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PubMed1993

Electrocardiogram interpretation in general practice: relevance to prehospital thrombolysis.

OBJECTIVE: To assess, in the context of their possible role in prehospital thrombolysis, the ability of general practitioners to recognise acute transmural myocardial ischaemia/infarction on an electrocardiogram. DESIGN: 150 doctors (every fifth name) were selected from the alphabetical list of 750 on Merseyside general practitioner register and without prior warning were asked to interpret a series of six 12 lead electrocardiograms. Three of these showed acute transmural ischaemia/infarction, one was normal, and two showed non-acute abnormalities. Details of doctors' ages, postgraduate training, and clinical practice were sought. SETTING: General practitioners' surgeries and postgraduate centres within the Merseyside area. PARTICIPANTS: 106 general practitioners (mean age 45 years) agreed to participate. MAIN OUTCOME MEASURE: Accuracy of general practitioners' interpretations of the six electrocardiograms. RESULTS: 82% of general practitioners correctly recognised a normal electrocardiogram. Recognition of acute abnormalities was less reliable. Between 33% and 61% correctly identified acute transmural ischaemia/infarction depending on the specific trace presented. Accurate localisation of the site of the infarct was achieved only by between 8% and 30% of participants, while between 22% and 25% correctly interpreted non-acute abnormalities. Neither routine use of electrocardiography nor postgraduate hospital experience in general medicine was associated with significantly greater expertise. CONCLUSION: The current level of proficiency of a sample of general practitioners in the Merseyside area in recognising acute transmural ischaemia/infarction on an electrocardiogram suggests that refresher training is needed if general practitioners are to give prehospital thrombolysis.

Adult↗

PubMed1995

Comparison of automatic QT measurement techniques in the normal 12 lead electrocardiogram.

OBJECTIVE: To undertake a quantitative assessment of different automatic QT measurement techniques and investigate the influence of electrocardiogram filtering and algorithm parameters. DESIGN: Four methods for identifying the end of the T wave were compared: (1) threshold crossing of the T wave (TH); (2) threshold crossing of the differential of the T wave (DTH); (3) intercept of an isoelectric level and the maximum T wave slope (SI); and (4) intercept of an isoelectric level and the line passing through the peak and the point of maximum slope of the T wave (PSI). Automatic QT measurements were made by all techniques following different electrocardiogram filtering and, when appropriate, with four different isoelectric levels and with three different threshold levels. SUBJECTS: 12 simultaneous standard electrocardiogram leads, containing at least two electrocardiogram complexes, were recorded from 25 healthy volunteers relaxing in a semirecumbent position. MAIN OUTCOME MEASURE: Mean and standard deviation of differences between reference and automatic QT measurements were compared for the four techniques. RESULTS: The mean automatic QT measurements varied by up to 62 ms, which was greater than has been found between manual measurements by experienced clinicians. Technique TH was particularly poor. The other techniques produced consistent results for most electrocardiogram filter, isoelectric level, and threshold level setting; but technique SI underestimated QT relative to the other techniques. CONCLUSION: Different QT measurement techniques produced results which were influenced, to varying degrees, by filtering and technique variables. This is relevant for the inter-comparison of studies using different techniques. Technique TH, a common approach, is not recommended.

Adult↗

PubMed2004

Correlation study on oral health and electrocardiogram abnormalities.

The purpose of this study was to investigate the association between periodontal conditions and electrocardiogram test results that were obtained to screen for coronary heart disease risk factors. The present study included a total of 578 subjects who underwent annual medical check-ups at the Total Health Care Center in Otsu, Shiga Prefecture, Japan. To calculate the odds ratios for the electromyography abnormalities, we performed a logistic regression analysis for the oral examination, electrocardiogram, and blood analysis data. The crude odds ratio was obtained by a logistic regression analysis of age, sex, number of missing teeth, number of filled teeth, simplified oral hygiene index, community periodontal index, and blood analysis factors and results indicated there was a statistically significant correlation with the prevalence of electrocardiogram abnormalities. However, electrocardiogram abnormalities have a strong correlation with demographic factors such as sex and age. Therefore the experimental factors representing oral status were reexamined after the odds ratios were adjusted for age and sex. As a result of this adjustment, the new odds ratios that were determined indicated that there were no correlations between the oral factors and the prevalence of electrocardiogram abnormalities.

Adult↗

PubMed2004

[The electrocardiogram in ventricular tachycardias].

