Simple electrocardiographic markers for the prediction of paroxysmal idiopathic atrial fibrillation

Maximum p wave duration and p wave dispersion in adult patients with secundum atrial septal defect: the impact of surgical repair

BACKGROUND

Patients with atrial septal defect (ASD) have an increased risk for atrial fibrillation (AF). Previously it was shown that maximum P wave duration and P wave dispersion in 12-lead surface electrocardiograms are significantly increased in individuals with a history of paroxysmal AF. We studied P maximum and P dispersion in adult patients with ASD during normal sinus rhythm. In addition, the impact of surgical closure of ASD on these variables within 1 year after surgery was evaluated.

METHODS

Thirty-four patients (21 women, 13 men; mean age: 35 +/- 11 years) operated on for ostium secundum type ASD and 24 age-matched healthy subjects (13 women, 11 men; mean age: 37 +/- 10 years) were investigated. P maximum, P minimum, and P dispersion (maximum - minimum P wave duration) were measured from the 12-lead surface electrocardiography.

RESULTS

P maximum was found to be significantly longer in patients with ASD as compared to controls (115.2 +/- 9 vs 99.3 +/- 14 ms; P < 0.0001). In addition, P dispersion of the patients was significantly higher than controls (37 +/- 9 vs 29.8 +/- 10 ms; P = 0.003). P minimum was not different between the two groups (P = 0.074). After surgical repair of ASD, 10 patients (29%) experienced one or more episodes of paroxysmal AF. Patients with postoperative AF were older (45 +/- 6 vs 30 +/- 10 years; P = 0.001), and had a higher preoperative pulmonary artery peak systolic pressure as compared to those without postoperative AF (51 +/- 11 vs 31 +/- 9 mmHg; P < 0.0001). No significant difference in the pulmonary-to-systemic flow ratio was observed preoperatively between the two groups (P = 0.56). P maximum and P dispersion were significantly higher in patients with postoperative paroxysmal AF at baseline and at postoperative first month, sixth month, and first year as compared to those without it (for P maximum P = 0.027, P = 0.014, P = 0.001, P < 0.0001, respectively; for P dispersion P = 0.037, P = 0.026, P = 0.001, P < 0.0001, respectively). In addition, in patients with postoperative AF, no significant changes were detected in both of these P wave indices during postoperative follow-up. However, in the other group, P maximum and P dispersion were found to be significantly decreased at postoperative 6 months and 1 year as compared to baseline. P minimum was similar throughout the postoperative follow-up as compared to baseline in both groups.

CONCLUSIONS

Mechanical and electrical changes in atrial myocardium may cause greater P maximum and P dispersion in patients with ASD. Surgical closure of the ASD can regress these pathological changes of atrial myocardium with a result in decreased P maximum and P dispersion. However, higher P maximum and P dispersion at baseline, which have not decreased after surgery, may be associated with postoperative paroxysmal AF, especially for older patients.

Increased P wave dispersion after the radiofrequency catheter ablation in overt pre-excitation patients: the role of atrial vulnerability

The pathogenesis of paroxysmal atrial fibrillation (PAF) in patients with overt pre-excitation and effect of elimination of accessory pathways on the appearance of AF are still controversial. We demonstrated the increased P max and P wave dispersion (PWD) reflecting more inhomogeneous and prolonged atrial conduction in patients with Wolff-Parkinson-White (WPW) syndrome and PAF attacks. One-hundred and fifty-one patients who underwent radiofrequency (RF) catheter ablation due to paroxysmal tachycardia medicated by accessory pathway were enrolled in this study. The patients were classified into two groups according to the presence of previous PAF attacks. We compared the clinical characteristics, echocardiograhic findings, P max and PWD values measured after normalization of PR intervals and disappearance of pre-excitation after ablation in overt pre-excitation patients. Although the differences in age, left atrial diameter and left ventricular ejection fraction (LVEF) were not significant in both groups, P maximum (130.0+/-8.4 vs. 122.3+/-8.7 ms, p=0.002) and P wave dispersion values measured after ablation (50.3+/-7.2 vs. 35.7+/-6.1 ms, p=0.001) were significantly higher in patients with previous PAF attacks. Accessory pathway (AP) antegrade and retrograde effective refractory period (ERP) values were shorter (276+/-27.3 vs. 321.0+/-48.7, p=0.001; 263.4+/-41.3 vs. 299.7+/-38.2, p=0.002, respectively) in patients with PAF attack when compared to those without PAF attacks. Higher P wave dispersion values in patients with previous PAF attacks suggest the important role of inhomogenous and discontinuous propagation of sinus impulses. Therefore, we concluded that not only the accessory pathway but also inhomogenous propagation of sinus impulses may play an important role in occurrence of AF in patients with pre-excitation.

An evaluation of postoperative P-wave variables after cardiothoracic surgery

Postoperative atrial fibrillation is common after cardiac surgery. Prediction of which patients will develop postoperative atrial fibrillation would be clinically useful. Increased P-wave duration, suggesting atrial conduction delay and measured from preoperative electrocardiograms, predicts postoperative atrial fibrillation. However, postoperative P-wave duration has not been evaluated after cardiac surgery. In this study, we evaluated postoperative P-wave variables (maximum P-wave duration and P-wave dispersion) over 5 days in cardiac surgery patients receiving amiodarone, pacing or no atrial fibrillation prophylaxis. P-wave variables gradually shortened as time passed from surgery. Amiodarone did not shorten P-wave measurements throughout therapy, while pacing shortened P-waves in the immediate postoperative period; however, shortening was not sustained. P-waves did not differ between those who did and did not develop atrial fibrillation with amiodarone or pacing. Our findings suggest that atrial conduction delay resulting from cardiothoracic surgery tends to resolve over time and may not play a critical role in the etiology of postoperative atrial fibrillation.

Inappropriate Implantable Cardioverter Defibrillator Discharge Following Consumption of a Dietary Weight Loss Supplement

This report describes the clinical course of a 40-year-old female who experienced repetitive ICD firing after consuming Metabolife 356, a multicomponent dietary weight loss supplement. Following the initiation of Metabolife 356, the patient experienced four shocks over a 3 day period with two 30 J shocks being delivered sequentially. Interrogation of the device revealed atrial tachycardia with 1:1 AV conduction at a rate of 240 beats/min. Metabolife 356 was discontinued and the dosage of sotalol was increased to 120 mg twice daily without recurrence of ICD discharge.

Clinical and echocardiographic predictors of left atrial appendage dysfunction in patients with mitral stenosis in sinus rhythm

BACKGROUND

Mitral stenosis (MS) causes left atrial (LA) appendage (LAA) dysfunction resulting in reduced LAA flow velocities. Low LAA peak emptying velocity (PEV), determined by transesophageal echocardiography, is a risk for thrombus formation and systemic embolism.

OBJECTIVE

We sought to investigate various clinical and echocardiographic predictors of low LAA blood flow velocities.

METHODS

A total of 44 patients with newly diagnosed MS were classified into two groups on the basis of the presence of high (PEV > or = 46 cm/s) or low (PEV < 46 cm/s) LAA flow profile on Doppler transesophageal echocardiography. LAA flow velocities were measured to be 27.38 +/- 8.17 cm/s in patients with LAA dysfunction and 70.75 +/- 16.71 cm/s in high-flow profile (P <.0001). Simultaneous 12-lead electrocardiogram was used to measure P waves.

