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E H Christiansen

Publications and source records attributed to E H Christiansen.

At least 19 recordsLinked to original sources
PubMed2001

Reproducibility of QT parameters derived from 24-hour ambulatory ECG recordings in healthy subjects.

AIM: To estimate the reproducibility of QT parameters derived from 24-hour ambulatory ECG recordings. METHOD: Ten healthy volunteers aged 25 to 41 years participated. In two 24-hour ambulatory ECG recordings obtained 1 day apart, the QT interval was measured manually at stable heart rates in approximately 16 periods during daytime and 6 periods during nighttime. The association between the QT and RR interval was described by linear regression for day and nighttime separately and the following QT parameters were calculated: the QT interval at heart rate 60 beats/min during daytime (QT(60)day), slope(day), slope(night), and the difference in QT(60) between day and nighttime (DeltaQT(60)). The QT parameters were assessed four times for each participant to discriminate method inaccuracy from day to day variation. The reproducibility was estimated as the coefficient of repeatability, the relative error, and the ratio between within-subject variability and between-subject variability. RESULTS: The coefficient of repeatability, the relative error and the ratio, respectively, were 19 ms, 1.8% and 0.5 for QT(60)day, 0.076, 21% and 0.68 for slope(day), 0.116, 43% and 1.37 for slope(night), and 37 ms, 325% and 1.19 for DeltaQT(60) when estimating the overall day to day reproducibility. Inaccuracy of QT measurement accounted for approximately 40% of this variation, whereas the error caused by selecting segments was small. CONCLUSION: QT(60)day has a high reproducibility and may with advantage replace the conventional QT interval measured on a resting ECG. To assess QT dynamics, the slope of the regression line during daytime is suitable and the short term reproducibility acceptable for clinical trials. Regarding slope(night) and DeltaQT(60), the variation is high and the parameters should be used with caution.

Adult↗
PubMed2000

Dose-related cardiac electrophysiological effects of intravenous magnesium. A double-blind placebo-controlled dose-response study in patients with paroxysmal supraventricular tachycardia.

AIMS: The role of magnesium as an antiarrhythmic drug is yet not conclusive. Therefore, we performed a double-blind, randomized, placebo-controlled dose-response study of cardiac electrophysiological effects of intravenous magnesium. METHODS AND RESULTS: Thirty-six patients undergoing an electrophysiological evaluation for paroxysmal supraventricular tachycardia were randomized to one of the following dosages of intravenous magnesium (0, 5, 10 or 20 mmol). Conventional electrophysiological variables for sinus node function, atrial, atrioventricular node and ventricular conduction and refractoriness were measured before and after magnesium administration. Prolongation of the atrial-His interval was found at 5 mmol of magnesium compared with placebo and no further prolongation was observed at higher doses (-3 +/- 8, 11 +/- 9, 7 +/- 15, 11 +/- 16, for the dosages of 0, 5, 10 and 20 mmol of magnesium, respectively, P < 0.05). Measures of sinus node function, intra-atrial conduction and conduction through the Purkinje system were unaffected by magnesium. Male gender was associated with prolongation in atrial effective refractory period, in contrast to shortening in females: 2 +/- 43, 35 +/- 44, 36 +/- 33, 13 +/- 12 ms for males and 3 +/- 6, -12 +/- 11, -13 +/- 12, 0 +/- 23 ms for females, respectively (P < 0.001). CONCLUSION: Atrioventricular node conduction was prolonged by 5 mmol intravenous magnesium and no further prolongation was observed at higher dosages. At dosages of 5 and 10 mmol magnesium the atrial effective refractoriness was prolonged in males and shortened in females.

Adolescent↗
PubMed1999

Increased QT dispersion in patients with insulin-dependent diabetes mellitus.