The electrocardiogram, as much as the clinical examination, is a basic tool for the cardiologist. Technological advances have led to a certain lack of interest in learning to read the electrocardiogram, for which close analysis can allow precise diagnosis, notably in the field of cardiac rhythm disorders. This article concerns the electrocardiogram in ventricular tachycardias with two themes: differential diagnosis of wide QRS complex tachycardias and recognition of the site of origin of a ventricular tachycardia. "Fine" analysis of the electrocardiogram is not an intellectual "game". Actually, careful analysis of the 12 lead ECG allows exact and rapid diagnosis in a large majority of cases, distinguishing a ventricular tachycardia from a supraventricular tachycardia with conduction defect; the appropriate management can be selected without delay. At the same time, close reading of the electrocardiogram also allows the site of origin of a ventricular tachycardia to be recognised. Combining this information with elements of the patient's record can allow the arrhythmia to be related to a known pathology or to prompt a targeted aetiological investigation.

Bundle-Branch Block↗

PubMed1991

Relation between epicardial electrograms and signal-averaged electrocardiograms after acute myocardial infarction in dogs.

Signal-averaged electrocardiograms allow the non-invasive detection of late potentials which represent locally delayed conduction in the myocardium. To validate this method, it is necessary to compare the signal-averaged data with electrograms recorded directly from the heart. However, the studies performed to date involve only a consecutive collection of the invasively and non-invasively obtained data. To obtain a more direct comparison, we examined this relation at operation by simultaneous epicardial and signal-averaged measurements. Acute infarction in animals was chosen, because the ischemic area is a zone of delayed conduction whose presence can be verified in a signal-averaged electrocardiogram. For this purpose, the left anterior descending artery, proximal of large septal and diagonal branches, was tied off in nine mongrel dogs after thoracotomy. Before infarction, a signal-averaged electrocardiogram was recorded from the body surface. At the same time, epicardial electrograms were performed using bipolar electrodes both from the supply area of the left anterior descending artery and from that of the circumflex artery. Five minutes after coronary ligation, both the epicardial measurements and the signal-averaged electrocardiogram were repeated on the open thorax. Before occlusion of the left anterior descending artery, narrow activation complexes occurred in general in the epicardial electrograms and no late potentials were recorded in any dog by the signal-averaged electrocardiogram. Five minutes after coronary ligation, fractionated and prolonged electrograms occurred in the epicardial recordings from the ischemic zone, while the activation complexes in the uninfarcted supply area of the circumflex artery remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

When the electrocardiogram fails to define site and extent of myocardial ischemia.

Information on the anatomical site of myocardial ischemia and infarction is commonly derived from the 12-lead electrocardiogram; however, correspondence between an electrocardiogram lead, showing ischemic changes and actual location of ischemia is not always present. In our experience, a good correspondence between the electrocardiogram and perfusion defects was found in patients with angina at rest and anterior ST segment elevation or normalization of negative T wave while patients with transient ST segment depression showed perfusion defects which correlated less with electrocardiographic changes. In addition, patients with ischemic episodes at rest and with inferior ST segment elevation, right or left ventricular ischemia were indistinguishable on the basis of the electrocardiogram as documented by Thallium-201 scintigraphy and radionuclide ventriculography. In effort angina, the site and extension of ST segment depression, even in patients with single vessel disease, failed to localize the actual anatomical location of myocardial ischemia. In patients with persistent ST segment depression and/or negative T waves, and clinically documented myocardial necrosis, transmural and non-transmural persistent perfusion defects were found in spite of absence of Q waves. In these patients, late normalization of the electrocardiogram did not correspond to normalization of flow. In conclusion, electrocardiographic changes do not always provide correct information regarding the presence, location and extent of myocardial ischemia and a multiparametric approach is often required in order to characterize ischemic and/or necrotic areas.

Angina Pectoris↗

PubMed1977

[Coronary stenosis in angina pectoris with normal resting electrocardiogram].

