Right bundle-branch block unmasking a myocardial infarction

A patient with an acute anteroseptal myocardial infarction and intermittent right bundle-branch block is presented. Abnormal Q waves in right precordial leads were only observed during right bundle-branch block. In the absence of right bundle-branch block, depolarization of the right ventricular free wall concealed the abnormal Q waves typical of an anteroseptal infarct. Right bundle-branch block, by preventing early activation of the right ventricular free wall, facilitated the correct diagnosis and localization of the infarction.     

Correlates of bundle-branch block in patients undergoing primary angioplasty for acute myocardial infarction.

BACKGROUND: Early reperfusion therapy has reduced the infarct size and mortality rate in patients with acute myocardial infarction (AMI). The occurrence of bundle-branch block in AMI is related to the amount of myocardial damage and the insult to the conduction system. HYPOTHESIS: To evaluate the clinical and angiographic factors related to the occurrence of bundle-branch block (BBB) in patients with primary percutaneous transluminal coronary angioplasty (PTCA), we investigated consecutive series of patients with their first Q-wave AMI and successful PTCA. METHODS: Coronary angiogram at the time of admission, electrocardiogram, and echocardiogram were evaluated in 279 patients with their first Q-wave AMI and successful PTCA. RESULTS: Bundle-branch block was detected in 26 patients (9%); 16 patients had transient and 10 patients had persistent block, while 16 patients had bifascicular block and 10 patients had right BBB. The patients with BBB had a significantly larger number of left ventricular asynergic segments, higher incidence of total occlusion of infarct-related artery, angiographic no reflow, and pericardial rub than those without BBB. When the multivariate analysis was performed using five clinical markers of infarct severity, angiographic no reflow (F = 20.2, p < 0.001) and total occlusion of infarct-re-lated artery (F = 4.2, p = 0.04) were found to be the significant variables related to BBB. CONCLUSIONS: Despite successful primary PTCA, absence of antegrade flow in the infarct-related artery at the onset of AMI and/or angiographic no reflow resulted in more severe transmural myocardial damage and, hence, the occurrence of BBB.     

Short- and long-term prognostic importance of complete bundle-branch block complicating acute myocardial infarction

Among 1013 consecutive patients with acute myocardial infarction (AMI), 104 (10%) developed complete bundle-branch block (BBB). The clinical characteristics and the short- and long-term prognosis were similar in the 53 patients with right and the 51 patients with left BBB. Compared to the 909 patients without this conduction disturbance, these 104 patients were older (64 +/- 9 vs. 58 +/- 10 years, p less than 0.001), more frequently women (26 vs. 17%, p less than 0.05), had a larger infarct (peak CK 1672 +/- 1124 vs. 1356 +/- 1089 IU/l, p less than 0.001), more frequently anterior (60 vs. 37%, p less than 0.001). They had a higher incidence of Killip class greater than 1 (63 vs. 38%, p less than 0.001), pericarditis (40 vs. 23%, p less than 0.001), atrial fibrillation or flutter (22 vs. 12%, p less than 0.01), ventricular fibrillation (15 vs. 9%, p less than 0.05), and atrioventricular block (23 vs. 11%, p less than 0.001). Both hospital mortality (32 vs 10%, p less than 0.001) and 3-year posthospital mortality (37 vs. 18%, p less than 0.001) were much higher among patients with complete BBB. Transient BBB had the same deleterious prognosis as BBB persistent at discharge (mortality 33 vs. 39%, NS). The prognostic importance of BBB was more prominent during the first 6 months after infarction (mortality between 6 and 36 months: 18% with BBB vs. 11% without BBB, NS).     

