Heart insufficiency in acute myocardial infarct. Long-term prognostic implications. Study of 213 cases of myocardial infarct

OBJECTIVE: To evaluate intra-hospital and first year prognosis of the acute myocardial infarction. DESIGN: Univariate analysis of hospital and late mortalities in 21 characteristics on the evolution of the acute phase of myocardial infarction of patients sequentially admitted in a coronary care unit. SETTING: Coronary care unit and out patient clinic of a school hospital. PATIENTS: A group of 213 patients with acute myocardial infarction admitted sequentially in a coronary care unit was studied. MATERIAL AND METHODS: Making use of a computerized information system the following characteristics f the patients were prospectively studied: age, sex, previous history of myocardial infarction, angor, diabetes, hypertension and tabacism, presence of left ventricular dysfunction electrocardiographic localization of the infarction, presence of angor in the acute phase of the infarction, epistenocardic pericarditis, hypertensive reaction, hypotension, sinus tachycardia, sinus bradycardia, supraventricular disrhythmias, ventricular disrhythmias, A-V block, complete right bundle branch block, complete left bundle block and peak of CPK values. Univariate analysis was made between each one of these characteristics and hospitalar and one year mortalities. RESULTS: Statistically significant differences were obtained in the hospitalar mortality in the following characteristics: age (p less than 0.001), sex (p less than 0.03), previous history of diabetes (p less than 0.05) and tabagism (p less than 0.005), left ventricular disfunction (p less than 0.0005), hypotension (p less than 0.005), sinus tachycardia (p less than 0.0005), sinus bradycardia (p less than 0.024), A. V. block (p less than 0.004), and peak of CPK (p less than 0.05). Statistically significant differences were found in one year mortality in the following characteristics: age (p less than 0.001), left ventricular disfunction (p less than 0.02), sinus tachycardia (p = 0.0116) and peak of CPK (p less than 0.05). Conclusion: Influence in the hospitalar mortality was demonstrated by the following characteristics of the patients with myocardial infarction: age, sex, previous history of diabetes and tabagism, left ventricular disfunction, infarct size expressed by the peak values of CPK, sinus tachycardia, sinus bradycardia, hypotensive reaction in the acute phase of the myocardial infarction and A-V block. Mortality in the late phase infarction was influenced by age, left ventricular dysfunction, sinus tachycardia and peak values of CPK.     

Incidence, clinical characteristics and prognostic significance of supraventricular tachyarrhythmias in acute myocardial infarction]

OBJECTIVES: The study of incidence and prognostic significance of supraventricular tachyarrhythmias in patients with acute myocardial infarction. PATIENTS AND METHODS: Prospective study on 1,239 patients consecutively admitted because of a diagnosis of acute myocardial infarction. Clinical characteristics, indexes of myocardial infarction and complications were analysed. RESULTS: Supraventricular tachyarrhythmias were observed in 116 (9.3%) cases: atrial fibrillation in 96 (7.7%); atrial tachycardia in 15 (1.2%); and atrial flutter in the remaining five cases (0.4%). Patients with supraventricular tachyarrhythmias were older, and presented higher heart rate, lower blood pressure, a higher number of affected leads in ECG, and higher Killip class. A higher creatine kinase peak and a lower left ventricular ejection fraction were associated with the presence of supraventricular tachyarrhythmias. Predictors of supraventricular tachyarrhythmias were: age, systolic blood pressure, number of affected leads in ECG, and congestive heart failure at admission. The following complications were found more frequently in patients with supraventricular tachyarrhythmias: bundle-branch block, complete A-V block, ventricular tachycardia, ventricular fibrillation; heart failure; stroke; and mortality, in-hospital 18.1% vs 11.1% (p < 0.05) and one-year, 38.7% vs 18.4% (p < 0.001). The logistic regression model showed that supraventricular tachyarrhythmias had no independent prognostic value on mortality. CONCLUSIONS: The appearance of supraventricular tachyarrhythmias during the acute phase of myocardial infarction is a relatively frequent finding, often associated with older age and larger infarctions. Supraventricular tachyarrhythmias are accompanied by higher short and long-term mortalities, although there is no independent prognostic significance.     

