急性心肌梗塞早期溶栓后心电图ST段改变与预后

目的:探索急性心肌梗塞(AMI)早期溶栓治疗后,心电图抬高的ST段回降的幅度对临床预后的影响。方法: 描记88例AMI早期患者溶栓治疗后1 h、2 h、3 h、1 d、3 d等时段的心电图,根据有、无早期(溶栓后2 h)ST段的恢复分为三组:A组,ST段基本恢复至等电线,即回降的幅度≥90％;B组,ST段回降的幅度在50％～90％之间; C组,ST段回降的幅度不到50％。比较三组心肌酶、左心功能及住院病死率。结果:血清肌酸激酶(CK)峰值、左室射血分数(LVEF)及病死率,A组与B组、C组相比较有显著差异(P<0．05,或<0．01):A组CK峰值低、LVEF 高、预后好;C组则相反。结论:AMI早期溶栓后的心电图ST段变化,有助于对临床预后的评估。     

国产重组链激酶急性心肌梗塞溶栓治疗临床试验

观察国产重组链激酶（ｒ－ＳＫ）在急性心肌梗塞（ＡＭＩ）静脉溶栓治疗中的临床疗效和不良反应，对其安全性和疗效作出评价。试验分为随机单盲对照试验组，即ｒ－ＳＫ（上海医科大学研制）５１例，链激酶（ＳＫ，德国赫斯特药厂产品）５１例和ｒ－ＳＫ开放组７１例。所有病例均符合入选和不入选标准，予ｒ－ＳＫ或ＳＫ各１５０万Ｕ于６０分钟静脉注入，观察血管再通的临床指标，过敏反应及出血并发症等。在随机单盲对照试验组中，５１例ｒ－ＳＫ的血管再通率（８０．４％）与ＳＫ（７４．５％）相近。总的１２２例ｒ－ＳＫ患者的血管再通率为７７．１％。ｒ－ＳＫ的不良反应中，寒颤发生率为４．１％，低血压为５．７％，出血发生率为１６．４％，均表现为皮肤，胃肠道或泌尿道的轻微出血，一般不需处理自行消失。由于ｒ－ＳＫ静脉溶栓治疗血管再通率高，过敏反应及低血压的发生率低，程度轻，出血并发症少，认为国产ｒ－ＳＫ为一安全有效的溶栓剂。     

Plasma levels of neuropeptide Y i patients with current myocardial infarction

Neuropeptide Y (NPY) has been recently characterised as one of the strongest circulating vasoconstrictor peptides, its elevated level may cause coronary artery spasm and increase of peripheral vascular resistance. All this contributes to ischemic myocardial damage and decrease of regional and global left ventricular function. The aim of the study was the examination of NPY plasma levels in patients with acute myocardial infarction (AMI) after thrombolytic therapy with or without reperfusion. The survey was made in 82 patients with AMI after thrombolytic therapy: 40 of them without reperfusion and 42 with reperfusion. The control group consisted of 20 healthy persons. Plasma levels of NPY were measured before thrombolysis, then 1, 3 and 5 days after, using a radioimmunologic method. All patients were treated with aspirin, glyceryl trinitrate and thrombolytic therapy (TT) with alteplase (r-TPA). In patients with AMI, NPY plasma levels were normal before and 1 day after TT, and were significant elevated 3 days after TT 5 days after TT, plasma NPY levels were still high in patients without reperfusion, but they decreased in patients with reperfusion. There was significant negative correlation between NPY level and left ventricular ejection fraction measured 5 days after AMI. During 30-days follow up systolic dysfunction of left ventricle with ejection fraction under 40% occurred in 21 patients and in 11 of them clinical symptoms of heart failure were observed. Using the multivariable regression analysis we showed that NPY concentration over 60 pg/ml is the independent factor leading to left ventricle systolic dysfunction. The results of our study suggest the contribution of NPY to the left ventricular remodeling after AMI.     

静脉溶栓后选择性PCI对急性心肌梗死患者远期预后的影响

目的探讨静脉溶栓后选择性经皮冠状动脉介入治疗(PCI)对急性心肌梗死(AMI)患者远期预后的影响.方法AMI患者114例,60例仅接受静脉溶栓者为药物组,54例静脉溶栓后平均(9.1±2.4)d行PCI者为手术组,分别于溶栓后及PCI后3、6、12个月随访主要心脏不良事件(MACE)发生情况.随访复查超声心动图,计算左室的整体室壁运动指数和左室射血分数.结果两组住院期间无死亡及心绞痛复发,手术组血管造影和操作成功率均为100%,无操作相关心肌梗死、急诊冠脉搭桥术(CABG).随访期间死亡率、因不稳定型心绞痛或心绞痛复发再次入院者手术组均显著少于药物组(P＜0.05),手术组总的临床终点事件发生率明显低于药物组(P＜0.01).结论 AMI患者静脉溶栓后选择性PCI能改善其远期预后.     

