 0.8 vs. 3.4 +/- 1.0, p < 0.05) significantly in patients with WPW syndrome compared with the control group; however, these parameters in patients with AVNRT showed intermediate values. Atrial fibrillation was more inducible in patients with WPW syndrome (4/28 [14.3%]) than in those with AVNRT (4.3% [1/23]) and the control group (0/25 [0%]). With respect to patients with WPW syndrome and with and without inducible AF, the %MAF increased (195 +/- 23 vs. 148 +/- 30%, p < 0.01) and the WLI decreased (2.2 +/- 0.3 vs. 2.9 +/- 0.9, p < 0.05) in subjects with inducible AF. CONCLUSIONS: Atrial electrophysiologic abnormalities, especially atrial conduction delays, are more prominent in patients with WPW syndrome, even if they had no previous history of PAF. These abnormalities may play an important role in determining the vulnerability to AF.     

静脉注射三磷酸腺苷对旁路前向有效不应期的影响及其临床意义

目的：探讨三磷酸腺苷（ＡＴＰ）静脉注射对旁路前向有效不应期（ＡＥＲＰＡＰ）的影响，为在预激综合征（ＷＰＷ）和心动过速的诊断、治疗工作中合理使用ＡＴＰ静脉注射提供指导。方法：对１８例预激综合征以特定的起搏周长起搏心房，同时静脉注射ＡＴＰ，观察心室预激波ＲＲ间期变化。结果：静脉注射ＡＴＰ后出现心室预激波ＲＲ间期延长、缩短或延长和缩短交替３种瞬间效应。结论：静脉注射ＡＴＰ能瞬时地延长或缩短ＡＥＲＰＡＰ，这对于指导ＡＴＰ静脉注射在诊断隐性预激综合征、判断旁路射频导管消融疗效以及鉴别和诊断心动过速时的临床应用具有重要意义。     

Prognostic significance of syncope in patients with Wolff-Parkinson-White syndrome

The prognostic value of syncope in symptomatic patients with Wolff-Parkinson-White syndrome (WPW) is unknown. Therefore, in order to evaluate the sensibility, specificity, positive and negative predictive value of syncope and compare those values with the one obtained for the shortest RR interval (less than or equal to 250 msec) as well as for the anterograde refractory period of the accessory pathway (less than 270 msec), we reviewed the clinical and electrophysiological data of 158 symptomatic patients with WPW. Fourty-eight patients (30%) reported at least one episode of syncope, and 24 out of 158 patients experienced an aborted sudden death, probably due to rapid conduction via the accessory pathway during atrial fibrillation. Syncope has poor sensibility but high specificity in recognizing an aborted sudden death. However, the syncope demonstrated it had a lower prognostic value when compared with other electrophysiological parameters in correctly identifying patients with a history of ventricular tachycardia and/or fibrillation. In conclusion, the data of this study propose the symptom "syncope" as a frequent event in the history of symptomatic patients with WPW referred to electrophysiological study. Generally its presence does not correctly identify patients who experienced an aborted sudden death. Furthermore, its prognostic value is significantly lower than a shorter RR interval (less than or equal to 250 msec) during atrial fibrillation and an anterograde effective refractory period less than 270 msec.     

Are the results of electrophysiological study different in patients with a pre-excitation syndrome, with and without syncope?

AIMS: Syncope in Wolff-Parkinson-White (WPW) syndrome may reveal an arrhythmic event or is not WPW syndrome related. The aim of the study is to evaluate the results of electrophysiological study in WPW syndrome according to the presence or not of syncope and the possible causes of syncope. METHODS AND RESULTS: Among 518 consecutive patients with diagnosis of WPW syndrome, 71 patients, mean age 34.5 +/- 17, presented syncope. Transoesophageal electrophysiological study in control state and after isoproterenol infusion was performed in the out-patient clinic. Atrioventricular re-entrant tachycardia (AVRT) was more frequently induced than in asymptomatic patients (n = 38, 53.5%, P < 0.01), less frequently than in those with tachycardia; atrial fibrillation (AF) and/or antidromic tachycardia (ATD) was induced in 28 patients (39%) more frequently (P < 0.05) than in asymptomatic patients or those with tachycardia. The incidence of high-risk form [rapid conduction over accessory pathway (AP) and AF or ATD induction] was higher in syncope group (n = 18, 25%, P < 0.001) than in asymptomatic subjects (8%) or those with tachycardias (7.5%). Maximal rate conducted over AP was similar in patients with and without syncope, and higher in patients with spontaneous AF, but without syncope. Results were not age-related. CONCLUSION: Tachycardia inducibility was higher in patients with syncope than in the asymptomatic group. The incidence of malignant WPW syndrome was higher in patients with syncope than in asymptomatic or symptomatic population, but the maximal rate conducted over AP was not higher and another mechanism could be also implicated in the mechanism of syncope.     