RESULTS

P maximum, P dispersion, and LA diameter were significantly higher in patients with low LAA PEV (n = 32) than in those with high LAA PEV (111.87 +/- 16.93 vs 96.66 +/- 14.97, P =.0084; 73.12 +/- 20.7 vs 49.16 +/- 9.96, P <.0001; 46.06 +/- 4.384 vs 38.08 +/- 7.42 mm, P =.004; respectively). Patients with MS and low LAA blood flow had smaller mitral valve area compared with those with high LAA blood flow velocity (1.48 +/- 0.431 vs 1.85 +/- 0.442 cm(2), P =.02). Male sex, spontaneous echocontrast, and thrombus were more frequent in patients with low LAA PEV [7 [21.87%] vs 5 [41.66%], P =.026; 21 [65.62%] vs 4 [33.3%], P =.088; 4 [12.5%] vs none; respectively]. Mild MS was more frequent in patients with high blood flow velocity [6 [27.2%] vs 14 [63.6%], P =.03].

CONCLUSION

At linear regression analysis, only P-wave dispersion and LA diameter predicted the LAA mechanical dysfunction reflected as low LAA PEVs.

P Wave Dispersion and Left Atrial Appendage Function for Predicting Recurrence after Conversion of Atrial Fibrillation and Relation of P Wave Dispersion to Appendage Function

BACKGROUND

We investigated P wave dispersion and left atrial appendage (LAA) function for predicting atrial fibrillation (AF) relapse, and the relationship between P wave dispersion and LAA function.

METHODS

Sixty-four consecutive patients with AF lasting </=3 months were evaluated to predict the recurrence after successful cardioversion. P wave duration and dispersion were measured in a 12-lead electrocardiograph (ECG). The size and function of the left atrium (LA) and LAA were assessed by transthoracic and transesophageal echocardiography.

RESULTS

After 6 months, 28 patients experienced recurrent AF and 36 remained in sinus rhythm. There was no difference between patients with and without recurrence in gender, age, underlying heart disease, AF patterns, left ventricular function, and maximum LAA area. AF duration >/=5 days, LA size >/=45 mm, maximum P wave duration >/=112 ms, P wave dispersion >/=47 ms, spontaneous echo contrast, minimum LAA area >/=166 mm(2), and LAA emptying velocity <36 cm/sec were univariate predictors of recurrence (each P < 0.05). By multivariate analysis, LA size (P = 0.02), P wave dispersion (P < 0.001), and LAA emptying flow (P = 0.01) identified patients with recurrent AF. Their positive predictive values were 91, 97, and 72%, respectively.

CONCLUSION

The increased P wave dispersion in addition to the dilated LA and the depressed LAA emptying flow can identify patients at risk of recurrent AF after cardioversion.

Intra- and interatrial conduction delay: implications for cardiac pacing

Atrial conduction disorders are frequent in elderly subjects and/or those with structural heart diseases, mainly mitral valve disease, hyperthrophic cardiomyopathies, and hypertension. The resultant electrophysiological and electromechanical abnormalities are associated with a higher risk of paroxysmal or persistent atrial tachyarrhythmias, either atrial fibrillation, typical or atypical flutter or other forms of atrial tachycardias. Such an association is not fortuitous because intra- and interatrial conduction abnormalities delays disrupt (spatial and temporal dispersion) electrical activation, thus promoting the initiation and perpetuation of reentrant circuits. Preventive therapeutic interventions induce variable, sometimes paradoxical effects as with the proarrhythmic effect of class I antiarrhythmic drugs. Similarly, atrial pacing may promote proarrhythmias or an antiarrhythmic effect according to the pacing site(s) and mode. Multisite atrial pacing was conceived to correct, as much as possible, abnormal activation induced by spontaneous intra- or interatrial conduction disorders or by single site atrial pacing, which are situations responsible for commonly refractory arrhythmias. Atrial electrical resynchronization can also be used to correct mechanical abnormalities like left heart AV dyssynchrony resulting from intraatrial conduction delays.

Magnesium for the Treatment and Prevention of Atrial Tachyarrhythmias

Atrial tachyarrhythmias, including atrial fibrillation and flutter, occur frequently. Magnesium has been studied in the early conversion and prevention of atrial tachyarrhythmias, as well as in prevention of atrial tachyarrhythmias after coronary artery bypass graft surgery. Early conversion of atrial tachyarrhythmias and control of heart rate may be greater with magnesium than with common antiarrhythmic agents. Magnesium appears to be less useful for preventing recurrent atrial tachyarrhythmias; however, discrepancies in study methodologies make interpretation of results difficult. The use of magnesium for prevention of postoperative atrial arrhythmias has produced conflicting results, likely due to differences in study design. From the limited data available, magnesium appears to have some inherent antiarrhythmic properties. Certain patient populations may derive benefit from magnesium for the treatment of atrial tachyarrhythmias. However, further study is necessary to define the role of magnesium clearly for the treatment or prevention of atrial tachyarrhythmias.

P-wave duration and P-wave dispersion in patients with dilated cardiomyopathy

BACKGROUND

P-wave dispersion (PWD) has been reported to be associated with inhomogeneous and discontinuous propagation of sinus impulses. In the present study, we aimed to investigate PWD in patients with dilated cardiomyopathy.

METHOD

The study population consisted of 72 patients with dilated cardiomyopathy and 72 healthy control subjects. Left atrial diameter, left ventricular end-diastolic and end-systolic diameters and left ventricular ejection fraction of all patients and control subjects were measured by means of transthoracic echocardiography. Maximum P-wave duration (Pmaximum) and minimum P-wave duration (Pminimum) were measured from the 12-lead surface electrocardiogram. PWD was calculated as the difference between Pmaximum and Pminimum.

RESULTS

Pmaximum and PWD of patients with dilated cardiomyopathy were significantly higher than those of control subjects (Pmaximum: 126+/-12 ms vs. 116+/-10 ms, PWD: 47+/-6 ms vs. 38+/-7 ms, respectively, P<0.001 for all). However, there was no statistically significant difference between patient group and control group regarding Pminimum (79+/-7 ms vs. 78+/-6 ms, respectively, P=0.27). Left atrial diameter was significantly higher in patients with dilated cardiomyopathy compared to control subjects (4.51+/-0.62 cm vs. 3.60+/-0.43 cm, respectively, P<0.001). Left ventricular ejection fraction was found to be significantly lower in patients with dilated cardiomyopathy compared to control subjects (33+/-5% vs. 63+/-7%, respectively, P<0.001).

CONCLUSION

PWD was found to be significantly higher in patients with dilated cardiomyopathy than in healthy control subjects.

Increased P wave dispersion and maximum P wave duration after hemodialysis

BACKGROUND

Atrial fibrillation is a frequent arrhythmia in patients undergoing hemodialysis. The consequences of hemodialysis on P wave durations and P wave dispersion have not been fully understood. The objective of this study was to study the effect of dialysis on P wave maximum (Pmax), P wave minimum (Pmin), and P wave dispersion (Pd).

METHODS

We studied Pmax, Pmin, and Pd in 32 patients (17 men and 15 women, mean age 54 +/- 18 years) with chronic renal failure undergoing hemodialysis. The difference between maximum and minimum P wave duration was calculated and defined as P wave dispersion (Pd= Pmax- Pmin).

RESULTS

There was a significant increase in Pmax at the end of dialysis compared to the beginning (98 +/- 13 ms vs. 125 +/- 12 ms, P < 0.001). Pmin did not show any significant change (71 +/- 11 ms vs. 73 +/- 10 ms, P = 0.42). Pd was significantly increased at the end of dialysis (27 +/- 9 ms vs. 52 +/- 11 ms, P < 0.001). There was a negative correlation between serum potassium, magnesium, phosphate, blood urea nitrogen, and creatinin at the end of dialysis and Pmax and Pd, respectively (P < 0.05). A weak positive correlation was found between serum calcium, bicarbonate at the end of dialysis and Pmax and Pd (P < 0.05).

CONCLUSION

Hemodialysis ends with significant increase in P wave maximum duration and P wave dispersion, which might be responsible for the increased occurrence of atrial fibrillation in these groups of patients.