The arteriographic abnormalities found in 104 patients with typical angina pectoris and an electrocardiogram at rest which was normal at the time of arteriography were compared with those of 238 cases with typical angina pectoris, but with an abnormal electrocardiogram (127 having ST/T changes, 111 having transmural necrosis). There was no major difference between the two groups as far as the degree of coronary stenosis was concerned, nor in its extent and distribution. However, by comparison with the group with an abnormal electrocardiogram, very tight stenoses of the three trunks or of one trunk alone were slightly less common in the patients with a normal electrocardiogram; also, for each of the three trunks, the index of the lesion was slightly less raised, and the circumflex and right coronary arteries were slightly less commonly, affected, although the difference was not usually great enough to achieve significance. The action of the left ventricle and/or the value of left ventricular end-diastolic pressure were, however, manifestly better conserved in those with a normal electrocardiogram (p less than 0.001). An aorta-coronary bypass graft is more likely to be indicated in this group of patients.

Adult↗

PubMed1996

ST segment monitoring with a derived 12-lead electrocardiogram is superior to routine cardiac care unit monitoring.

BACKGROUND: Prior studies have shown that a derived 12-lead electrocardiogram with a simple electrode configuration is comparable with the standard electrocardiogram for arrhythmia analysis. METHODS: A prospective, comparative, within subjects design was used to compare the value of the derived 12-lead electrocardiogram with that of routine monitoring of leads V1 and II for detection of transient myocardial ischemia in 250 patients treated for unstable angina or myocardial infarction. RESULTS: During 11,532 hours of derived 12-lead ST segment monitoring, 55 (22%) of 250 patients had 176 episodes of ischemia. Of the 55 patients with ischemia, 75% reported no chest pain and 64% had no ischemic ST changes with routine monitoring leads. All five patients who developed angiographically confirmed abrupt reocclusion after percutaneous transluminal coronary angioplasty had ischemic ST changes with the derived electrocardiogram (sensitivity, 100%), compared with only two patients with routine monitoring (sensitivity, 40%). Serious complications occurred in 17% of angina patients with ischemic events compared to 3% of those without ischemia. Length of stay in the cardiac care unit was twice as long in angina patients who had ischemic events. In patients with acute myocardial infarction, ischemic events were not associated with a more complicated hospital course; however, length of stay in the cardiac care unit was longer in patients with recurrent ischemia. CONCLUSIONS: The findings show that derived 12-lead ST monitoring is superior to routine monitoring of leads V1 and II for detecting transient myocardial ischemia. ST monitoring of the derived 12-lead electrocardiogram may identify high-risk patients with unstable angina and provide prognostic information that would not be otherwise available from the usual clinical measures.

Adult↗

PubMed1985

Mechanism underlying the absence of ischemic changes on the exercise electrocardiogram in patients with abnormal exercise thallium-201 imaging and coronary artery disease.

Patients with coronary artery disease may have reversible abnormalities on a thallium myocardial perfusion study without simultaneous ischemic changes on the exercise electrocardiogram, but the mechanisms responsible for this disparity have not been fully elucidated. A group of 37 patients with angiographically demonstrated coronary artery disease and abnormal thallium perfusion imaging were divided into two groups on the basis of their exercise electrocardiographic ST segment response. Thirteen patients (Group A) had no significant electrocardiographic changes with exercise, while 24 patients (Group B) had ST changes consistent with ischemia during the test. There were no significant differences in clinical or angiographic characteristics between the two groups. Stress test results showed a similar mean duration of exercise in the two groups (6.2 +/- 1.8 versus 6.7 +/- 2.5 min, p = NS), but the patients in Group A achieved a significantly lower mean maximal heart rate (117 +/- 26 versus 132 +/- 21 beats/min, p less than 0.05) and mean maximal double product (19,650 +/- 5116 versus 22,650 +/- 4871, p less than 0.05). There was no consistent pattern of thallium perfusion abnormality noted in Group A to suggest that a particular region of electrically silent myocardium was responsible for ischemia in the absence of electrocardiographic changes. These results suggest that exercise thallium-electrocardiogram discordance is mediated by the level of myocardial workload achieved. An abnormal perfusion scan accompanying an exercise electrocardiogram which does not demonstrate any ischemic ST change may occur when there is sufficient increase in myocardial oxygen demand to result in differential augmentation of myocardial blood flow, but insufficient imbalance of supply and demand to result in signs of ischemia on the surface electrocardiogram.

Cardiac Catheterization↗

PubMed1988

Role of the electrocardiogram in determining electrophysiologic end points of drug therapy.

