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Evaluation of P wave duration and P wave dispersion in adult patients with secundum atrial septal defect during normal sinus rhythm
International Journal of Cardiology 91 (2003) 75–79 www.elsevier.com / locate / ijcard
Evaluation of P wave duration and P wave dispersion in adult patients with secundum atrial septal defect during normal sinus rhythm ´ Umit Guray*, Yesim Guray, M. Birhan Yylmaz, Burcu Mecit, Hatice Sasmaz, Sule Korknaz, Emine Kutuk Yuksek Ihtisas Hospital, Cardiology, Ankara, Turkey
Abstract 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 (Q p /Qs) and these P wave indices were investigated. Methods and results: Sixty-two consecutive patients [39 women, 23 men; mean age 33613 years (range 16 to 61 years)] with ostium secundum type ASD and 47 healthy subjects [25 women, 22 men; mean age 36.669.5 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 (P50.08), gender (P50.3), heart rate (P50.3), left atrial diameter (P50.5) and left ventricular ejection fraction (P50.3) 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 (P50.001). P minimum was not different between groups (P50.12). Mean Q p /Qs of the patients with ASD was 2.560.7 (minimum 1.5; maximum 4.1) and found to be significantly correlated with P maximum (r50.34; P50.006) and P dispersion (r50.61; 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. 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Atrial septal defect; Electrocardiography; P wave duration; P wave dispersion
1. Introduction Atrial septal defects (ASD) are among the most common congenital cardiac defects found in adults (Only bicuspid aortic valve and mitral valve prolapse are more common) [1]. Atrial arrhythmias especially atrial fibrillation (AF) are frequently encountered in adult patients with ASD and are responsible for *Corresponding author. Boncuk Sokak 7 / 2, 06600, Kurtulus, Ankara, Turkey. Tel.: 190-312-432-3383. E-mail address: [email protected] (U. Guray).
substantial morbidity and mortality even after surgical closure [2–5]. Previous studies have reported that prolonged intra- and interatrial conduction and inhomogeneous propagation of sinus impulses would be the characteristics of paroxysmal AF during sinus rhythm [6– 11]. Recently two simple electrocardiographic marker maximum P wave duration (P maximum) and P wave dispersion (P dispersion) were evaluated as the reflection of these conduction abnormalities in patients with paroxysmal AF [12–15]. In a recent study, Ho et al. [16] investigated P
0167-5273 / 03 / $ – see front matter 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016 / S0167-5273(02)00598-3
76
U. Guray et al. / International Journal of Cardiology 91 (2003) 75–79
maximum and P dispersion in children with ostium secundum ASD and P dispersion was found to be significantly increased in children with ASD as compared to age-matched healthy controls. They also showed that in children with ASD, P maximum and P dispersion were significantly prolonged with increasing ASD size. However, there has been no study performed in adult patients with ASD concerning P maximum and P dispersion in the literature so far. 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 and these P wave indices were investigated.
2. Methods
2.1. Study population This study comprised 62 consecutive patients [39 women, 23 men; mean age 33613 years (range 16 to 61 years)] with ostium secundum type ASD who underwent two-dimensional echocardiography followed by cardiac catheterization for the definite diagnosis. Pulmonary to systemic flow ratio (Q p /Qs) was calculated from cardiac catheterization by the Fick method. Patients over 40 years of age or who had a history of angina pectoris were also evaluated with coronary angiography for flow limiting coronary artery disease. All patients were in sinus rhythm during evaluation and none of them were taking antiarrythmic medication. Previous clinical and electrocardiography (ECG) recordings were carefully reviewed for the history of paroxysmal AF. None of the patients had a documented AF episode. Patients with other congenital cardiac defects associated with ASD such as pulmonary stenosis, Ebstein’s anomaly of the tricuspid valve or ventricular septal defect were excluded. Significant mitral valve regurgitation assessed with color-flow Doppler echocardiography and left ventriculography during cardiac catheterization associated with ASD was also excluded from the study. Other exclusion criteria were history of systemic hypertension, diabetes mellitus, hyperthyroidism, chronic obstructive pulmonary disease, pericardial effusion, ventricular preexcitation, abnormal
serum electrolytes and presence of coroner artery disease during coronary angiography. The control group consisted of 47 healthy subjects [25 women, 22 men; mean age 36.669.5 years (range 18–50 years)] without history of cardiovascular disease. All subjects were evaluated with physical examination, 12-lead ECG, chest roentgenogram and echocardiography before the inclusion. Each subject gave informed consent to participate in the study.