Mechano-Electrical Interaction Late After Fontan Operation

Background— The growing population with Fontan operation surviving into adulthood has significant morbidity and mortality rates from recurrent atrial tachyarrhythmias. We hypothesized that the structural characteristics and electrical behavior of atria may differ in these patients compared with those without arrhythmias.

Methods and Results— We studied 33 consecutive patients (age, 25.4±9.5 years) with Fontan circulation, of whom 19 had a history of documented sustained atrial tachyarrhythmias. We analyzed their clinical and investigational data, including echocardiographic assessment of atrial dimensions and surface 12-lead ECG measurement of the P-wave duration and its dispersion between leads. Twenty age- and sex-matched healthy control subjects were also studied. First, patients who had the Fontan procedure overall had longer P-wave duration (144±33 versus 100±7 ms, P <0.001) and greater P-wave dispersion (74±33 versus 34±9 ms, P <0.001) than control subjects. Among the patients who had the Fontan procedure, those with atrial tachyarrhythmias had longer P-wave duration (159±28 versus 123±28 ms, P <0.001) and greater P-wave dispersion (91±30 versus 50±19 ms, P <0.001) than those without. Second, the patients with atrial tachyarrhythmias who had the Fontan procedure had larger right atrial dimension than those without arrhythmias (6.4±1.4 versus 5.0±1.0 cm, P =0.01). Third, both P-wave duration and dispersion were significantly correlated to right atrial dimension within the Fontan group ( r =0.55, P =0.002, and r =0.56, P =0.002, respectively).

Conclusions— Patients with atrial tachyarrhythmias late after Fontan operation have longer P-wave duration and P-wave dispersion and larger right atrial dimension than those without the arrhythmias; these abnormalities are interrelated. This observation represents an atrial mechano-electrical remodeling phenomenon in parallel to an increase in arrhythmia propensity in this vulnerable population and warrants further investigation.

Sinus and Paced P Wave Duration and Dispersion as Predictors of Atrial Fibrillation After Pacemaker Implantation in Patients with Isolated Sick Sinus Syndrome

The aim of this study was to prospectively evaluate the sinus and the paced P wave duration and dispersion as predictors of AF after pacemaker implantation in patients with isolated sick sinus syndrome (SSS). The study included 109 (69 women, mean age 72 +/- 11 years) patients with SSS, 59 with bradycardia-tachycardia syndrome (BTS). A 12-lead ECG was recorded before pacemaker implantation and during high right atrial and septal right atrial pacing at 70 and 100 beats/min. The ECGs were scanned into a computer and analyzed on screen. The patients were treated with AAIR (n = 52) or DDDR pacing. The P wave duration was measured in each lead and mean P wave duration and P wave dispersion were calculated for each ECG. AF during follow-up was defined as: AF in an ECG at or between follow-up visits; an atrial high rate episode with a rate of > or =220 beats/min for > or =5 minutes, atrial sensing with a rate of > or =170 beats/min in > or =5% of total counted beats, mode-switching in >/=5% of total time recorded, or a mode switching episode of > or =5 minutes recorded by the pacemaker telemetry. The ECG parameters were correlated to AF during follow-up. Mean follow-up was 1.5 +/- 0.9 years. None of the ECG parameters differed between patients with AF and patients without AF during follow-up, nor was there any difference between groups after correction for BTS and age. BTS was the strongest predictor of AF during follow-up (P < 0.001). P wave duration and dispersion measured before and during pacemaker implantation were not predictive of AF after pacemaker implantation in patients with isolated SSS.

P-wave durations as a predictor for atrial fibrillation development in patients with hypertrophic cardiomyopathy

Atrial fibrillation (AF) is the most common arrhythmia observed in hypertropic cardiomyopathy (HCM) and is associated with an acute deterioration. Recently, P wave dispersion (PWD) reflecting inhomogeneous atrial conduction has been proposed as being useful for the estimation of paroxysmal AF. In this study, we aimed to define the clinical, echocardiographic and electrocardiographic predictors for AF occurrence in patients with HCM. Twenty-seven patients diagnosed with HCM and having a history of documented AF attack were compared with 53 age- and gender-matched patients who had no such history. LA diameter was significantly greater and gradient in the left ventricle outflow tract was lower in patients with AF than those without AF. Maximum P-wave duration (Pmax), PWD and PTF1 values were significantly higher in patients with AF. A Pmax>134.5 ms separated the patients with AF from controls with a sensitivity of 92%, specificity of 89% and a positive predictive value of 80%. APWD value>52.5 ms separated patients from controls with a sensitivity of 96%, a specificity of 91% and a positive predictive accuracy of 84%. An LA diameter>4.2 cm separated patients from controls with a sensitivity of 96% and a specificity of 81%. We concluded that LA diameter and PWD values are the most significant predictors for AF occurrence in patients with HCM, and simply by measuring Pmax and PWD values, we could easily identify the patients with high risk, and prescribe the necessary treatment and follow-up protocols for such patients.

Does impaired left ventricular relaxation affect P wave dispersion in patients with hypertension?

OBJECTIVE

P wave dispersion (PD) is considered to reflect the heterogeneous conduction in atria. We investigated whether there was a correlation between the left ventricular (LV) relaxation and PD.

METHOD AND RESULTS

Fifty-three hypertensive patients < or =60 years old were divided into two groups: Group A, 27 patients, aged 54+/-5 years with the impaired LV relaxation and Group B, 26 patients, aged 51+/-8 years with normal LV relaxation. The P wave durations were measured in all 12 leads of ECG and PD was defined as the difference between maximum and minimum P wave duration (Pmax-Pmin). Mitral inflow velocities (E and A), E deceleration time (DT), isovolumic relaxation time (IVRT), left atrial and ventricular diameters, and wall thickness of LV were obtained by echocardiography. Clinical characteristics of both groups were comparable. The wall thickness of LV, Pmax, and left atrial dimension were not different in both groups. A velocity was higher (P<0.001), but E velocity (P=0.03) and E/A ratio (P<0.001) were lower in group A than in group B. IVRT and DT were also significantly longer in group A. PD was significantly higher in group A compared to group B (51+/-9 vs 41+/-11 ms, P=0.01). This difference resulted from the Pmin (61+/-10 vs 67+/-9 ms, P=0.03, respectively). Multivariate analysis revealed a significant correlation between PD and A velocity (r=0.46, P=0.01), E/A ratio (r=-0.53, P=0.001), DT (r=0.65, P<0.001), and IVRT (r=0.73, P<0.001).

CONCLUSION

This study suggests that impaired LV relaxation contributes to the heterogeneous atrial conduction in hypertensive patients.

Detection of patients with hypertrophic cardiomyopathy at risk for paroxysmal atrial fibrillation during sinus rhythm by P-wave dispersion

BACKGROUND

Paroxysmal atrial fibrillation (PAF) in hypertrophic cardiomyopathy (HCM) is associated with poor prognosis. Previous studies have shown good correlation between P-wave dispersion (Pd) and occurrence of PAF. However, Pd in patients with HCM for predicting PAF has not been studied.

HYPOTHESIS

The aim of the study was to determine whether Pd could identify patients with HCM who are likely to suffer from PAF.

METHODS

Twenty-two patients with HCM with a history of PAF (Group 1) and 26 patients with HCM without a history of PAF (Group 2) were studied. Maximum (Pmax) and minimum (Pmin) P-wave durations, as well as P-wave dispersion (Pd = Pmax - Pmin) were calculated from 12-lead surface electrocardiograms (ECG).

