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P Kulakowski

Publications and source records attributed to P Kulakowski.

32 records · Page 2Linked to original sources
PubMed1993

Long-term reproducibility of individual indices of time-domain analysis, spectral temporal mapping, and spectral turbulence analysis of signal-averaged ECGs.

This study compared short-term (1 day) and long-term (1 week and 1 month) reproducibility of the numerical results of 21 individual indices of time-domain analysis, spectral temporal mapping, and spectral turbulence analysis of the signal-averaged electrocardiogram in 28 healthy volunteers (18 men, 10 women, mean age, 31 years; range, 22-39 years). For each of the 21 indices and for each of the repeated recordings (ie, recordings on day 1, 7, and 30), the mean relative error versus recording of day 0 was calculated together with the rank correlation coefficient. The study showed that (1) reproducibility of time-domain analysis with the 40-Hz high-pass filter was superior to that of time-domain analysis performed with the 25-Hz high-pass filter, (2) reproducibility of time-domain variables was similar to that of spectral turbulence analysis of the entire QRS complex and was superior to that of spectral temporal mapping, (3) reproducibility of frequency-domain techniques not based on time-domain measurements (such as spectral turbulence analysis of the entire QRS complex) was significantly better than that of frequency-domain techniques combined with time-domain measurements (such as spectral turbulence analysis of the low-power terminal QRS region or spectral temporal mapping), and (4) short- and long-term reproducibility of signal-averaged electrocardiographic indices is similar in a healthy population.

Adult↗
PubMed1992

Effect of thrombolytic therapy on the predictive value of signal-averaged electrocardiography after acute myocardial infarction.

Standard time domain variables from signal-averaged electrocardiography were examined in a population of 331 survivors of acute myocardial infarction. Of these subjects, 130 received early (less than 24 hours) thrombolytic therapy. During a follow-up of greater than or equal to 10 months, there were 17 arrhythmic events (8.5%) (sudden death or sustained symptomatic ventricular tachycardia) in the group without thrombolysis and 8 (6.2%) in those with thrombolysis. Statistically, highly significant differences between the signal-averaged electrocardiographic variables of patients with and without arrhythmic events were found in the group without thrombolysis, whereas only root-mean-square voltage of the terminal 40 ms of the signal-averaged QRS complex was statistically associated with outcome (the differences in the other 2 indexes being not significant) in patients with thrombolysis. When using 2 previously published categoric criteria for the diagnosis of abnormal signal-averaged electrocardiography, the performance of these criteria in predicting arrhythmic events was substantially better in the group without thrombolysis than in those with thrombolysis (positive predictive accuracy greater than 3 times lower). Retrospectively adjusted receiver-operator characteristics showed that for a sensitivity of 30%, the maximum achievable positive predictive accuracy of signal-averaged electrocardiography for arrhythmic events was 100% in the group without thrombolysis, but only 27% in those with thrombolysis. It is concluded that standard signal-averaged electrocardiography after acute myocardial infarction is less informative in patients who receive thrombolytic treatment.

Adult↗
PubMed1992

Differences between predictive characteristics of signal-averaged electrocardiographic variables for postinfarction sudden death and ventricular tachycardia.

Several studies indicate that the electrophysiologic substrate for sustained ventricular tachycardia differs from that of ventricular fibrillation. This prospective study examined whether there were clinically relevant differences between the predictive values of the standard time-domain signal-averaged (SA) electrocardiographic (ECG) variables for ventricular tachycardia and sudden death after myocardial infarction. Predischarge SA electrocardiograms were recorded in 332 patients after infarction. During a follow-up period of greater than or equal to 6 months, there were 12 sudden deaths (3.6%), 14 patients (4.2%) developed spontaneous sustained ventricular tachycardia and 20 patients (6%) died of circulatory failure. The sensitivity, specificity and positive predictive accuracy of the numerical values of the time-domain SA electrocardiographic variables for predicting sudden death and ventricular tachycardia were compared. The optimal criteria for predicting ventricular tachycardia required the positivity of greater than or equal to 2 of the standard time-domain SA variables, whereas the optimal criteria for predicting sudden death required the positivity of all 3 variables. A high specificity was sustained over a wider range of sensitivity for sudden death than it was for ventricular tachycardia and the values of the variables which provided the same sensitivity for sudden death and ventricular tachycardia were different. For a sensitivity of 70%, the positive predictive accuracy was 31% for predicting sudden death and 13% for predicting ventricular tachycardia. The study concludes that differences in the predictive characteristics of variables for ventricular tachycardia and sudden death may be used to refine postinfarction risk stratification.

Adult↗
PubMed1992

Frequency versus time domain analysis of signal-averaged electrocardiograms. I. Reproducibility of the results.

