Quantitative improvement in signal-averaged electrocardiography after coronary artery bypass grafting.

Abnormal signal-averaged electrocardiography (SAECG) reflects slow and heterogeneous myocardial conduction, predicting ventricular arrhythmia and sudden cardiac death in patients with ischemic heart disease. The purpose of this study was to investigate the quantitative effect of coronary artery bypass grafting (CABG) on SAECG, which is still controversial, and to identify the factors that are related to it. Pre- and postoperative SAECGs were recorded in 100 patients who underwent CABG. Compared parameters included filtered QRS duration (dQRS), root mean square voltage in the terminal 40 ms of the QRS complex (RMS40), and duration of the terminal low-amplitude signal less than 40 microV (LAS40). All 3 parameters in SAECG improved significantly after CABG (dQRS: 105+/-21 ms-->99+/-18 ms, RMS40: 55+/-45 microV-->65+/-41 microV, LAS40: 29+/-19 ms-->25+/-12 ms). The improvements in SAECG were greater in patients who underwent complete revascularization and in those without prior myocardial infarction. In conclusion, CABG improved SAECG quantitatively, even in patients with normal SAECG. However, this improving effect was variable and closely related to the presence of prior myocardial infarction and the completeness of revascularization.     

Effect of pre-infarction angina on ventricular late potentials in patients with acute myocardial infarction and successful thrombolysis

OBJECTIVE: Pre-infarction angina is considered as a good clinical model of ischaemic preconditioning which facilitates myocardial protection. Late potentials (LP) have prognostic significance following acute myocardial infarction (AMI). It is also well established that thrombolytic therapy reduces the incidence of LP. Our aim was to evaluate the relationship between pre-infarction angina and LP in patients receiving successful thrombolytic therapy. METHODS AND RESULTS: We prospectively studied 55 patients presenting with AMI (<6 hours). All patients received thrombolytic therapy and were evaluated with coronary angiography at predischarge. Signal-averaged recordings (SAECG) were obtained serially prior to thrombolysis, 48 hours after and 10 days later. Pre-infarction angina was present in 14 (25%) patients. There were no significant differences between the clinical characteristics and angiographic findings of the groups. Baseline SAECG parameters of the groups were also similar. After thrombolysis, the 48th hour values of LAS (the duration of the terminal low amplitude signals), and both the 10th day values of LAS and RMS (root mean square voltage of the last 40 ms of the QRS) were significantly better in the pre-infarction angina group. The mean filtered QRS duration and RMS 40 values changed significantly at the 10th day recordings of patients with pre-infarction angina [QRS duration, 110+/-34 ms before to 91+/-11 ms after (p = 0.039); RMS 40, 40+/-17 microV before to 50+/-14 microV after (p = 0.02)]. The incidence of LP significantly decreased after thrombolytic therapy in the pre-infarction angina group, however, this change was not observed in patients without angina. CONCLUSION: Presence of pre-infarction angina reduces the incidence of LP following thrombolysis in AMI. This might be explained by the possible beneficial effect of ischaemic preconditioning on the arrhythmogenic substrate.     

Absence of change of signal-averaged electrocardiogram identifies patients with ventricular arrhythmias who are non-responders to amiodarone