RESULTS

P-wave dispersion was significantly different between the groups (Group 1: 55 +/- 6 ms vs. Group 2: 37 +/- 8 ms; p<0.001), while Pmax (Group 1: 134 +/- 11 ms vs. Group 2: 128 +/- 13 ms; p = 0.06) and Pmin (Group 1: 78 +/- 9 ms vs. Group 2: 81 +/- 7 ms; p = 0.07) was not significantly different. Patients with a history of PAF had higher left atrial diameter than the patients without PAF (Group 1: 52 +/- 8 mm vs. Group 2: 48 +/- 10 mm; p = 0.02). A cut-off value of 46 ms for Pd had a sensitivity of 76% and a specificity of 82% in discriminating between patients with and without PAF.

CONCLUSION

This study suggests that P-wave dispersion could identify patients with HCM who are likely to develop PAF.

P-wave dispersion for predicting maintenance of sinus rhythm after cardioversion of atrial fibrillation

P-wave measurements and left atrial function were investigated to predict the maintenance of sinus rhythm after cardioversion of atrial fibrillation. Left atrial dimension <45 mm (p = 0.02) and P-wave dispersion <46 ms (p <0.001) were independent predictors of sinus rhythm maintenance, with a sensitivity of 89% and 96%, respectively. Duration of atrial fibrillation, maximum P-wave duration, and no spontaneous echocardiographic contrast were also univariate predictors.

Increases in P-Wave Dispersion Predict Postoperative Atrial Fibrillation After Coronary Artery Bypass Graft Surgery

Atrial fibrillation (AF) is a common complication after coronary artery bypass graft (CABG) surgery. In this study we examined the effect of surgery on atrial electrophysiology as measured by P-wave characteristics and to determine the potential predictive value of P-wave characteristics on the incidences of postoperative AF in patients undergoing CABG surgery. Patients undergoing elective CABG surgery were monitored by continuous electrocardiogram (ECG) telemetry during the in-hospital period until discharge for the occurrence of postoperative AF. Differences in P-wave characteristics (P-wave duration, amplitude, axis, dispersion, PR interval, segment depression, and dispersion) were compared between the pre- and postoperative 12-lead ECG measurements, and also between patients with and without postoperative AF. The association of postoperative AF and potential clinical predictors and P-wave characteristics were determined by multivariate logistic regression. Postoperative AF occurred in 81 (27%) of 300 patients. Univariate analysis showed that patients who subsequently developed postoperative AF compared with those without AF were significantly older (mean age 68 +/- 8 versus 63 +/- 10 yr, P < 0.0001), had a larger body surface area (BSA) (2.03 +/- 0.24 versus 1.92 +/- 0.22 m(2), P = 0.0002), were more likely to have a history of AF (8 of 81 versus 1 of 219, P = 0.003), used preoperative antiarrhythmic medications more frequently (7 of 81 versus 4 of 219, P = 0.01), and had a more frequent rate of return to the operating room for postoperative complications (9 of 81 versus 9 of 219, P = 0.029). Furthermore, the postoperative P-wave duration decreased to a larger extent (mean change -11.3 +/- 0.1 ms versus -8.4 +/- 0.1 ms, P < 0.0001), and the P-wave dispersion increased postoperatively to a larger extent (3.1 +/- 15.5 ms versus -1.6 +/- 14.6 ms, P = 0.028) in those who subsequently developed AF compared with those without AF. Multivariate logistic regression showed age (odds ratio [OR] = 1.1, 95% confidence interval [CI]: 1.06-1.15, P < 0.0001), BSA (OR = 38.1, 95% CI: 8.2-176, P < 0.0001), and an increase in postoperative P-wave dispersion (OR = 1.03, 95% CI: 1.01-1.05, P = 0.01) to be independent predictors of postoperative AF. No surgical factor was identified to be responsible for this postoperative change in atrial electrophysiology.

IMPLICATIONS

In addition to clinical factors, such as advanced age and body surface area, we demonstrated that electrophysiologic changes involving an increase in P-wave dispersion postoperatively independently predict atrial fibrillation after coronary artery bypass graft surgery.

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.

Comparison of p-wave duration and dispersion in patients aged ≥65 years with those aged ≤45 years

P-wave dispersion (PWD) is a new electrocardiographic marker that reflects discontinuous and inhomogeneous propagation of sinus impulses, which has been studied in some cardiac conditions as a useful predictor of paroxysmal atrial fibrillation (AF). The aim of the peresent study was to compare P-wave duration and PWD in patients < or =45 versus > or =65 years of age. The study consisted of 2 groups. Group I included 118 patients aged > or =65 years (86 men, 32 women, mean age= 69 +/- 4 years). Group II included 72 patients aged < or =45 years (53 men, 19 women, mean age= 41 +/- 4 years). All patients were selected from those who were undertaken coronary angiography in our hospital with a suspicion of coronary artery disease and detected as having angiographically normal coronary arteries. All patients were undertaken transthoracic echocardiography to evaluate the presence of any structural and functional cardiac abnormality. Maximum and minimum P-wave durations and PWD were calculated from 12-lead surface electrocardiogram. Maximum P-wave duration and PWD were significantly higher in group I patients than in group II patients (P <.001). However, there was no statistically significant difference between group I patients and group II patients regarding minimum P-wave duration (p=0.9). Left atrial diameter, left ventricular wall thicknesses, mitral A velocity, deceleration time and isovolumic relaxation time were significantly higher in group I patients than in group II patients. However, mitral E velocity were significantly lower in group I patients than in group II patients. A significant positive correlation was detected between PWD and age, left atrial diameter, mitral A velocity, deceleration time and isovolumic relaxation time. In addition, we found a significant negative correlation between PWD and mitral E velocity. PWD, indicating increased risk for paroxysmal AF, was found to be significantly higher in patients > or =65 years of age than in those < or =45 years of age. Further prospective studies that include larger series and long term follow-up are needed to clarify the clinical utility of PWD as a predictor of increased risk for paroxysmal AF in old patients.

Evaluation of P wave duration and P wave dispersion in adult patients with secundum atrial septal defect during normal sinus rhythm

BACKGROUND

Paroxysmal atrial arrhythmias especially atrial fibrillation (AF) are frequently encountered in adult patients with atrial septal defect (ASD). Previously it was shown that maximum P wave duration and P wave dispersion in 12-lead surface electrocardiograms are significantly increased in individuals with a history of paroxysmal AF. The aim of this study was to determine whether P maximum and P dispersion in adult patients with ASD and without AF are increased as compared to healthy controls. In addition, the relationship of pulmonary to systemic flow ratio (Qp/Qs) and these P wave indices were investigated.

METHODS AND RESULTS

Sixty-two consecutive patients [39 women, 23 men; mean age 33+/-13 years (range 16 to 61 years)] with ostium secundum type ASD and 47 healthy subjects [25 women, 22 men; mean age 36.6+/-9.5 years (range 18 to 50 years)] were investigated. P maximum, P minimum and P dispersion (maximum minus minimum P wave duration) were measured from the 12-lead surface ECG. There were no significant differences with respect to age (P=0.08), gender (P=0.3), heart rate (P=0.3), left atrial diameter (P=0.5) and left ventricular ejection fraction (P=0.3) between patients and controls. Pulmonary artery peak systolic pressure was significantly higher in patients with ASD as compared to controls (P<0.0001). P maximum was significantly longer in patients with ASD as compared to controls (P<0.0001). In addition, P dispersion of the patients was significantly higher than controls (P=0.001). P minimum was not different between groups (P=0.12). Mean Qp/Qs of the patients with ASD was 2.5+/-0.7 (minimum 1.5; maximum 4.1) and found to be significantly correlated with P maximum (r=0.34; P=0.006) and P dispersion (r=0.61; P<0.0001).

CONCLUSIONS

Prolongation of P maximum and increased P dispersion could represent mechanical and electrical changes of atrial myocardium in patients with ASD. These changes of atrial myocardium may be more prominent with higher left to right shunt volumes.