右束支传导阻滞在急性心肌梗死中的临床意义

目的　评价伴随急性心肌梗死 (AMI)出现的右束支传导阻滞 (RBBB)的临床意义。方法　 2 94例 AMI分为RBBB组和非 RBBB组 ,比较两组患者的年龄、梗死部位、血清磷酸肌酸激酶 (CK)及其同工酶 (CK- MB)水平、心功能状态、严重并发症及住院死亡率。结果　 RBBB组血清 CK、CK- MB平均峰值为 (2 2 82 .0± 6 74.3) u/ L、(2 5 2 .6±137.3) u/ L ,明显高于非 RBBB组的 (192 0 .4± 5 6 9.2 ) u/ L、(114.8± 5 6 .7) u/ L (P<0 .0 0 5和 P<0 .0 1)。 RBBB组killip平均级别为 2 .33± 0 .5 4级 ,非 RBBB组为 1.46± 0 .6 3级 (P<0 .0 5 ) ,RBBB左心室舒张期末内径 (5 3.2± 9.6 m m )大于非 RBBB组 (4 5 .8± 8.2 m m,P<0 .0 5 ) ,左心室射血分数 [(4 8.9± 7.6 ) %]小于非 RBBB组 [(6 7.0± 3.7) %,P<0 .0 1]。 RBBB组心脏并发症发生率和住院死亡率高于非 RBBB组 (分别为 70 .8%和 39.0 %,P<0 .0 1;43.8%和 14.6 %,P<0 .0 1)。结论　 AMI并 RBBB患者梗死面积大 ,严重心脏并发症发生率和住院死亡率高。     

急性前壁心肌梗死并发束支阻滞的近期与远期预后

156例急性前壁心肌梗死.其中36例并发束支阻滞(A 组).120例无束支阻滞(B 组)。心律失常的发生率 A 组77.7%.B 组45.8%(P>0.05).住院病死率 A 组14.0%.B 组4.8%有显著差异(P<0.01)。     

右束支阻滞在急性心肌梗死中的意义

目的　了解伴随急性心肌梗死出现的右束支阻滞的临床和预后意义。　方法　将我院近5年收治的伴有新出现的持续性右束支阻滞的急性心肌梗死共 12例作为观察组 ,梗死部位均累及前间壁或前壁 ,故将同期收治的无束支阻滞的前间壁或前壁急性心肌梗死共 2 0例作为对照组 ,两组急性心肌梗死患者都在症状发生后 2 4h内收入院。分析两组的临床经过、住院病死率和随访 1年的情况。　结果　观察组血清 CK- MB平均峰值为 (2 48.2± 15 4.9) u,明显高于对照组的 (10 8.6± 6 4.2 ) u(P<0 .0 2 )。观察组 5 0 %并发室性心动过速或心室颤动 ,对照组为 2 5 %。观察组心功能受损也更严重 ,Killip平均级别为 2 .45± 0 .6 8,对照组为 (1.2 0± 0 .42 ,P<0 .0 0 5 ) ,左心室舒张末内径在观察组为 (5 6 .8± 11.0 ) mm ,对照组为 (4 7.0± 4.4) mm (P<0 .0 5 ) ,左心室射血分数在观察组为 0 .47± 0 .0 6 ,对照组为 (0 .6 5± 0 .0 9,P<0 .0 0 2 )。观察组的住院病死率为 2 5 % ,1年内因心力衰竭恶化再住院率为 44 %。　结论　伴随急性心肌梗死新出现的持续性右束支阻滞是临床经过凶险和预后不良的标志     

A critique of the new ST-segment criteria for the diagnosis of acute myocardial infarction in patients with left bundle-branch block

