Prolonged Signal-averaged P-wave Duration Research Articles

Effects of Obstructive Sleep Apnea and its Treatment on Signal-Averaged P-Wave Duration in Men

Prolonged P-wave duration, indicating atrial conduction delay, is a potent precursor of atrial fibrillation. Obstructive sleep apnea (OSA) is a risk factor for atrial fibrillation development. We investigated the association of P-wave duration with OSA and its treatment. We enrolled 80 consecutive men with normal sinus rhythms who underwent polysomnography, had no history of atrial fibrillation or ischemic heart disease, and no evidence of heart failure. Signal-averaged P-wave duration (SAPWD) was measured in all participants. Multivariable regression analysis showed that age, hypertension, and log-transformed apnea-hypopnea index were significantly and independently correlated with SAPWD. SAPWD was repeatedly measured after 1 month of continuous positive airway pressure (CPAP) therapy in 62 patients with moderate-to-severe OSA. As controls, 18 patients with moderate-to-severe OSA were enrolled. Their SAPWD was also measured at baseline and after 1 month without CPAP therapy. No significant change in SAPWD was found between baseline and after 1 month in the controls. However, SAPWD was significantly shortened after 1 month of CPAP therapy (from 137.5±8.6 to 129.7±8.5 ms; P<0.001), and the SAPWD change was significantly different in patients with CPAP therapy compared with controls (P<0.001). In addition, the SAPWD change in patients with CPAP therapy correlated inversely with nightly CPAP usage (r=-0.52; P<0.001). OSA severity was significantly associated with prolonged SAPWD. CPAP therapy significantly shortened SAPWD in patients with moderate-to-severe OSA. Thus, OSA may cause atrial conduction disturbances, leading to an increased risk of atrial fibrillation development, which may be modifiable by alleviating OSA with CPAP therapy.

Evaluation of the Relationship between Atrial Septal Aneurysm and Cardiac Arrhythmias via P‐Wave Dispersion and Signal‐Averaged P‐Wave Duration

The aim of the study was to investigate the relationship between atrial septal aneurysms (ASAs) and cardiac arrhythmias via signal-averaged P-wave duration (SAPWD) and P-wave dispersion (Pd). Sixty-six patients with ASA served as the study group (group 1; 28 men and 38 women; mean age, 34 +/- 10 years) and 62 healthy volunteers served as the control group (group 2; 29 men and 33 women; mean age, 31 +/- 8 years) in the current study. ASAs were diagnosed by transthoracic echocardiography based on the criteria of a minimal aneurysmal base of > or =15 mm; and an excursion of > or =10 mm. All subjects were evaluated by 24-hour Holter monitoring, 12 lead body surface electrocardiogram for P-wave analysis, and signal-averaged electrocardiogram for P-wave duration (PWD). There was no significant difference between the study and control groups in terms of age, gender, left atrium diameter, and left ventricular ejection fraction. Supraventricular arrhythmias (SVAs) were detected in 29 patients with ASA (43.9%) and 5 controls (8.1%; P < 0.001). The mean Pd in patients with ASA was significantly longer compared to the control group (14.1 +/- 8 ms vs 7.0 +/- 2.9 ms; P < 0.001). Similarly, the mean SAPWD in group 1 was significantly longer compared to group 2 (127.4 +/- 17.6 ms vs 99.8 +/- 12.3 ms; P < 0.001). Prolonged SAPWD and Pd were determined to indicate electrical disturbances in the atrial myocardium, and predict the increase in the prevalence of SVA in patients with ASA.

Right ventricular apical lead position is associated with prolonged signal-averaged P-wave duration

Aim The study aimed to determine if right ventricular apical pacing is associated with adverse change in atrial substrate compared with right ventricular septal pacing. Methods Patients with septal leads and dual-chamber devices with more than 3 months of follow-up and 70% or higher cumulative percentage of ventricular pacing were compared with a matched group of apically implanted leads with a cumulative percentage ventricular pacing of 70% or higher. Device parameters were recorded, and high-resolution recordings were obtained for signal-averaged P-wave (SAPW) analysis. Previously obtained SAPW recordings taken from 49 healthy patients and 73 patients with paroxysmal atrial fibrillation were used as negative and positive controls, respectively. Results Ten patients with septal leads (mean age, 71.9 ± 12.1 years; mean months implanted, 10.5 ± 3.2 months) and 9 patients with apical leads (mean age, 71.9 ± 5.7 years; mean months implanted, 11.4 ± 6.4 months) were enrolled. The SAPW duration was longer in the apical cohort compared with the septal cohort (144.8 ± 6.9 and 133.0 ± 5.5 milliseconds, respectively; P = .001), whereas there was no significant difference between septal and normal cohorts (133.0 ± 5.5 and 129.3 ± 7.1 milliseconds, respectively; P = .08). Conclusions Apical pacing is associated with prolonged P-wave duration relative to septal pacing and controls: this may manifest as increased risk of atrial tachycardias and presents a potentially novel benefit of septal pacing.