Ventricular fibrillation in the Wolff-Parkinson-White syndrome

Ventricular fibrillation (VF) is a well-known but rare complication of the Wolff-Parkinson-White syndrome (WPW). Clinical and electrophysiological data of 23 patients with spontaneous VF were compared with data from 100 consecutive patients with WPW without VF but with symptomatic supraventricular tachycardia. The 23 patients were collected in a multicentre retrospective study in seven European centres. VF occurred in only one patient who was receiving antiarrhythmic drugs, and was the first manifestation of the syndrome in six. No significant differences were found between those with VF and without VF in age, complaints of palpitations, syncope, and presence of structural heart disease. The retrograde effective refractory period of the accessory pathway, the atrial refractory period and the fastest atrial pacing rate with 1:1 anterograde conduction over the accessory pathway were similar in both groups. Significant differences were found for sex, permanent pre-excitation on the electrocardiogram, type of documented supraventricular tachyarrhythmias, shortest RR interval less than or equal to 220 ms during spontaneous atrial fibrillation (AF), inducibility of supraventricular tachycardias, ventricular effective refractory period less than or equal to 190 ms, mean shortest RR interval during induced AF less than or equal to 180 ms and presence of multiple accessory pathways.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of amiodarone in the Wolff-Parkinson-White syndrome with rapid ventricular response via accessory pathway during atrial fibrillation

Sudden death in Wolff-Parkinson-White syndrome (WPW) is related to a very fast ventricular response to spontaneous atrial fibrillation (AF) conducted via accessory pathway (AP). The effect of oral amiodarone was studied in 12 patients with WPW syndrome and life-threatening rapid ventricular response via an AP during spontaneous AF. The effective refractory period of the AP in the anterograde direction was 280 ms or less during control study in all patients. After amiodarone therapy, the effective refractory period remained 280 ms or less in 7 of the 12 patients. During incremental atrial pacing, the longest atrial pacing cycle length that produced block over an AP ranged from 200 to 310 ms (mean 261 +/- 42) during the control period and 240 to 980 ms (mean 377 +/- 198) after amiodarone therapy. During AF the shortest ventricular response via the AP could be measured in 10 of 12 of the patients both before and after amiodarone treatment and ranged from 200 to 290 ms (234 +/- 30) and 250 to 500 (mean 302 +/- 75), respectively (p less than 0.01). The average RR interval during AF before and after the drug ranged from 200 to 390 ms (mean 280 +/- 55) and 280 to 650 ms (mean 396 +/- 116), respectively (p less than 0.01). Thus, the safety of amiodarone in the WPW syndrome should be established by electrophysiologic studies and induction of AF, because amiodarone is not protective in all patients with WPW.     

Prediction of a fatal atrial fibrillation in patients with asymptomatic Wolff-Parkinson-White pattern

Paroxysmal atrial fibrillation (PAF) in patients with manifest WPW syndrome can be a life-threatening arrhythmia by deterioration into ventricular fibrillation. In patients with asymptomatic WPW pattern, the first PAF may lead to ventricular fibrillation or sudden death. Therefore, the purpose of this study was to predict a fatal PAF in patients with asymptomatic WPW pattern. The patient population was divided into two groups: (1) 145 patients with manifest WPW syndrome, excluding intermittent ones (32 with an episode of PAF, 49 with AV reciprocating tachycardia alone, and 64 without any episode of paroxysmal tachyarrhythmia), and (2) mixed group of patients with and without WPW syndrome (36 with an episode of PAF and 66 without PAF). The results were as follows: (1) (a) out of 32 patients with WPW syndrome and PAF, 8 patients were observed to have both the shortest preexcited R-R interval of less than 200 msec during PAF and the shortest antegrade effective refractory period of the accessory pathway (ERP-AP) of less than 250 msec, 7 of whom had dizziness or syncope during PAF and 2 died suddenly during the follow-up period; (b) 21 (32.8%) out of 64 patients with asymptomatic WPW pattern showed the shortest antegrade ERP-AP less than 250 msec; (2) patients with PAF had a higher tendency to develop repetitive atrial firing (RAF), as well as fragmented atrial activity (FAA), which were induced using programmed atrial stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Usefulness of invasive electrophysiologic testing to stratify the risk of arrhythmic events in asymptomatic patients with Wolff-Parkinson-White pattern: results from a large prospective long-term follow-up study