BACKGROUND: Recently, electrocardiogram (ECG) criteria have been proposed for the diagnosis of acute myocardial infarction (AMI) in the presence of left bundle-branch block (LBBB). However, clinical experience indicates that such ECG changes indicative of AMI are occasionally noted in clinically stable patients with LBBB, raising concerns about the specificity of the proposed criteria. HYPOTHESIS: The aim of this study was to evaluate the frequency of ST-segment abnormalities suggestive of AMI in ambulatory patients with cardiovascular disease and chronic LBBB, who did not have an AMI. In addition, the ECG determinants of such ST-segment abnormalities were sought. METHODS: The files of all (4,193) patients followed in the outpatient cardiology clinic were reviewed to identify patients with LBBB. Electrocardiograms of these patients were evaluated as to the duration of the QRS complex, frontal QRS axis, amplitude of QRS in leads V1-V3, and the presence and magnitude of ST-segment depression (-ST) in leads V1-V3, and ST-segment elevation (+ST) in leads with predominantly positive or negative QRS complexes. Correlations of these ECG variables were carried out. RESULTS: In 124 patients with LBBB only 1 patient with -ST of 1 mm in leads V1-V3, and 1 patient with +ST of 1 mm in a predominantly positive ECG lead were found; the latter patient also had +ST of 6 mm in V3. Nine patients were detected with > or = 5 mm +ST in at least one ECG lead with predominantly negative QRS complex. Regression analysis of amplitude of +STs on corresponding QRS amplitudes in leads V1-V3 yielded Rs of 0.69, 0.68, and 0.69, all with a p value of 0.00005. A similar analysis of the amplitudes of +STs > or = 5 mm with the corresponding QRSs yielded an R = 0.76 and a p value of 0.0018. CONCLUSIONS: Thus, recently proposed ST-segment criteria for the diagnosis of AMI in patients with LBBB are appropriate. However, stable > or = 5 mm +STs are occasionally found in leads with predominantly negative QRS complexes, particularly of large amplitude (mean value 46.0, range [28.0-71.0] mm) in the absence of AMI. In such patients presenting with symptoms suggestive of AMI, further non-ECG confirmation of probable underlying AMI should be sought.     

急性心肌梗死伴新发右束支阻滞的临床意义

目的 探讨急性心肌梗死（AMI）合并新发右束支阻滞（RBBB）的临床特征及意义.方法 回顾性分析同期住院的AMI伴新发RBBB（观察组）与同期住院的无新发RBBB患者（对照组）,比较两组的基线资料、心电图、冠状动脉造影（CAG）、肌钙蛋白（cTNI）滴度、血清肌酸激酶同工酶（CK-MB）峰值、心功能及院内主要不良心脏事件（MACE）.结果 观察组新发RBBB多继发于急性前侧壁心肌梗死,梗死相关动脉（IRA）以左冠状动脉前降支（LAD）近端多见;观察组cTNI滴度、（CK-MB）峰值、Killip平均分级、住院期间MACE发生率均明显高于对照组,而左室射血分数（LVEF）则低于对照组.结论 AMI合并新发RBBB提示心梗面积大,病情凶险,预后不良,应尽早行再灌注治疗.     

Delay time in suspected acute myocardial infarction and the importance of its modification

This paper summarizes the present knowledge of delay time in suspected acute myocardial infarction. More than 50% of deaths in acute myocardial infarction occur outside of the hospital setting. Recent experiences indicate that early and even late mortality can be dramatically reduced by intervention in the early phase. This points up the importance of bringing patients with suspected acute myocardial infarction to the hospital as early in the course of MI as possible. The predominating cause of delay is the time it takes for the patient to decide to go to hospital regardless of a previous history of cardiovascular disease. Patients arriving in hospital in later stages of MI are at a very high risk of mortality. Therefore one of the most important problems to be resolved is how to reduce delay time in suspected acute myocardial infarction. Such efforts have been surprisingly few. Limited experiences indicate that public education can reduce delay time dramatically.     