Activation of the contact system and inflammation after thrombolytic therapy in patients with acute myocardial infarction

Thrombolytic therapy activates the contact system, and factor XII activation may activate the coagulation cascade and inflammation. It is not known whether an early inflammatory response is induced by thrombolytic therapy in patients with acute myocardial infarction (AMI). We prospectively measured the plasma levels of activated factor XII, cleaved kininogen, prothrombin fragment 1 + 2 (as indexes of the contact phase and coagulation activation), and interleukin-6 and C-reactive protein (CRP) (as indexes of inflammation) in 39 patients hospitalized for AMI within 12 hours of symptom onset: 26 receiving thrombolytic therapy and 13 heparin alone. Blood samples were collected at baseline and after 90 minutes and 24 hours. Patients undergoing thrombolysis had a significant early increase in activated factor XII (from 2.2 ng/ml at baseline to 4.7 ng/ml after 90 minutes; p = 0.0001), cleaved kininogen (from 26% to 37%; p = 0.001), and fragment 1 + 2 (from 1.4 to 2.1 nmol/L; p = 0.0001), whereas the 24-hour levels were similar to baseline levels. The levels of interleukin-6 significantly increased during the first 90 minutes (from 3.9 to 6.3 microg/ml; p = 0.001), and were even higher after 24 hours (11.9 ng/ml, p = 0.0001). CRP levels increased only after 24 hours (p = 0.0001). There were no changes in these parameters in patients receiving heparin alone, except for a 24-hour increase in interleukin-6 and CRP levels. Thus, in patients with AMI receiving thrombolytic therapy, early activation of inflammation parallels the activation of the contact system and the coagulation cascade, which might contribute to microvascular obstruction and reperfusion injury.     

Levels of tumor necrosis factor (TNF-alpha) and interleukin 6 (IL-6) in serum of patients with acute myocardial infarction

In acute myocardial infarction may increase the synthesis of cytokines, which can enlarge the myocardial lesion owing to their direct toxic action on myocytes or induction of inflammatory changes that lead to myocardiofibrosis. All this may quickening the appearance of congestive heart failure after myocardial infarction. The aim of the study was examination of tumor necrosis factor (TNF-alpha) and interleukin 6 (IL-6) plasma levels in patients with acute myocardial infarction and analysis of correlation between concentrations of these cytokines and myocardial lesions during infarction. The study was made in 94 patients admitted to the Department of Cardiology with acute myocardial infarction (AMI). Of these, 40 were women aged from 41 to 85 (mean 67 years) and 54 were men aged from 39 to 86 (mean 63 years). Anterior AMI was diagnosed in 40 patients, inferior AMI was diagnosed in 54 patients. 63 patients underwent the thrombolytic therapy, reperfusion appeared in 45 patients, 24 patients were excluded from the thrombolytic therapy. Control group consisted of 28 healthy persons aged from 35 to 76 (mean 61 years). Blood samples for determination of TNF-alpha and IL-6 plasma levels were taken just after admission prior to the treatment. Then patients were taken streptokinase or tissue-type plasminogen activator with typical doses. Blood samples for determination of cytokines were obtained in 3. and 7. day after treatment. TNF-alpha and IL-6 plasma levels were determined with radioimmunological assay. Creatine kinase activity were monitored in patients with AMI as well as ejection fraction was checked in echocardiography in 3. and 7. day after treatment. We showed increased plasma levels of TNF-alpha and IL-6 in patients with AMI with maximum in 3. day of infarction. Concentrations of cytokines were higher in patients with anterior AMI than in patients with inferior AMI. In anterior infarction concentrations of cytokines were significantly lower after thrombolytic therapy with reperfusion than after treatment without reperfusion. There is a correlation between infarct size and concentrations of TNF-alpha and IL-6.     

