Quantitative Improvement in Signal-Averaged Electrocardiography After Coronary Artery Bypass Grafting.

Abstract

ignal-averaged electrocardiography (SAECG) is a non-invasive technique to detect ventricular late potentials (LP), which are low-amplitude and highfrequency signals at the end of the QRS complex, from the body surface. 1 The presence of LP in an abnormal SAECG reflects slow and heterogeneous conduction in myocardium, which is predictive of ventricular arrhythmia and sudden cardiac death in patients with ischemic heart disease, 2-4 and successful coronary angioplasty of an occluded infarctrelated artery reduces the incidence of ventricular LP. [5][6][7][8] It has been reported that coronary artery bypass grafting (CABG) also reduced the incidence of LP perioperatively, 9,10 but that study focused on patients with abnormal SAECG before CABG. In the present study, we investigated changes in the parameters of SAECG after CABG, in a patient group that included those with normal preoperative SAECG, to determine the quantitative effect of CABG on SAECG and to identify the factors that are related to it. Methods PatientsPre-and postoperative SAECGs were recorded in consecutive 100 patients (78 men, 22 women; mean age, 66.5±7.7 years) undergoing an elective CABG who did not have a conduction disturbance on a standard ECG. Their coronary risk factors included smoking (n=63), diabetes (n=42), hyperlipidemia (n=50), hypertension (n=55), and obesity (n=11); 35 patients had a prior myocardial infarction (MI): 19 with an antero-lateral MI and 16 with a postero-inferior MI. Of the 100 CABG procedures, 78 had cardiopulmonary bypass (CPB) and 22 did not have CPB. Combined procedures included mitral valve replacement (n=4), mitral valve plasty (n=2), aortic valve replacement (n=4), and abdominal aneurysmectomy (n=3). Cardiac CatheterizationBased upon the preoperative cardiac catheterization results, the left ventricular ejection fraction (LVEF) and myocardial score, which reflects the degree of myocardial ischemia, were calculated for each patient. The myocardial scores were obtained by the method described by Brandt et al; 11 that is, the left ventricle is given 15 units, comprising 7 units for the antero-septal area, 3 units each for the obtuse marginal and inferior areas, and 2 units for the diagonal area. The myocardial value is the total number of units of the myocardium supplied by a particular artery distal to the stenosis or obstruction. Using the grade of stenosis and the myocardial value, each artery is given a myocardial score using the table described by Brandt et al. 11 The separate scores are summed to give the total myocardial score, which cannot exceed 15.Postoperative catheterization was performed a mean of 14±5 days after CABG, at which time all bypass grafts were examined from at least 3 different views. Complete revascularization was defined as all diseased arterial systems receiving patent grafts with stenosis of less than 50%. SAECG RecordingTime domain SAECGs were recorded with an HM-1000 electrocardiograph (Fukuda Denshi Co, Tokyo, Japan) a mean of 5±2 days before and a mean of 14±2 days after CABG. Signal ...

Impact of Diabetes Mellitus on the Improvement in Signal-Averaged Electrocardiography After Coronary Artery Bypass Grafting

“…3 Amelioration of chronic myocardial ischemia by elective CABG also leads to improvement in the SAECG parameters, probably by salvaging and stabilizing the border zone area that generates LPs, where normal cells are interspersed with areas of fibrosis and ischemia. [6][7][8][9][10] The present study showed that CABG lead to quantitatively beneficial effects on the SAECG parameters in patients even with normal SAECG both pre-and postoperatively. However, there were some patients whose SAECG remained abnormal after CABG.…”

“…9 We have reported that the improvements in SAECG were greater in CABG patients who underwent complete revascularization and in those without prior myocardial infarction. 10 We hypothesized that the presence of diabetes mellitus (DM) also affects the improvement in SAECG after CABG and in the present study, the perioperative SAECG changes in diabetic patients were compared with those in non-diabetic patients. …”

“…4,5 Coronary artery bypass grafting (CABG) has also been reported to reduce the incidence of LPs perioperatively. [6][7][8][9][10] Although it has been reported that multiple CABG for multivessel disease markedly improves several parameters of SAECG, its beneficial effect on SAECG is variable. 9 We have reported that the improvements in SAECG were greater in CABG patients who underwent complete revascularization and in those without prior myocardial infarction.…”

Correlation of Connexin43 Expression and Late Ventricular Potentials in Nonischemic Dilated Cardiomyopathy

“…34,35 LP is characterized by slow conduction, heterogeneous wavefront propagation and/or a localized unidirectional block that triggers and maintains the reentrant electrical circuits commonly seen in many or most monomorphic VT. [4][5][6][7][8]36,37 In the present study, the expression of Cx43 was heterogeneously reduced in those patients who were LP positive and had developed monomorphic VT. Such changes in the Cx43 signal in the RV tissue at the cellular level may be clinically manifested as LP on SAECG and therefore, SAECG may provide the fundamental information that bridges the gap between Cx43 expression and the elucidation of the mechanism of lethal ventricular arrhythmias in DCM.…”

Portable-Type Signal-Averaged Electrocardiography With Dipyridamole to Detect Patients With Coronary Artery Disease A Prospective Study

“…However, these can be evaluated by using the filtered QRS wave duration (fQRSd) on the signal-averaged ECG (SAECG). [13][14][15][16][17] In our previous study, 18 using a portable SAECG recording device, we performed bedside recording of SAECG before and after dipyridamole stress and measured subtle changes in QRS prolongation. QRS prolongation by more than 5 ms suggested the presence of CAD with high sensitivity and specificity.…”