OBJECTIVES: The aim of this study was to assess the ability of a non-invasive study, the signal-averaged ECG (SAECG), to predict the effect of amiodarone at ventricular level. BACKGROUND: Amiodarone is the main drug drug used in the treatment of ventricular arrhythmias. Standard ECG does not detect any change in QRS complex resulting from amiodarone therapy. SAECG is more sensitive than ECG for detecting changes in QRS complex. METHODS: The study examined the effects of amiodarone on SAECG in relation to the results of programmed ventricular stimulation in 68 patients with old myocardial infarction, spontaneous and inducible sustained ventricular tachycardia (VT). RESULTS: Amiodarone prolonged the total QRS duration (dur) (129+/-28 vs. 140+/-30 ms, P<0.05) and low amplitude signal (LAS) dur (45+/-20 vs. 51+/-20 ms, P<0.1), whereas the root-mean-square voltage of the last 40 ms of QRS complex (RMS 40) was significantly reduced (20+/-16 vs. 14+/-9 microV, P<0.05). Changes in SAECG parameters did not differ significantly in patients in whom amiodarone prevented the inducibility of VT (n=15) and those in whom VT remained inducible with amiodarone (n=53), but in baseline QRS duration was significantly shorter in patients in whom amiodarone prevented the VT induction (118+/-26 vs. 133+/-28 ms, P<0.05). In patients in whom amiodarone did not prolong the cycle length of VT (n=15), SAECG did not change significantly (QRS dur 131+/-29 vs. 132+/-27 ms, LAS 42+/-20 vs. 42+/-19 ms, RMS 40 22+/-14 vs. 19+/-11 microV). Comparison of the SAECG data in patients with no inducible VT and those with slowed VT differed significantly (P<0.05) between the control state and the recording with amiodarone. CONCLUSIONS: The effects of amiodarone on VT inducibility are predicted by a shorter baseline QRS duration and the degree of drug-induced prolongation of filtered QRS duration. Amiodarone prolonged the QRS duration, LAS duration and decreased RMS 40; this effect was more important in patients with no inducible VT and in those with only slowed VT, than in patients with unchanged or accelerated VT. The absence of changes of QRS duration predicted the induction of a more rapid or not slowed VT with amiodarone with a sensitivity of 87% and a specificity of 83%. Therefore, SAECG appears as an useful and simple means to predict the effects of amiodarone in patients with myocardial infarction and VT.     

The effect of preinfarction angina on clinical reperfusion time in patients with acute myocardial infarction receiving successful thrombolytic therapy

BACKGROUND: Preinfarction angina (PA) and early reperfusion of infarct-related arteries have been shown to reduce infarct size in patients with acute myocardial infarction (AMI). The beneficial effects of PA on infarct size have been attributed to the development of ischemic preconditioning and faster coronary recanalization in patients treated with thrombolytic therapy (TT). OBJECTIVE: To evaluate the effect of PA on clinical coronary reperfusion time in patients with AMI receiving successful TT. METHODS: Seventy-five patients presenting with AMI (within 6 h after the initial onset of symptoms) were studied. All patients received TT and were evaluated with coronary angiography (CA) at predischarge. The patients were divided into two groups: group 1 (PA-positive) comprised those who experienced a new onset of prodromal angina within 72 h before the onset of AMI. Group 2 (PA-negative) comprised those who had a sudden onset of AMI without the preceding angina. The successful myocardial reperfusion criteria after TT were ST segment resolution of 50% or greater, the appearance of reperfusion arrhythmias and the resolution of chest pain. The time of reperfusion criteria was recorded after TT. CA was performed in all patients at predischarge. Patients with no patent infarct-related arteries on CA and clinical failure of reperfusion were excluded from the study. RESULTS: Clinical characteristics, risk factors and angiographic findings did not differ significantly between the groups. The time interval from the start of continuous chest pain to TT was also similar between the groups. The left ventricular ejection fraction was higher and there were less frequent ventricular arrhythmias in patients with PA than in those without PA (47.9+/-7.4 versus 44.4+/-8.1, P=0.041, and 17.1% versus 37.5%, P=0.043, respectively). The clinical reperfusion time was significantly shorter in the patients with PA than in those without PA (68.2+/-24.5 min versus 81.4+/-19.3, P=0.012). The clinical reperfusion time was positively correlated with age and the time interval from the start of continuous chest pain to TT but inversely related to the presence of PA. CONCLUSIONS: In patients with AMI preceded by PA, TT resulted in more rapid clinical reperfusion than in patients without PA. Thus, earlier myocardial reperfusion may account for smaller infarct size and better prognosis in patients with PA.     

Clinical implications of serial changes in ST-segment elevation after reperfusion in patients with anterior acute myocardial infarction.