急性心肌梗死静脉溶栓后补救介入治疗的临床疗效

目的探讨急性心肌梗死静脉溶栓后90min未通补救经皮冠状动脉内介入疗法的安全性和有效性。方法102例AMI患者分别行直接PCI术(38例)和64例接受rtPA(爱通力)或尿激酶静脉溶栓,限定自溶栓开始后90min内仍未再通者立即行补救性PCI,溶栓再通者则行择期冠状动脉造影,选择治疗方案。对以上两种方法的再通率、并发症、一个月后的左室射血分数等临床资料进行分析,对静脉溶栓和90min内补救PCI顺序疗法的安全性,有效性进行评价。结果直接PCI组再通率为94.7%(36/38),静脉溶栓 补救PCI组90min溶栓再通率为31.3%(20/64),补救PCI再通率为95.5%(42/44);直接PCI组2例于支架置入后出现无再流现象,补救PCI组1例出现无复流,静脉溶栓再通到择期介入治疗前无梗死相关血管(IRA)再闭塞;直接PCI组消化道出血1例,补救PCI组2例出现血尿。延迟PCI组1例出现脑出血后死亡。1个月后超声心动图检查结果:直接PCI组平均为58.2%,静脉溶栓未通 补救PCI组57.4%,溶栓再通 延迟PCI组为61.3%(P>0.05)。12h以内再通者LVEF为63.2%,12h以后再通者LVEF为51.3%(P<0.05).结论静脉溶栓失败后补救性PCI是合理有效安全的方法。     

Serum lipid peroxides and antioxidant defense components of rural and urban populations and aging

Serum lipid peroxides, antioxidant vitamins such as vitamin C, vitamin E and an antioxidant enzyme glutathione peroxidase activity were determined among urban (175M + 139F) and rural (135M + 87F) inhabitants, with an age range of 40–78 years. Serum lipid peroxide (LPO) levels showed no significant difference in the 40–49 and 50–59 age groups between rural and urban populations; however, these levels were elevated in the >60 age group in urban individuals. The main mechanism of cellular defense against free radical-mediated oxidative stress effectively functioned until the concentration of LPO reached a level of 4.0 nmol/ml, in both groups; further increase in LPO resulted in a depletion of antioxidants. The percentage of individuals possessing >4.0 nmol/ml of LPO with age was increased in the urban population as compared to the rural population. These data indicate that an impairment of the antioxidant system would render older individuals in urban settings more susceptible to peroxidative stress.     

A pilot study of streptokinase-induced endothelial injury and platelet activation following acute myocardial infarction

OBJECTIVE: To relate the changes in serum vitamin E, an essential antioxidant, to changes in fibrinogen, as well as indices of endothelial damage [as indicated by plasma markers, soluble thrombomodulin (sTM) and von Willebrand factor (vWf), and an index of platelet activation (soluble P selectin (sPsel)], in myocardial infarction treated with thrombolytic therapy. DESIGN AND SETTING: Prospective longitudinal pilot study in a teaching hospital Coronary Care Unit. SUBJECTS AND INTERVENTION: Seventeen patients (12 men: mean age (62 years +/- SD 11 years) admitted with acute myocardial infarction (AMI), who were given thrombolytic therapy, and 59 healthy controls. RESULTS: Baseline levels of fibrinogen (Mann-Whitney test, P = 0.0055) and vWf (P < 0.001) were significantly higher than controls, but sPsel, sTM or vitamin E levels were not significantly different. Following thrombolysis, as expected, median concentrations of plasma fibrinogen fell profoundly (Friedman ANOVA P < 0.001) so that after 45 min, levels were undetectable in 13 patients. At 24-h median fibrinogen concentration had recovered to approximately 30% of baseline (P < 0.01) and was still undetectable in three patients. Levels of vWf and sPsel increased steadily, reaching significance after three hours (both P < 0.05). However, levels of sTM rose immediately after thrombolysis, peaking between 1 and 3 h, and remained elevated at 24 h. These increases corresponded to a simultaneous early fall in serum vitamin E concentrations. CONCLUSION: The present pilot study demonstrates significant endothelial damage and platelet activation in association with increased oxidative stress following streptokinase therapy for AMI.     

