Ventricular Late Potentials Are Associated with the Presence of Viable Myocardium After Anterior Myocardial Infarction

Abstract

Background: The aim of the study was to evaluate the relationship between myocardial viability (MV) detected by TI-201 rest/redistribution protocol (RR-SPECT) and the presence of ventricular late potentials (VLPs) in acute myocardial infarction (AMI). We analyzed signal-averaged ECGs (SAECGs) in 28 patients (age 57 ± 10 years) with a first anterior AMI within 48 hours of symptoms (SAECG1) and prior to discharge (SAECG2). VLPs were defined according to the presence of filtered QRS (QRS-D) ≥ 114 ms and duration of low amplitude signals (LAS) ≥ 30 ms or root mean square voltage (RMS40) ≤ 25 μV, using a 25-Hz filter, or a duration of LAS ≥ 39 ms or RMS40 ≤ 20 μV, using a 40-Hz filter. RR-SPECT was performed 17 ± 6 days after AMI. Segments were considered viable when counts were ≥ 60% in early images or when a fill-in ≥ 10% was detectable on delayed images of those segments with a first count between 31% and 59%. Methods: Patients were divided into two groups: with MV (group 1 = 16 patients) if almost one third of segments appeared to be viable; without MV (group 2 = 12 patients). No difference was found between the two groups in SAECG1, whereas, using a 25-Hz filter, a greater QRS-D (106.6 ± 13.5 vs 93.5 ± 6 ms) and LAS (31.2 ± 8.7 vs 18.1 ± 6.4 ms) as well as a smaller RMS40 (43 ± 33.5 vs 71.3 ± 30.4 μV) characterized the SAECG2 of group 1. Sensitivity and specificity of VLPs in detecting MV were 31% and 100%. When using cut-off values derived from median distribution of the population (QRS-D ≥ 99 ms, LAS ≥ 24 ms and RMS40 ≥ 51 μV), sensitivity raised to 75% and specificity was 92% with a positive and negative predictive value of 92% and 73%. Conclusions: The presence of MV is associated with a greater incidence of VLPs. SAECG performed at the time of discharge may facilitate the identification of patients with MV after anterior AMI.