Three repeated signal-averaged electrocardiographic (ECG) recordings were made in 40 subjects (15 healthy volunteers, 10 patients with ventricular tachycardia without apparent heart disease and 15 patients with ventricular tachycardia after myocardial infarction). In each subject, the three recordings were made within 25 min. The recordings were subsequently analyzed by 1) the conventional time domain method of signal-averaged ECG analysis with use of filter settings of 25 to 250 Hz and 40 to 250 Hz, 2) a spectral analysis method computing the energy area within the spectral boundaries of 40 to 140 Hz and the ratio between the energies of areas within the boundaries 40 to 140 Hz and 0 to 40 Hz, and 3) spectral temporal mapping computing the "normality factor." The study compared the reproducibility of these three approaches to the analysis of signal-averaged ECGs. First, the reproducibility of the diagnostic conclusions (that is, of the diagnosis of late potentials) was compared for the time domain method and for spectral temporal mapping. Second, the reproducibility of the numeric values of individual indexes provided by different methods was compared for all methods by computing the ratios between standard deviations of measurements in individual patients and standard deviation of all measurements. The reproducibility of diagnostic conclusions was significantly higher for the time domain method than for spectral temporal mapping (p less than 0.05, sign test). The numeric reproducibility of the normality factors produced by spectral temporal mapping was significantly lower than the numeric reproducibility of the values of all indexes provided by time domain, spectral area and spectral area ratio methods (p less than 0.05 to 0.00005, Wilcoxon tests). Spectral temporal mapping was the least reproducible method for the analysis of signal-averaged ECGs.

Adult↗
PubMed1992

Frequency versus time domain analysis of signal-averaged electrocardiograms. II. Identification of patients with ventricular tachycardia after myocardial infarction.

Late potentials detected by the time domain signal-averaged electrocardiogram (ECG) are a well established marker for ventricular tachycardia in patients after a myocardial infarction, but the value of frequency domain analysis of the signal-averaged ECG in identifying these patients remains controversial. This study compared the results of time domain, frequency domain and spectral temporal mapping analyses of the signal-averaged ECG in 30 postinfarction patients with spontaneous sustained ventricular tachycardia and in 30 postinfarction patients without ventricular tachycardia matched for age, gender and infarct site. No patient with bundle branch block was included. Time domain signal-averaged ECG indexes were significantly different in patients with and without ventricular tachycardia (p less than 0.001). Frequency domain results were not consistently different between these groups. The values of the normality factor of spectral temporal mapping were significantly lower in patients with ventricular tachycardia (p less than 0.04). Results of the time domain signal-averaged ECG were abnormal in 22 patients with ventricular tachycardia (73%) but in only 3 control patients (10%) (p less than 0.001). Spectral temporal mapping results were abnormal in 21 patients with ventricular tachycardia (70%) compared with 12 control patients (40%) (p less than 0.04). When the optimal numeric values of dichotomy points were computed for patient stratification at different sensitivity levels, time domain analysis identified patients with ventricular tachycardia with significantly fewer false positive results than were obtained with either frequency analysis or spectral temporal mapping. It is concluded that frequency domain analysis and spectral temporal mapping of the signal-averaged ECG did not improve the identification of postinfarction patients with ventricular tachycardia and without bundle branch block.

Aged↗
PubMed1992

Frequency versus time domain analysis of signal-averaged electrocardiograms. III. Stratification of postinfarction patients for arrhythmic events.

The predictive characteristics of spectral temporal analysis and time domain analysis of the signal-averaged electrocardiogram (ECG) for postinfarction arrhythmic events were compared in 257 patients. During a 6-month follow-up period, 7 patients (2.7%) died suddenly and 9 (3.5%) developed spontaneous sustained ventricular tachycardia. The mean numeric values of the standard time domain signal-averaged ECG variables in patients without arrhythmic events differed significantly from those in patients with arrhythmic events. The mean values of the spectral temporal signal-averaged ECG variables did not differ between the two patient groups. A strategy requiring positivity in any two time domain signal-averaged ECG variables provided the optimal receiver operating characteristic curves for predicting arrhythmic events. With spectral temporal analysis, a strategy using the Hanning window and diagnosing a positive signal-averaged ECG when two variables were abnormal provided the optimal curve for predicting arrhythmic events. Receiver operating characteristic curves showed that over a wide range of sensitivity, time domain variables had higher specificity for predicting arrhythmic events than did spectral temporal variables. Time domain analysis also provided significantly fewer false positive results than did spectral temporal analysis up to sensitivity values of 70%. It is concluded that time domain analysis of the signal-averaged ECG is superior to spectral temporal analysis for predicting arrhythmic events after myocardial infarction.