Electrocardiographic monitoring can be a useful adjunct to antiarrhythmic therapy, since the electrocardiogram is a simple indicator of net cardiac drug effect, irrespective of factors such as pharmacokinetic variability, drug-metabolite interactions or intraindividual variability in drug sensitivity. Changes associated with antiarrhythmic drug therapy include markers of sodium channel block, such as increased QRS or sinus-ectopic coupling intervals and increased QT interval, a marker of action potential prolongation. Electrocardiographic changes can serve 3 purposes: They can correlate with arrhythmia suppression, they may be a guide to impending drug toxicity, and they can indicate the presence of an antiarrhythmic drug at some electrophysiologically active site in the heart. This latter indication may be used as an assessment of compliance, as a clue to drug-drug interactions that may lower antiarrhythmic drug concentrations or preparatory to electrophysiologic testing when it is desirable to avoid testing patients who have no demonstrable drug effect. Drug-induced changes in the microelectrophysiologic environment may sometimes fail to express themselves on the surface electrocardiogram. Overall, however, the electrocardiogram is an inexpensive, readily available tool to monitor net antiarrhythmic drug effects on the heart. Monitoring of the electrocardiogram should, therefore, be an integral part of managing antiarrhythmic drug therapy in patients with arrhythmias.

Anti-Arrhythmia Agents↗

PubMed1991

Usefulness of QRST time-integral values of 12-lead electrocardiograms in diagnosing healed myocardial infarction complicated by left bundle branch block.

The usefulness of QRST time-integral (IQRST) values of 12-lead electrocardiograms for diagnosing a prior myocardial infarction complicated by left bundle branch block (LBBB) was determined. The study consisted of 25 patients with LBBB (11 with and 14 without myocardial infarction). The IQRST values in each lead point of 12-lead electrocardiograms were calculated. Data from 607 normal subjects were used as controls and mean +/- 2 standard deviations was regarded as the normal range. The following parameters were derived: number of leads less than the normal range of IQRST values (nQRST) and sum of the differences between the normal mean IQRST value and IQRST value of a given patient in leads where this value was less than the normal range (sigma QRST). The criteria of nQRST (12-lead) greater than or equal to 5 and sigma QRST (12-lead) greater than or equal to 500 microV in 12-lead electrocardiograms were selected on a relative cumulative frequency distribution and demonstrated the presence of a myocardial infarction in LBBB with a sensitivity of 82% and a specificity of 100% for each. With regard to the localization of the myocardial infarction, the criterion of sigma QRST (V1-6) greater than or equal to 300 microV in leads V1-6 of 12-lead electrocardiograms demonstrated the presence of an anterior myocardial infarction in the LBBB with a sensitivity of 88% and a specificity of 77%. It was difficult to localize an inferior myocardial infarction in patients with LBBB by using IQRST values of inferior leads.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Usefulness of ST-segment changes in greater than or equal to 2 leads on the emergency room electrocardiogram in either unstable angina pectoris or non-Q-wave myocardial infarction in predicting outcome.

To determine the reliability of the admission electrocardiogram in predicting outcome in patients hospitalized for chest pain at rest, 90 patients were randomized into a trial of aspirin versus heparin in unstable angina or non-Q-wave myocardial infarction, and prospectively followed for 3 months. The emergency room admission electrocardiogram was analyzed for ST-segment deviation greater than or equal to 1 mm/lead and T-wave changes. Unfavorable outcomes were recurrent ischemic pain, myocardial infarction and coronary revascularization with angioplasty or surgery. In patients who underwent coronary arteriography, a myocardium in jeopardy score ranging from 0 to 10 was assigned, based on the number of vessels with a diameter stenosis greater than or equal to 70% and the location of the stenoses. Considering all 90 patients, an admission electrocardiogram with ST-segment deviation in greater than or equal to 2 leads had a positive predictive value for adverse clinical events of 79% and a negative predictive value of 64%. In the subset of patients without left ventricular hypertrophy and whose admission electrocardiograms were recorded during chest pain (62 of 90), the positive predictive value of ST deviation in greater than or equal to 2 leads improved to 89% and the negative value to 72%. Of the 62 patients, 53 underwent coronary arteriography. There was a positive linear correlation between the total number of leads with ST-segment deviation and the myocardium in jeopardy score (r = 0.80, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1993

Value of the electrocardiogram in diagnosing the number of severely narrowed coronary arteries in rest angina pectoris.