2.2. Twelve-lead surface ECG A 12-lead surface ECG was obtained from all patients and controls at a paper speed of 50 mm / s with 1 mV/ cm standardization. Subjects were allowed breath freely but not to speak or cough during recordings. P wave duration was measured manually using a electronic digital caliper and a magnifying lens by one investigator who was blinded to clinical data. The onset of the P wave was defined as the junction between isoelectric line at the beginning of the P wave deflection and the offset of the P wave was defined as the junction between the end of the P wave and the isoelectric line. If the onset or offset of the P wave were not clearly determined the lead was excluded from the analysis. This method was performed previously by different investigators [12–15]. Maximum P wave duration and minimum P wave duration (P minimum) were both measured from the 12-lead ECG and then P wave dispersion defined as the difference between P maximum and P minimum was calculated.
2.3. Statistical analysis Continuous variables are presented as mean values6SD and categorical variables are expressed as frequency. Continuous variables were compared by Mann–Whitney U-test and categorical variables were compared by means of chi-square test. Spearman rank correlation coefficients were used to calculate the correlations between Q p /Qs and P wave indices. A P value50.05 was considered statistically significant. The SPSS 10.0 statistical software package (SPSS Inc., Chicago, Illinois, USA) was used for all calculations.
U. Guray et al. / International Journal of Cardiology 91 (2003) 75–79 Table 1 Clinical and echocardiographic characteristics of study population
Number of subjects Age (years) Gender (men / women) Heart rate (beats / min) Left atrial diameter (mm) LVEF (%) PAPSP (mmHg)
Patients
Controls
P
62 33613 23 / 39 76611 3364 7062 35611
47 3669 22 / 25 7368 3365 6963 1464
0.08 0.3 0.3 0.5 0.3 ,0.0001
LVEF5Left ventricular ejection fraction; PAPSP5pulmonary artery peak systolic pressure.
3. Results Clinical and echocardiographic characteristics of patients and controls are shown in Table 1. There were no significant differences with respect to age (P50.08), gender (P50.3), heart rate (P50.3), left atrial diameter (P50.5) and left ventricular ejection fraction (P50.3) between patients and controls. Pulmonary artery peak systolic pressure was significantly higher in patients with ASD as compared to controls (P,0.0001). The measurements of P maximum, P minimum and P dispersion in two groups are shown in Table 2. P maximum was found to be 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 (P50.001). P minimum was not different between groups (P50.12). Mean Q p /Qs of the patients with ASD was 2.560.7 (minimum 1.5; maximum 4.1) and found to be significantly correlated with P maximum (r50.34; P50.006) and P dispersion (r50.61; P,0.0001).