P wave amplitude and duration may predict immediate recurrence of atrial fibrillation after internal cardioversion

BACKGROUND

Although internal cardioversion (IC) for atrial fibrillation (AF) is effective at restoring sinus rhythm, immediate recurrence (IR) of AF after IC is a major and largely unpredictable clinical problem. The purpose of the study was to determine the role of P wave duration and amplitude in prediction of IR of AF after IC. Forty-five consecutive patients undergoing IC for chronic AF were evaluated.

MATERIAL AND METHODS

After successful IC, 1-minute ECG recording was obtained in all patients. P wave duration and amplitude in Lead II and V1 were measured using computer. Forty patients (88%) had successful IC. Thirteen patients experienced IR of AF within 1 minute of restoring sinus rhythm.

RESULTS AND CONCLUSION

As a result, the incidence of IR of AF after IC was higher in the patients with shorter P wave amplitude (for lead II P<0.01, for V1 P<0.01) and larger P wave duration (for lead II P<0.01, for V1 P<0.05).

Can P wave parameters obtained from 12-lead surface electrocardiogram be a predictor for atrial fibrillation in patients who have structural heart disease?

This study was planned to investigate the parameters detecting risk of developing atrial fibrillation (AF) in patients with sinus rhythm with structural heart disease. Forty-five patients with AF and 37 patients without AF but with structural heart disease (Group I) were included in this study. Thirty-eight patients (Group II) had successfully undergone medically or electrically cardioversion after transesophageal echocardiography. The restoration of sinus rhythm could not be achieved in 7 patients who were excluded from this study. After providing sinus rhythm, amiodarone was given orally to the patients to prevent recurrences. Left ventricular ejection fraction (LVEF) was calculated and left atrial diameter (LAD) was measured by echocardiography in group I and in group II after cardioversion. A 12-lead electrocardiography (ECG) was simultaneously obtained from all the patients. In these ECG recordings, maximum P wave duration (P max), minimum P wave duration (P min), and P wave dispersion (P dispersion) were calculated. P dispersion was expressed as "P max-P min." Also, the highest P wave voltage is expressed as P amplitude maximum (P amp max), the lowest P wave as P amplitude minimum (P amp min), and P amplitude dispersion (P amp dispersion) was calculated as the difference of both. In univariate analysis, P max, P dispersion, P amp max, P amp dispersion, LAD, LVEF, and old age were significant predictors of chronic AF (p < 0.001, p < 0.01, p < 0.01, p < 0.01, p = 0.003, p = 0.02, and p = 0.01, respectively). However, in multivariate analysis, P max and LAD were independent predictors of chronic AF in patients with structural heart disease (r = 0.39, p < 0.05; r = 0.34; p < 0.05, respectively). In conclusion, in estimating the risk of developing chronic AF, P max and LAD are predictive parameters in patients with sinus rhythm with structural heart disease.

A comparison of P-wave duration and dispersion in patients with short-term and long-term atrial fibrillation

This study compared P-wave duration and dispersion (PD) in patients with short-term (<or=48 hours) and long-term (>48 hours) atrial fibrillation (AF) after cardioversion. We studied 96 consecutive patients with short-term (group A; n:51, age: 61 +/- 11 years) and long-term AF (group B; n:45, age: 64 +/- 10 years). P-wave measurements were calculated from 12-lead electrocardiogram. There was no difference related to clinical characteristics. Left atrial dimension was significantly higher in group B (P =.003). P maximum (124 +/- 12 vs. 113 +/- 11 ms, P =.001) and PD (57 +/- 8 vs. 49 +/- 9 ms, P =.001) were also significantly longer in group B compared with group A, but P minimum did not. In univariate analysis, PD were related to AF duration (P =.002) and left atrial size (P =.02). This relation remained in multivariate analysis (P =.01, P =.02, respectively). P maximum >112 ms and PD >47 ms had accuracy values of 74% and 83% respectively for separating group B. Our results suggest that P wave duration and dispersion is prolonged in patients with long-term AF compared to short-term AF.

Duration of the P wave and P wave dispersion in subclinical hyperthyroidism

OBJECTIVE

To determine whether the values for P wave dispersion (Pdis) and adjusted Pdis, which are simple noninvasive electrocardiographic markers to detect paroxysmal atrial fibrillation, differ in patients with endogenous subclinical hyperthyroidism in comparison with those in healthy control subjects.

METHODS

We measured the maximal P wave duration and the difference between the maximal and the minimal P wave duration (Pdis) from the 12-lead surface electrocardiogram of 36 patients with endogenous subclinical hyperthyroidism and of 22 age- and sex-matched healthy control subjects. Adjusted Pdis (Pdis/square root of the number of measured electrocardiographic leads) was also calculated from each electrocardiogram.

RESULTS

The minimal P wave duration was significantly shorter in patients with subclinical hyperthyroidism than in healthy control subjects (P<0.001). Pdis and adjusted Pdis were also significantly higher in the patient group than in the control subjects (P<0.05). By univariate analysis, only thyrotropin levels were found to be associated with adjusted Pdis (r = -0.28; P = 0.03).

CONCLUSION

Pdis and adjusted Pdis differed in patients with endogenous subclinical hyperthyroidism in comparison with those values in healthy control subjects. Thus, these simple electrocardiographic markers may be useful for identifying patients with endogenous subclinical hyperthyroidism who are at risk for paroxysmal atrial fibrillation.

Effects of P-wave dispersion on atrial fibrillation in patients with acute anterior wall myocardial infarction

BACKGROUND

P-wave dispersion (P dispersion), defined as the difference between the maximum and the minimum P-wave duration (P minimum), and maximum P-wave duration (P maximum) have been used to evaluate the discontinuous propagation of sinus impulse and the prolongation of atrial conduction time respectively. The aim of this study was to investigate whether early assessment of P dispersion predicts paroxysmal atrial fibrillation (AF) in patients with acute anterior wall myocardial infarction (MI).

METHODS

We prospectively evaluated 147 consecutive patients (45 women, 102 men; aged 55 +/- 9 years) with a first acute anterior wall MI. All patients were evaluated by echocardiography to measure the left atrial diameter and left ventricular ejection fraction (LVEF). Electrocardiography was recorded from all patients on admission and every day during hospitalization.

RESULTS

AF occurred in 25 patients. In 122 patients, AF did not occur. P maximum was found to be significantly higher in patients with AF than in patients without AF (115 +/- 17.3 ms vs 101 +/- 14.7 ms, P = 0.001). P dispersion also was significantly higher in patients with AF than in patients without AF (50 +/- 12.5 ms vs 43 +/- 10.1 ms, P = 0.01). There was no significant difference between the two groups in P minimum (64 +/- 12.5 ms vs 59 +/- 11.7 ms, P = 0.057). The echocardiographically left atrial diameters were not significantly higher in the patients with AF than those without (25 +/- 3.38 mm and 23 +/- 3.36 mm, respectively, P = 0.76). LVEF was found to be significantly different in the patients who developed AF and in those who did not (37.96 +/- 6.18% vs 47.70 +/- 6.01%, P = 0.0001).

CONCLUSIONS

Although P maximum and P dispersion are significant predictive factors of AF in patients with acute anterior wall MI in the univariate analysis, on the basis of multivariate analysis, only age and LVEF were independent predictive parameters for AF.

Long-term effects of beta blocker therapy on P-wave duration and dispersion in congestive heart failure patients: a new effect?