AIM: To compare the QT dispersion in unselected patients with insulin-dependent diabetes mellitus to non-diabetic control subjects and to assess the association between the QT dispersion and cardiac autonomic neuropathy, ischaemic heart disease, blood pressure level and nephropathy. METHODS: 42 patients with insulin-dependent diabetes mellitus and 80 control subjects aged 40-57 years participated. The QT interval was measured in a resting 12-lead electrocardiogram (ECG) and the QT dispersion defined as the difference between the maximum and minimum QT interval. Bazett's formula was used to correct for heart rate (QTc). The degree of cardiac autonomic neuropathy was assessed by five function tests and ischaemic heart disease was defined by a previous myocardial infarction, ECG abnormalities or a positive exercise test. RESULTS: Compared to control subjects, diabetic patients had a longer QTc interval (433 vs. 416 ms; P=0.002) and a higher QT dispersion (36 vs. 30 ms; P=0.02). In the diabetic group, the QTc interval was prolonged in patients with autonomic neuropathy (449 vs. 420 ms; P=0.007) and the QT dispersion was increased in patients with ischaemic heart disease (51 vs. 33 ms; P=0.004). No association was found to urinary albumin excretion rate or blood pressure. CONCLUSION: The QT dispersion as well as the QTc interval is increased in patients with insulin-dependent diabetes mellitus. The association between QT dispersion and ischaemic heart disease indicates that abnormalities in cardiac repolarisation may be caused by complications to diabetes rather than diabetes in itself.

Adult↗
PubMed1999

Efficacy and safety of intravenously administered dofetilide in acute termination of atrial fibrillation and flutter: a multicenter, randomized, double-blind, placebo-controlled trial. Danish Dofetilide in Atrial Fibrillation and Flutter Study Group.

BACKGROUND: This study was designed to assess the efficacy and safety of intravenous dofetilide in acute termination of atrial fibrillation (AF) and flutter (AFL). Dofetilide, an investigational class III antiarrhythmic agent, selectively inhibits the rapid component of the delayed rectifier potassium current, thus prolonging the effective refractory period and duration of the action potential. Dofetilide can be administered intravenously and has a rapid onset of electrophysiologic action. METHODS AND RESULTS: Ninety-six patients with AF (n = 79) or AFL (n = 17) with a median arrhythmia duration of 62 days (range 1 to 180) were randomized to placebo (n = 30) or 8 micrograms/kg IV dofetilide (n = 66) over 30 minutes. Conversion was defined as termination of the atrial arrhythmia within 3 hours from the start of infusion. The conversion rate was 30.3% after dofetilide and 3.3% after placebo (P <.006). Conversion rate was higher in AFL than in AF: 64% versus 24% (P =. 012). In nonconverters, there was no statistically significant difference between the change in heart rate among the dofetilide-treated compared with the placebo-treated patients (P =. 42). Torsade de pointes ventricular tachycardia developed in 2 patients (3%). In both patients, drug infusion was discontinued before the event because of prolongation of the QT interval. CONCLUSIONS: Intravenous dofetilide is effective in acute termination of AF and AFL of medium duration, with a particularly high efficacy rate in AFL. A small but serious risk of proarrhythmia must be anticipated.

Aged↗
PubMed1999

Predicting abuse-prone parental attitudes and discipline practices in a nationally representative sample.

OBJECTIVE: According to sociological and ecological models of abuse, typically nonabusive parents could behave abusively towards their children under certain circumstances. The purpose of this study was to examine factors that place parents at risk of abusing their children by predicting parents' use of discipline practices and attitudes that may bias parents towards abusive behaviors, which we refer to as abuse-proneness. METHOD: A telephone interview was administered by the Gallup Organization to a nationally representative sample of 1,000 parents. Using a set of theoretically relevant risk factors, multiple regression was used to predict variations in parental attitudes (i.e., attitudes towards physical discipline and attitudes that devalue children) and parental discipline practices (i.e., physical discipline, nonphysical discipline, and verbal abuse). RESULTS: The findings confirmed the importance of examining elements of parental attitudes, history, personality characteristics, as well as religion and ideology in predicting abuse proneness. Child age also was an important predictor in all analyses except predicting parental attitudes that devalue children. The findings suggest also, however, that it may be unduly simplified to regard parents as somewhere on a continuum of nonpunitive to punitive disciplinarians. Social isolation was not a significant predictor in any of the analyses. CONCLUSIONS: Although many important theoretical predictors of abuse proneness were confirmed, many questions arise regarding the diversity of discipline practices that parents use, and the relevance of child's age and social isolation in predicting abuse proneness. Implications for practitioners and future research are discussed.

Adolescent↗
PubMed1999

Population effects of the bombing of Oklahoma City.

