160例平板运动试验诱发心律失常分析

目的：分析平板运动试验诱发心律失常的特点。方法：选择160例患者应用标准Bruce方案进行次极量平板运动试验,同步监测血压和12导联心电图,记录运动前、运动中及恢复期的血压和心电图。结果：160例运动试验诱发心律失常共36例,发生率为22.5%,运动试验阳性组心律失常发生率（44.9%）高于阴性组（12.7%）。结论：运动试验可辅助临床对冠心病的诊断,运动试验阳性组诱发的心律失常多于阴性组,以室性心律失常多见,运动中、运动后发生心律失常可能与心肌缺血等因素有关。     

Regional myocardial metabolism of high-energy phosphates during isometric exercise in patients with coronary artery disease

BACKGROUND. The maintenance of cellular levels of high-energy phosphates is required for myocardial function and preservation. In animals, severe myocardial ischemia is characterized by the rapid loss of phosphocreatine and a decrease in the ratio of phosphocreatine to ATP. METHODS. To determine whether ischemic metabolic changes are detectable in humans, we recorded spatially localized phosphorus-31 nuclear-magnetic-resonance (31P NMR) spectra from the anterior myocardium before, during, and after isometric hand-grip exercise. RESULTS. The mean (+/- SD) ratio of phosphocreatine to ATP in the left ventricular wall when subjects were at rest was 1.72 +/- 0.15 in normal subjects (n = 11) and 1.59 +/- 0.31 in patients with nonischemic heart disease (n = 9), and the ratio did not change during hand-grip exercise in either group. However, in patients with coronary heart disease and ischemia due to severe stenosis (greater than or equal to 70 percent) of the left anterior descending or left main coronary arteries (n = 16), the ratio decreased from 1.45 +/- 0.31 at rest to 0.91 +/- 0.24 during exercise (P less than 0.001) and recovered to 1.27 +/- 0.38 two minutes after exercise. Only three patients with coronary heart disease had clinical symptoms of ischemia during exercise. Repeat exercise testing in five patients after revascularization yielded values of 1.60 +/- 0.20 at rest and 1.62 +/- 0.18 during exercise (P not significant), as compared with 1.51 +/- 0.19 at rest and 1.02 +/- 0.26 during exercise before revascularization (P less than 0.02). CONCLUSIONS. The decrease in the ratio of phosphocreatine to ATP during hand-grip exercise in patients with myocardial ischemia reflects a transient imbalance between oxygen supply and demand in myocardium with compromised blood flow. Exercise testing with 31P NMR is a useful method of assessing the effect of ischemia on myocardial metabolism of high-energy phosphates and of monitoring the response to treatment.     

Design,implementation and evaluation of amicrocomputer-based portable arrhythmia monitor

The design of a portable, battery-operated microcomputer-based monitor for ambulatory ECG recording and analysis is described. Designed for real-time cardiac arrhythmia analysis, it is suitable for use on ambulator, patients for several weeks, and is about the size and weight of a Holter recorder. The device differs from a Holter recorder in that is does not store normal complexes but recognises and alarms on significant arrhythmias. It sotres 16 s of the arrhythmic event, which it can transmit by telephone to a central receiving station for immediate appraisal by a cardiologist. The monitor uses a CMOS microcomputer and has 2kbytes of program memory and 2kbytes of data memory. The arrhythmia monitor program recognises tachycardia, bradycardia, asystole, dropped beats, and PVCs. The alarm limits are physician programmable. The performance of the monitor was evaluated with standard annotated ECG tapes provided by MIT/BIH. This device should be useful for applications such as antiarrhythmic drug studies, for pacemaker and postsurgery evaluations, and for detecting premonitory as well as life-threatening arrhythmias.     

