Determinants of arrhythmogenic ventricular activity detected on the body surface QRS in patients with coronary artery disease

Abstract

The prevalence of arrhythmogenic ventricular activity (AVA) was investigated in 166 patients with coronary artery disease. Thirty patients had documented ventricular tachycardia (VT)/ventricular fibrillation (VF). Bipolar X,Y,Z leads were signalaveraged and filtered with a 40-Hz, bidirectional, high-pass digital filter. The filtered QRS signals were analyzed for the amplitude of the last 40 and 50 ms; duration of low-amplitude potentials (< 40 μV) in the terminal portion; and duration of the filtered QRS. A positive AVA test result was defined as the presence of 2 or more abnormal indexes. Of the 30 patients with VT/VF, 66% had positive AVA test results (AVA-positive patients). Of the 136 patients without VT/VF, 25% had positive AVA test results. The following univariate variables showed significant correlation with an AVA-positive test: age, previous myocardial infarction, previous VT/VF, left ventricular wall motion abnormalities and left ventricular ejection fraction. Multivariate stepwise discriminant function analysis revealed that the presence of previous myocardial infarction and history of sustained VT/VF were the only independent determinants of AVA. During electrophysiologic studies, sustained VT/VF could be induced in 77% of the AVA-positive patients (24 of 31) and in 30% of the AVA-negative patients (3 of 10). The survival probabilities for 6, 12 and 18 months of follow-up were 92%, 85% and 85% for the AVA-positive and 97%, 92% and 90% for the AVA-negative patients. Our findings support the concept that a positive AVA test result reflects areas of delayed ventricular activation. The areas of delayed ventricular activation are associated with previous myocardial injury and scar tissue and serve as an anatomic basis for reentry. Quantitative analysis of the high-frequency components of the terminal portion of the signalaveraged body surface QRS may be a helpful screening test for detection of patients at high risk of VT/VF.