BACKGROUND AND PURPOSE: The explosion at the Murrah Federal Building in Oklahoma City on April 19, 1995, affected many members of the community as well as direct victims. Our goal was to measure the exposure and effects among the general population. METHODS: We conducted surveys of the Oklahoma City metropolitan area and a control area to measure exposure and impact, primarily stress and psychological distress. RESULTS: Of the adults in the Oklahoma City MSA, 61.5 percent (58.5 percent to 64.5 percent with 95 percent confidence) reported experiencing at least one direct result of the bombing. In population terms, about 433 thousand adults (between 412 thousand and 457 thousand, with 95 percent confidence) were exposed to one or more of the consequences of the bombing. Oklahomans reported higher rates (about double) of increased alcohol use, smoking more or starting smoking. They reported more stress (about double), psychological distress (about double), post-traumatic stress-disorder components, and intrusive thoughts (double) related to the bombing than in the control area. Oklahomans also reported higher rates of seeking help for their stress or taking steps to reduce stress. The differences persisted into 1996, more than a year after the bombing. CONCLUSION: The exposure to the bombing was widespread, including more than half the adults in the metropolitan area surrounding Oklahoma City. The psychological effects were high and, while decreasing, persisted more than a year after the bombing. Primary care practitioners should screen their patients, who may normally not be considered victims, for exposure to the effects of a terrorist disaster for an extended period of time.

Adult↗
PubMed1998

[From paroxysmal to chronic atrial fibrillation].

Chronic atrial fibrillation is by definition always preceded by paroxysmal atrial fibrillation. The electropathophysiological mechanisms underlying paroxysmal atrial fibrillation are reviewed: atrial electrophysiological inhomogeneity, atrial ectopic activity, and cardiac autonomic dysfunction. Safe and effective interventions that prevent the progression from paroxysmal into chronic atrial fibrillation have not yet been developed. Such developments should be given high priority, as the consequences of chronic atrial fibrillation--stroke and heart failure--are unacceptable.

Atrial Fibrillation↗
PubMed1998

Effect of parasympathetic blockade on the signal-averaged electrocardiogram.

Low parasympathetic activity is associated with late potentials detected at a noise level of 0.4 microV in a signal-averaged electrocardiogram (SAECG) following myocardial infarction. In contrast, at a noise level of 0.2 microV, lowering parasympathetic activity influences late potential parameters in the opposite direction in healthy subjects. The aim of this study was to estimate the relationship between parasympathetic activity and the SAECG obtained at noise levels of 0.4 and 0.2 microV in healthy subjects. Two SAECG recordings in 10 healthy subjects were obtained at noise levels of 0.2 and 0.4 microV before and after parasympathetic blockade using atropine (1 mg). Signal-averaged QRS duration (SA-QRS), late potential duration (LPD) defined as duration of terminal signals below 40 microV, and root mean square voltage of the terminal 40 ms of the averaged QRS (RMS40) were measured. At a noise level of 0.2 microV SA-QRS reduced from 124 +/- 14 to 114 +/- 17 ms (P = 0.008), LPD from 37 +/- 10 to 28 +/- 14 ms (P = 0.01), and RMS40 increased from 26 +/- 22 to 41 +/- 25 microV (P = 0.006) during parasympathetic blockade compared to baseline values. At a noise level of 0.4 microV the SA-QRS (115 +/- 15 ms) and LPD (29 +/- 11 ms) were lower and the RMS40 (37 +/- 23 microV) was higher compared to the noise level 0.2 microV, and no systematic alterations of the three variables were found during parasympathetic blockade. The parasympathetic nervous system may induce a very low-amplitude late potential in the SAECG. The data suggest that parasympathetic activity and a low noise level may lead to a false late potential-positive SAECG in low arrhythmia risk subjects. Therefore, we recommend the use of a noise level of 0.4 microV or identification of high arrhythmia risk patients by late potential and low parasympathetic activity.

Adult↗
PubMed1998

Recovery of beat-to-beat variations of QRS.

There is a growing interest in the analysis of beat-to-beat variations of the morphology (BBM) of cardiac waves in electrocardiograms (ECG). Such analyses are confronted with the low BBM-to-noise ratio. An ECG clustering technique is introduced that brings the benefits of signal averaging to BBM analysis and recovers the beat-to-beat pattern of BBM. ECG clustering aligns waves and sorts them into clusters. The precision of the alignment was enhanced by sub-sample alignment. Kohonen's self-organising neural networks identified the clusters of the cardiac waves during training. The subsequent clustering of a wave results in a label for the closest cluster, a distance to the cluster and optimal alignment. Furthermore, ECG clustering avoids base-line variations and amplitude modulation sufficiently to be applied to the QRS wave in the raw ECG. The technique is demonstrated on 14 subjects with coronary heart disease and no myocardial infarction, myocardial infarction, or inducible ventricular tachycardia. ECG clustering is a general-purpose technique for beat-to-beat analysis, where the variations are cyclic as in the sinus rhythm. Results show that beat-to-beat variations in the QRS morphology are in general cyclic, with a main period of about four cardiac cycles. All calculations were performed with the Cardio software.