Transmission and non-transmission portable ECG in home care medicine

Portable electrocardiography is advantageous in that patients can record ECG by themselves at any time and place. Portable ECG can be classified into two kinds of devices, transmission type and non-transmission type. By using transmission-type portable ECG, patients can obtain an ECG diagnosis from the center by transmitting the recorded ECG. Transmission-type portable ECG is extremely useful for patients needing emergency treatment for such as an attack of ischemic heart disease or arrhythmic event. On the other hand, a patient has to go to a specialist to obtain an ECG diagnosis with the non-transmission-type portable ECG device after recording the ECG alone. As this model is slightly cheaper, and is easy to use, the non-transmission-type portable ECG is good in non-emergency use for early diagnosis and prevention of cardiac disease. Portable ECG is useful for ECG monitoring over time without seeing the patient, not only for symptomatic analysis of the patient. For example, silent myocardial ischemia and arrhythmic events developing during exercise will become clear in periodical portable ECG recording. In particularly, portable ECG is useful for noncontinual ECG monitoring of patients with Brugada syndrome and those administered with antiarrhythmic drugs. Portable ECG increases the opportunity to discover cardiac disease from the aspect of preventive medicine. When patients use a portable ECG during exercise, they can understand whether the exercise is suitable for their heart. Portable ECG is a useful measurement in preventive medicine as described above, not only for the home care of patients.     

Life-threatening ventricular arrhythmias in patients with silent myocardial ischemia due to coronary-artery spasm.

BACKGROUND. Silent myocardial ischemia in patients with coronary atherosclerosis is associated with an increased risk of adverse cardiac events, including sudden death. The relation between silent ischemia and the initiation of potentially fatal ventricular arrhythmias has not been defined, however. METHODS. As part of a long-term study of sudden cardiac death, data on arrhythmias, coronary anatomy, and responses to ergonovine testing to provoke coronary-artery spasm were collected prospectively among survivors of out-of-hospital cardiac arrest who had no flow-limiting coronary-artery lesions, prior myocardial infarctions, or other structural causes of cardiac arrest and no angina pectoris. Associations between silent myocardial ischemia due to coronary-artery spasm and the occurrence and characteristics of life-threatening ventricular arrhythmias were studied by both invasive and noninvasive techniques. RESULTS. Silent ischemic events were associated with the initiation of life-threatening ventricular arrhythmias in five patients with induced or spontaneous focal coronary-artery spasm (or both). These patients were identified among a group of 356 survivors of out-of-hospital cardiac arrest who were evaluated between 1980 and 1991. In two of the five patients reperfusion, rather than ischemia itself, correlated with the onset of the ventricular arrhythmia. Only one of the five had an inducible arrhythmia during electrophysiologic testing. Titration of the dose of a calcium-entry-blocking agent (verapamil, diltiazem, or nifedipine) against the ability of ergonovine to provoke spasm was successful in preventing both the provocation of spasm and arrhythmias in all four patients who were tested. CONCLUSIONS. Silent myocardial ischemia due to coronary-artery spasm can initiate potentially fatal arrhythmias in patients without flow-limiting structural coronary-artery lesions. The role of silent ischemia, reperfusion, or both in the initiation of fatal arrhythmias in larger groups of patients with advanced coronary-artery lesions remains to be defined.     

Electrophysiological tests in clinical laboratory]

We briefly described recently developed methods for testing cardiac electrophysiological phenomena such as 24-hour Ambulatory ECG, high resolution ECG, body surface mapping ECG, heart rate variability, QT and QT dispersion, and T wave alternans. Of these methods ambulatory ECG monitoring is important and useful for detecting malignant arrhythmias and ischemia attacks, especially in cases of vasospastic angina. Using this method, it is possible to quantitatively analyze arrhythmia and elucidate the pathophysiology of vasospastic angina. The monitoring system is useful not only for diagnosis, but also for assessing treatment efficacy. Heart rate variability is currently used for analyzing the autonomic nervous system; however, the exact meaning of each index still remains to be confirmed. The concept of QT dispersion was recently introduced as an index for detecting dispersion of ventricular repolarization and QT dispersion is still controversial. T wave alternans monitoring has been recently introduced as a new method of assessing the microvolt level of T wave alternans, which has been hypothesized to correlate with the occurrence of arrhythmic events in myocardial infarction. The possible roles of these methods and their applications for clinical practice are discussed.     

Early exercise thallium-201 single photon emission computed tomography in unstable angina: a prospective study.