Adult↗
PubMed1992

Late potentials after acute myocardial infarction. Performance of different criteria for the prediction of arrhythmic complications.

In order to compare different criteria for the definition of late potentials in patients after myocardial infarction, three signal averaged ECG variables, duration of the signal-averaged QRS complex (QRS), root-mean-square voltage of the terminal 40 ms (RMS-40), and the duration of low amplitude signals less than 40 microV (LASD-40), were assessed in 332 survivors of acute myocardial infarction who were followed-up for at least 6 months, during which 12 patients died suddenly and 14 suffered symptomatic sustained ventricular tachycardia. The associations of the three variables with arrhythmic events were analysed in the total population, in infarct site and age-specific subgroups. The sensitivity and specificity for the prediction of arrhythmic events was computed (for all dichotomy points) and compared with nine published criteria for late potentials based on the same three variables. Analysis showed that (a) the total signal averaged QRS duration was a better predictor of arrhythmic events than the other two variables, (b) for arrhythmic events in cases of anterior infarctions, higher RMS-40 dichotomy limits and lower QRS and LASD-40 dichotomy limits were needed for cases of inferior infarction, (c) a multivariate stratification of arrhythmic events based on all three variables performed better in the anterior infarction population than in the inferior infarction population, (d) the strategy defining late potentials, which requires that two variables reach critical values, is better than the strategies that require that any one or all three variables reach critical values, (e) all the definitions of late potentials performed differently in the populations with anterior as compared to inferior infarctions; to identify groups at similar risk of arrhythmic events, different criteria defining late potentials should be used in these subpopulations.

Action Potentials↗
PubMed1992

Flecainide-related alterations in the signal-averaged electrocardiogram: similarity between patients with or without ventricular tachycardia.

The signal-averaged electrocardiogram (SAECG) identifies patients at risk of sustained ventricular tachycardia (VT), but the influence of anti-arrhythmic agents on the SAECG is not yet established. We have evaluated the effects of flecainide on the SAECG (XYZ leads, high-pass filters 25 Hz and 40 Hz, noise level 0.2 microV-0.4 microV, Model 1200 EPX, ART) in 25 patients: 15 (VT group) had documented sustained VT (nine post-MI, two dilated cardiomyopathy, four normal hearts) and 10 (control group) had supraventricular arrhythmias and structurally normal hearts. The SAECG was recorded in all patients prior to, and 5 min following a flecainide infusion (2 mg.kg-1 over 10 min). Before flecainide administration an abnormal SAECG was recorded in six patients from the VT group and in no control patient. Following flecainide, 13 patients from the VT group and eight control subjects demonstrated abnormal SAECG. Flecainide produced similar significant percentage changes in all SAECG indices in both the VT and control groups: total QRS duration was prolonged by 26.0 +/- 10.4% vs 26.7 +/- 15.7%, late potential duration under 40 microV was prolonged by 55.5 +/- 62.0% vs 106.1 +/- 61.4%, and the root mean square voltage of the last 40 ms of the QRS was reduced by 42.1 +/- 34.9% vs 55.3 +/- 24.4%, respectively. We conclude that flecainide significantly changes the SAECG parameters in patients with and without a history of VT, irrespective of the underlying disease.

Electrocardiography↗
PubMed1992

Prediction of antiarrhythmic efficacy of class I and III agents in patients with ventricular tachycardia by signal-averaged ECG analysis.

The effects of procainamide and dofetilide (pure Class III antiarrhythmic agent) on the signal-averaged ECG (SAECG) were examined in relation to the results of programmed ventricular stimulation studies in 25 patients with inducible sustained monomorphic ventricular tachycardia. Procainamide prolonged significantly the total QRS and low amplitude signal durations (140 +/- 31 msec vs 166 +/- 48 msec, P < 0.0001; 50 +/- 25 msec vs 65 +/- 38 msec, P < 0.002, respectively) whereas the root mean square voltage of the last 40 msec of the QRS complex was significantly reduced (22 +/- 21 microV vs 13 +/- 12 microV, P < 0.006). Procainamide was effective (prevention of the inducibility of sustained ventricular tachycardia or prolongation of the cycle length of ventricular tachycardia by > 100 msec) in 15 of 27 drug trials. Of the procainamide induced SAECG changes, the fractional prolongation of the total QRS duration was the best parameter that identified effectively treated patients (24% +/- 16% in responders vs 10% +/- 11% in nonresponders, P < 0.014). A fractional prolongation of the total QRS duration by > 15% identified effectively treated patients with a sensitivity of 87%, specificity of 81%, and an overall predictive accuracy of 84%. Dofetilide did not change the SAECG, and no SAECG parameter predicted the results of programmed ventricular stimulation. The effects of both drugs on the spectral analysis (area ratios) and on the spectral temporal mapping (the values of normality factor) of the SAECG were not consistent. In conclusion, antiarrhythmic efficacy of procainamide can be predicted by the degree of drug induced prolongation of the signal-averaged QRS complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗
PubMed1992

The value of transesophageal atrial pacing in predicting the efficacy of antiarrhythmic drugs in patients with paroxysmal narrow QRS complex tachycardia.