急性心肌梗死冠状动脉再通后ST段回落缓慢的意义

５４例急性心肌梗死患者溶栓或经皮冠状动脉腔内成形术后梗死相关冠状动脉再通，９０分钟时ＳＴ段上移总和回落，≥５０％为乙组。与乙组比较，甲组溶栓距发病时间及肌酸激酶峰值距发病时间延长。住院期间心脏事件发生率甲组显著高于乙组，而且出院前超声心动图检查显示，甲组收缩末期容量较乙组增大，射血分数减低。     

Changes in plasma vitamin levels in the first 48 hours after onset of acute myocardial infarction

To establish whether plasma vitamin measurements made after acute myocardial infarction (AMI) can be used in case-control studies of coronary artery disease, the short-term effect of AMI on plasma concentrations of 25-hydroxyvitamin D3, beta-carotene, vitamin E and retinol was investigated. Sequential measures of these vitamins were made during the first 48 hours after AMI in 13 patients admitted to the hospital within 4 hours after the onset of symptoms. Plasma levels of 25-hydroxyvitamin D did not change significantly during the first 12 hours after onset of symptoms. Beta-carotene levels increased significantly (p less than 0.05) during the first 12 hours and then decreased, whereas levels of vitamin E and retinol progressively decreased during the first 48 hours by 26 and 25%, respectively. These results suggest that, of these vitamins, only plasma measurements of 25-hydroxyvitamin D3 collected within 12 hours of onset of symptoms may provide reliable information for case-control studies of AMI.     

Depletion of antioxidants is associated with no-reflow phenomenon in acute myocardial infarction

BACKGROUND: No-reflow phenomenon is observed in approximately one-third of patients after percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI), and is associated with poor functional and clinical outcomes. On the other hand, the formation of free radicals in vasculature exerts deleterious effects on coronary microcirculation. HYPOTHESIS: We hypothesized that redox state in coronary circulation may play a crucial role in no-reflow phenomenon in AMI. METHODS: Consecutive 26 patients with first AMI who underwent primary PCI < 24 h after onset were enrolled. Before PCI, blood samples were obtained from coronary sinus to measure plasma or serum antioxidative vitamins (vitamin C, vitamin E, and beta-carotene) and antioxidative enzymes (extracellular glutathione peroxidase [GPX], superoxide dismutase, and catalase). After PCI, the corrected Thrombolysis In Myocardial Infarction (TIMI) frame count (CTFC) was measured in the target vessel. Patients with TIMI < or = 2 flow despite an optimal PCI result were designated as no-reflow group (Group NR, n = 6) and the others as reflow group (Group R, n = 20). RESULTS: Levels of vitamin C, vitamin E, and GPX before PCI were significantly lower in Group NR than in Group R. The CTFC correlated inversely with levels of vitamin C, vitamin E, and GPX (p < 0.05). CONCLUSIONS: Depletion of antioxidants is associated with no-reflow phenomenon in AMI. These findings strongly suggest that the redox state in coronary circulation plays an important role in the pathogenesis of no-reflow phenomenon.     

急性心肌梗死早期溶栓治疗对QT离散度及恶性室性心律失常的影响

研究急性心肌梗死（ＡＭＩ）后溶栓治疗对ＱＴ离散度（ＱＴｄ）及恶性室性心律失常（ＭＶＡ）事件的影响。回顾性选择分析ＡＭＩ患者７５例（溶栓治疗组４３例、未溶栓组３２例）,通过测量入院时及入院后２４ｈ常规心电图计算ＱＴｄ、校正ＱＴｃ（ＱＴｃｄ）,并在入院后一周内心电监护观察ＭＶＡ事件发生情况。溶栓再通组ＱＴｄ、ＱＴｃｄ较溶栓前显著缩短（４２．６±１４．３ｍｓｖｓ７１．７±１６．９ｍｓ,４５．９±１７．４ｍｓｖｓ７４．８±１８．５ｍｓ,Ｐ均＜０．０１）;溶栓未通组、未溶栓组入院２４ｈ期间ＱＴｄ、ＱＴｃｄ无明显变化（Ｐ＞０．０５）。ＱＴｄ、ＱＴｃｄ≥９０ｍｓ者ＭＶＡ事件明显高于＜９０ｍｓ者（７０．６％ｖｓ１０．２％,Ｐ＜０．０１）,溶栓再通组ＭＶＡ事件与溶栓未通组比较趋于减少（１１％ｖｓ２８％）。结论：ＡＭＩ后成功的溶栓治疗可以缩短心室复极的ＱＴｄ,从而可能减少ＡＭＩ后早期ＭＶＡ的发生;无效的溶栓治疗对ＡＭＩ近期预后无任何影响。     

Early coronary intervention following pharmacologic therapy for acute myocardial infarction (the combined TIMI 10B-TIMI 14 experience).