To evaluate the safety and diagnostic value of early symptom-limited exercise electrocardiography (ECG) and exercise thallium-201 single photon emission computed tomography (SPECT) in unstable angina (UA), 39 patients were studied prospectively soon after stabilization on medical treatment. No patient had a history of myocardial infarction (MI) or revascularization and patients with left bundle branch block were excluded. Exercise ECG and exercise thallium-201 SPECT were performed 8 +/- 4 days and 11 +/- 6 days respectively after admission to hospital. Seventeen out of 39 patients (44%) had positive exercise ECGs and 22 (56%) negative or inconclusive ones. Exercise thallium-201 SPECT was positive in 26 patients (67%) and negative in 13 patients (33%). Thirty-one patients underwent coronary arteriography and 24 of them proved to have significant coronary artery disease (CAD). The sensitivity, specificity and positive predictive value of exercise ECG in detecting CAD are 62%, 86%, and 94% respectively while the corresponding results are 96%, 100%, and 100% for exercise thallium-201 SPECT. Therefore, it is concluded that the early symptom-limited exercise test is safe in medically stabilized patients with UA. Early exercise thallium-201 SPECT is highly sensitive and predictive of the presence of significant CAD among patients in the early recovery phase of UA and can be used in selecting this group of patients for coronary angiography and other therapeutic strategies.     

Effect of burden and origin sites of premature ventricular contractions on left ventricular function by 7-day Holter monitor

Recent studies have shown that premature ventricular contractions (PVCs) could enlarge the heart, but its risk factors are incompletely understood as a single 24-hour recording cannot reflect the true PVC burden due to day-to-day variability. Our purpose was to investigate the effect of burden and origin sites on left ventricular (LV) function in patients with PVCs by 7-day Holter electrocardiography (ECG). From May 2012 to August 2013, 112 consecutive patients with PVCs were recruited from the authors'' affiliated hospital. All patients received 2-dimensional transthoracic echocardiography, 12-lead routing ECG and 7-days Holter ECG. Serum N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were measured. A total of 102 participants with PVCs were included in the final analysis. Origin of PVCs from the tricuspid annulus had the highest burden and NT-proBNP level. LV papillary muscle had a higher LV ejection fraction (EF) level and a lower LV end-systolic dimension (ESD) than other PVC foci (P<0.05). The high burden group had a higher LV end-diastolic dimension (EDD) and LVESD but lower LVEF than the other two groups (P<0.05). Female, older age, physical work, and history of PVCs had a significantly positive correlation with symptoms. Male, older age, physical work, and high burden were positive predictors of enlarged LVEDD, LVESD and higher serum NT-proBNP level, but lower LVEF. Seven-day dynamic ECG Holter monitor showed the true PVC burden on patients with PVCs. PVCs with a lower burden or origin from the LV papillary muscle and the fascicle were relatively benign, while PVCs with a higher burden or origin from the tricuspid annulus may lead to cardiac dysfunction.     

Exercise test in patients with sarcoidosis. The importance of repolarization disturbances

The study population comprises 28 patients with sarcoidosis who all had repolarization disturbances in their exercise ECGs. None of the patients had hypertension or known cardiovascular disease, and all but two were non-smokers. The mean age was 45 years. Exercise test with beta-adrenergic blockade was performed within one month of the first examination. Persisting abnormal ST-T changes in exercise ECGs after beta-blockade were seen in 12 (43%) patients. No significant relationship was found between persisting ST-T changes and age, sex, chest X-ray stage, lung function or working capacity. In an earlier study, we found ST-T abnormalities in exercise ECG in 56 of 127 individuals (44%) in a consecutive 5-year study of patients with newly detected sarcoidosis. From this and the present report we postulate that, in our region, as much as 20% of the patients with newly detected sarcoidosis might have organic myocardial disease, possibly of sarcoid origin, as shown by repolarization disturbances in exercise ECG. If ECG abnormalities in the ST-T region are present in patients with sarcoidosis, exercise ECG with beta-blockade is a simple way of establishing suspicion of organic myocardial lesions. If exercise ECG abnormalities in the ST-T region persist after beta-blockade, careful clinical follow-up is recommended, and, in some patients early steroid therapy should be considered.     