BACKGROUND: In patients with acute myocardial infarction (AMI), the relationship of serial changes in ST-segment elevation after reperfusion to left ventricular (LV) function remains unclear. METHODS AND RESULTS: The study group comprised 164 patients with reperfused anterior AMI within 6 h of symptom onset. The sum of ST-segment deviation was calculated on admission (SigmaST-admission), and 1 h (SigmaST-1 h) and 24 h (SigmaST-24 h) after reperfusion. ST resolution was defined as a reduction in SigmaST-1 h of > or =50% as compared with SigmaST-admission. Patients were classified into 3 groups: group A, 82 patients with ST resolution in whom SigmaST-1 h > or = SigmaST-24 h; group B, 37 patients with ST resolution in whom SigmaST-1 h < SigmaST-24 h; group C, 45 patients without ST resolution. Peak creatine kinase were higher in groups B and C than in group A (4,578+/-2,176, 4,236+/-2,638, 2,222+/-1,926 mU/ml, p<0.01). At 6 months follow-up, the LV ejection fraction were lower in groups B and C than in group A (53+/-8, 54+/-12, 62+/-9%, p<0.01). CONCLUSIONS: An increase in ST-segment elevation 1-24 h after reperfusion, despite ST resolution, is associated with a larger infarction and poorer LV function in patients with reperfused anterior AMI.     

Impact of diabetes mellitus on the improvement in signal-averaged electrocardiography after coronary artery bypass grafting.

BACKGROUND: Although it has been reported that coronary artery bypass grafting (CABG) for multivessel disease markedly improves several parameters of signal-averaged electrocardiography (SAECG), its beneficial effect on SAECG is variable. The hypothesis of the present study was that the presence of diabetes mellitus (DM) affects the improvement in SAECG after CABG. METHODS AND RESULTS: Pre- and post-operative SAECGs were recorded in 100 consecutive patients who underwent complete surgical revascularization. Changes in the following parameters were compared between the diabetic (n=43) and non-diabetic (n=57) patients: filtered QRS duration (dQRS), root mean square voltage in the terminal 40 s of the QRS complex (RMS40), and duration of the terminal low-amplitude signal lower than 40 microV (LAS40). Although baseline characteristics and the occurrence of late potentials were similar in both groups, quantitative improvements in the SAECG parameters after CABG were significantly greater in non-diabetic than in diabetic patients (dQRS: 109 +/- 22 ms vs 102 +/- 19 ms in diabetics and 106 +/- 21 ms vs 88 +/- 11 ms in non-diabetics; p=0.028, RMS40: 55 +/- 46 microV vs 65 +/- 38 microV in diabetics and 50 +/- 37 microV vs 76 +/- 37 microV in non-diabetics; p=0.037, LAS40: 31 +/- 20 ms vs 26 +/- 17 ms in diabetics and 32 +/- 12 ms vs 17 +/- 8 ms in non-diabetics; p=0.007, respectively). CONCLUSIONS: The presence of DM limits the CABG-induced improvement in SAECG. In diabetic patients, therefore, perioperative changes of the SAECG must be interpreted with caution.     

Relatively benign clinical course in asymptomatic patients with brugada-type electrocardiogram without family history of sudden death

INTRODUCTION: The incidence of sudden death or ventricular fibrillation (VF) in asymptomatic Brugada syndrome patients with a family history of sudden death is reported to be very high. However, there are few reports on the prognosis of asymptomatic Brugada syndrome patients without a family history of sudden death. METHODS AND RESULTS: Eleven patients (all male; mean age 40.5 +/- 9.6 years, range 26 to 56) with asymptomatic Brugada-type ECG who had no family history of sudden death were evaluated. The degrees of ST segment elevation and conduction delay on signal-averaged ECG (SAECG) before and after pilsicainide were evaluated in all 11 patients. VF inducibility by ventricular electrical stimulation also was evaluated in 8 of 11 patients. Patients were followed for a period of 9 to 84 months (mean 42.5 +/- 21.6). The J point level was increased (V1: 0.19 +/- 0.09 mV to 0.36 +/- 0.23 mV; V2: 0.31 +/- 0.12 mV to 0.67 +/- 0.35 mV) by pilsicainide. Conduction delay was increased (total QRS: 112.2 +/- 6.3 msec to 131.7 +/- 6.3 msec; under 40 microV: 42.0 +/- 8.5 msec to 52.7 +/- 12.7 msec; last 40 msec: 17.4 +/- 5.9 microV to 10.4 +/- 6.1 microV) on SAECG by pilsicainide. VF was induced in only 1 of 8 patients. None of the patients had syncope or sudden death during a mean follow-up of 42.5 +/- 21.6 months. CONCLUSION: This study suggests that asymptomatic patients with Brugada-type ECG who have no family history of sudden death have a relatively benign clinical course.     