Coronary Disease↗
PubMed1998

Increased left ventricular systolic function in insulin dependent diabetic patients with normal albumin excretion.

Alterations in cardiovascular function may be an aetiological factor for the development of microalbuminuria in patients with insulin-dependent diabetes mellitus. We studied cardiac function with echocardiography in relation to the degree of albuminuria in 27 insulin-dependent diabetes mellitus patients and 13 healthy subjects. Patients were grouped according to urinary albumin excretion: <20 microg x min(-1) (normoalbuminuric), and 20 to 200 microg x min(-1) (microalbuminuric). None were or had been treated with cardiovascular drugs. The normoalbuminuric patients had a higher heart rate, mean velocity of circumferential shortening, stroke velocity index (a measure of contractility), and aortic peak velocity than controls. No difference in diastolic function was present. In the microalbuminuric group, the stroke velocity index was comparable to values observed in healthy subjects. The increased systolic performance (heart rate and contractility) may contribute to the renal hyperperfusion and glomerular hyperfiltration observed in insulin-dependent diabetes mellitus patients before the development of micro- and in turn macroalbuminuria. The possible cause effect mechanisms should be further studied, as preventive medical treatment of the hypercontractile heart is possible. In conclusion, cardiac contractility is increased in insulin-dependent diabetes mellitus patients with normoalbuminuria and returns to levels observed in healthy subjects when microalbuminuria develops.

Adult↗
PubMed1997

Efficacy and safety of dofetilide, a new class III antiarrhythmic agent, in acute termination of atrial fibrillation or flutter after coronary artery bypass surgery. Dofetilide Post-CABG Study Group.

Ninety-eight patients, who developed atrial fibrillation/flutter after coronary artery bypass grafting within 1-6 days after surgery, were included into a double-blind, placebo-controlled, randomized trial to assess the efficacy and safety of dofetilide. Patients were randomly allocated to dofetilide 4 micrograms/kg i.v. (n = 33), dofetilide 8 micrograms/kg i.v. (n = 32) or placebo (n = 33) given intravenously over 15 min at a constant infusion rate. Responders were defined as patients who converted to sinus rhythm at any time during the initial 3 h after the start of the infusion. The conversion rates were 24% (8/33) on placebo, 36% (12/33) on dofetilide 4 micrograms/kg, and 44% (14/32) on dofetilide 8 micrograms/kg. The P-values (two-tailed) were 0.27 for dofetilide 4 micrograms/kg vs. placebo, 0.11 for dofetilide 8 micrograms/kg vs. placebo, and 0.10 for dose-response relationship. Short episodes of aberrant ventricular conduction and ventricular tachycardia were seen separately in three subjects after dofetilide 8 micrograms/kg. No episodes of torsades de pointes were noted. No negative inotropic effect was noted. In conclusion, dofetilide was well tolerated, but the effects on atrial fibrillation/flutter did not attain statistical significance, possibly due to the high placebo conversion rate.

Aged↗
PubMed1996

[Atrial fibrillation after coronary artery bypass surgery. The significance of preoperative vagus modulation and ectopic atrial activity].

To investigate the impact of pre-operative autonomic balance and atrial ectopic activity on the risk of atrial fibrillation or flutter after aorto-coronary artery bypass surgery 24-hour Holter monitoring was analyzed in 102 patients before coronary artery bypass grafting. Index for vagal tone was calculated as % successive RR-interval differences > 6%. Twenty-nine (28%) of the 102 patients developed atrial fibrillation or flutter. Independent predictors (90% confidence interval) of postoperative atrial fibrillation or flutter were identified by logistic regression analysis: the independent predictors were older age, relative risk 1.07/year (1.02-1.12), vagal index < 10%, relative risk 4.50 (1.40-14.5), > or= 10 ectopic supraventricular beats/24 hour, relative risk 3.03 (1.05-8.72), and one or more event of non-sustained supraventricular tachycardia, relative risk 3.02 (1.11-8.22). Thus, age of the patient, attenuated preoperative cardiac vagal modulation, ectopic supraventricular beats, and paroxysmal non-sustained supraventricular tachycardia are independent risk factors for the development of atrial fibrillation or flutter after coronary artery bypass surgery.

Atrial Fibrillation↗
PubMed1996

[Treatment with implantable cardioverter-defibrillators. Experiences from Skejby hospital during the period 1989-1994].