4. Discussion Our study demonstrated for the first time that in adult patients with ASD and normal sinus rhythm, maximum P wave duration is significantly longer and Table 2 P wave duration measurements of study population
Number of subjects P maximum (ms) P minimum (ms) P dispersion (ms)
Patients
Controls
P
62 115612 75612 40613
47 102613 70613 3169
,0.0001 0.12 0.001
77
P wave dispersion is significantly increased as compared to age matched healthy controls. Furthermore we found significant correlations between Q p /Qs and both of these two P wave indices. Electrophysiological studies by programmed atrial stimulation have shown that intraatrial conduction delay [9–11], fragmented atrial activity [9–11] and anisotropic conduction [6,7] were associated with paroxysmal AF. Besides right atrial mapping studies during sinus rhythm have demonstrated that prolonged, fractionated atrial electrocardiograms were found more frequently and were more distributed within the entire right atrium in patients with paroxysmal AF [17]. This peculiar atrial electrophysiological feature characterized by slow inhomogeneous conduction of atrial impulse could be reflected by prolongation of P wave duration and P wave dispersion. Prolonged P wave duration in 12-lead surface ECG and signal-averaged ECG was commonly used for prediction of paroxysmal AF and considered to represent intra- and interatrial conduction delays predisposing to AF [12–14,18,19]. Moreover P dispersion is a relatively novel ECG index in noninvasive electrocardiology and seems to be quite useful in prediction of AF in various clinical settings [12–14,20]. It is believed that increased P dispersion simply reflects inhomogeneous and discontinuous propagation of sinus impulses [12,13]. Atrial fibrillation is a common arrhythmia found in conjunction with ASD in adults and a significant cause of morbidity [2–4]. Although incidence of AF increases with age even in general population [21], the incidence of AF in patients with ASD is strikingly high even after surgical closure [3,22]. Recently Oliver et al. [5] demonstrated that advanced age is the most important condition related to presence of AF in patients with ASD both before and after surgical closure. Furthermore they also noted that the development of this arrhythmia in adult patients with ASD occurs much more earlier than the general population. In a review from the Mayo Clinic regarding late results of 27 to 32 years after surgical repair of isolated ASD, patients who had surgical correction of an ASD after age 41 years had a 59% chance of having AF or atrial flutter at late follow up [3]. Same review also reported that 22% of late deaths were related to stroke and all these deaths occurred in patients with AF.
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U. Guray et al. / International Journal of Cardiology 91 (2003) 75–79
In a recent study conducted in children with ostium secundum ASD [16], P dispersion was found to be significantly longer in patients with ASD than the age-matched healthy controls. Although our study population were consisted of patients over 15 years of age (mean 33613 years, range 16–61 years) increased P dispersion in our study is in accordance with their findings. Another important finding in the aforementioned study was that P maximum and P dispersion were significantly prolonged with increasing ASD size. We did not evaluate defect size in our study but pulmonary to systemic flow ratio was calculated during cardiac catheterization. It was shown that the most important hemodynamic parameter, Q p /Qs, has a strong positive relation to ASD size [23]. We found significant correlations between Q p / Qs and P maximum as well as Q p /Qs and P dispersion. Although all patients were in sinus rhythm and none of them had a prior history of documented AF; we believe that prolongation of P maximum and increased P dispersion simply represents mechanical and electrical changes of atrial myocardium in patients with ASD. These changes could be the results of atrial dilatation, increased atrial stretch and atrial conduction disturbances, all of which are common in ASD [2,24]. With higher left to right shunt volumes, these changes of atrial myocardium may be more prominent. The significant correlation between Q p /Qs and two P wave indices (P maximum and P dispersion) in our study is possibly related to the more prominent changes in atrial macro- and microarchitecture and site-dependent conduction slowings [6,7,25].
5. Conclusions It is concluded that in adult patients with ASD and sinus rhythm, P maximum is significantly longer and P dispersion is significantly increased as compared to the age matched healthy controls. Additionally, there are significant correlations between Q p /Qs and both of these P wave indices. However, it is unclear that if longer P maximum and higher P dispersion can confidently predict atrial arrhythmias in patients with ASD. Earlier detection of patients at risk for AF during sinus rhythm may reduce future morbidity. Therefore, further assessment of the clinical utility of
these simple ECG markers in patients with ASD for the prediction of AF and effects of surgical closure on these P wave indices require large prospective studies.