Atrial fibrillation (AF) is associated with heart failure in approximately 20%-50% of patients with increased morbidity and mortality. P-wave maximum duration (PWM) and P-wave dispersion (PWD) are recent ECG markers and reflect increased risk of AF. The aim of our study was to investigate the long-term effects of metoprolol on atrial conduction abnormalities as estimated by PWM and PWD, which were calculated on 12-derivation surface ECG in heart failure patients. Forty-two NYHA class 3 to 4 patients (23 males, 19 females and aged 52.9 +/- 11.2) were enrolled in the study. At the end of the 6 months, PWM and PWD values were significantly decreased (for PWM: from 115.2 +/- 12.6 to 105.4 +/- 13.5; for PWD: from 39.3 +/- 9.1 to 28.6 +/- 10.5; P <.001 for both). Metoprolol treatment is associated with a decreased duration of PWM and PWD and this may reflect a reduction in the probability of atrial fibrillation in heart failure patients.

Increased p-wave duration and p-wave dispersion in patients with aortic stenosis

BACKGROUND

P-wave dispersion (PWD), defined as the difference between the maximum and minimum P-wave duration, has been proposed as being useful for the prediction of paroxysmal atrial fibrillation (AF). AF is the most common arrhythmia and an important prognostic indicator for clinical deterioration in patients with aortic stenosis (AS). The aim of the present study was to evaluate PWD in patients with AS.

METHODS

The study population consisted of two groups: Group I consisted of 98 patients with AS (76 men, 22 women; aged 63 +/- 8 years) and group II consisted of 98 healthy subjects (same age and sex) without any cardiovascular disease. A 12-lead electrocardiogram was recorded for each subject. The P-wave duration was calculated in all leads of the surface electrocardiogram. The difference between the maximum and minimum P-wave duration was calculated and was defined as the PWD. All patients and control subjects were also evaluated by echocardiography to measure the left atrial diameter, left ventricular ejection fraction, left ventricular wall thicknesses, and the maximum and mean aortic gradients. Patients were also evaluated for the presence of paroxysmal AF.

RESULTS

Maximum P-wave duration and PWD of group I were found to be significantly higher than those of group II. In addition, patients with paroxysmal AF had significantly higher PWD than those without paroxysmal AF. There was no significant difference between the two groups regarding minimum P-wave duration. In addition, there was no significant correlation between echocardiographic variables and PWD.

CONCLUSION

PWD, indicating increased risk for paroxysmal AF, was found to be significantly higher in patients with AS than in those without it. Further assessment of the clinical utility of PWD for the prediction of paroxysmal AF in patients with severe AS will require longer prospective studies.

Determinants of persistent atrial fibrillation in patients with DDD pacemaker implantation

Occurrence of AF in a pacemaker implanted patient is a significant cause of morbidity and mortality. The aim of this study was to prospectively investigate the clinical, echocardiographic, and electrocardiographic determinants of persistent AF in patients with DDD pacemakers. A 101 consecutive patients were followed for an average of 19.8 +/- 11.8 months. Persistent AF was documented in 21 (20.8%) patients and 80 (79.2%) patients were in sinus or physiologically paced rhythm. In patients with persistent AF, previous AF attacks were observed more frequently (P < 0.03) and left atrial dimension was higher (3.5 +/- 0.6 vs 3.0 +/- 0.5 cm, P < 0.001). Average P maximum and P wave dispersion (PWD) values calculated in a 12-lead surface electrocardiogram were also found to be significantly higher in patients with persistent AF (P < 0.001). Cox regression analysis demonstrated that the presence of previous AF attacks (RR 8.95, P < 0.001), increased left atrial dimension (RR 2.1, P < 0.02), P maximum duration 120 ms (RR 6.1, P < 0.001), and PWD 40 ms (RR 12.2, P < 0.001) were associated with an increased risk of persistent AF. Cut-off points were 120 ms for P maximum and 40 ms for PWD. Sensitivity, specificity, and positive and negative predictive values were calculated as 76.2, 82.5, 53.3, and 92.9 for P maximum and as 85.7, 87.5, 64.3, and 95.9 for PWD, respectively. In patients with DDD pacemakers, previous AF attacks, increased left atrial dimension, P maximum value of 120 ms, and a PWD value of 40 ms were associated with a significantly increased risk of persistent AF. These patients must further be managed with other treatment modalities to prevent the development of persistent AF.

P wave analysis indices in young healthy men: data from the digital electrocardiographic study in Hellenic Air Force Servicemen (DEHAS)

P wave analysis from the 12-lead ECG is a recent contribution of noninvasive electrocardiology. P wave analysis indices (maximum and minimum P wave duration, P wave dispersion [Pdis = Pmax-Pmin], adjusted P wave dispersion [APdis = Pdis/square root of measured leads], summated P wave duration [Psum], standard deviation of P wave duration [Psd], mean P wave duration [Pmean]) can predict atrial arrhythmias. However, the definitions of all these indices are based on few studies. The aim of this analysis was to define normal values of these indices and the examine possible associations between P wave indices and clinical variables. The study included 1,353 healthy men, 24 +/- 3 years of age, who answered a questionnaire and underwent a detailed physical examination and a digitized 12-lead surface ECG. All P wave indices were analyzed by two independent investigators. Mean values of the ECG indices were: Pmax: 96 +/- 11 ms, Pmin: 57 +/- 9 ms, Pdis: 38 +/- 10 ms, Psum: 924 +/- 96 ms, Psd: 12 +/- 3, APdis: 11 +/- 3 ms, and Pmean: 77 +/- 8 ms. Age was significantly related with Pmax (r = 0.277, P < 0.01), Pmin (r = 0.255, P < 0.001), Psum (r = 0.074, P < 0.01), and Pmean (r = 0.074, P < 0.01). All ECG indices were significantly associated with the R-R interval, and among each other. This study defined normal indices of wave duration and correlations among them. These markers may play an important predictive role in patients with atrial conduction abnormalities.

Time interval from the initiation of the electrocardiographic P wave to the start of left atrial appendage ejection flow: A novel method for predicting atrial fibrillation recurrence

OBJECTIVE

The incidence of paroxysmal and persistent atrial fibrillation (AF) recurrence is high and unpredictable. In this study, a novel noninvasive method that was thought to reflect the interatrial conduction time was investigated to predict AF recurrence. This method was on the basis of the measurement of time interval from initiation of the electrocardiographic P wave to the start of left atrial (LA) appendage (LAA) ejection flow (P-LAA).

METHODS AND RESULTS

Forty-five consecutive patients (age, 61 +/- 11 years; 20 male) with newly diagnosed AF (mean duration, 132 hours; range: 6 hours-3 months) who converted to in sinus rhythm spontaneously or with cardioversion were studied prospectively. Transthoracic and transesophageal echocardiography were performed to measure LA size, mechanical functions, LAA ejection velocity, and P-LAA. Transesophageal echocardiography was performed for the measurement of P-LAA 1 to 2 days after conversion to in sinus rhythm. The patients were followed up for a period of 163 +/- 72 days for the recurrence of AF. AF recurred in 17 (38%) patients after a mean time of 81 +/- 67 days. P-LAA was significantly higher in patients with AF recurrence (123 +/- 36 vs 92 +/- 24 milliseconds, P =.0047) and multiple regression analysis indicated that P-LAA was an independent predictor of AF recurrence. Multiple regression analysis revealed no significant differences in LA size parameters, or in clinical and LA mechanical function parameters recorded after restoration of in sinus rhythm between patients with and without AF recurrence.

CONCLUSION

P-LAA may be considered to be an independent predictor of recurrent AF.

The value of P dispersion on predicting atrial fibrillation after coronary artery bypass surgery: effect of magnesium on P dispersion

BACKGROUND

AF is a frequent arrhythmia complicating CABG, and it is well known that dispersion and prolongation of P wave increases the risk of AF. The aim of this study was to investigate the effect of magnesium (Mg) treatment on P-wave duration and dispersion in patients undergoing CABG.