OBJECTIVES: The aim of this study was to assess in a large cohort of asymptomatic subjects with Wolff-Parkinson-White (WPW) pattern the usefulness of invasive electrophysiologic testing (EPT) in predicting the occurrence of arrhythmic events over a five-year follow-up. BACKGROUND: Sudden death may be the first clinical manifestation of the WPW syndrome in previously asymptomatic patients. Serial EPTs have been proposed to identify patients at risk. METHODS: A total of 212 consecutive asymptomatic WPW patients were enrolled after a baseline EPT; patients were followed for five years, and 162 patients (115 noninducible and 47 inducible) patients underwent a second EPT. RESULTS: After a mean follow-up of 37.7 months, 33 patients became symptomatic. Of the 115 noninducible patients, 18.2% lost anterograde accessory pathway (AP) conduction, 30% retrograde AP conduction, and only 4 (3.4%) developed symptomatic supraventricular tachycardia (SVT). Of the 47 inducible patients, 25 with sustained atrioventricular reciprocating tachycardia (AVRT) and atrial fibrillation (AF), and 4 with nonsustained AVRT and AF became symptomatic for SVT (n = 21) and AF (n = 8). They were younger, had shorter AP anterograde refractory periods, and multiple APs compared to patients who remained asymptomatic (for all comparisons, p < 0.0001). Of the eight patients with symptomatic episodes of AF and inducible sustained AF, two had a resuscitated cardiac arrest and one died suddenly; all three patients were inducible for AVRT and AF and had multiple APs. CONCLUSIONS: In asymptomatic WPW subjects, EPT may be a valuable tool to stratify the risk of symptomatic and fatal arrhythmic events.     

Double Atrial Potentials Recorded in the Coronary Sinus in Patients with Wolff-Parkinson-White Syndrome: A Possible Mechanism of Induced Atrial Fibrillation

BACKGROUND: Double atrial potentials recorded in the coronary sinus are not an unusual phenomenon in patients with supraventricular tachyarrhythmias. They have been demonstrated to potentiate the occurrence of atrial tachyarrhythmias. METHODS: Two hundred and forty-eight patients were included for investigating the presence of double atrial potentials on the coronary sinus recordings during electrophysiologic study. Group 1 consisted of 136 patients with WPW syndrome and group 2 consisted of 112 patients with atrioventricular nodal reentrant tachycardia (AVNRT). Group 1 patients had a higher incidence of induced atrial fibrillation (AF) (27% vs. 15%, P = 0.045) than group 2 patients. In addition, the incidence of double atrial potentials was significantly higher in group 1 than in group 2 patients (14% vs. 2%, P = 0.001). In group 1, 19 patients with double atrial potentials had a significantly higher incidence of left lateral bypass tracts (79% vs. 39%, P = 0.001) and induced AF (47% vs. 22%, P = 0.01) than 117 patients without double atrial potentials. CONCLUSIONS: WPW syndrome, especially with a left lateral bypass tract, had a higher incidence of double atrial potentials and induced AF than AVNRT. WPW patients with double atrial potentials had a higher incidence of induced AF than those without double atrial potentials. These findings may contribute to understanding the mechanism of induced AF in WPW syndrome.     

Interventricular septal motion during preexcitation and normal conduction in Wolff-Parkinson-White syndrome: echocardiographic and electrophysiologic correlation.

Interventricular septal motion was studied by echocardiogram in 20 consecutive patients with documented Wolff-Parkinson-White (WPW) syndrome before and during electrophysiologic evaluation using His bundle recordings and pacing techniques. Characteristic abnormal interventricular septal motion was seen in 8 of 11 patients with type B WPW syndrome (groups I and II). All eight patients had electrocardiographic patterns consistent with an anomalous pathway located in the anterior right ventricular wall (group I). In five of these eight patients normalization of the QRS complex for one or more beats was accomplished and produced normalization of the septal motion in four; whereas in the fifth patient, who had an underlying atrial septal defect, the abnormal septal motion remained abnormal. All nine patients with type A WPW syndrome (groups III to V) had normal septal motion both during total preexcitation and during normalization of the QRS complex. The normalization of the abnormal interventricular septal motion with normalization of the QRS complex in type B WPW syndrome strongly suggests that the abnormal motion is related to an abnormal sequence of ventricular depolarization during preexcitation. Furthermore, persistent abnormal septal motion after normalization of the QRS complex suggests that other factors such as right ventricular volume overload may be responsible. Likewise, when abnormal septal motion occurs in the presence of type A WPW syndrome, an explanation other than preexcitation must be sought.