Vectorcardiographic monitoring of patients with acute myocardial infarction and chronic bundle branch block

AIM: This study was set up to describe vectorcardiographic patternsin patients with bundle-branch block and acute myocardial infarction. METHODS AND RESULTS: Sixty-five patients admitted to the coronary care unit withbundle-branch block and suspected acute myocardial infarctionwere monitored by dynamic vectorcardiography with trend analysis.In 28 patients, a clinical diagnosis of acute myocardial infarctionwas made. In patients with left bundle-branch block and acutemyocardial infarction, the pattern of QRS vector-differenceevolution was similar to that in patients with the narrow QRScomplex, while ST vector-magnitude changes increased over time.Using a cut-off value for QRS vector-difference at 12 h of morethan 20 µVs and a specific trend curve pattern, acutemyocardial infarction in the presence of left bundle-branchblock could be diagnosed with an accuracy of 71%. For patientswith right bundle branch block, using a maximum ST vector-magnitudeof >200 µV during the first 4 h, acute myocardial infarctioncould be diagnosed with a 78% accuracy. CONCLUSION: Our results indicate that dynamic vectorcardiography is a valuabletool in diagnosing and monitoring acute myocardial infarctionin patients with bundle branch block.     

Continuous ST-segment monitoring of patients with left bundle branch block and suspicion of acute myocardial infarction

OBJECTIVES: Patients with left bundle branch block comprise 5-9% of all patients with acute myocardial infarction. Limited data exist on the usefulness of continuous electrocardiographic monitoring of these patients. We have investigated prospectively the usefulness of real-time continuous vectorcardiography for monitoring patients with left bundle branch block and suspicion of acute myocardial infarction. DESIGN: A prospective multi-centre study. SETTING: Fourteen Swedish coronary care units. SUBJECTS: Patients with left bundle branch block and suspicion of acute myocardial infarction with <6-h symptom duration were included. MAIN OUTCOME MEASURES: All patients were monitored with continuous vectorcardiography for 12-24 h. RESULTS: One hundred thirty-three patients were included, 47% had acute myocardial infarction. Patients with acute myocardial infarction showed a marked relative decrease in ST-vector than those without (P = 0.0002). These changes were most marked in the first 90 min. When comparing patients with acute myocardial infarction receiving thrombolytic therapy or not, those treated with thrombolytics showed more marked decline in ST-vector magnitude (P < 0.0001) and in shorter time (P = 0.0017). All patients showed STC-vector magnitude changes that were more marked in patients with acute myocardial infarction (P = 0.0002). An STC-vector magnitude cut-off value of 65 microV after 90 min of monitoring gave 54% sensitivity and 72% specificity for diagnosis of acute myocardial infarction. CONCLUSION: Real-time continuous vectorcardiographic monitoring of patients with left bundle branch and suspicion of acute myocardial infarction shows significant differences between those with and without acute myocardial infarction and could be of use for early diagnosis and subsequent monitoring.     

Recurrent extensive anterior myocardial infarction with left and right bundle branch block

The diagnosis of myocardial infarction with left bundle branch block is difficult. We report a case of 56‐year‐old man with old extensive anterior myocardial infarction and left bundle branch block (masked each other). The recurrent myocardial infarction indicated right bundle branch block and first‐degree atrioventricular block, making a clear diagnosis of complicated and interesting ECG.     

急性心肌梗死合并新发生完全性右束支传导阻滞的临床意义

目的了解伴随急性心肌梗死出现的完全性右束支传导阻滞的临床特点和预后意义.方法观察有新出现持续性完全性右束支传导阻滞的急性心肌梗死患者45例(观察组),同期收治的无右束支传导阻滞的急性心肌梗死患者90例(对照组)的CK峰值、KilliP分级、严重心律失常发生率、LVEF和住院病死率的情况.结果观察组CK峰值(2498±1369U/L),明显高于对照组(1757±1026U/L)(P＜0.05).观察组Killip平均级别2.5±1.1,非常明显高于对照组(1.7±0.9),(P＜0.01).观察组缓慢型心律失常及室性恶性心律失常发生率(20%、16%),明显高于对照组(4%、4%)(P均＜0.05).观察组的住院病死率(15.6%)显著高于对照组(4.4%)(P＜0.05).结论急性心肌梗死新出现的持续性完全性右束支传导阻滞提示临床病情危险,预后不良.     