右室心肌梗死对急性下壁心肌梗死临床特征和预后的影响

目的：分析右室心肌梗死(心梗)对急性下壁心梗临床特征和预后的影响。方法：比较急性单纯性下壁心梗(第一组)和急性下壁心梗合并右室心梗(第二组)两组患的临床特征和院内病死率。结果：共176例患符合入选条件，第一组115例，第二组61例。第一组低血压、快速心律失常(包括阵发性室上性心动过速，阵发性心房颤动，领发室性早搏，室性心动过速，心室纤颤等)、缓慢心律失常(包括窦性心动过缓，房室传导阻滞)、心功能不全的发生率和院内病死率显低于第二组(P＜0．05)。静脉溶栓、急诊PTCA和未行再灌注治疗的院内病死率在第一组的分别为3．23％，3．33％和29．17％，在第二组分别为9．25％，13．04％和82．35％。结论：当急性下壁心梗合并右室心梗时，患的临床表现更为严重，院内病死率增高。积极行溶栓或急诊PTCA治疗，可显降低其院内病死率.     

190例心电图危急值的临床应用与分析

目的探讨心电图危急值的临床应用。方法分析我院2012年1月至2013年8月报告的190例心电图危急值结果及临床处理措施,总结心电图危急值报告在临床的应用价值。结果此期间共出心电图报告46962例,危急值报告190例,危急值报告率0.40%,其中门诊患者71例,住院患者119例,报告全心停搏54例,窦性停搏22例,显著性窦性心动过缓19例,心房颤动伴长间歇5例,高度及以上房室阻滞9例,阵发性室上性心动过速20例,室性心动过速4例,心室颤动1例,心房颤动伴快速心室反应5例,窦性心动过速3例,急性心肌梗死/急性心肌缺血30例,QTc〉0.50s有18例。结论按照心电图危急值制度对临床科室及时反馈,能够使临床医生在最短的时间内了解患者的检查结果,并进行相应的处理,降低了医疗的风险性,为临床提供了帮助。     

Sinus node dysfunction in acute myocardial infarction.

The frequency, clinical course, and prognosis of sinus node dysfunction in 431 patients with acute myocardial infarction admitted to the coronary care unit were studied. Sinus node dysfunction occurred in 20 patients. In 13, the principal manifestation consisted of severe sinus bradycardia. In the remaining 7, periods of bradycardia alternating with episodes of supraventricular tachycardia were noted. Though several of the patients with sinus bradycardia required intravenous atropine or temporary pacing, normal sinus rhythm returned in virtually all during follow-up. The clinical course of patients with both bradycardia and tachycardia was less benign, during the acute phase and during follow-up; 5 of the 6 survivors required continued antiarrhythmic therapy or permanent pacing. The differences in the clinical course between these two groups of patients may reflect distinct underlying pathological changes. The findings in this study suggest that in contrast to sinus bradycardia, the occurrence of bradycardia-tachycardia syndrome during the acute phase of myocardial infarction may have important prognostic implications.     

Sinus node dysfunction in acute myocardial infarction.

The frequency, clinical course, and prognosis of sinus node dysfunction in 431 patients with acute myocardial infarction admitted to the coronary care unit were studied. Sinus node dysfunction occurred in 20 patients. In 13, the principal manifestation consisted of severe sinus bradycardia. In the remaining 7, periods of bradycardia alternating with episodes of supraventricular tachycardia were noted. Though several of the patients with sinus bradycardia required intravenous atropine or temporary pacing, normal sinus rhythm returned in virtually all during follow-up. The clinical course of patients with both bradycardia and tachycardia was less benign, during the acute phase and during follow-up; 5 of the 6 survivors required continued antiarrhythmic therapy or permanent pacing. The differences in the clinical course between these two groups of patients may reflect distinct underlying pathological changes. The findings in this study suggest that in contrast to sinus bradycardia, the occurrence of bradycardia-tachycardia syndrome during the acute phase of myocardial infarction may have important prognostic implications.     