Heart rate, magnitude and duration of ST-segment depression in symptomatic and asymptomatic episodes of myocardial ischemia in patients with coronary artery disease recorded by Holter

In the group of 85 patients with coronary artery disease the exercise and 24-hour ambulatory electrocardiograms were recorded in order to analyse the frequency of asymptomatic episodes of myocardial ischemia and to determine differences between symptomatic and asymptomatic episodes of myocardial ischemia. All patients had ischemic ST-segment depression (greater than or equal to 1 mm) on the exercise electrocardiogram. During exercise testing, 23 (27%) patients had ST-segment depression without anginal pain or dyspnea. On the 24-hour ambulatory electrocardiogram transient episodes of myocardial ischemia were found in 50 (58.8%) patients. In 16 patients all episodes were asymptomatic, in 9 all episodes were symptomatic, and in 25 patients some episodes were symptomatic and some asymptomatic. During a 24-hour electrocardiogram in 25 patients with both types of ischemia, 175 transient episodes of myocardial ischemia were recorded. Most of them (125, i.e. 71.4%) were asymptomatic. The heart rate in symptomatic and asymptomatic episodes was similar. The magnitude of ST-segment depression in symptomatic episodes was higher than in asymptomatic episodes (P less than 0.01). There was not significant difference in the duration of the two types of myocardial ischemia. This study suggests: 1. During daily activities, in patients with the positive exercise test, asymptomatic episodes of myocardial ischemia are more frequent than symptomatic episodes. 2. The magnitude of ST-segment depression is the main factor in the determination of the presence of anginal pain.     

Mental stress-induced ischemia in patients with coronary artery disease: echocardiographic characteristics and relation to exercise-induced ischemia

Objective The aims of this study were to investigate the incidence and parameters associated with myocardial ischemia during mental stress (MS) as measured by echocardiography and to evaluate the relation between MS-induced and exercise-induced myocardial ischemia. Methods Study participants were 79 patients (63 men; mean [M] [standard deviation {SD}] age = 52 [8] years) with angiographically confirmed coronary artery disease and previous positive exercise test result. The MS protocol consisted of mental arithmetic and anger recall task. The patients performed a treadmill exercise test 15 to 20 minutes after the MS task. Data of post-MS exercise were compared with previous exercise stress test results. Results The frequency of echocardiographic abnormalities was 35% in response to the mental arithmetic task, compared with 61% with anger recall and 96% with exercise (p < .001, exercise versus MS). Electrocardiogram abnormalities and chest pain were substantially less common during MS than were echocardiographic abnormalities. Independent predictors of MS-induced myocardial ischemia were: wall motion score index at rest (p = .02), peak systolic blood pressure (p = .005), and increase in rate-pressure product (p = .004) during MS. The duration of exercise stress test was significantly shorter (p < .001) when MS preceded the exercise and in the case of earlier exercise (M [SD] = 4.4 [1.9] versus 6.7 [2.2] minutes for patients positive on MS and 5.7 [1.9] versus 8.0 [2.3] minutes for patients negative on MS). Conclusions Echocardiography can be successfully used to document myocardial ischemia induced by MS. MS-induced ischemia was associated with an increase in hemodynamic parameters during MS and worse function of the left ventricle. MS may shorten the duration of subsequent exercise stress testing and can potentiate exercise-induced ischemia in susceptible patients with coronary artery disease.     

Non-invasive computerised detection of acute coronary occlusion

The goal of this study was to evaluate the role of a computerised, non-invasive ECG method for detecting acute coronary occlusion (ACO). Ninety-five standard ECG leads were recorded, before and during ACO, from 18 patients undergoing balloon angioplasty. ECG amplitude and derivative parameters were calculated for the QRS, ST and T components of the ECG signal, before and during ACO. Results were obtained for each lead. Sensitivity of the standard visual ECG analysis for detecting ACO was 48%, whereas the percentage of conventional ECG changes during baseline was 14%. For the best ECG parameter, the amplitude parameter of the QRS component, sensitivity was 82%, and the percentage of parameter changes during baseline was 20%. The sensitivity for detecting ACO with five of the six ECG parameters studied was greater than that of the standard visual analysis. Ischaemic changes were detected in 4.3±1.6 leads per patient using the amplitude parameter of the QRS component, whereas, with the standard visual analysis, 2.5±2.1 leads demonstrated such changes (p<0.001). Results were then summarized per patient. The standard visual ECG analysis detected ACO in 15 of 18 patients (83%), if at least one lead showed ischaemic changes. The computerised analysis detected ACO in all 18 patients using the same criterion. The sensitivity of the computerised method for detecting ACO in the clinical setting of angioplasty was greater than that of the standard visual analysis. It is suggested that the computerised method may be useful for detecting myocardial ischaemia in other clinical settings of acute myocardial ischaemia.     

Depression and type A behavior pattern in patients with coronary artery disease: relationships to painful versus silent myocardial ischemia and beta-endorphin responses during exercise.