The aim of this study was to assess the value of the electrocardiogram recorded during chest pain for identifying high-risk patients with 3-vessel or left main stem coronary artery disease (CAD). Therefore, the number of leads with abnormal ST segments, the amount of ST-segment deviation, and specific combinations of leads with abnormal ST segments were correlated with the number of coronary arteries with proximal narrowing of > 70%. Electrocardiograms recorded during chest pain were compared with one from a symptom-free episode. In this retrospective analysis, 113 consecutive patients were included. One-vessel CAD was present in 47 patients, 2-vessel CAD in 22, 3-vessel CAD in 24 and left main CAD in 20. Stratification was performed according to the presence of an old myocardial infarction. The number of leads with ST-segment deviations, and the amount of ST-segment deviation in the electrocardiogram obtained during chest pain at rest showed a positive correlation with the number of diseased coronary arteries. These findings were more marked when the absolute shifts from baseline were considered, because ST-segment abnormalities could be present also in the electrocardiogram obtained during the symptom-free episode. Left main and 3-vessel CAD showed a frequent combination of leads with abnormal ST segments: ST-segment depression in leads I, II and V4-V6, and ST-segment elevation in lead aVR. The negative predictive and positive accuracy of this pattern were 78 and 62%, respectively. When the total amount of ST-segment changes was > 12 mm, the positive predictive accuracy for 3-vessel or left main stem CAD increased to 86%.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1994

Impact of the electrocardiogram on the delivery of thrombolytic therapy for acute myocardial infarction.

The initial electrocardiogram is crucial in accurately selecting patients with chest pain for thrombolytic therapy. An electrocardiogram with a large amount of ST-segment elevation and depression is "visually alarming," and therefore, may influence the efficiency of patient treatment with thrombolytic therapy. It was hypothesized that the amount of ST-segment deviation present on the initial electrocardiogram was an important variable in determining the time to initiation of thrombolysis in the emergency department. The time from arrival at the emergency department to thrombolysis was measured in 93 consecutive patients with suspected acute myocardial infarction (AMI) who were treated with intravenous thrombolytic therapy by emergency department physicians. This was correlated with the sum of ST-segment elevation and depression present on the initial electrocardiogram. AMI was proved in 83 patients (89%). In patients with proved AMI, the average time to thrombolysis was 50.8 +/- 25.6 minutes. Treatment began within the goal of < or = 30 minutes in 18 patients (22%) and was excessively delayed at > or = 60 minutes in 24 (29%). Regression analysis of multiple clinical variables revealed that ST-segment sum was the only variable that significantly influenced the time to thrombolysis (r = -0.42; p < 0.001). For patients treated in < or = 30 minutes, the average ST-segment sum was 21.1 +/- 13.5 vs 11.5 +/- 11.4 mm for those treated in > or = 60 minutes (p = 0.01). In 10 patients mistakenly treated with thrombolytic therapy, the electrocardiographic processes responsible for ST-segment elevation included the early repolarization variant, left ventricular hypertrophy, old anterior AMI with persistent ST-segment elevation, and conduction delay.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography↗

PubMed1990

Routine electrocardiograms after cardiac catheterization. Are they useful?

In order to assess the value of routine electrocardiograms after cardiac catheterization (ECGs), 150 consecutive patients undergoing diagnostic cardiac catheterization were studied prospectively. The physician performing each catheterization was asked to rate his or her clinical index of suspicion that the electrocardiogram would be changed as a result of events during the procedure. Clinical index of suspicion and electrocardiograms were then compared for their ability to predict outcomes. Urgent clinical events within 24 hours of cardiac catheterization were defined as (1) new intensive care unit admission; (2) myocardial infarction; (3) coronary artery bypass graft surgery; (4) percutaneous transluminal coronary angioplasty; or (5) death. Chi square analysis demonstrated that neither ECGs (x2 = 2.12, p greater than 0.1) nor clinical index of suspicion (x2 = 2.43, p greater than 0.1) was better than chance alone in predicting urgent clinical events. The addition of ECGs to positive clinical index of suspicion did not increase the ability to predict urgent clinical events (x2 = 2.38, p greater than 0.1). Both ECGs and clinical index of suspicion were found to be relatively insensitive tests (sensitivity = 29% for ECGs, 43% for clinical index of suspicion). While both tests demonstrated high specificity, (89% for ECGs, 79% for clinical index of suspicion), their predictive value was equally poor (21% for ECGs, 17% for clinical index of suspicion). The addition of ECGs to clinical index of suspicion marginally increased the sensitivity of both tests to 50%. We conclude that routine postcatheterization electrocardiograms are no better at predicting urgent clinical events than clinical observation during catheterization alone, and should be performed only when index of suspicion dictates.