Syncopes and brief spells of feeling faint: value of Holter monitoring?

A retrospective study of Holter monitoring of 250 patients referred for syncope and short spells of dizziness suspected of being cardiac in origin was undertaken to assess the diagnostic value of the investigation. The arrhythmias observed were classified in 3 groups, significant, suspect and physiological with respect to their true or potential severity and to previously reported results of Holter monitoring in healthy subjects. The following arrhythmias were classified as significant: supraventricular tachycardia with a ventricular rate greater than or equal to 200 bpm; sustained ventricular tachycardia (greater than 30 s and greater than or equal to 150 bpm), bradycardia (less than bpm), sinus arrest (waking greater than 2 s sleeping greater than or equal to 6 s), complete AV block with wide QRS complexes and pacemaker dysfunction. The following arrhythmias were classified as suspect: paroxysmal supraventricular tachycardia with a ventricular rate less than 200 bpm, salvos of ventricular tachycardia (120 greater than 150 bpm); R/T phenomenon and doublets (greater than or equal to 50/24 hours), sinus arrest of 2 to 6 seconds during sleep, complete AV block with narrow QRS complexes or second degree Mobitz II block. This classification led to a diagnosis of certitude in 20 patients (5.7%) with significant arrhythmias concomitant with syncope or a minor form in only 5 cases, supraventricular tachycardia (4 cases), ventricular tachycardia (4 cases), AV block (5 cases), sinus arrest (3 cases), pacemaker dysfunction (4 cases); a diagnosis of presumption in 74 patients (21.1%) with suspect arrhythmias in the absence of syncope or minor equivalent.(ABSTRACT TRUNCATED AT 250 WORDS)     

前壁及下壁急性心肌梗死并发心律失常比较分析

目的:比较分析前壁及下壁急性心肌梗死(AMI)后并发心律失常的类型。方法:收集了186例急性心肌梗死患者梗塞后出现的各种心律失常的类型,并作统计分析。结果:①前壁心梗后窦速和室内传导阻滞发生率显著高于下壁心梗(P分别<0.05,<0.01),而下壁心梗后窦缓及房室传导阻滞发生率显著高于前壁心梗(P均<0.01)。②下壁心梗并发房性及室性异位节律(未包括室颤)均显著高于前壁心梗(P均<0.05)。结论:前壁心梗及下壁心梗并发心律失常的类型有差别:前者以窦速和室内传导阻滞较常见,后者以窦缓、房室传导阻滞及房室异位心律常见。     

The relation of sinus rate to the frequency of paroxysmal ventricular tachycardia during acute myocardial infarction in man.

Continuous tape recordings of cardiac rhythm were made in 51 male patients with acute myocardial infarction within 24 hours of their infarction. These tracings were analyzed for the incidence of paroxysmal ventricular tachycardia (PVT) and the sinus rate immediately preceding each episode of PVT. In 26 patients, 112 episodes of PVT at a rate greater than 100 beats/min were documented. Although 67 per cent of the episodes of PVT were preceded by sinus rates between 60 and 100 beats/min, 15 per cent occurred at sinus rates below 60 beats/min and 18 per cent occurred at sinus rates above 100 beats/min. The data remained essentially unchanged regardless of whether ventricular tachycardia was defined at rates in excess of 100, 120 or 140 beats/min. The results of this study show that during the early phases of acute myocardial infarction in man, PVT was most common during sinus rates generally thought to be within the normal range (60 to 100 beats/min). A lower, but close to equal incidence of PVT was observed during sinus bradycardia and sinus tachycardia.     