References [1] Dickinson DF, Arnold R, Wilkinson JL. Congenital heart disease among 160 480 liveborn children in Liverpool 1960 to 1969: implications for surgical treatment. Br Heart J 1981;46:55–62. [2] Berger F, Vogel M, Kramer A et al. Incidence of atrial flutter / fibrillation in adults with atrial septal defect before and after surgery. Ann Thorac Surg 1999;68:75–8. [3] Murphy JG, Gersh BJ, McGoon MD et al. Long-term outcome after surgical repair of isolated atrial septal defect. N Engl J Med 1990;323:1645–50. [4] Cowen ME, Jeffrey RR, Drakeley MJ, Mercer JL, Meade JB, Fabri BM. The results of surgery for atrial septal defect in patients aged fifty years and over. Eur Heart J 1990;11:29–34. ´ [5] Oliver JM, Gallego P, Gonzalez A, Benito F, Mesa JM, Sobrino JA. Predisposing conditions for atrial fibrillation in atrial septal defect with and without operative closure. Am J Cardiol 2002;89:39–43. [6] Spach MS, Miller WT, Geselowitz DB, Barr RC, Kootsey JM, Johnson EA. The discontinuous nature of propagation in normal canine cardiac muscle: evidence for recurrent discontinuity of intracellular resistance that effect the membrane currents. Circ Res 1981;48:39–54. [7] Spach MS, Dolber PC. Relating extracellular potentials and their derivatives to anisotropic propagation at a microscopic level in human cardiac muscle: evidence for electrical uncoupling of side– side fiber connections with increased age. Circ Res 1986;58:356–71. [8] Leier CV, Meacham JA, Schall SF. Prolonged atrial conduction: a major predisposing factor for atrial flutter. Circulation 1978;57:213– 6. [9] Hashiba K, Tanigawa M, Fukatani M et al. Electrophysiologic properties of atrial muscle in paroxysmal atrial fibrillation. Am J Cardiol 1989;64:20J–3J. [10] Cosio FG, Palacios J, Vidal JM, Cocina EG, Gomez-Sanchez MA, Tamargo L. Electrophysiologic studies in atrial fibrillation. Slow conduction of premature impulses: a possible manifestation of the background for reentry. Am J Cardiol 1983;51:122–30. [11] Simpson RJ, Foster JR, Gettes LS. Atrial excitability and conduction defect. Am J Cardiol 1982;50:1331–7. [12] Dilaveris PE, Gialafos EJ, Sideris SK et al. Simple electrocardiographic markers for the prediction of paroxysmal idiopathic atrial fibrillation. Am Heart J 1998;135:733–8. [13] Aytemir K, Ozer N, Atalar E et al. P wave dispersion on 12-lead electrocardiography in patients with paroxysmal atrial fibrillation. Pace 2000;23:1109–12. [14] Ciaroni S, Cuenoud L, Bloch A. Clinical study to investigate the predictive parameters for the onset of atrial fibrillation in patients with essential hypertension. Am Heart J 2000;139:814–9. [15] Tsikouris JP, Klugger J, Song J, White CM. Changes in p-wave dispersion and p-wave duration after open heart surgery are associated with peak incidence of atrial fibrillation. Heart Lung 2001;30:466–71. [16] Ho TF, Chia EL, Yip WC, Chan KY. Analysis of p wave and p wave dispersion in children with secundum atrial septal defect. Ann Noninvas Electrocardiol 2001;6:305–9.
U. Guray et al. / International Journal of Cardiology 91 (2003) 75–79 [17] Tanigawa M, Fukatani M, Konoe A, Isomoto S, Kadena M, Hashiba K. Prolonged and fractionated right atrial electrograms during sinus rhythm in patients with paroxysmal atrial fibrillation and sick sinus syndrome. J Am Coll Cardiol 1991;17:403–8. [18] Fukunami M, Yamada T, Ohmori M et al. Detection of patients at risk for paroxysmal atrial fibrillation during sinus rhythm by p-wave triggered signal-averaged electrocardiogram. Circulation 1991;83:162–9. [19] Guidera SA, Steinberg JS. The signal-averaged P wave duration: a rapid and noninvasive marker of risk of atrial fibrillation. J Am Coll Cardiol 1993;21:1645–51. [20] Weber UK, Osswald S, Huber M et al. Selective versus nonselective antiarrhythmic approach for prevention of atrial fibrillation after coronary surgery: Is there a need for pre-operative risk stratification. Eur Heart J 1998;19:794–800. [21] Wolf PA, Abbott RD, Kannel WB. Atrial fibrillation: a major contributor to stroke in the elderly: the Framingham Study. Arch Intern Med 1987;147:1561–4.