Transesophageal atrial pacing (TAP) is used in the diagnosis and treatment of paroxysmal narrow QRS complex tachycardia (NQT). The aim of this study was to assess the value of this technique in predicting the efficacy of antiarrhythmic therapy. The study group consisted of 30 consecutive patients with spontaneous NQT whose clinical tachycardia was inducible by TAP. Baseline TAP was performed off all antiarrhythmic medication and repeated during oral antiarrhythmic drug therapy. The pacing protocol consisted of three stages: a single extrastimulus introduced at progressively shorter coupling intervals during sinus rhythm, pacing at incremental rates to the point of second-degree AV block, and bursts of rapid pacing. On repeat stimulation while on oral antiarrhythmic therapy (37 pacing studies) NQT was still inducible in 12 cases. During the follow-up period ten patients developed a recurrence of NQT:nine cases out of 12 (75%), in whom NQT was inducible while on antiarrhythmic therapy, and one case out of 25 (4%), in whom NQT was not inducible (P less than 0.001). The sensitivity of TAP in predicting the outcome of the patients with NQT was 90%, and the specificity 89%. The negative predictive value of TAP (prediction of no recurrence of NQT) was 96%, and the positive predictive value (prediction of recurrence of NQT) was 75%. We conclude that TAP is a simple and accurate method for predicting the efficacy of antiarrhythmic treatment in patients with NQT.

Adult↗
PubMed1991

Age-related normal values of signal-averaged electrocardiographic variables after acute myocardial infarction.

The study examined standard time domain variables of a signal-averaged electrocardiogram (SAECG) in 328 survivors of acute myocardial infarction. The correlation of these variables with age and the influence of age on the prediction of postinfarction arrhythmic complication (sudden death [n = 12] or sustained ventricular tachycardia, or both [n = 14]) from the SAECG were investigated. Statistically highly significant correlations (p less than or equal to 0.00002) between age and SAECG variables were found. Compared with patients aged less than 60 years, the SAECG-based stratification of arrhythmic complications after myocardial infarction in patients greater than 60 years had lower sensitivity for the same values of specificity and lower specificity for the same values of sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Critical noise level reduction for correct identification of late potentials: an illustrative case report.

The precision of detection of late potentials (LPs) on signal-averaged electrocardiography (SAECG) depends on the degree of noise reduction. The recommended low-noise endpoint is 0.3 microV. We describe a patient with sustained ventricular tachycardia after myocardial infarction with very low amplitude LPs in whom a noise level lower than 0.3 microV was necessary in order to obtain an abnormal result of the SAECG. The presence of LPs was confirmed by spectral temporal mapping of the SAECG.

Aged↗
PubMed1991

Relationship between signal-averaged electrocardiography and dangerous ventricular arrhythmias in patients with left ventricular aneurysm after myocardial infarction.

We performed signal-averaged electrocardiography (SAECG) and Holter monitoring, and subsequently followed-up 53 ambulatory patients with left ventricular aneurysm (LVA) after myocardial infarction (MI). A history of spontaneous episodes of sustained ventricular tachycardia (VT) was also analysed. Out of 53 patients, 25 (47%) had an abnormal SAECG. Abnormal SAECG correctly identified nine out of 10 cases with a history of sustained VT. Complex ventricular arrhythmias were detected on Holter monitoring in 23 patients: in five out of 28 with normal SAECG (18%) and in 18 out of 25 with abnormal SAECG (72%) (P less than 0.001). During follow-up (mean 19 months) sustained VT and/or sudden cardiac death (SCD) occurred in eight cases, out of which seven had an abnormal SAECG. The negative predictive value of SAECG (no VT or SCD during follow-up) was very high, 96%, similar to the negative predictive value of a history of sustained VT (93%). Using multivariate analysis only a history of sustained VT was an independent factor in predicting the outcome of patients in this study. We conclude that an abnormal SAECG identifies those post infarction patients with LVA who are prone to complex ventricular arrhythmias. A normal SAECG and an absence of a history of sustained VT strongly indicate that the risk of developing arrhythmic events is very low.

Adult↗