急性下壁心肌梗死伴右室梗死的临床表现和预后分析

目的探讨急性下壁心肌梗死(心梗)不伴或伴右室心梗患者的临床特征、治疗和预后。方法回顾既往6年住我院的103例急性下壁心梗患者,比较下壁心梗不伴右室心梗(65例)和伴右室心梗(38例)两组患者的临床特征和院内死亡率。结果发生低血压、心源性休克、快速心律失常(阵发性心房颤动,非持续性室性心动过速)、缓慢心律失常(包括窦性心动过缓,Ⅲ度房室传导阻滞)在下壁伴右室心梗组高于下壁心梗组,两组比较有显著性差异(P<0.05)。两组左心室射血分数(LVEF)及经皮冠脉介入(PCI)治疗患者的院内病死率比较无显著差异(P>0.05)。结论血流动力学障碍和心律失常是右室心梗住院并发症高的主要因素,右室心梗是独立于左室功能损害的危险因素,早期介入治疗能改善住院死亡率。     

Ventricular fibrillation and asystole precursors in myocardial infarct]

Ventricular fibrillation and asystole are a frequent cause of death in myocardial infarction. The data of continuous monitoring the heart in 134 patients with acute myocardial infarction and ventricular fibrillation and asystole. The immediate precursors of ventricular fibrillation were predominantly ventricular extrasystoles. A frequent precursor of ventricular fibrillation consists in paroxysmal ventricular tachycardia. In some patients the ventricular fibrillation was preceded by the block of the bundle of His, non-paroxysmal ventricular tathycardia, escaping contractions and some other arrhythmias. A factor providing for the development of ventricular fibrillation consists in the Q-T interval lengthening on ECG. Ventricular asystole is usually preceeded by atrioventricular block, Stage II-III, and the block of the bundle of His, as well as by ventricular tachycardia and extrasystole, in some cases--by sinus bradycardia and sinoauricular block (weakness of the sinus node). The examination of the rhythm and conductivity disorders preceeding the ventricular fibrillation is of great importance in view of the possibilities of prevention of "arrhythmic death".     

动态心电图与常规心电图在临床心脏病诊断中的应用价值对比

目的比较临床心脏病诊断过程中采用动态心电图与常规心电图的应用价值。方法选取我院2010年12月—2012年12月收治的并实施心电图检查的患者322例,对患者的心电图资料进行回顾性分析。结果采用动态心电图监测室上性期前收缩、室性期前收缩、阵发性室上性心动过速、阵发性心房纤颤、窦性心动过速、窦性心动过缓、阵发性房速、室性心动过速、窦性静止与窦房传导阻滞检出率高于采用常规心电图检查(P0.05);其中≥70岁年龄段患者窦性静止与窦房传导阻滞和房室传导阻滞检出率高于其他年龄段患者(P0.05)。结论在临床心脏病诊断过程中采用动态心电图监测较常规心电图检查,临床诊断效果更为显著,因此采用动态心电图监测是临床诊断心脏病的理想选择,同时更应该针对老年患者实施动态心电图监测。     

Independent prognostic value of supraventricular arrhythmias on 24-h ambulatory monitoring following myocardial infarction.

To determine the prognostic value of supraventricular arrhythmias, in addition to ventricular arrhythmias and clinical variables after myocardial infarction, 99 consecutive patients had 24-h ambulatory monitoring within 2 weeks of discharge. All patients completed at least 4-year follow-up (mean 56 +/- 6 months). During follow-up there were 29 cardiac events (13 cardiac deaths and 16 reinfarctions). The highest risk was associated with ventricular tachycardia (positive predictive accuracy 100%, negative predictive accuracy 75%, risk ratio 4.0) and supraventricular tachycardia i.e. paroxysmal tachycardia or AV nodal tachycardia (positive predictive accuracy 86%, negative predictive accuracy 80%, risk ratio 4.2). By multivariate analysis, supraventricular tachycardia proved to be an independent predictive variable, in addition to ventricular tachycardia, premature ventricular depolarisations greater than or equal to 10 h-1 and the presence of Killip class greater than or equal to II while in the coronary care unit for future cardiac events. These data suggest that supraventricular tachycardias detected on 24-h ambulatory monitoring shortly after discharge carry a poor prognosis and may indicate a different pathophysiology as compared to ventricular tachycardias.     

Prognostic significance of programmed ventricular stimulation in patients surviving complicated acute myocardial infarction: a prospective study.