METHOD

The study included 148 consecutive patients (33 women, 115 men; mean age 62.1 +/- 7.0 years) undergoing CABG who were randomly allocated to two groups. Group A consisted of 93 patients to whom 1.5 g daily MgSO(4) infusion was applied the day before surgery, just after operation, and 4 days following surgery, and group B consisted of 55 control patients. From the preoperative and postoperative fourth day, 12-lead ECG recordings, duration of the P waves, and P-wave dispersions were calculated.

RESULTS

There were no differences between the two groups with regard to age, sex, and blood Mg level. Comparison of the baseline and day 4 ECG measurements showed no difference as far as heart rates, duration of PQ, and QRS intervals were concerned. AF developed in 2 (2%) cases in group A and in 20 (36%) cases in group B (P < 0.001). There was no difference between the two groups when average basal P max, P min, P dispersion, and day 4 P min values were compared. In group A, fourth day P max (94.3 +/- 11.8 vs 101.0 +/- 13.2 ms; P = 0.0025) and P dispersion (38.2 +/- 9.2 vs 44.9 +/- 10.9 ms; P = 0.0002 ) were significantly lower as compared to group B. Comparing the patients who developed AF, and who did not, no difference was detected with regard to baseline P max, P min, P dispersion, and day 4 P min. Day 4 P max (95.1 +/- 11.8 vs 106.4 +/- 14.0 ms, P = 0.0015) and P dispersion (38.9 +/- 8.8 vs 50.7 +/- 13.0 ms, P = 0.001) of patients who developed AF were significantly higher. Baseline Mg levels were similar in patients who developed AF, and who did not, but the day 4 Mg level was significantly lower in AF group (2.0 +/- 0.23 vs 2.15 +/- 0.26 mg/dL, P < 0.001).

CONCLUSION

Perioperative Mg treatment reduces P dispersion and the risk of developing AF in patients undergoing CABG.

The effect of Valsalva maneuver on P wave in 12-lead surface electrocardiography in patients with paroxysmal atrial fibrillation

The previous studies relating to the effect of the Valsalva maneuver on P wave do not provide detailed information. In those studies, the parameters related to P wave duration during the release phase of the Valsalva maneuver were evaluated. The authors evaluated P wave amplitude as well as P wave duration during the strain phase of the Valsalva maneuver. Thirty-seven normal subjects and 36 patients with paroxysmal atrial fibrillation (PAF) were included in the study. Twelve-lead surface electrocardiography (ECG) was obtained from all the patients before and during the strain phase of the Valsalva maneuver. The authors evaluated the parameters related to both P wave duration and P wave amplitude. The highest P wave voltage was expressed as the P wave amplitude maximum (P amp max), the lowest P wave voltage as the P wave amplitude minimum (P amp min), and the P wave amplitude dispersion (P amp dispersion) as "the P amp max - the P amp min." Also, the maximum P wave duration was expressed as the P maximum (P max), the minimum P wave duration as the P minimum (P min), and the P wave dispersion as "the maximum P wave duration (P max) - the minimum P wave duration (P min)." All these parameters were measured before and during the strain phase of the Valsalva maneuver. P max, P dispersion, P amp max, and P amp dispersion were higher in patients with PAF compared to those of normal subjects before the Valsalva maneuver. In normal subjects, P max, P wave dispersion, P amp max, and P amp dispersion values were significantly higher in the strain phase of the Valsalva maneuver than before (p<0.01, p<0.01, p<0.05, and p<0.05, respectively). In the patients with PAF, P max, P wave dispersion, P amp max, and P amp dispersion values were significantly lower during the strain phase of the Valsalva maneuver than before. In conclusion, in the patients with PAF, P wave parameters were decreased during the strain phase of the Valsalva maneuver, approaching to the normal levels.

Effect of diuresis on P-wave duration and dispersion

STUDY OBJECTIVE

To evaluate the effects of changing volume status on P-wave duration and dispersion in patients with decompensated heart failure.

DESIGN

Prospective analysis.

SETTING

Hospital cardiology unit.

PATIENTS

Twenty-one patients with symptoms of decompensated heart failure who were treated with diuretics on admission.

INTERVENTION

Twelve-lead electrocardiograms were obtained at baseline and after diuresis. Average, minimum, and maximum P-wave duration and P-wave dispersion (minimum minus maximum duration) were determined.

MEASUREMENTS AND MAIN RESULTS

P-wave duration was measured manually in all 12 leads by using a 0.5-mm-scale precision ruler and magnifying lens. After 40+/-23 hours of diuresis, 3+/-1 L of fluid was removed. A significant correlation was found between average P-wave duration and amount of fluid removed (r = -0.59, p=0.015). Also, average and maximum P-wave duration were significantly decreased with diuresis (p=0.001 and 0.022, respectively). No other P-wave variables were significantly affected.

CONCLUSIONS

Diuresis may attenuate electrophysiologic changes caused by fluid overload.

Acute short-term effect of VVI pacing mode on P wave dispersion in patients with dual chamber pacemakers

The acute or chronic effect of VVI pacing on P wave duration in the same patient with dual chamber pacemaker has not been studied before. Hence, with the purpose of determining whether VVI pacing increases dispersion of atrial refractoriness, we undertook a comparative study with the aid of a simple noninvasive approach, namely P wave dispersion (PWD) determined from surface electrocardiogram in the same patients who were implanted with dual chamber pacemakers. Pmax duration calculated in VVI paced mode was significantly higher than in VDD paced mode (121+/-21 vs. 111+/-17 ms, P=0.021). PWD (33+/-15 vs. 40+/-23 ms, P=0.062) did not demonstrate any significant difference between VDD and VVI paced modes, respectively. In conclusion, the findings of our study suggest that short-term VVI pacing itself does not have any direct effect on PWD in patients with dual chamber pacemakers. Different pacing modes in the long term might be responsible for altering PWD and the occurrence of atrial fibrillation while affecting the autonomic nervous system.

Changes in P-wave dispersion and P-wave duration after open heart surgery are associated with the peak incidence of atrial fibrillation

BACKGROUND

Increased P-wave dispersion (P-disp) and maximum P-wave duration (P-max) predict the development of atrial fibrillation (AF) in the general population. The present study evaluates the time-dependent relationship of P-disp and P-max after open heart surgery.

METHODS AND RESULTS

P-disp and P-max were measured in the perioperative period of open heart surgery (one day before surgery through postoperative day 4). Compared with the baseline, P-max decreased immediately after open heart surgery (112.63 +/- 7.4 ms vs 106.9 +/- 8.2 ms, P =.005). An increase in P-disp was observed between postoperative days 1 and 2 (37.5 +/- 6.8 ms vs 43.1 +/- 4.5 ms, P <.05), and postoperative days 1 and 3 (37.5 +/- 6.8 ms vs 44.1 +/- 6.6 ms, P <.05). There was also an increase in the P-max between postoperative day 1 and 3 (103 +/- 8.3 ms vs 110 +/- 7.7 ms, P <.05).

CONCLUSIONS

Nonuniform atrial conduction (P-disp) is greatest on days 2 and 3 after open heart surgery, and the longest atrial conduction time (P-max) is greatest on day 3 after open heart surgery, findings that coincide with the time of greatest risk for AF. (Heart Lung((R)) 2001;30:466-71.)

Analysis of P wave and P dispersion in children with secundum atrial septal defect

BACKGROUND

P maximum and P dispersion are evaluated as predictors of paroxysmal atrial fibrillation in adults. In this study, these variables are being investigated in children with secundum ASD in comparison with that of normal controls and in relation to size of ASD and the presence or absence of atrial dilation.