Effects of exercise on the signal-averaged electrocardiogram in coronary artery disease

The effects of exercise on the signal-averaged electrocardiogram (SAECG) were investigated in 52 patients with stable coronary artery disease. The SAECG was recorded before and immediately after the exercise test and analyzed at 25 to 250 Hz and 40 to 250 Hz. All patients had SAECG with noise level less than or equal 0.8 microV at 25 Hz and less than or equal to 0.6 microV at 40 Hz and with the difference in noise level between control SAECGs and SAECGs after exercise less than or equal to 0.2 to 0.3 microV. Twenty-eight patients developed ST changes consistent with transient subendocardial ischemia that persisted during the SAECG recording after exercise. There was no significant difference between control SAECGs and SAECGs after exercise in patients with or without a positive exercise test. The absence of significant change on the SAECG was not related to the presence or absence of prior myocardial infarction, site of infarction, development of exercise-induced ventricular arrhythmias or presence of an abnormal recording at baseline. These data suggest that exercise-induced electrophysiologic changes and ventricular arrhythmias may not be related to the anatomic-electrophysiologic substrate that underlies late potentials on the SAECG.     

Spectral and bidirectional filters give different results for signal-averaged ECG analysis in patients with postmyocardial infarction. GISSI-3 Arrhythmias Substudy Investigators

This study aims at assessing the specific effects of bidirectional filters (BF) and spectral filters (SF) on signal-averaged ECG (SAECG) analysis. The GISSI-3 Arrhythmias Substudy collected SAECGs of 598 patients 10 +/- 4 days after myocardial infarction (MI) from 20 Italian coronary care units. BF and SF were applied on 340 and 258 patients, respectively. QRS duration (QRSD), low amplitude signal duration (LAS40), and root mean-square-voltage (RMS40) were measured with filters set at 40 to 250 Hz. For ventricular late potentials (VLP) detection filter-specific criteria were adopted: QRSD > 114 ms, LAS40 > 38 ms, RMS40 < 20 microV for BF and QRSD > 120 ms, LAS40 > 38 ms, RMS40 < 20 microV for SF. VLP were considered present if any 2 of the criteria were met. The QRSD obtained by BF (100.6 +/- 13 ms) was shorter (P < .0001) than that obtained by SF (109.1 +/- 12 ms). Nevertheless, a higher prevalence of VLP for patients with BF than for patients with SF was found (23.8% vs 16.7%; P < .04). Indeed, filter-specific criteria were able to avoid any differences in the prevalence of abnormal QRSD and LAS40, but not of RMS40 (25.6% vs 17.1%, P < .02). Finally, the difference of VLP prevalence was mainly owing to the higher number of abnormal pairs of RMS40 + LAS40 (58% vs 44%) for BF than for SF. This multicentric study suggests that after MI, BF and SF produce discordant results on low-amplitude signals of filtered QRS that are not avoided by adopting filter-specific criteria. On the contrary, specific criteria seem to be suitable for comparison of QRSD between different SAECG devices in post-MI patients.     