In survivors of complicated myocardial infarction, the inducibility of sustained ventricular tachycardia may help identify a subset that is at increased risk for subsequent sudden cardiac death or spontaneous sustained ventricular tachycardia. We performed prehospital discharge programmed ventricular stimulation in 86 survivors of acute myocardial infarction complicated by heart failure, angina pectoris, or nonsustained ventricular tachycardia. These patients also underwent cardiac catheterization with coronary angiography and 24-hour ambulatory ECG recording. Programmed ventricular stimulation induced sustained ventricular tachycardia in 19 patients (22%) and ventricular fibrillation in six (7%) and did not induce these arrhythmias in 61 patients (71%). During an average follow-up of 18 +/- 13 months, 11 patients had arrhythmic events (seven sudden death and four nonfatal spontaneous sustained ventricular tachycardia) and 10 patients had nonsudden cardiac death. The total cardiac mortality rate was 20%. Arrhythmic events occurred in 32% of the 19 patients with inducible sustained ventricular tachycardia compared with 7% of the remaining 67 patients (p less than 0.003). By multivariate analysis the occurrence of arrhythmic events was independently predicted by both inducible sustained ventricular tachycardia and Killip class III or IV heart failure. The risk of arrhythmic events was 4.4% in the absence of both variables versus 38.4% (p less than 0.001) when both variables were present. The total cardiac mortality rate was best predicted by low left ventricular ejection fraction (less than 30%). Thus programmed ventricular stimulation is useful in risk stratification of survivors of complicated acute myocardial infarction. The prognostic utility appears to be particularly high in patients with infarction complicated by Killip class III or IV heart failure.     

Difficulties in the use of electrocardiographic criteria for the differential diagnosis of left bundle branch block pattern tachycardia in patients with a structurally normal heart.

In patients with left bundle branch block pattern tachycardia, electrocardiographic criteria, based on leads V1, V2 and V6, have been shown to be effective for the diagnosis of ventricular tachycardia in patients with a previous myocardial infarct. To test these criteria on a wider population, we studied 53 consecutive patients with left bundle branch block pattern tachycardia. Seventeen patients had supraventricular tachycardia and 36 had ventricular tachycardia, 18 with a previous myocardial infarction, two with cardiomyopathy, and 16 with a normal heart. The sensitivity for the diagnosis of ventricular tachycardia in patients with a previous myocardial infarct of the combined criteria was 100% but was only 50% for the other patients, which was not significantly different from the patients with supraventricular tachycardia (29%). Two other criteria, right axis shift in tachycardia and ventricular ectopics during sinus rhythm with the same morphology as the tachycardia, were only seen in patients with ventricular tachycardia, and combined with the other criteria allowed the correct identification of 35/36 patients with ventricular tachycardia. To conclude, the electrocardiographic criteria based on leads V1, V2 and V6 are not sensitive for the diagnosis of a ventricular origin of left bundle branch block pattern tachycardia in patients with a normal heart and additional criteria are required for the diagnosis in these patients.     