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[22] McNamara DG, Latson LA. Long-term follow-up of patients with malformations for which definitive surgical repair has been available for 25 years or more. Am J Cardiol 1982;50:560–8. [23] Fuse S, Tomita H, Hatakeyama K, Kubo N, Abe N. Effect of size of a secundum atrial septal defect on shunt volume. Am J Cardiol 2001;88:1447–50. [24] Brandenburg Jr. RO, Holmes Jr. DR, Brandenburg RO, McGoon DC. Clinical follow-up study of paroxysmal supraventricular tachyarrhythmias after operative repair of a secundum type atrial septal defect in adults. Am J Cardiol 1983;51:273–6. [25] Papageorgiou P, Monahan K, Boyle NG et al. Site-dependent intraatrial conduction delay: relationship to initiation of atrial fibrillation. Circulation 1996;94:384–9.
Evaluation of P wave duration and P wave dispersion in adult patients with secundum atrial septal defect during normal sinus rhythm ´ Umit Guray*, Yesim Guray, M. Birhan Yylmaz, Burcu Mecit, Hatice Sasmaz, Sule Korknaz, Emine Kutuk Yuksek Ihtisas Hospital, Cardiology, Ankara, Turkey
Abstract 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 (Q p /Qs) and these P wave indices were investigated. Methods and results: Sixty-two consecutive patients [39 women, 23 men; mean age 33613 years (range 16 to 61 years)] with ostium secundum type ASD and 47 healthy subjects [25 women, 22 men; mean age 36.669.5 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 (P50.08), gender (P50.3), heart rate (P50.3), left atrial diameter (P50.5) and left ventricular ejection fraction (P50.3) 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 (P50.001). P minimum was not different between groups (P50.12). Mean Q p /Qs of the patients with ASD was 2.560.7 (minimum 1.5; maximum 4.1) and found to be significantly correlated with P maximum (r50.34; P50.006) and P dispersion (r50.61; 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. 2003 Elsevier Ireland Ltd. All rights reserved. Keywords: Atrial septal defect; Electrocardiography; P wave duration; P wave dispersion
1. Introduction Atrial septal defects (ASD) are among the most common congenital cardiac defects found in adults (Only bicuspid aortic valve and mitral valve prolapse are more common) [1]. Atrial arrhythmias especially atrial fibrillation (AF) are frequently encountered in adult patients with ASD and are responsible for *Corresponding author. Boncuk Sokak 7 / 2, 06600, Kurtulus, Ankara, Turkey. Tel.: 190-312-432-3383. E-mail address: [email protected] (U. Guray).
substantial morbidity and mortality even after surgical closure [2–5]. Previous studies have reported that prolonged intra- and interatrial conduction and inhomogeneous propagation of sinus impulses would be the characteristics of paroxysmal AF during sinus rhythm [6– 11]. Recently two simple electrocardiographic marker maximum P wave duration (P maximum) and P wave dispersion (P dispersion) were evaluated as the reflection of these conduction abnormalities in patients with paroxysmal AF [12–15]. In a recent study, Ho et al. [16] investigated P
0167-5273 / 03 / $ – see front matter 2003 Elsevier Ireland Ltd. All rights reserved. doi:10.1016 / S0167-5273(02)00598-3
76
U. Guray et al. / International Journal of Cardiology 91 (2003) 75–79
maximum and P dispersion in children with ostium secundum ASD and P dispersion was found to be significantly increased in children with ASD as compared to age-matched healthy controls. They also showed that in children with ASD, P maximum and P dispersion were significantly prolonged with increasing ASD size. However, there has been no study performed in adult patients with ASD concerning P maximum and P dispersion in the literature so far. 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 and these P wave indices were investigated.