Detection of atrial late potentials with P wave signal averaged electrocardiogram among patients with paroxysmal atrial fibrillation

The analysis of the QRS-complex with signal averaged ECG (SAECG) has been evaluated for patients affected by ventricular tachycardia for a long time. A longer filtered QRS-complex was a marker of a slower ventricular conduction velocity and reentry tachycardia. This method was modified for an analysis of the P wave (P-SAECG). Different filter methods were evaluated for the analysis of atrial late potentials. METHOD: We measured the bidirectional P wave signal averaged ECG of 45 consecutive patients with (group A) and without (group B) paroxysmal atrial fibrillation (PAF) and 15 young volunteers without a cardiac disease (group C). RESULTS: As a result patients with PAF had a significantly lower root mean square voltage of the last 20 ms (RMS 20) (2.59 +/- 0.89) vs 4.08 +/- 1.45 microV, p < 0.0003) and a significantly longer filtered P wave duration (FPD) than patients of the control collective (139.2 +/- 17.5 vs 115.1 +/- 17.7 ms, p < 0.0001) and the young volunteers (3.44 +/- 0.95 microV, p < 0.0001/101.9 +/- 14.2 ms, p < 0.009). Furthermore we found an age-dependent relationship of FPD between group B and C (115.1 +/- 17.7 vs 101.9 +/- 14.2 ms, p < 0.05) but not an age-dependent relationship of the RMS 20 (4.08 +/- 1.45 vs 3.44 +/- 0.95 microV, p = n.s.). A specificity of 80% and a sensitivity of 78% was achieved for identifying patients with atrial fibrillation by using a definition of atrial late potentials as FPD > 120 ms and a RMS 20 < 3.5 microV. CONCLUSIONS: The analysis of the P-SAECG can be used as a non-invasive method for identifying atrial late potentials. Atrial late potentials might be a reason for PAF. The predictive power of atrial late potentials has to be examined by prospective investigations of a larger patient population.     

ST-segment depression in lead aVR predicts predischarge left ventricular dysfunction in patients with reperfused anterior acute myocardial infarction with anterolateral ST-segment elevation.

BACKGROUND: Patients with an anterolateral acute myocardial infarction (AMI) have a worse prognosis, and those with additional inferolateral wall involvement might be higher risk because of more extensive area at risk. Lead -aVR obtained by inversion of images in lead aVR has been reported to provide useful information for inferolateral lesion. METHODS: We examined the relation between ST-segment deviation in lead aVR on admission electrocardiogram (ECG) and left ventricular function in 105 patients with an anterolateral AMI undergoing successful reperfusion < or = 6 hours after onset. Patients were classified according to ST-segment deviation in lead aVR on admission ECG: group A, 23 patients with ST elevation of > or = 0.5 mm; group B, 47 patients without ST deviation; and group C, 35 patients with ST depression of > or = 0.5 mm. RESULTS: There were no differences among the 3 groups in age, sex, or site of the culprit lesion. In groups A, B, and C, the peak creatine kinase level was 3661 +/- 1428, 4440 +/- 1889, and 6959 +/- 2712 mU/mL, and the left ventricular ejection fraction (LVEF) measured by predischarge left ventriculography was 54% +/- 9%, 48% +/- 7%, and 37% +/- 9%, respectively(P < .01). During hospitalization, congestive heart failure occurred more frequently in group C than in groups A or B (P < .05). ST-segment depression in lead aVR had a higher predictive accuracy than other ECG findings in identifying patients with predischarge LVEF < or = 35%. CONCLUSIONS: We conclude that in patients with an anterolateral AMI, ST-segment depression in lead aVR on admission ECG is useful for predicting larger infarct and left ventricular dysfunction despite successful reperfusion.     

Reliability of resolution of ST-segment elevation after coronary reperfusion in predicting myocardial salvage in anterior wall acute myocardial infarction