Earlier studies have suggested that immediate percutaneous coronary intervention (PCI) following thrombolytic therapy for acute myocardial infarction (AMI) is associated with an increase in adverse events and that routine PCI in this setting has offered no advantage over a conservative strategy. To reassess this issue in a more recent era, we evaluated 1,938 patients from the Thrombolysis in Myocardial Infarction (TIMI) 10B and 14 trials of AMI. Patients in TIMI 10B were randomized to receive tissue plasminogen activator or TNK tissue plasminogen activator, whereas patients in TIMI 14B trial were randomized to receive thrombolytic therapy with or without abciximab. All patients underwent angiography 90 minutes after receiving pharmacologic therapy. Patients who underwent PCI were classified as having undergone a rescue procedure (TIMI 0 or 1 flow at 90 minutes), an adjunctive procedure (TIMI 2 or 3 flow at 90 minutes), or a delayed procedure (performed >150 minutes after symptom onset, median of 2.75 days). Among patients with TIMI 0 or 1 flow, there was a trend for lower 30-day mortality among patients who underwent rescue PCI than among those who did not (6% vs 17%, p = 0.01, adjusted p = 0.28). Patients who underwent adjunctive PCI had similar 30-day mortality and/or reinfarction as those who underwent delayed PCI. In a multivariate model both had lower 30-day mortality and/or reinfarction than patients with "successful thrombolysis" (i.e., TIMI 3 flow at 90 minutes) who did not undergo revascularization (p = 0.02). Thus, early PCI following AMI is associated with excellent outcomes. Randomized trials of an early invasive strategy following thrombolysis are warranted.     

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。     

急性心肌梗死患者溶栓后血浆中脑钠素浓度变化的研究

目的研究血中脑钠素(BNP)水平与急性心肌梗死溶栓后左心室射血分数(LVEF)和心肌缺血程度的关系。方法将198例顺序入选的急性心肌梗死行链激酶静脉溶栓治疗的患者分为溶栓成功组(105例)和溶栓未成功组(93例),检测所有患者的血BNP水平及测定LVEF,比较溶栓成功组与溶栓未成功组LVEF>40%和LVEF≤40%的BNP水平。结果溶栓成功组BNP水平明显低于溶栓未成功组的BNP水平(725.4±169.8)ng/L(P<0.05),溶栓成功组和未成功组中LVEF>40%患者的BNP水平[(107.7±46.5)ng/L,(488.5±88.9)ng/L]明显低于LVEF≤40%患者的BNP水平[(515.5±121.2)ng/L,(856.7±129.5)ng/L,P<0.01]。结论急性心肌梗死患者血中BNP水平与LVEF和心肌缺血程度有关。     

急性心肌梗塞溶栓治疗期间血浆D-二聚体的动态变化及其临床意义

目的 :探讨血浆 D-二聚体对评价溶栓治疗急性心肌梗塞 (AMI)的价值及意义。　　方法 :2 9例 AMI患者分为溶栓组 (n=2 1) ,未溶栓组 (n=8) ;溶栓组根据溶栓治疗后冠状动脉 (冠脉 )是否开通又分为溶栓再通组 (n=12 ) ,溶栓未通组 (n=9) ;采用酶联免疫吸附试验 (EL ISA)法检测血浆 D-二聚体的水平 ,并与正常对照组 (n=2 0 )进行比较。　　结果 :AMI未溶栓组血浆 D-二聚体较正常对照组显著升高 (P<0 .0 5 ) ;溶栓组血浆 D-二聚体较未溶栓组显著升高(P<0 .0 5 ) ,溶栓后血浆 D-二聚体较溶栓前显著升高 (P<0 .0 1) ,于溶栓后 6小时达高峰 ;溶栓再通组血浆 D-二聚体较溶栓未通组显著升高 ,溶栓前及溶栓后 6小时两组比较有极显著统计学意义 (P<0 .0 1)。　　结论 :AMI早期已有纤溶系统亢进 ,应用溶栓药后进一步激活纤溶系统而发挥作用 ,且以溶栓再通组更显著。     

Primary percutaneous transluminal coronary angioplasty accelerates early myocardial reperfusion compared to thrombolytic therapy in patients with acute myocardial infarction

Background

Successful early reperfusion of the infarcted myocardium as indicated by complete resolution of ST-segment elevations has been shown to be associated with an improved outcome in patients with acute ST-elevation myocardial infarction (AMI). The aim of this study was to compare early ST resolution in patients treated with primary percutaneous transluminal coronary angioplasty (PTCA) or thrombolytic therapy for AMI.