2. Methods
2.1. Study population This study comprised 62 consecutive patients [39 women, 23 men; mean age 33613 years (range 16 to 61 years)] with ostium secundum type ASD who underwent two-dimensional echocardiography followed by cardiac catheterization for the definite diagnosis. Pulmonary to systemic flow ratio (Q p /Qs) was calculated from cardiac catheterization by the Fick method. Patients over 40 years of age or who had a history of angina pectoris were also evaluated with coronary angiography for flow limiting coronary artery disease. All patients were in sinus rhythm during evaluation and none of them were taking antiarrythmic medication. Previous clinical and electrocardiography (ECG) recordings were carefully reviewed for the history of paroxysmal AF. None of the patients had a documented AF episode. Patients with other congenital cardiac defects associated with ASD such as pulmonary stenosis, Ebstein’s anomaly of the tricuspid valve or ventricular septal defect were excluded. Significant mitral valve regurgitation assessed with color-flow Doppler echocardiography and left ventriculography during cardiac catheterization associated with ASD was also excluded from the study. Other exclusion criteria were history of systemic hypertension, diabetes mellitus, hyperthyroidism, chronic obstructive pulmonary disease, pericardial effusion, ventricular preexcitation, abnormal
serum electrolytes and presence of coroner artery disease during coronary angiography. The control group consisted of 47 healthy subjects [25 women, 22 men; mean age 36.669.5 years (range 18–50 years)] without history of cardiovascular disease. All subjects were evaluated with physical examination, 12-lead ECG, chest roentgenogram and echocardiography before the inclusion. Each subject gave informed consent to participate in the study.
2.2. Twelve-lead surface ECG A 12-lead surface ECG was obtained from all patients and controls at a paper speed of 50 mm / s with 1 mV/ cm standardization. Subjects were allowed breath freely but not to speak or cough during recordings. P wave duration was measured manually using a electronic digital caliper and a magnifying lens by one investigator who was blinded to clinical data. The onset of the P wave was defined as the junction between isoelectric line at the beginning of the P wave deflection and the offset of the P wave was defined as the junction between the end of the P wave and the isoelectric line. If the onset or offset of the P wave were not clearly determined the lead was excluded from the analysis. This method was performed previously by different investigators [12–15]. Maximum P wave duration and minimum P wave duration (P minimum) were both measured from the 12-lead ECG and then P wave dispersion defined as the difference between P maximum and P minimum was calculated.
2.3. Statistical analysis Continuous variables are presented as mean values6SD and categorical variables are expressed as frequency. Continuous variables were compared by Mann–Whitney U-test and categorical variables were compared by means of chi-square test. Spearman rank correlation coefficients were used to calculate the correlations between Q p /Qs and P wave indices. A P value50.05 was considered statistically significant. The SPSS 10.0 statistical software package (SPSS Inc., Chicago, Illinois, USA) was used for all calculations.
U. Guray et al. / International Journal of Cardiology 91 (2003) 75–79 Table 1 Clinical and echocardiographic characteristics of study population
Number of subjects Age (years) Gender (men / women) Heart rate (beats / min) Left atrial diameter (mm) LVEF (%) PAPSP (mmHg)
Patients
Controls
P
62 33613 23 / 39 76611 3364 7062 35611
47 3669 22 / 25 7368 3365 6963 1464
0.08 0.3 0.3 0.5 0.3 ,0.0001
LVEF5Left ventricular ejection fraction; PAPSP5pulmonary artery peak systolic pressure.
3. Results Clinical and echocardiographic characteristics of patients and controls are shown in Table 1. There were no significant differences with respect to age (P50.08), gender (P50.3), heart rate (P50.3), left atrial diameter (P50.5) and left ventricular ejection fraction (P50.3) between patients and controls. Pulmonary artery peak systolic pressure was significantly higher in patients with ASD as compared to controls (P,0.0001). The measurements of P maximum, P minimum and P dispersion in two groups are shown in Table 2. P maximum was found to be 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 (P50.001). P minimum was not different between groups (P50.12). Mean Q p /Qs of the patients with ASD was 2.560.7 (minimum 1.5; maximum 4.1) and found to be significantly correlated with P maximum (r50.34; P50.006) and P dispersion (r50.61; P,0.0001).