Prolonged Signal-Averaged P-Wave Duration as an Intermediate Phenotype for Familial Atrial Fibrillation

This study sought to perform a genome-wide linkage analysis in a large atrial fibrillation (AF) kindred using AF and abnormally prolonged signal-averaged (SA) P-wave duration as the phenotype. Although inherited forms of AF exist, phenotypic complexity has limited efforts to ascertain mutation carriers and thus identify causal genes. The identification of intermediate or endophenotypes may accelerate this effort. A genome-wide linkage analysis was performed in a 4-generation AF kindred of 27 individuals, 8 with AF documented by electrocardiogram. The analysis was performed using AF as the phenotype, and repeated using an abnormally prolonged SA P-wave duration as the phenotype. Linkage analysis and fine mapping generated a maximum multipoint logarithm of the odds (LOD) score of 3.0 at chromosome 5p15 between markers D5S406 and D5S635. Importantly, 8 heterozygous carriers had a prolonged SA P-wave (203 +/- 21 ms) compared with 17 noncarriers (116 +/- 12 ms, p < 0.00001). Using prolonged SA P-wave (conventionally defined as >155 ms) as an endophenotype, a maximum LOD score of 3.6 was obtained in the same region of chromosome 5p15, a span of 5.75 centi-Morgans. In a large AF kindred, we have identified a novel AF locus on chromosome 5p15 and shown that affected individuals with AF and mutation carriers can be identified by a prolonged SA P-wave duration. Importantly, identification of an endophenotype in this kindred not only aided ascertainment of additional family members but also increased the LOD score, providing increased support for linkage at this locus. Identification of the causal gene, mapped to chromosome 5p15, will advance our understanding of the molecular basis of AF.

Signal-averaged P wave duration and the long-term risk of permanent atrial fibrillation

Objective. To assess the long-term risk of developing permanent AF in relation to the signal-averaged P wave duration (SAPWD) and clinical and echocardiographic characteristics. Design. In an observational study design we studied 131 patients with earlier ECG-documented AF and successfully restored sinus rhythm attending a long-term, follow-up visit at hospital or at home. Established permanent AF was examined in relation to primary clinical, echocardiographic, and electrophysiological parameters. Results. Only prolonged SAPWD (p =0.006) was associated with an increased risk of development of permanent AF. The risk of permanent AF after 3 years follow-up was 0.72 with an SAPWD equal to 180 ms versus 0.39 with a normal SAPWD (130 ms). We found no prognostic effect of age, gender, dilated left atrium, long duration of AF history, or long duration of the most recent episode of AF. Co-existing hypertension reduced the risk of permanent AF; this could be explained by concomitant treatment with angiotensin-converting-enzyme-inhibitors. Conclusion. Prolonged SAPWD (a marker of atrial remodelling) appears to be a risk factor for long-term development of permanent AF.

Atrial Fibrillation Recurrence: The Roles of Hypertension, Duration of Atrial Fibrillation Disease, and Prolonged Signal-Averaged P Wave Duration

Objective - To assess the risk of atrial fibrillation (AF) recurrence requiring hospitalisation or its transition to long-lasting AF in patients with earlier or present AF from the clinical characteristics, the duration of AF-disease, and the signal-averaged P wave duration (SAPWD). Design -We studied 111 consecutive patients (40 women; median age 65 years, range 30-85 years) with earlier or present AF. The SAPWD was measured on inclusion; the follow-up median follow-up time was 184 days (range 171-437). Endpoints were hospitalisation due to recurrent AF or transition to AF lasting longer than two days. Results -During follow-up 5 patients died, 33 patients were hospitalised with AF, and 9 patients developed long-lasting AF. Multiple logistic regression analysis showed three risk factors of interest: history of hypertension, OR=3.67 (95% CI 1.61 to 8.37), duration of AF disease longer than two years, OR=3.22 (95% CI 1.31 to 7.86), and non-significantly prolonged SAPWD above 140 ms, OR=1.87 (95% CI 0.60 to 5.82). The probability of relapse in patients without risk factors was 9%, with one risk factor 16-27%, with two risk factors 37-54%, and with three risk factors 74% (p=0.0005). Conclusions -Hypertension and long history of AF disease were associated with an increased risk of AF-relapse.