A sample of 45 patients with a history of coronary heart disease and documented myocardial ischemia during exercise testing were evaluated in an investigation of the possible relationships between psychological factors (depression and Type A behavior pattern), plasma beta-endorphin response and pain experience during maximal exercise-induced ischemia. Depression was assessed using the MMPI-D subscale, while Type A was evaluated using the Structured Interview. All patients developed ischemia during exercise as defined by ST-segment depression; however, only 18 patients reported anginal pain. Patients with high depression scores (MMPI-D greater than or equal to 70; n = 13) showed lesser increases in plasma beta-endorphin levels, tended more often to report anginal pain and rated pain as more severe during exercise than patients with low depression scores (MMPI-D less than 60; n = 18). Hemodynamic responses and severity of ischemia (assessed by ejection fraction changes and wall-motion abnormalities) did not differ between depression groups. Even after adjustment for group differences in exercise duration, depression was significantly associated with a lesser beta-endorphin response in the sample as a whole and, among patients reporting angina, with earlier pain onset and greater pain duration and severity. In contrast, when Type A versus B/X subgroups were compared, no differences in pain experience, beta-endorphin response or measures of ischemia were obtained. These findings suggest that in patients with ischemic heart disease, there may be a relationship between depression and anginal pain which may in part involve a blunted or absent beta-endorphin response.     

Same ablation may be used for frequent premature ventricular contractions and supraventricular tachycardia

Radiofrequency catheter ablation (RFCA) has been increasingly used for the treatment of various kinds of cardiac arrhythmias over the past 20 years. RFCA of symptomatic premature ventricular contractions (PVCs) has been reported to be a safe and effective treatment option and may be considered in patients with extremely symptomatic or incapacitating cases who do not respond to medications. Long-term prognosis in patients with truly idiopathic PVCs is excellent, despite frequent recurrences of tachycardia. Sudden death is rare in patients with initially normal left and right ventricular function, in such patients, occult cardiomyopathy is usually identified on postmortem examination. Similarly, progression to diffuse cardiomyopathy is rare. Ablation of PVCs may equal that of supraventricular tachycardia in terms of success rate, safety. These new views will help understand the diagnosis and treatment method for frequent PVCs in patients without heart disease.     

Painless myocardial ischemia during the treadmill test in the elderly

PURPOSE: Myocardial infarction without chest pain occurs in high incidence in elderly. However, the pathophysiological significance of the silent ischemia is still unknown. To elucidate the significance of the "painless" symptom during myocardial ischemia induced by exercise, we analyzed the incidence of silent ischemia on treadmill tests and attempted to examine the severity of the coronary stenosis in such painless subjects. METHOD AND RESULTS: Treadmill test was conducted on 580 patients aged 65 to 92 years (man: 261, woman: 319) with suspected myocardial ischemia. One hundred and seventy-nine patients (man: 89, woman: 90) showed positive results. Among them 126 patients (70%) did not complain of chest pain (painless group) during treadmill tests of these. Forty four patients showed dyspnea and 82 patients did not have any symptoms during the tests. The incidence of painless ischemia tended to increase in women (77%) over men (62%) (p=0.02). The incidence of diabetes in the painless group did not differed from that in the group of patients with chest pain. Coronary angiography was conducted on 79 patients (31: chest pain group, 15: painless group with dyspnea, 33: painless group without dyspnea). Coronary artery stenosis more than 75% were observed in 25 (80%), 13 (86%) and 24 (73%) patients respectively, suggesting chest pain itself did not mean the existence of severe coronary disease. CONCLUSION: Painless ischemia during the treadmill test was found in high incidence in the elderly. Painless ischemia must be treated as same as ischemia with chest pain.     

Post-myocardial infarction exercise testing: clinical significance of a left ventricular function index and ventricular arrhythmias. A prospective study

A predischarge exercise test was performed in a prospective series of 187 patients, less than 70 years old, with acute myocardial infarction. A survival analysis confirmed previous retrospective findings of a significantly increased long-term mortality in patients with a low increase in the pressure-rate-product (PRP) and/or with major exercise-induced arrhythmias. ST segment depression was without prognostic significance. By a graduated, quantitative re-evaluation of the significance of exercise-induced ventricular arrhythmias, an appropriate, significantly discriminating cutoff point for the frequency of solitary ventricular premature beats (VPBs) was found at two or more VPBs/min. Repetitive VPBs had an equal significance. The probability of 4.5-year survival in patients with these arrhythmias and a low increase in PRP was 0.49 vs. 0.85 in patients with less frequent arrhythmias and with a high increase in PRP (p less than 10(-6)).     