Resolution of ST-segment elevation (ST resolution) after reperfusion therapy has been shown to correlate with improved left ventricular (LV) function in patients with acute myocardial infarction (AMI). However, not all patients with ST resolution have preserved LV function. We evaluated the clinical significance of ST resolution in 129 patients with anterior wall AMI who underwent successful coronary recanalization within 6 hours after symptom onset by studying the relation to myocardial blush grade, another angiographic marker of myocardial reperfusion. A reduction of > or =50% in ST-segment elevation after recanalization was defined as ST resolution. Ninety-eight patients had ST resolution and 31 patients did not. Patients with ST resolution were subdivided into 2 groups according to myocardial blush grade after recanalization: 67 patients with blush grade 2 or 3, and 31 with blush grade 0 or 1. The QRS score after recanalization was higher (5.9 +/- 1.9 vs 3.4 +/- 2.0, p <0.01) and predischarge LV ejection fraction was lower (39 +/- 8% vs 57 +/- 9%, p <0.01) in patients with blush grade 0 or 1 than in those with blush grade 2 or 3. However, the QRS score after recanalization and the predischarge LV ejection fraction were similar in patients who had ST resolution with blush grade 0 or 1 and in those without ST resolution. Our findings suggest that ST resolution after recanalization does not consistently predict myocardial salvage in patients with anterior AMI.     

Quantitative assessment of ST segment elevation in Brugada patients

BACKGROUND: ST segment elevation in the right precordial leads constitutes the electrocardiogram (ECG) hallmark of Brugada syndrome (BS). This pattern is variable and can be concealed, but the magnitude and the cause of ST segment fluctuations have been poorly investigated. OBJECTIVE: Our goal was to quantify ST changes and to assess rate and autonomic influences on ST level. METHODS: A 12-lead ECG was continuously recorded during 24 hours in 20 patients with BS (ages 49 +/- 12) and 10 healthy subjects (ages 32 +/- 7). Using two-dimensional binning we obtained average QRS-T complexes every 30 minutes (time bins) and at different RR intervals (rate bins) for each subject. ST level was measured at five different points located 90, 100, 110, 120, and 140 ms after Q onset (Qo). In BS patients, the highest ST elevation was measured 110 ms after Qo (Qo+110). RESULTS: ST level changes between time points were significantly greater in patients with BS compared with control subjects: on lead V2, the range of ST level at Qo+110 was 264 +/- 85 microV in BS and 91 +/- 22 microV in control subjects (P <.01). In BS, ST level decreased with heart rate acceleration: the difference in ST level at Qo+110 for RR = 900 and 600 ms was 55 +/- 53 microV (P <.01). HFnu was positively, although weakly, correlated with ST level (R(2) = 0.02, P <.01). CONCLUSIONS: ECG changes observed in patients with BS are related in part to heart rate influences on ST segment level. These spontaneous fluctuations over a 24-hour time period suggest that Holter recordings may improve the ECG diagnosis sensitivity in BS.     

Predictive Value of Admission Electrocardiogram For Multivessel Disease in Acute Anterior and Anterior‐Inferior Myocardial Infarction

Background: Our aim was to investigate the correlation between admission ECG and coronary angiography findings in terms of predicting the culprit vessel responsible for the infarct or multivessel disease in acute anterior or anterior‐inferior myocardial infarction (AMI). Methods: We investigated 101 patients with a diagnosis of anterior AMI with or without ST‐segment elevation or ST‐segment depression in at least two leads in Dll, III, aVF. The patients were classified as those with vessel involvement in the left anterior descending (LAD) coronary artery and patients with multivessel disease. Vessel involvement in LAD + circumflex artery (Cx) or LAD + right coronary artery (RCA) or LAD + Cx + RCA were considered as multivessel disease. Thus, (a) anterior AMI patients with reciprocal changes in inferior leads, (b) anterior AMI patients with inferior elevations, (c) all anterior AMI patients according to the ST‐segment changes in the inferior region were analyzed according to the presence of LAD or multivesssel involvement. Results: Presence of ST‐segment depression in aVL and V6 was significantly correlated with the presence of multivessel disease in anterior AMI patients with reciprocal changes in the inferior leads (P = 0.005 and P = 0.003, respectively). No statistically significant difference between the leads were detected in terms of ST‐segment elevation in predicting vessel involvement in the two groups of anterior AMI patients with inferior elevations. When all the patients with anterior AMI were analyzed, the presence of ST‐segment depression in leads aVL, V4, V5 and V6 were significantly associated with the presence of multivessel disease (P = 0.035, P = 0.010, P = 0.011, P = 0.001, respectively). Conclusions: The presence of ST‐segment depression in anterolateral leads in the admission ECG of anterior AMI patients with reciprocal changes in inferior leads was associated with multivessel disease.     