Angioplasty, Balloon, Coronary↗

PubMed1986

The electrocardiogram of European shrews.

A recording method of electrocardiograms in resting animals is described. The electrocardiograms of Crocidura russula, Crocidura leucodon, Crocidura suaveolens, Neomys fodiens and Sorex araneus are similar to those of other small mammals. T-wave directly follows the QRS-complex. The duration of electrocardiograms depends on heart mass and body temperature. Heart rate shows no influence on the duration of electrocardiograms.

Animals↗

PubMed1986

Detection of late potentials on the surface electrocardiogram in unexplained syncope.

To assess the usefulness of signal averaging of the surface electrocardiogram for detecting hitherto undocumented ventricular tachycardia (VT) in patients with unexplained syncope, 24 such patients were evaluated by electrocardiography and programmed ventricular stimulation. The surface electrocardiograms of 15 normal volunteers and 22 patients with documented sustained VT were also examined. No study subject had a bundle branch block or a QRS duration longer than 120 ms. Sustained VT was recorded in 9 of the 24 patients with syncope (8 patients with inducible VT and 1 with a spontaneous episode of recorded sustained VT). The signal-processed electrocardiogram contained late potentials and a filtered QRS duration longer than 120 ms in 8 of these 9 patients (89% sensitivity). None of the remaining 15 patients had these electrocardiographic abnormalities. Similar results were found in the patients with previously documented sustained VT (82% sensitivity) and in normal volunteers (no instances of abnormal recordings). In patients with unexplained syncope, signal processing of the surface electrocardiogram may be a sensitive and specific noninvasive test for detecting a high-risk subset of patients prone to lethal ventricular tachyarrhythmias.

Adult↗

PubMed2000

Predictive value of wavelet decomposition of the signal-averaged electrocardiogram in idiopathic dilated cardiomyopathy.

BACKGROUND: Wavelet decomposition of the signal-averaged electrocardiogram has been proposed as a method of detecting small and transient irregularities hidden within the QRS complex and of overcoming some of the limitations of time domain analysis of the signal-averaged electrocardiogram. AIM: This study evaluated the potential utility of wavelet decomposition analysis in the risk stratification of patients with idiopathic dilated cardiomyopathy. METHODS AND RESULTS: Both wavelet decomposition and time domain analysis were applied to the signal-averaged electrocardiogram recordings of 82 patients with idiopathic dilated cardiomyopathy (mean age 43 +/- 14 years, 60 men) and 72 normal controls (mean age 44 +/- 15 years, 48 men). Three conventional time domain indices and four wavelet decomposition analysis parameters (QRS length, maximum count, surface area, and relative length) were derived from each recording using a Del Mar CEWS system and an in-house software package, respectively. The results showed that (1) more patients with idiopathic dilated cardiomyopathy than without had late potentials, and that the filtered QRS duration was significantly longer in patients than in controls (P<0.001). Similarly, abnormal wavelet decomposition analysis was more common in patients and wavelet decomposition measurements were significantly different between patients and controls (P<0.01); (2) conventional time domain analysis did not distinguish between clinically stable patients and patients who developed progressive heart failure, or between patients with and without arrhythmic events; (3) wavelet decomposition analysis identified patients who went on to develop progressive heart failure but failed to distinguish patients with arrhythmic events from those without; (4) survival analyses of a mean follow-up of 23 months showed that patients with late potentials tended to develop progressive heart failure more frequently than others (P=0.06). Patients with an abnormal wavelet decomposition result more frequently developed progressive heart failure than those with a normal wavelet decomposition result (P=0.027); (5) in a univariate analysis (Cox model), wavelet decomposition measurements but not time domain indices significantly correlated with the development of progressive heart failure (P=0.01). Multivariate analysis showed that only left ventricular end-diastolic dimension and peak oxygen consumption during exercise remained significant predictors of progressive heart failure. CONCLUSION: Wavelet decomposition analysis of the signal-averaged electrocardiogram is superior to conventional time domain analysis for identifying patients with idiopathic dilated cardiomyopathy at increased risk of clinical deterioration. Wavelet decomposition analysis, however, is unlikely to prospectively distinguish patients at a high risk of arrhythmic events in idiopathic dilated cardiomyopathy in its present form.

Adult↗