The aim of the present study was to evaluate survival and therapy for ventricular tachyarrhythmia in patients treated with implantable cardioverter-defibrillator (ICD)-implantation at Skejby Hospital. Seventy-two patients, of which 54 were male, have received an ICD since 1989. Mean (range) age was 54 (16-74) years. Forty-nine (68%) had ischaemic heart disease. The patients were followed for a median (range) of 14 (1/2-50) months. Kaplan-Meyer plots are presented for total mortality, cardiac mortality, sudden cardiac mortality, appropriate therapy, and therapy for life-threatening tachyarrhythmia. After one, two and three years respectively, mortality was respectively 13, 27, and 32%, cardiac mortality was 5, 19, and 24%, sudden cardiac mortality was 3, 6, and 12%, cumulative incidence of appropriate therapy was 56, 66, and 90%, and cumulative incidence of therapy for life-threatening tachyarrhythmia was 19, 29 and 52%. It is concluded, that the majority of patients treated with an ICD developed ventricular tachyarrhythmia and had appropriate or lifesaving ICD-therapy during follow-up.

Adolescent↗
PubMed1996

Effect of residual noise level on reproducibility of the signal-averaged ECG.

Late potentials are detected at various noise levels in clinical studies. The aim of this study was to assess the effect of residual noise level on the reproducibility of the signal-averaged electrocardiogram (ECG). Two consecutive raw 15-minute ECG from each of 188 patients with coronary artery disease were digitized and stored on optical discs. Each raw ECG was analyzed by two signal-averaging procedures to noise level 0.2 microV or 0.4 microV. Standard time-domain parameters were measured: QRS duration (SA-QRS), late potential (LP) duration, and root-mean-square voltage of the terminal 40 ms of the filtered QRS (RMS40). The SA-QRS was prolonged by 12 +/- 14 ms by the reduction in noise level from 0.4 microV to 0.2 microV, LP duration was prolonged by 10 +/- 10 ms, and RMS40 was reduced by 19 +/- 22 microV. The temporal variation of the measured SA-QRS from ECG1 to ECG2 was significantly lower at noise level 0.2 microV (9 +/- 13 ms) than at noise level 0.4 microV (13 +/- 14 ms) (P < .001). The LP duration was also more stable at noise level 0.2 microV than at noise level 0.4 microV (0.5 +/- 11 ms vs 2 +/- 13 ms, P < .05). The presence of any two of three abnormal parameters (SA-QRS > 120 ms, RMS40 < 25 microV, LP duration > 40 ms) was used as the criterion for the presence of LPs. At noise level 0.4 microV, the proportion of patients with diagnosed LPs in ECG1 was 25% and at noise level 0.2 microV it was 62%. At noise level 0.4 microV, 20% were reclassified from LP-negative in ECG1 to LP-positive in ECG2, and 7% were reclassified from LP-positive in ECG1 to LP-negative in ECG2. At noise level 0.2 microV, 20% were reclassified from LP-negative in ECG1 to LP-positive in ECG2, and 9% were reclassified from LP-positive in ECG1 to LP-negative in ECG2. It was concluded that (1) the diagnosis of LPs is significantly dependent on the extent of noise reduction by signal averaging: and (2) the numerical reproducibility of signal-averaged QRS duration and LP duration is lower at noise level 0.4 microV then at noise level 0.2 microV; and the diagnostic reproducibility of LPs is similar at both noise levels.

Aged↗
PubMed1996

Noise in the signal-averaged electrocardiogram and accuracy for identification of patients with sustained monomorphic ventricular tachycardia after myocardial infarction.

Late potentials are detected at various noise levels in clinical studies. The aim of this study was, in a case-control design, to assess the effect of residual noise level on the identification of patients with sustained monomorphic ventricular tachycardia after myocardial infarction. Electrocardiograms from 16 patients with prior myocardial infarction and documented sustained monomorphic ventricular tachycardia and 41 patients with prior myocardial infarction and without ventricular tachycardia, were analysed by two signal averaging procedures to noise level 0.2 and 0.4 muV. Standard time domain parameters were measured. Two definitions of late potential were analysed: (1) if any two of the following criteria were present (signal-averaged QRS duration > 120 ms, late potential duration > 40 ms, and root-mean-square voltage of the terminal 40 ms of the filtered QRS < 25 muV); or (2) if the signal-averaged QRS duration > or = 120 ms. Overall the signal-averaged electrocardiogram performed better at noise level 0.4 muV compared to noise level 0.2 muV with respect to identification of patients with or without ventricular tachycardia after myocardial infarction. Reducing noise level from 0.4 to 0.2 muV increased the sensitivity, but the consequence was a substantial decrease in specificity. Our data indicate that when a high sensitivity is the goal, the definition based only on signal-averaged QRS duration > or = 120 ms should be applied; sensitivity was 88% and specificity 59% at noise level 0.4 muV. If a high specificity is the goal, the definition should be based on the definition with two abnormal parameters; sensitivity was 69% and specificity 68% at noise level 0.4 muV.