METHODS

Ninety-four children with isolated secundum ASD (33 boys, 60 girls; mean +/- SD age at diagnosis 2.9 +/- 4.1 years) and 65 age-matched controls (mean +/- SD age 4.2 +/- 4.2 years) were evaluated. Resting 12-lead ECG was used to measure P waves from which P maximum and P dispersion (difference between maximum and minimum P-wave duration) were derived. ASD children were arbitrarily subgrouped according to ASD sizes (small: 1-3 mm, moderate: 4-7 mm, large: > or = 8 mm). The presence of right atrial dilation was noted from echocardiography.

RESULTS

Children with ASD had significantly longer mean P dispersion compared to controls (P dispersion: 30.2 +/- 11.1 vs 26.4 +/- 6.6 ms, P = 0.008). Mean P maximum and P dispersion were significantly prolonged with increasing ASD size (P < 0.001). Children with right atrial dilation had significantly longer P maximum (102.3 +/- 15.2 vs 82.8 +/- 13.4 ms, P < 0.001) and larger P dispersion (36.1 +/- 12.5 vs 27.6 +/- 9.4 ms, P = 0.003) compared to those without right atrial dilation.

CONCLUSION

Prolonged atrial conduction time and inhomogeneity of atrial conduction may possibly be present in children with moderate to large sized ASD and in those with atrial dilation.

An evaluation of the change in electrocardiographic P-wave variables after acute caffeine ingestion in normal volunteers

BACKGROUND

Caffeine's effect on supraventricular dysrhythmias is poorly understood, and establishing a marker to predict atrial fibrillation may help to explain supraventricular dysrhythmias caused by caffeine.

OBJECTIVE

To evaluate the effects of caffeine (mean 6.1 mg/kg) on maximum P-wave duration and P-wave dispersion in normal volunteers.

METHOD

A randomised, double-blind, placebo-controlled, crossover study in 10 healthy volunteers at least 17 years of age at the University of Connecticut. Participants abstained from caffeinated products for at least 2 days before study initiation and were randomly allocated on different days to receive placebo or caffeine 400 mg. For each of the study phases, a baseline 12-lead electrocardiogram (ECG) was performed and a subsequent 12-lead ECG was performed 3 h after ingesting the study drug.

RESULTS

No significant changes were found within intra- or intergroup comparisons for any P-wave variables measured.

CONCLUSION

Single dose caffeine (400 mg) does not affect average P-wave duration, maximum P-wave duration or P-wave dispersion in normal individuals.

P wave dispersion in hypertensive patients with paroxysmal atrial fibrillation

It is important to assess the risk of developing paroxysmal atrial fibrillation (PAF) in hypertensive patients since hypertension is a common disorder predisposing to PAF. We sought to determine if patients with hypertension at risk of PAF can be identified while in sinus rhythm by measurements of P wave dispersion. Twelve-lead surface electrocardiograms were recorded in 44 hypertensive patients with history of PAF (group I, mean age = 60) and in 50 hypertensive patients without history of AF (group II, mean age = 57). The maximum P wave duration, the minimum P wave duration, and P wave dispersion (Pd = Pmax - Pmin) were calculated from 12-lead surface ECGs. Left atrial dimension (LAD) and left ventricular ejection fraction (LVEF) were measured by echocardiography. P wave dispersion was significantly greater in group I than group II (50 +/- 12 vs 38 +/- 8 ms, P = 0.001). P minimum (75 +/- 13 vs 87 +/- 11 ms, P = 0.001) and LVEF (0.63 +/- 0.05 vs 0.67 +/- 0.04, P = 0.03) were significantly lower in group I than group II. However P maximum and LAD were not significantly different in group I than group II (P > 0.05). In univariate analysis, P minimum, P wave dispersion, and LVEF were significant predictors of PAF, whereas only P wave dispersion remained a significant independent predictor of PAF in a multivariate analysis. Measurement of P wave dispersion in sinus rhythm may be a useful noninvasive clinical tool to identify patients with hypertension at risk of developing atrial electrical instability and atrial fibrillation.

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.

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.

The acute effects of biatrial pacing on atrial depolarization and repolarization

Permanent biatrial and/or multisite atrial pacing may prevent atrial fibrillation (AF), but the effects on atrial electrophysiology remain incompletely understood. Acute biatrial pacing was studied in 20 patients with and 28 without (controls) a history of atrial fibrillation and/or flutter. Twelve-lead electrocardiograms were recorded during pacing from the high right atrium (RA), from the distal coronary sinus (LA), and biatrial pacing. P wave duration was measured in each lead and the difference between maximum and minimum P duration was termed P wave dispersion. Effective refractory periods (ERPs) were measured during each pacing mode. The dispersion of P wave duration was 35 +/- 14 ms in controls and 40 +/- 29 ms in AF patients (P = 0.17). Compared to RA pacing, LA pacing shortened P duration in controls (127 +/- 18 to 107 +/- 16 ms, P < 0.05) and biatrial pacing markedly shortened P duration in controls (127 +/- 18 to 93 +/- 14 ms, P < 0.05) and AF patients (114 +/- 43 to 97 +/- 21 ms, P < 0.05). P wave dispersion was unaffected. In controls, the LA ERP was longer than the RA ERP. This phenomenon was not present in AF patients, whose LA ERP was shorter than that of controls. Biatrial pacing had no effect on atrial ERPs or the dispersion of atrial refractoriness. In conclusion, acute biatrial pacing does not affect atrial repolarization but it does cause a marked shortening of global biatrial depolarization. Distal coronary sinus pacing produces a shorter P wave than RA pacing. There is substantial dispersion in the surface P wave of the electrocardiogram, the significance of which awaits further study.

Clinical study to investigate the predictive parameters for the onset of atrial fibrillation in patients with essential hypertension

BACKGROUND

The risk factors involved in the onset of atrial fibrillation (AF) are well known, but the predictive clinical and paraclinical parameters for the onset of AF in hypertensive patients have not been investigated specifically.

METHODS AND RESULTS

We retrospectively analyzed 97 consecutive patients with hypertension and no known history of AF or cardiovascular events who attended the cardiology outpatient clinic. The analysis was based on clinical data, the noninvasive ambulatory 24-hour measurement of blood pressure (AMBP), a standard 12-lead electrocardiogram, and a Doppler echocardiogram. After a mean follow-up of 25 +/- 3 months, 19 (19. 5%) patients had AF, 3 (15.8%) of whom had a cerebrovascular accident. The patients with AF were older than the others and their AMBP showed higher mean systolic diurnal and nocturnal blood pressures, though no differences in the clinical blood pressure readings were present. On the electrocardiogram, the maximum duration of the P wave and its dispersion were more prolonged in the patients with AF. On the Doppler echocardiogram, left ventricular mass and left atrial dimension were higher in the patients with AF, and the A-wave velocity of diastolic mitral flow was reduced in these patients. In the multivariate analysis, age (odds ratio 3.28, P <.001), diurnal systolic blood pressure (odds ratio 1.35, P <.01) and nocturnal systolic blood pressure (odds ratio 1.16, P <.01), maximum duration of the P wave (odds ratio 2.09, P <.01), dispersion of the P wave (odds ratio 2.52, P <.001), echocardiographic left ventricular mass (odds ratio 1.43, P <.01), left atrial dimension (odds ratio 2.81, P <.001), and velocity of the A wave (odds ratio 2. 24, P <.01) were independent predictors for the onset of AF. After correction for age, maximum duration of the P wave (odds ratio 1.34, P <.01), dispersion of the P wave (odds ratio 1.63, P <.001), and the velocity of the A wave (odds ratio 1.42, P <.01) remained independent predictors for the onset of AF.

CONCLUSIONS

In patients with hypertension, age and the level of diurnal and nocturnal systolic blood pressures measured by 24-hour AMBP are important independent predictors for the onset of AF. Independent of age, increases in left atrial dimension and left ventricular mass, prolongation of the maximum duration and dispersion of the P wave and reduced A-wave velocity are also predictors for the onset of AF.