Prolonged signal‐averaged P wave duration after elective cardioversion increases the risk of recurrent atrial fibrillation

Objective—To assess the risk of atrial fibrillation (AF) recurrence after elective cardioversion of AF in relation to the signal‐averaged P wave duration (SAPWD), clinical characteristics of the patient, and the duration of the AF disease.Design—We studied 131 consecutive patients (88 men, 43 women), median age 67 years (range 29–87 years), after elective cardioversion of AF into sinus rhythm. The SAPWD was measured on inclusion, and the follow‐up period was 1 month. Recurrent AF within the first month after cardioversion was regarded as endpoint.Results—AF recurred in 73 patients (56%). Multiple logistic regression analysis showed that prolonged SAPWD above 160 ms was the only significant risk factor for recurrent AF, OR=2.22 (95% CI 1.07–4.60), p=0.03. There was no significant effect of age, diagnosed hypertension, diagnosed congestive heart failure, dilated left atrium, or long duration of AF on the risk of AF relapse.Conclusion—Prolonged SAPWD above 160 ms is a risk factor for recurrent AF after elective cardioversion of persistent AF.

Prolonged signal-averaged P wave duration as a prognostic marker for morbidity and mortality in patients with congestive heart failure

Objective --To evaluate the prognostic roles of prolonged signal-averaged P wave duration (SAPWD), raised levels of natriuretic peptides, and clinical characteristics in patients with stable congestive heart failure (CHF). Design --The SAPWD was assessed from a signal-averaged electrocardiogram (SAECG), and the plasma levels of N-terminal pro-atrial natriuretic peptide (Nt-proANP) and N-terminal pro-brain natriuretic peptide (Nt-proBNP) were measured in 43 consecutive patients with stable CHF without prior supraventricular arrhythmia. Echocardiographic and clinical data were also recorded. Time to death, hospitalization due to deteriorated CHF, or ECG-documented atrial fibrillation (AF) was recorded over a 438-day median follow-up. Results --During follow-up, 17 patients met an endpoint defined as death, AF, or hospitalization due to deteriorated CHF. Proportional hazard regression including the variables high age, prolonged SAPWD, raised levels of Nt-proANP and Nt-proBNP, and low ejection fraction (EF) showed that only prolonged SAPWD S 149 r ms was associated with an increased risk of meeting an early endpoint; the hazard ratio 3.94 with 95% confidence interval 1.50-10.42; p r = r 0.006. Conclusion --Prolonged SAPWD appears to predict early death, AF development, or hospitalization due to deterioration of CHF in patients with stable CHF.

History Repeats Itself

To the Editor: In a recent issue of Circulation , Zaman et al1 report a model for the preoperative risk stratification of patients at risk for developing atrial fibrillation (AF) after isolated coronary artery bypass grafting (CABG). They studied 326 patients prospectively and demonstrated that prolonged signal-averaged P-wave duration (SAPD), advanced age, and male sex identified patients at a high risk for post-CABG AF. Moreover, there was an incremental increase in risk for patients with >1 of these 3 variables. We agree with the authors that a predictive model for patients at risk for post-CABG AF could be useful for the management of this common complication. Advanced age was identified as an important predictor, and this has been consistently reported as a risk factor in prior studies.2 3 Male sex was identified as a risk in one prior report but not in the majority of other existing studies.4 The authors also highlight the …

Signal-averaged P-wave duration does not predict atrial fibrillation after thoracic surgery.

Atrial fibrillation (AF) is the most common dysrhythmia seen early after major thoracic surgery but occurs infrequently after minor thoracic or other operations. A prolonged signal-averaged P-wave duration (SAPWD) has been shown to be an independent predictor of AF after cardiac surgery. The authors sought to determine whether a prolonged SAPWD alone or in combination with clinical or echocardiographic correlates predicts AF after elective noncardiac thoracic surgery. Of the 250 patients enrolled, 228 were included in the final analysis. Preoperative SAPWD was obtained in 155 patients who had major thoracic surgery and in 73 patients undergoing minor thoracic or other operations who served as comparison control subjects. The SAPWD was recorded from three orthogonal leads using a sinus P-wave template. The filtered vector composite was used to measure total P-wave duration. Clinical, surgical, and echocardiographic parameters were collected and patients followed for 30 days after surgery for the development of symptomatic AF. Symptomatic AF developed in 18 of 155 (12%) patients undergoing major thoracic surgery and in 1 of 73 (1%) patients having minor thoracic or abdominal surgery, most commonly 2 or 3 days after surgery. In comparison with similar patients undergoing major thoracic surgery without AF, those who developed AF were older (66+/-8 vs. 62+/-10 yr; P = 0.04) but did not differ in SAPWD (145+/-17 vs. 147+/-16, ms) in standard electrocardiographic P-wave duration (105+/-7 vs. 107+/-10 mns), incidence of left-ventricular hypertrophy on 12-lead electrocardiography, male sex, history of hypertension, diabetes, or coronary heart disease. Thoracic-surgery patients at risk for postoperative AF did not differ from all other patients at low risk for AF in clinical or SAPWD parameters. Under the conditions of this study, SAPWD did not differentiate patients who did or did not develop AF after noncardiac thoracic surgery, and therefore its measurement cannot be recommended for the routine evaluation of these patients. Older age continues to be a risk factor for AF after thoracic surgery.