Polymorphous ventricular tachycardia associated with acute myocardial infarction

BACKGROUND. During a 2.9-year period, 11 patients developed polymorphous ventricular tachycardia 1-13 days after acute anterior (seven patients) or inferior (four patients) myocardial infarction. None of the 11 patients had sinus bradycardia (mean heart rate, 90 +/- 23 beats/min), but three had a sinus pause immediately before the onset of polymorphous ventricular tachycardia. In all 11 patients, the QT interval and corrected QT interval (QTc) were normal or minimally prolonged (QT, 385 +/- 34 msec; QTc, 442 +/- 40 msec). None had significant hypokalemia (mean serum potassium concentration, 4.3 +/- 0.5 meq/l) or a grossly abnormal serum magnesium or calcium concentration (2.1 +/- 0.4 and 8.9 +/- 0.7 mg/dl, respectively). METHODS AND RESULTS. Immediately before the onset of polymorphous ventricular tachycardia, symptoms and/or electrocardiographic changes consistent with recurrent myocardial ischemia occurred in nine of 11 patients. One patient died before drug therapy could be initiated. Lidocaine was used in 10 patients and proved to be effective in only one. Intravenous procainamide was used in six patients: one improved, and five had recurrence of polymorphous ventricular tachycardia. Bretylium was used in five patients and was ineffective in all cases. Overdrive pacing was used in four patients and failed to suppress recurrent arrhythmias in all cases. Four patients with persistent polymorphous ventricular tachycardia unresponsive to lidocaine, procainamide, or bretylium responded to intravenous amiodarone. One patient with polymorphous ventricular tachycardia that was consistently preceded by ST segment elevation responded to intravenous nitroglycerin. Two patients with persistent polymorphous ventricular tachycardia and obvious recurrent ischemia unresponsive to pharmacological intervention responded to emergency coronary revascularization. A third patient who experienced recurrent angina and polymorphous tachycardia was initially stabilized with pharmacological therapy but subsequently underwent elective revascularization and has remained stable without antiarrhythmic therapy. CONCLUSIONS. Post-myocardial infarction polymorphous ventricular tachycardia is not consistently related to an abnormally long QT interval, sinus bradycardia, preceding sinus pauses, or electrolyte abnormalities. This arrhythmia has a variable response to class I antiarrhythmics but may be suppressed by intravenous amiodarone therapy. It is often associated with signs or symptoms of recurrent myocardial ischemia. Furthermore, coronary revascularization appears to be effective in preventing the recurrence of polymorphous ventricular tachycardia when associated with recurrent postinfarction angina.     

Prolongation of the averaged QRS complex. A simple prognostic factor in patients with post-infarction bundle branch block and a history of syncope

Patients with a history of myocardial infarction and complete bundle branch block with syncopal episodes have a high risk of sudden death: the identification of the cause of the syncope is therefore essential. The aim of the study was to assess the diagnostic value of non-invasive techniques used in the investigations of syncope: 24 hour Holter recording, high amplification ECG and measurement of left ventricular ejection fraction. The results of these investigations were compared with those of complete electrophysiological investigation evaluating atrioventricular conduction and the inducibility of tachycardia. The patient population was 134 patients, 83 with right bundle branch block and 51 with left bundle branch block. Ninety one patients had inducible sustained ventricular tachycardia and 24 had atrioventricular conduction defects: of these, 14 also had ventricular tachycardia. During follow-up, there were 12 sudden deaths and 13 deaths from cardiac failure. Uni- and multivariate analysis showed induction of ventricular tachycardia to be a significant risk factor for global mortality and sudden death but prolongation of the averaged QRS complex (> 165 msec) was also an independent risk factor of global cardiac mortality. The authors conclude that simple prolongation of the averaged QRS duration > 160 ms in patients with right bundle branch block and > 170 ms in patients with left bundle branch block after myocardial infarction and syncope is a significant poor prognostic factor. However, this sign is not predictive of sudden death.     

Efficacy of intravenous sotalol in the treatment of supraventricular tachycardia

20 patients with supraventricular tachycardia, received one to three intravenous injections of 0.5 mg/kg of sotalol. This group included 8 atrial fibrillations, 5 atrial flutters, 2 systolic tachycardias and 5 junctional tachycardias. Return to a normal sinus rhythm is obtained in 2 of the 8 patients with atrial fibrillation while a decreased heart rate under 100 per minute is noted in 3 of them. Among the 5 patients with atrial flutter, only one returned to a normal sinus rhythm and in 2 the tachycardia decreased. In the 2 patients with systolic tachycardia, the heart rate decreased without return to a normal sinus rhythm while the heart rate decreased in all 5 cases of junctional tachycardia. A left ventricular failure with hypotension, a bradycardia at 30/min. and a transient left bundle branch block were observed during treatment. The bundle branch block is explained by an increased ventricular effective, refractory period induced by this beta-blocker. Intravenous sotalol appears as an interesting alternative in the treatment of supraventricular tachycardias with an efficacy of about 70 p. cent; it is well tolerated if the contraindications of the beta-blockers are respected.     