ST段早期恢复反映急性心肌梗死溶栓治疗后心肌再灌注

目的 比较溶栓再通后早期ST段恢复与未恢复者住院期间临床结局的差异，探讨ST段早期恢复在心肌再灌注中的作用。方法 108例溶栓经酶学等指标临床判定再通的急性心肌梗死（AMI）患者，按照有无早期（溶栓后2h)ST段恢复分为两组。连续测定血清肌酸激酶（CK）水平，了解心肌酶峰出现时间及峰值；放射性核素评估左心室功能。观察4周住院期间充血性心力衰竭（CHF）、室壁瘤、心肌梗死后心绞痛发生情况及病死率。结果 无论是前壁MI还是下壁MI，ST段早期恢复组左心室射血分数均高于未恢复组（P＜0．05）；CK峰值则低于未恢复组（P＜0．05）。住院期间ST段恢复组核素心肌显像充盈缺损、CHF及室壁瘤发生率低，心肌梗死后心绞痛发生率高（P值均小于0.05)。结论 同ST段未恢复组相比，溶栓再通后ST段早期恢复者临床预后好。心电图模式可以反映再灌注程度。     

Reciprocal ST-Segment Changes in Myocardial Infarction: Ischemia at Distance Versus Mirror Reflection of ST-Elevation

Background

Reciprocal ST-depression in the electrocardiograms (ECGs) of patients with ST-elevation myocardial infarction (STEMI) results from either true ischemia at a distance via collateral circulation diverting blood to the infarcted region or an electrical phenomenon that results from a mirror reflection of ST-elevation. We aimed to identify the role of reciprocal ECG changes in predicting collateral circulation to the infarcted area determined angiographically.

Reperfusion arrhythmias during coronary angioplasty for acute myocardial infarction predict ST-segment resolution

BACKGROUND: Despite early recanalization of an occluded infarct-related artery, myocardial reperfusion may remain impaired due to microvascular injury. Reperfusion arrhythmias may indicate successful microvascular reperfusion. METHODS: Microvascular reperfusion was assessed prospectively in 42 consecutive patients with ST-segment elevation acute myocardial infarction (AMI) by evaluation of the resolution of ST-segment elevation (<50% of initial level) immediately after successful coronary angioplasty. Patients were divided into two groups: those with ST resolution (n=24) and those without ST resolution (n=18). The presence of reperfusion arrhythmias immediately after recanalization was recorded. RESULTS: Patients with ST resolution were younger (54+/-12 years compared with 64+/-17 years, P=0.04), their pain-to-recanalization time was shorter (195+/-87 min compared with 294+/-179 min, P=0.05), they were less often diabetic (13% compared with 24%, P=0.05) and were more often given IIb/IIIa inhibitors (58% compared with 22%, P=0.02). Reperfusion arrhythmias were observed in 15 out of 24 patients with ST resolution (62%) but in only one out of 18 without ST resolution (5%) (P<0.01). Reperfusion arrhythmias included accelerated idioventricular rhythm, 13 (81%); multifocal ventricular premature beats, two (13%); and ventricular tachycardia, one (6%). The sensitivity and specificity of reperfusion arrhythmias for ST resolution were 62 and 95%, respectively. In a logistic regression model including age, time to treatment, diabetes, use of IIb/IIIa inhibitors and reperfusion arrhythmias, only the latter was found to be an independent predictor of ST resolution (P<0.01). CONCLUSION: Reperfusion arrhythmias following coronary angioplasty for AMI are a highly specific marker for ST resolution and may indicate successful microvascular reperfusion.     

The effects of thrombolytic therapy on the high-resolution electrocardiogram after myocardial infarction.