Adult↗
PubMed1996

Re-evaluation of the role of P-wave duration and morphology as predictors of atrial fibrillation and flutter after coronary artery bypass surgery.

To evaluate the significance of P-wave duration and morphology for the development of post-operative atrial fibrillation/flutter, we investigated 189 consecutive patients scheduled for elective coronary artery bypass surgery. The longest pre-operative total P-wave duration was measured from the standard electrocardiogram at a paper speed of 50 mm.s-1 (mean of two independent observers). By the signal averaging technique we determined the pre-operative total P-wave duration, and root-mean square voltage of the last 10, 20, and 30 ms of the filtered (40-250 Hz) P-wave from a vector composite of three orthogonal leads at noise level 0.2 microV. Forty-two (22%) of the patients developed atrial fibrillation/flutter. Older age (mean +/- SD) 62 +/- 8 vs 56 +/- 8 years (P < 0.000), increasing body weight 83 +/- 11 vs 79 +/- 12 kg (P = 0.05), treatment for hypertension 26 vs 13% (P = 0.04), and a longer P-wave duration in the standard electrocardiogram 129 +/- 12 vs 124 +/- 12 ms (P = 0.01) were associated with development of atrial fibrillation/flutter documented by a 12-lead electrocardiogram. Logistic regression analysis identified independent predictors, estimated adjusted relative risk (95% confidence interval) of atrial fibrillation/flutter: with age > 60 years, the relative risk was 4.46 (2.05-9.73), and body weight > 80 kg, the relative risk was 3.81 (1.71-8.46). Thus, P-wave duration and morphology did not provide significant information on the risk of atrial fibrillation/flutter when controlling for the effects of increasing age and body weight.

Aged↗
PubMed1996

Within- and between-patient variation of the signal-averaged P wave in coronary artery disease.

OBJECTIVES: To estimate interobserver, within-patient and between-patient variation of the signal-averaged P wave. To determine whether demographic, clinical, conventional ECG information, and coronary angiographic data are associated with the signal-averaged P wave duration in patients with documented coronary artery disease. BACKGROUND: A prolonged signal-averaged P wave may indicate the presence of a substrate for atrial tachyarrhythmias and may predict subsequent development of atrial fibrillation. However, information on variation, reproducibility, and determinants of the signal-averaged P wave are sparse. METHODS: One hundred ninety-three patients with angiographically documented coronary artery disease underwent two consecutive procedures of signal-averaging of P waves (SAECG1 and SAECG2). Interobserver, within-patient, and between-patient variation of the signal-averaged P wave was estimated (coefficient of variation: SD/mean). Multiple linear regression analysis was applied to identify parameters independently associated with signal-averaged P wave duration (SA-P). Atrial late potentials were considered if SA-P > 140 ms, and logistic regression analysis was applied to identify parameters associated with the presence of atrial late potentials. RESULTS: The interobserver, within-patient, and between-patient coefficients of variation for the signal-averaged P wave duration were 7.5%, 6.0% and 8.4%, respectively. The signal-averaged P wave duration correlated significantly with standard ECG P wave duration and height of the patient (r = 0.59). Forty-nine percent of the patients had atrial late potentials. P wave duration in the standard ECG correctly classified 73% (140/188) of the patients with respect to atrial late potential positivity or negativity. The sensitivity was 67% and the specificity was 78%. Agreement on the presence or absence of atrial late potentials between two observers was present in 71% (136/193) of the patients, and in 78% (151/193) between SAECG1 and SAECG2. CONCLUSIONS: The signal-averaged P wave has limited reproducibility in patients with coronary artery disease, and a normal or abnormal signal-averaged P wave can be predicted from the conventional ECG with high accuracy. It is recommended that the signal-averaged P wave be compared with the standard ECG P wave duration in follow-up studies with the aim of predicting atrial fibrillation.

Action Potentials↗