Site of myocardial infarction. A determinant of the cardiovascular changes induced in the cat by coronary occlusion.

The influence of site of acute myocardial infarction on heart rate, blood pressure, cardiac output, total peripheral resistance (TPR), cardiac rhythm, and mortality was determined in 58 anesthetized cats by occlusion of either the left anterior descending (LAD), left circumflex or right coronary artery. LAD occlusion resulted in immediate decrease in cardiac output, heart rate, and blood pressure, an increase in TPR, and cardiac rhythm changes including premature ventricular beats, ventricular tachycardia, and occasionally ventricular fibrillation. The decrease in cardiac output and increase in TPR persisted in the cats surviving a ventricular arrhythmia. In contrast, right coronary occlusion resulted in a considerably smaller decrease in cardiac output. TPR did not increase, atrioventricular condition disturbances were common, and sinus bradycardia and hypotension persisted in the cats recovering from an arrhythmia. Left circumflex ligation resulted in cardiovascular changes intermediate between those produced by occlusion of the LAD or the right coronary artery. Mortality was similar in each of the three groups. We studied the coronary artery anatomy in 12 cats. In 10, the blood supply to the sinus node was from the right coronary artery and in 2, from the left circumflex coronary artery. The atrioventricular node artery arose from the right in 9 cats, and from the left circumflex in 3. The right coronary artery was dominant in 9 cats and the left in 3. In conclusion, the site of experimental coronary occlusion in cats is a major determinant of the hemodynamic and cardiac rhythm changes occurring after acute myocardial infarction. The cardiovascular responses evoked by ligation are related in part to the anatomical distribution of the occluded artery.     

Risk factors for cardiac mortality in cases of syncope with previous history of myocardial infarction

Syncope is considered to be a clinical sign predictive of sudden death in patients with a previous history of myocardial infarction. The aim of this study was to determine the prognostic factors in this population. The study population included 228 patients with myocardial infarction over one month old and who had no documented ventricular tachycardia. The patients were referred for investigation of syncope. The left ventricular ejection fraction (LVEF) was measured by echocardiography or radionucleide technique. Complete electrophysiological study including programmed atrial and ventricular stimulation was performed in all cases. The patients were followed up for 6 months to 5 years or until cardiac transplantation (average 3+/-1 years). One hundred and nineteen patients had a LVEF <40% (Group I) and 109 patients had a LVEF >40% (Group II). Sustained monomorphic ventricular tachycardia (VT) with a rate inferior to 280/min was induced in 44 patients in Group I (37%) and in 18 patients in Group II (16.5%), p<0.05. Ventricular flutter or fibrillation was induced in 24 patients in Group I (19%) and in 19 patients in Group II (17%) (NS). Different causes of syncope (conduction disturbances, supraventricular tachycardia, increased vagal tone, severe coronary ischaemia) were found in 23 patients in Group I (19%) and 32 patients in Group II (29%) (NS). Syncope was unexplained in 43 patients in Group I (36%) and 40 patients in Group II (37%) (NS). The prognosis was very different. In Group I, the cardiac mortality was 49% in patients with inducible monomorphic VT <280/min, 35% in those with inducible ventricular flutter or fibrillation but only 9% in patients without inducible ventricular arrhythmias. In Group II, the prognosis was independent of the results of programmed stimulation and much better: cardiac mortality was 5.5% in patients with inducible VT, 5% in those with inducible ventricular flutter or fibrillation and 4% in patients without inducible ventricular arrhyhtmias. The authors conclude that LVEF is the most powerful predictor of cardiac mortality and sudden death in cases of syncope with a past history of myocardial infarction. The prognosis also depends on the results of programmed ventricular stimulation when the LVEF is inferior to 40%. Sustained monomorphic VT is the most frequently induced arrhythmia in this case and the prognosis of these patients is particularly poor. On the other hand, syncope does not appear to be a poor prognostic factor in the group with normal LVEF, even when it is possible to induce VT.