Methods

A total of 1379 patients with AMI whose symptoms began <6 hours previously were enrolled in the Evaluation of the Safety and Cardioprotective effects of eniporide in Acute Myocardial Infarction (ESCAMI) trial and treated with primary PTCA (n = 528) or thrombolytic therapy (n = 851). Twelve-lead electrocardiograms (ECG) were obtained at baseline, directly after PTCA and at 90 minutes after the initiation of thrombolytic therapy.

Results

There were no differences with respect to clinical or ECG baseline variables between the 2 groups. The time intervals between hospital admission and ECG 2 (obtained 0-30 min after PTCA and 90 min after start of thrombolysis) were 121 ± 62 minutes in the PTCA group and 137 ± 57 minutes in the thrombolysis group, respectively. In ECG 2, complete (≥70%) ST resolution was observed more often in the PTCA treated patients (35 vs 27%, P = .003). The incidence of congestive heart failure until 6 weeks was lower in the PTCA group (11.2% vs 17.6, P = .001). Mortality after 6 weeks (3.4% vs 5.6%, P = .07) and after 6 months (4.5% vs 7.1%, P = .06) tended to be lower in the PTCA group.

Conclusion

Primary PTCA compared to thrombolytic therapy is associated with an accelerated myocardial reperfusion within 90 minutes after the start of reperfusion therapy. This early advantage in myocardial reperfusion is associated with an improved clinical outcome.     

Detection, characterization and functional assessment of reperfused Q-wave acute myocardial infarction by cine magnetic resonance imaging

The capability of dynamic gradient-refocused magnetic resonance imaging (cine MRI) to detect, localize and functionally assess acute myocardial infarction (AMI) in 25 patients at a mean time interval of 7 days after AMI was evaluated. Fifteen asymptomatic volunteers were also examined to determine the specificity of the observations. Upon presentation, each patient received intravenous thrombolytic therapy, underwent immediate cardiac catheterization and had percutaneous transluminal coronary angioplasty performed when coronary reperfusion was absent. Twenty-four of the patients had documented coronary reperfusion at a mean interval of 259 +/- 129 minutes. Global ejection fraction and regional wall motion abnormalities were evaluated at 7 days by cine MRI, left ventriculography and radionuclide angiography. Twenty patients with both an absolute decrease in myocardial signal and a matched regional wall motion abnormality had AMI properly identified by cine MRI. In contrast, the finding of both decreased signal intensity and a matched regional wall motion abnormality was absent in the group of asymptomatic volunteers. The ejection fraction by cine MRI correlated better with the ejection fraction by left ventriculography (r = 0.94, standard error of the estimate = 3.6) than did the ejection fraction by radionuclide angiography (r = 0.82, standard error of the estimate = 5.8). The regional wall motion concordance rate in comparison to left ventriculography was similar for both cine MRI (69%) and radionuclide angiography (65%). These findings suggest that cine MRI may play an important role in the future detection and functional characterization of AMI.     

Do antioxidant vitamins reduce infarct size following acute myocardial ischemia/reperfusion?

Summary There is controversy concerning the ability of antioxidant vitamins to reduce myocardial infarct size. We sought to determine whether a brief prophylactic treatment of vitamin C or vitamin C plus Trolox (a water-soluble form of vitamin E) could reduce myocardial infarct size in an experimental model. We used an anesthetized open-chest rabbit model in which a branch of the circumflex coronary artery was ligated for 30 minutes followed by 4 hours of reperfusion. Experiments were performed in a randomized and blinded fashion. An IV injection of normal saline pH balanced to 7.4 (control group n=15), vitamin C (150 mg/kg, n=14), or vitamin C plus Trolox (150 mg/kg plus 100 mg/kg, respectively, n=15) was administered prior to coronary occlusion. Collateral blood flow during coronary occlusion was measured by radioactive microspheres, myocardial risk zone (AR) was assessed by blue dye injection, and myocardial infarct size (AN) was assessed by triphenyltetrazolium chloride staining. All rabbits received comparable ischemic insult: Collateral blood flow and AR were similar among all three groups. Infarct size, measured as a percent of AR, did not differ significantly among the controls (21%), vitamin C (29%), or the vitamin C plus Trolox (18%) groups. Therefore, in this ischemia/reperfusion model, antioxidant vitamins did not alter myocardial infarct size.