Evaluation of T-wave alternans in high-resolution ECG maps recorded during the stress test in patients after myocardial infarction

Introduction

Recent studies point to analysis of T-wave alternans as a promising indicator of an increased risk of life-threatening ventricular arrhythmias. In this study the occurrence of T-wave alternans in the high-resolution ECGs recorded during the exercise stress test and scintigraphic tests (SPECT) in patients with ischemic heart disease was examined.

Material and methods

The study group consisted of 33 patients after myocardial infarction. In the group of patients after myocardial infarction and with low left ventricular ejection fraction correlations of 70% between the test results of T-wave alternans and SPECT and 60% between the test results of T-wave alternans and stress test were found.

Results

In the group of patients after myocardial infarction but with high left ventricular ejection fraction correlations were respectively 39% and 48%. The analysis of the electrocardiographic maps showed a strong dependence of this correlation on the T-wave alternans amplitude and location of the ECG measuring electrode on the chest. The results might suggest that in patients after myocardial infarction and at increased risk for sudden cardiac death T-wave alternans may also provide information about cardiac electrical instability associated with ischemia.

Conclusions

It can also be assumed that the position of the electrode where the highest level of the T-wave alternans was detected can indicate the location of the ischemic region of the heart.     

Problems of Mason-Likar lead system in treadmill exercise electrocardiography

A Mason-Likar (M-L) leads system has been widely used in the exercise electrocardiography (ECG) using treadmill for the detection of myocardial ischemia. In routine treadmill exercise ECG using M-L lead, we often observe different patterns of ST-T forms those of II, III and aVF on bipolar leads. In this study, on 213 patients, conventional 12 lead ECG and the M-L lead placement ECG were recorded both at supine and standing positions. A careful analysis was made on all the records of patterns, durations, and amplitudes of QRS and T waves. We also evaluated the ST trendgram of patients with no ischemic changes proven exercise TI-201 myocardial single photon emission tomography (SPECT). Quantitative examination showed no significant differences between those in precordial leads of the standard and the M-L lead system in any subjects. The augmented amplitude of QRS and T waves, the disappearance of abnormal Q-waves in II, III, aVF lead, the negative inversion in QRS phase in lead aVL an left axis deviation were often recognized with M-L lead placement. In treadmill exercise ECG, ST depression more than 1 mm in II, III, aVF lead was noted 14 out of 17 patients with no ischemic changes. The all ST-T changes showed "not-decrescendo" type in ST trendgram. We concluded that rigorous evaluation for electrical axis, the configuration of ST-T waves and the existence of myocardial ischemia in leads II, III, aVF was necessary on treadmill exercise ECG using M-L lead replacement.     

The occurrence of arrhythmias in hospitalized asthmatic patients.

Twenty-four hour continuous ECG monitoring was performed on 20 patients hospitalized for asthma to evaluate the occurrence of potentially dangerous arrhythmias. Most patients (19/20) had sinus tachycardia on admission; premature ventricular contractions (PVCs) were present in 4; 1 had angina associated with runs of increased sinus tachycardia. With improvement in PaO2 and FEV1, the heart rate decreased in 17 patients and fewer PVCs were present in 2. Arrhythmias were not a serious problem in the patients studied.     

42例老年冠心病临床与病理对比分析

对比分析42例老年冠心病的临床与病理资料。结果表明:心电图对心肌缺血的诊断符合率为79.0％,对心肌肥厚的诊断符合率为52.0％。其中31例血脂增高者以甘油三酯更明显。血脂水平与冠状动脉阻塞程度无关。伴有高血压组的心脏重量、左室后壁厚度明显高于非高血压组。多数病人的临床表现与冠脉关系密切,但也有冠脉几乎阻塞而缺乏临床症状者。8例170岁以上心肌梗塞患者的临床及病理特点为:冠脉受累支数多,冠脉阻塞以环形狭窄为主,多伴有斑块出血,可无心绞痛,易伴意识丧失,并发症较多,易发生猝死。