微量白蛋白尿对非糖尿病急性心肌梗死预后的意义

目的：探讨微量白蛋白尿（MA）与非糖尿病急性心肌梗死（NDM－AMI）患者预后的关系。方法：收集1996年10月－2001年5月期间肾功能处于代偿期的NDM－AMI住院病人43例，分MA阳性组和MA阴性组，对入院后心肌梗死面积大小（心电图、心肌酶谱分析）、冠状动脉造影结果、AMI后3月心内绞痛、再发心肌梗死，心衰发生率及死亡率进行统计学分析。结果：NDM－AMI患者MA阳性占53．49％，冠状动脉造影提示MA阳性组冠状动脉粥样硬化病变程度较MA阴性组广泛和严重；EKG和血清心肌酶谱显示MA阳性组心肌梗死面积大于MA阴性组（P＜0．05）；两组AMI后3月内心绞痛、再发心肌梗死、心衰发生率和死亡率具有显著性差异（P＜0．01）。结论：MA阳性提示NMD－AMI患者体内广泛性血管病变，且近期预后不良。     

早期发生急性肾衰竭与急性心肌梗死后心源性休克患者预后的关系

目的了解急性心肌梗死后心源性休克患者早期发生急性肾衰竭与其预后的关系.方法回顾性分析解放军总医院1993～2003年间,因急性心肌梗死或冠心病心绞痛住院,并出现心源性休克的病例,以24h内是否出现急性肾衰竭为标准,比较其住院期间死亡率,并采用多元Logistic回归分析,评估早期发生急性肾衰竭对患者预后的影响.结果符合统计分析标准的患者共172例,其中51例(30%)于24h内出现急性肾衰竭.有无早期发生急性肾衰竭的患者,其住院死亡率分别为90%(46/51)和56%(68/121).逐步回归分析表明,早期发生急性肾衰竭是影响急性心肌梗死后心源性休克患者预后的独立因素(OR=6.7,95%可信限2.5～18;P＜0.001).结论急性心肌梗死后心源性休克患者,早期发生急性肾衰竭,与其住院死亡率显著相关,可作为判断患者不良预后的指标.     

急性下壁心肌梗塞中右室心肌梗塞与房室传导阻滞的关系

目的 探讨急性下壁心肌梗塞(MI)并发右室MI与发生房室传导阻滞的关系.方法 共有120例确诊急性下壁MI的住院患者,根据是否发生房室传导阻滞分为房室传导阻滞组(AVB)和非房室传导阻滞(NAVB)组;是否合并右室MI,则分为右室MI(RVI)组和非右室MI(NRVI)组.结果 急性下壁MI并发AVB组住院死亡率明显高于NAVB组(P<0.05);合并RVI患者,其AVB的发生率明显高于NRVI病人(P<0.01).合并RVI及高血压组患者,其AVB的发生率最高,明显高于RVI组(P<0.05).结论 右室心肌MI是急性下壁心肌MI发生AVB的重要原因之一.     

Prognostic importance of previous myocardial infarction in patients receiving thrombolytic therapy for acute infarction

This study evaluated the prognostic significance of reinfarction location by considering the previous site or type of myocardial infarction (MI) among 1601 patients with a history of previous MI who took part in the International (non-Italian) tPA/STK trial and/or the Israeli GUSTO study population. These patients were accordingly divided and hospital mortality was compared by six location groups as follows: acute inferior with previous inferior (8.1% hospital mortality), acute inferior with previous anterior (12.8%), acute anterior with previous inferior (13.3%), acute anterior with previous anterior (11.1%), acute inferior with previous non-Q-wave MI (7.6%), and acute anterior with previous non-Q-wave MI (11.2%) (p = 0.17 for comparison between the six groups). Hospital mortality tended to increase among patients with an anterior reinfarction compared with those with an inferior one (12.1% vs. 9.5%, p = 0.12). Among patients with a reinfarction at a different ECG location from the previous event, mortality tended to be higher compared with patients with two MIs at the same location (13.1% vs. 9.7%, p = 0.07). Recurrent MI following a previous Q-wave MI did not cause a higher mortality compared with a previous non-Q-wave type of MI (11.5% vs. 9.5%, p = 0.24). Among patients sustaining reinfarction, overall mortality did not differ between STK- and tPA-treated patients (11.0% vs. 11.4%, p = NS). In conclusion, the current study identified trends for higher mortality rates in patients with anterior compared with inferior reinfarction, with remote compared with the same ECG location of the two infarctions but not following a previous non-Q-wave compared with Q-wave MI. However, no particular combination of successive MIs location was significantly associated with a higher risk for hospital mortality.     