4. Discussion Our study demonstrated for the first time that in adult patients with ASD and normal sinus rhythm, maximum P wave duration is significantly longer and Table 2 P wave duration measurements of study population
Number of subjects P maximum (ms) P minimum (ms) P dispersion (ms)
Patients
Controls
P
62 115612 75612 40613
47 102613 70613 3169
,0.0001 0.12 0.001
77
P wave dispersion is significantly increased as compared to age matched healthy controls. Furthermore we found significant correlations between Q p /Qs and both of these two P wave indices. Electrophysiological studies by programmed atrial stimulation have shown that intraatrial conduction delay [9–11], fragmented atrial activity [9–11] and anisotropic conduction [6,7] were associated with paroxysmal AF. Besides right atrial mapping studies during sinus rhythm have demonstrated that prolonged, fractionated atrial electrocardiograms were found more frequently and were more distributed within the entire right atrium in patients with paroxysmal AF [17]. This peculiar atrial electrophysiological feature characterized by slow inhomogeneous conduction of atrial impulse could be reflected by prolongation of P wave duration and P wave dispersion. Prolonged P wave duration in 12-lead surface ECG and signal-averaged ECG was commonly used for prediction of paroxysmal AF and considered to represent intra- and interatrial conduction delays predisposing to AF [12–14,18,19]. Moreover P dispersion is a relatively novel ECG index in noninvasive electrocardiology and seems to be quite useful in prediction of AF in various clinical settings [12–14,20]. It is believed that increased P dispersion simply reflects inhomogeneous and discontinuous propagation of sinus impulses [12,13]. Atrial fibrillation is a common arrhythmia found in conjunction with ASD in adults and a significant cause of morbidity [2–4]. Although incidence of AF increases with age even in general population [21], the incidence of AF in patients with ASD is strikingly high even after surgical closure [3,22]. Recently Oliver et al. [5] demonstrated that advanced age is the most important condition related to presence of AF in patients with ASD both before and after surgical closure. Furthermore they also noted that the development of this arrhythmia in adult patients with ASD occurs much more earlier than the general population. In a review from the Mayo Clinic regarding late results of 27 to 32 years after surgical repair of isolated ASD, patients who had surgical correction of an ASD after age 41 years had a 59% chance of having AF or atrial flutter at late follow up [3]. Same review also reported that 22% of late deaths were related to stroke and all these deaths occurred in patients with AF.
78
U. Guray et al. / International Journal of Cardiology 91 (2003) 75–79
In a recent study conducted in children with ostium secundum ASD [16], P dispersion was found to be significantly longer in patients with ASD than the age-matched healthy controls. Although our study population were consisted of patients over 15 years of age (mean 33613 years, range 16–61 years) increased P dispersion in our study is in accordance with their findings. Another important finding in the aforementioned study was that P maximum and P dispersion were significantly prolonged with increasing ASD size. We did not evaluate defect size in our study but pulmonary to systemic flow ratio was calculated during cardiac catheterization. It was shown that the most important hemodynamic parameter, Q p /Qs, has a strong positive relation to ASD size [23]. We found significant correlations between Q p / Qs and P maximum as well as Q p /Qs and P dispersion. Although all patients were in sinus rhythm and none of them had a prior history of documented AF; we believe that prolongation of P maximum and increased P dispersion simply represents mechanical and electrical changes of atrial myocardium in patients with ASD. These changes could be the results of atrial dilatation, increased atrial stretch and atrial conduction disturbances, all of which are common in ASD [2,24]. With higher left to right shunt volumes, these changes of atrial myocardium may be more prominent. The significant correlation between Q p /Qs and two P wave indices (P maximum and P dispersion) in our study is possibly related to the more prominent changes in atrial macro- and microarchitecture and site-dependent conduction slowings [6,7,25].
5. Conclusions It is concluded that in adult patients with ASD and sinus rhythm, P maximum is significantly longer and P dispersion is significantly increased as compared to the age matched healthy controls. Additionally, there are significant correlations between Q p /Qs and both of these P wave indices. However, it is unclear that if longer P maximum and higher P dispersion can confidently predict atrial arrhythmias in patients with ASD. Earlier detection of patients at risk for AF during sinus rhythm may reduce future morbidity. Therefore, further assessment of the clinical utility of
these simple ECG markers in patients with ASD for the prediction of AF and effects of surgical closure on these P wave indices require large prospective studies.
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