DIAGNOSTIC METHODS ELECTROPHYSIOLOGY Identification of patients with ventricular tachycardia after myocardial infarction: signal-averaged electrocardiogram, Holter monitoring, and cardiac catheterization

Electrocardiographic signal averaging techniques have demonstrated a low-amplitude late potential and a long filtered QRS complex in patients with ventricular tachycardia (VT) after myocardial infarction. Complex ventricular ectopy and left ventricular aneurysms have also been associated with VT. The purposes of this study were (1) to determine whether the findings from the signal-averaged electrocardiogram (ECG) were independent of those from Holter monitoring and cardiac catheterization and (2) to determine the combination of findings from the signal-averaged ECG, cardiac catheterization, and Holter monitoring that best characterize patients with VT after myocardial infarction. We studied 174 patients after myocardial infarction, 98 of whom had recurrent sustained VT. By multivariate logistic regression only three parameters were found to be independently significant, listed in order of power: positive signal-averaged ECG (presence of a late potential or a long filtered QRS duration), peak premature ventricular contraction greater than 100/hr, and presence of a left ventricular aneurysm (p < .001). The signal-averaged ECG provides independent information in identifying patients with VT after myocardial infarction. Circulation 70, No. 2, 264-270, 1984. SUDDEN DEATH in patients after myocardial infarction is generally caused by ventricular tachyarrhythmias.'4 Accurate identification of patients prone to ventricular arrhythmias by noninvasive methods is highly desirable to rationally treat the group of patients at high risk. At the present time there is no such test or combination of tests to reliably predict which patients are at risk for ventricular arrhythmias after a myocardial infarction. Holter monitoring, cardiac catheterization, exercise testing, and clinical findings have been used separately and in combination to identify patients with ventricular tachycardia (VT).5'10 Recently, invasive electrophysiologic stimulation studies have been From the Clinical Electrophysiology Laboratory, Hospital of the University of Pennsylvania, Cardiovascular Section, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia. Supported in part by grants HL24278, HL27925, and HL223 15 from the NHLBI; grants from the American Heart Association, Southeastern Pennsylvania Chapter, Philadelphia; and Arrhythmia Research Technology, Inc. Address for correspondence: Michael B. Simson, M.D., 945 Gates Bldg., Hospital of the University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104. Received June 22, 1983; revision accepted May 10, 1984. Dr. Simson is the Samuel Bellet Associate Professor of Medicine in Cardiology. 264 suggested as a means to identify these patients.3 11-14 However, because of the invasive nature of the electrophysiologic test, it is not desirable as a screening test for large numbers of patients. Within the last few years, several investigators have used a noninvasive signal-averaged electrocardiogram (ECG) to detect low-amplitude, high-frequency potentials at the end of the QRS complex in patients with VT.15-22 These signals, termed "late potentials," appear to correspond to the delayed and fragmented ventricular activation that has been observed with direct electrogram recordings in patients and animals with VT. 15 23-25 Several studies have demonstrated that the signal-averaged ECG can distinguish patients with and without VT after myocardial infarction.'7-22 The purposes of this study were (1) to determine whether the signal-averaged ECG provides information useful in identifying patients with VT that is independent from that which can be obtained from Holter monitoring and catheterization and (2) to determine the combination of findings from the signal-averaged ECGs, cardiac catheterization, and Holter monitoring that best characterize patients with VT after myocardiCIRCULATION by gest on M ay 3, 2017 http://ciajournals.org/ D ow nladed from DIAGNOSTIC METHODS-ELECTROPHYSIOLOGY al infarction. A study population with a high incidence of VT was used on the assumption that if a test cannot identify patients with VT in such a group, it would be unlikely to distinguish patients with VT in a study group with a lower incidence of the arrhythmia.