Acute myocardial infarction and left bundle branch block with changing axis deviation

Changing axis deviation has been reported also during atrial fibrillation or atrial flutter. Changing axis deviation has been also reported during acute myocardial infarction associated with atrial fibrillation too or at the end of atrial fibrillation during acute myocardial infarction. Left bundle branch block is usually associated with normal or left axis deviation. Rarely the ECG shows a LBBB with changing QRS morphology and changing axis deviation. There are several possible explanations for the intermittent shift in the QRS axis in the presence of complete left bundle branch block. The most plausible explanation is the coexistence of left posterior hemiblock and predivisional left bundle branch block. We present a case of a left bundle branch block with changing axis deviation in a 93-year-old Italian woman admitted to the Cardiology Unit with an acute myocardial infarction.     

Tachycardia-dependent right bundle-branch block with supernormal conduction

This paper reports the case of a 76-year-old man in whom atrial flutter with varying atrioventricular block and intermittent right bundle-branch block was found. This is the first report on tachycardia-dependent right bundle-branch block associated with supernormal conduction in a case of atrial flutter. When an impulse is conducted to the ventricles beyond 0.72 s after a QRS complex of right bundle-branch block configuration, the impulse falls after the abnormally long effective refractor period of the right bundle branch and passes through the right bundle branch. When the conducted impulse occurs within 0.72 s after a QRS complex of right bundle-branch block configuration, the impulse usually falls in the refractory period and is blocked in the right bundle branch; however, only when the impulse occurs 0.48 or 0.49 s after that does it fall in the supernormal period and passes through the right bundle branch. The findings in the present report strengthen our previous suggestion that the presence of supernormal conduction plays an important role in the initiation of reentrant ventricular tachycardia.     

Prognostic significance of the initial electrocardiographic pattern in patients with inferior wall acute myocardial infarction

The purpose of the study was to determine whether the initial electrocardiographic pattern is predictive of in-hospital mortality in inferior wall acute myocardial infarction. It is commonly perceived that patients with acute myocardial infarction presenting with greater ST elevation have a worse prognosis. The initial electrocardiogram of patients (n = 213) with inferior wall myocardial infarction was categorized based on the pattern of ST-segment elevation in inferior leads: (A) ST< 1 mm with tall T waves, (B) ST ≥ 1 mm with normal terminal QRS, and (C) ST≥ 1 mm with distortion of terminal QRS. ST deviation from baseline was calculated for all leads. Patients with maximal precordial ST depression in V₄-V₆ and pattern A had an in-hospital mortality rate of 68.8% compared with 16.9% for the entire study group. By univariate analysis, only pattern A was significantly predictive of in-hospital mortality [odds ratio = 2.91,95% confidence interval (CI) 1.22–6.93], but by multivariate analysis adjusted for (1) age, (2) diabetes mellitus, (3) previous myocardial infarction, (4) thrombolytic therapy, (5) precordial ST-depression pattern, and (6) patterns of ST elevation, maximal ST depression in V₄-V₆ was significantly predictive (odds ratio = 4.93, 95% CI 1.79–13.56), whereas pattern A was not (odds ratio = 1.12, 95% CI 0.36–3.52). Contrary to popular perception, patients with inferior wall myocardial infarction presenting with minimal ST-segment elevation are at highest risk for in-hospital mortality, especially if accompanied by maximal precordial ST depression in V₄-V₆.