Effects of a .BETA.-Blocker on Ventricular Late Potentials in Patients With Acute Anterior Myocardial Infarction Receiving Successful Thrombolytic Therapy

Abstract

SUMMARYLate potentials (LP) detected on the signal-averaged electrocardiogram (SAECG) predict arrhythmic events after acute myocardial infarction (AMI). It is also well established that successful thrombolytic therapy reduces the incidence of LP. Our aim was to evaluate the effects of a beta-blocker on LP in patients receiving thrombolytic therapy. We studied 40 patients presenting with anteroseptal AMI (< 6 hours). All patients received thrombolytic therapy and were evaluated with coronary angiography at predischarge. Eighteen patients received metoprolol (5 mg IV on admission followed by 50 mg BID). SAECG recordings were obtained serially using an ART system (40-250 Hz filter, noise < 0.5 mV) prior to thrombolytic therapy, after 48 hours and after 10 days. LP was defined as positive if the SAECG met at least 2 of the Gomes criteria. Changes observed in SAECG recordings after thrombolytic therapy were correlated with angiographic and clinical data with regard to the usage of BB. The frequencies of LP before and after thrombolytic therapy were compared with the McNemar test. There were no significant differences between the clinical characteristics, risk factors, and angiographic findings (including infarct related artery patency and LV functions) of the groups. Baseline SAECG findings were also similar between the groups. The incidence of LP significantly decreased after TT in the BB group, however, this change was not observed in patients who did not receive BB (P = 0.012, McNemar test). Beta-blockers reduce the incidence of LPs following thrombolytic therapy in patients with anterior AMI. This might be explained by the possible beneficial effect of BB on the arrhythmogenic substrate. (Jpn Heart J 2004; 45: 11-21)

American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society Scientific Statement on Noninvasive Risk Stratification Techniques for Identifying Patients at Risk for Sudden Cardiac Death

“…Thus, thrombolytic therapy reduces the incidence of an abnormal SAECG in MI survivors. [91][92][93][94] SAECG performed early after MI is abnormal in 15% to 35% of patients. SCD or cardiac arrest occurs in 3.3% to 9% of these patients over the following 1 to 3 years.…”

American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society Scientific Statement on Noninvasive Risk Stratification Techniques for Identifying Patients at Risk for Sudden Cardiac Death

“…Because the SAECG appears to be linked to the substrate of the underlying infarction, it would be expected that therapies that alter the substrate or its development will alter the SAECG and perhaps the risk of SCD. Thus, thrombolytic therapy reduces the incidence of an abnormal SAECG in MI survivors (91)(92)(93)(94). SAECG performed early after MI is abnormal in 15% to 35% of patients.…”

The association between pre-infarction angina and care-seeking behaviors and its effects on early reperfusion rates for acute myocardial infarction

“…Recent clinical studies show that PA results faster and more coronary recanalization and smaller infarcts in patients receiving reperfusion therapy [30,31]. Thus the occurrence of PA may provide more benefits for AMI patients in the era of reperfusion therapy.…”