The effects of thrombolytic treatment was studied in 109 consecutive patients 9-11 days after their first acute myocardial infarction by high-resolution electrocardiography (ECG), 24 h Holter monitoring, exercise test and radionuclide ventriculography. Thirty-seven patients were treated with intravenous thrombolytic agents. Thrombolytic treatment was assessed by clinical criteria to be successful in 22 patients and probably successful in 12 patients. Thrombolysis failed in three patients and 72 patients did not receive thrombolytic treatment (control group). Measurements made on the high-resolution and filtered (60 Hz high-pass) vectormagnitude complex included the total duration, the duration of the potential less than 40 microV, the root mean square (RMS) voltage in 10 ms intervals over the first 50 ms and RMS voltage of the last 40, 50 and 60 ms. The filtered QRS duration was significantly shorter in reperfused patients compared with the control group (83 +/- 10 vs 89 +/- 12 ms; P = 0.017). In inferior infarcts (n = 57) the filtered QRS duration was 83 +/- 11 ms in reperfused and 89 +/- 10 ms in non-reperfused patients (P = 0.044), but in anterior infarcts (n = 52) there was no difference. The RMS voltage of the initial 50 ms of the QRS was higher in the reperfused than in non-reperfused anteroseptal infarcts (38 +/- 14 v 23 +/- 10 microV; P = 0.022). Patients successfully treated with thrombolytic agents within the first 2 h had higher RMS voltage of the terminal 40 ms of the QRS than patients treated within 2-4 h (38 +/- 17 vs 27 +/- 17 microV; P = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)     

Consideration of the total ST-segment deviation on the initial electrocardiogram for predicting final acute posterior myocardial infarct size in patients with maximum ST-segment deviation as depression in leads V1 through V3. A FRISC II substudy

BACKGROUND: Because patients with acute left circumflex occlusion are typically characterized primarily on the standard 12-lead electrocardiogram (ECG) by ST depression, they do not qualify to receive reperfusion therapy. Documentation of a relationship between the quantities of acute ST change and final QRS estimated acute myocardial infarction (AMI) size could form the basis for clinical trials to determine the value of reperfusion therapy. METHOD: The Fragmin and Fast Revascularization during Instability in Coronary artery disease trial included 3214 patients with unstable coronary artery disease. Two percent of the patients (n = 69) had maximum ST-segment depression in leads V 1 through V 3 and were selected for this study. Initial ECG changes were compared to final myocardial infarction size, using the Selvester QRS score as the end point. RESULTS: The quantity of initial ST-segment deviation correlated with the final AMI size (r = 0.43, P < .0005). The formula 3[0.22 (SigmaST downward arrow + SigmaST upward arrow) -0.02], where downward arrow indicates depression and upward arrow elevation, derived from measurements on the initial ECG, predicted the size of the AMI in percentage of the left ventricle as estimated on the final ECG. The study population had a large proportion of AMI (73%) indicated to be in or adjacent to the posterior left ventricular wall. CONCLUSION: The quantitative initial ST-segment deviation correlates linearly to the final AMI size in patients with maximum ST-segment depression in leads V 1 through V 3. The formula derived could be valuable for selecting patients who fail to meet strict ST-elevation AMI criteria for emergency intravenous or intracoronary reperfusion therapy.     

持续监测ST段对评估急性心肌梗死早期梗死相关动脉动态变化的意义

目的 持续监测ST段变化评估急性心肌梗死（AMI）早期梗死相关动脉（IRA）动态变化的意义。方法 对发病≤6h的55例（男40例,女15例,年龄39－80岁）AMI患进行动态心电图监测,持续观察24hST段变化并与冠状动脉造影结果作对照。结果 （1）IRA未开通ST段持续抬高并伴有逐渐下降趋势.(2)溶栓疗法和直接经皮冠状动脉腔内形成术成功后ST段迅速下降并保持相对稳定。（3）所有患24h内均见有间断的ST段抬高和下降的波动性变化,尤其多见于溶栓成功早期。结论 AMI发病早期IBA处于动态的开放－关闭状态,持续监测ST段可较全面反应IRA变化。