Copyright © 1995 by the European Society of Cardiology.
© 1995 The European Society of Cardiology
Comparison and combination of late potentials and spectral turbulence analysis to predict arrhythmic events after myocardial infarction in the Post-Infarction Late Potential (PILP) study
Hospital of the Westfälische Wilhelms-Universität, Münster, Department of Cardiology and Angiology, and Institute for Arteriosclerosis Research Münster, Germany
revised 1 August 1994; accepted 5 September 1994.
Correspondence: Prof. Dr Günter Breithardt, Medizinische Klinik and Poliklinik, Innere Medizin C (Kardiologie u Angiologie), Westfalische Wilhelms-Universität Münster, D-48129 Münster, Germany.
Abstract
Ventricular late potentials detected at the end of the QRS complex by the signal-averaged ECG have been shown to predict arrhythmic events after acute myocardial infarction. Spectral turbulence analysis is a novel technique for detecting abnormalities of cardiac electric activation inside the QRS complex. The purpose of this study was to combine these two analysis methods in order to increase the predictive power of the signal-averaged ECG in post-infarction patients.
The study comprised a prospective series of 778 males under 66 years of age who survived the acute phase of myocardial infarction. Signal-averaged ECG recordings were performed before hospital discharge 2 to 3 weeks after infarction. The original Simson method was used for recording and analysing the time-domain signal-averaged ECG. Spectral turbulence analysis was performed using the same averaged vector magnitude QRS complexes (Del Mar Avionics). During the follow-up period of 6 months, 33 patients (4.2%) had an arrhythmic event (sustained monomorphic ventricular tachycardia in 13 cases, ventricular fibrillation in eight cases and sudden cardiac death in 12 cases). The predictive power of late potentials in the time domain, spectral turbulence analysis and their combinations were tested together with clinical variables using the Cox regression method. The combination of late potentials and a spectral turbulence analysis score (one or both abnormal) had the greatest influence on the prediction of arrhythmic events: late potentials+spectral turbulence analysis (regression coefficient B=0.75; P=0.0014), Selvester ECG score >10 (B=0.44; P=0.027), history of previous infarction (B=0.49; P=0.018) and non-sustained ventricular tachycardia during long-term ECG recording (B=0.50; P=0.035). The combination of late potentials and spectral turbulence analysis reached a sensitivity of 76%, a specificity of 63%, a positive predictive value of 8% a negative predictive value of 98%) and a total predictive accuracy of 61%. Patients with late potentials and/or abnormal spectral turbulence analysis were significantly less often free of arrhythmic events compared to patients with normal findings (92% vs 98%, P<0.0001, Breslow test). The relative risk ratio of combining late potentials+spectral turbulence analysis was 5.0 (CI 95% 2.1–11.5) for arrhythmic events.
The combination of late potentials in the time domain and a spectral turbulence analysis score (one or both abnormal) is recommended for identification of patients at risk of arrhythmic events after acute myocardial infarction. Optimization of the criteria of abnormality could further improve the rather low positive predictive accuracy of the signal-averaged ECG in this setting.
Key Words: Ventricular late potentials • spectral turbulence analysis • myocardial infarction • prognosis
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