Emergency coronary artery bypass surgery after intracoronary thrombolysis for evolving myocardial infarction

Sixteen patients underwent emergency coronary artery bypass surgery immediately after intracoronary streptokinase infusion for acute evolving myocardial infarction. Of these, 11 patients had 70% residual stenosis in the recanalised vessel, and in five thrombolysis was unsuccessful. There were no hospital deaths. All the patients sustained myocardial necrosis, the peak activity of creatine phosphokinase correlating with the time to reperfusion. Chest tube drainage (mean 960 ml) was significantly higher than for control patients but did not correlate with the total dosage of streptokinase. No patients had further myocardial infarction or developed recurrent angina. Selected patients may benefit from coronary bypass surgery after intracoronary streptokinase infusion. If necessary this may be performed immediately with low mortality and morbidity.     

Role of coronary artery bypass surgery after intracoronary streptokinase infusion for myocardial infarction

Intracoronary streptokinase infusion has been shown to improve left ventricular function and reduce hospital mortality in patients with acute myocardial infarction. Adjuvant coronary artery bypass surgery is of value in many of these patients who have recurrent angina, circulatory instability, severe coronary artery occlusive disease, or a high risk of reinfarction. There is little, if any, evidence that immediate coronary artery bypass surgery affects the results adversely—either because of recent myocardial infarction or recent streptokinase infusion, and early operation appears to be a safe and worthwhile modality of treatment in this group of patients with myocardial infarction.     

冠状动脉搭桥围术期急性心肌梗死紧急再搭桥

目的：回顾性分析冠状动脉搭桥围术期急性心肌梗死急诊再搭桥的临床经验。方法：在510例冠状动脉搭桥患中，5例患在术后4h内因急性心肌梗死需急诊再搭桥，发生率0．98％。5例患中，男女比例为4：1，年龄56－77岁（平均63．6岁），均为冠状动脉三支血管病变（3例伴左主干病变），手术中搭桥3－5支（人均搭桥3．6支），左乳内动脉桥5根，其余为大隐静脉桥。2例在关胸后20min，3例在回重症监护病房后2－4h出现急性心肌缺血表现（明显心电图ST－T变化），伴室颤2例，5例血液动力学均不稳定，药物处理难以稳定血液动力学。全部患均立即送手术室（2例仍在手术室），急诊再次开胸。探查发现，2例患静脉桥（分别搭桥到回旋支第二钝缘支和右冠状动脉后降支）内急性血栓形成；另3例所有静脉桥良好，但左室前壁收缩运动明显减弱，结合心电图变化，诊断为左乳内动脉灌注不良。重新建立体外循环，清除桥内血栓重新搭桥2例（1例在非体外循环心脏跳动下进行）；另取一段静脉搭桥到左乳内动脉－左前降支吻合口远端的左前降支3例。结果：5例患顺利度过手术，均置入主动脉内球囊反搏，支持22－25h（平均42h）。手术后呼吸机支持4h－18d（平均7．3d）合并消化道出血4例，肾功能不全2例，肺部感染2例，切口感染1例。手术后住院时间12－35d，平均21d。全组均痊愈出院。结论：冠状动脉搭桥围术期急性心肌梗死应重在预防。如怀疑桥有问题，急诊再搭桥是良好选择，但手术后并发症发生率明显增加。     

Serial myocardial lactate metabolic changes after intracoronary thrombolysis in evolving myocardial infarction

To investigate whether early reperfusion (less than or equal to 3 hours) preserves aerobic myocardial metabolism in acute myocardial infarction, we examined serial changes in trans-cardiac lactate extraction after thrombolysis in 43 patients with acute antero-septal myocardial infarction. In the chronic phase, we also determined abnormally contracting segments as an index of infarct size and regional ejection fraction as an index of chronic regional cardiac function. In the early reperfusion group (less than or equal to 3 hours), positive lactate extraction was restored and there were small abnormally contracting segments and a high regional ejection fraction. The intermediate reperfusion group (3-5 hours), however, had sustained anaerobic lactate extraction, large abnormally contracting segments and a low regional ejection fraction. The late reperfusion (greater than 5 hours) group showed apparently aerobic lactate extraction, but had large abnormally contracting segments and a low regional ejection fraction. Thus, early reperfusion preserves aerobic lactate metabolism and good chronic ventricular function.     

Serial myocardial lactate metabolic changes after intracoronary thrombolysis in evolving myocardial infarction

To ascertain whether early intracoronary reperfusion (less than 3 hours) preserves aerobic myocardial metabolism in acute myocardial infarction, serial changes in trans-cardiac lactate extraction after intracoronary thrombolysis were examined in 35 patients with acute anteroseptal myocardial infarction. Eight patients without intracoronary reperfusion served as controls. In the chronic phase, we also observed abnormally contracting myocardial segments as an index of infarct size and the regional ejection fraction as an index of chronic regional cardiac function. In the early reperfusion group (less than 3 hours; 15 cases), positive lactate extraction was restored; there were small abnormally-contracting segments and a high regional ejection fraction. However, the intermediate reperfusion group (3-5 hours; 10 cases) had sustained anaerobic lactate extraction, large abnormally-contracting segments and a low regional ejection fraction. The late reperfusion (greater than 5 hours; 10 cases) group showed apparent aerobic lactate extraction, but had large abnormally-contracting segments and a low regional ejection fraction. Thus, early reperfusion preserves aerobic lactate metabolism and good ventricular function in the chronic phase.     

Quantification of peri-operative myocardial infarction after coronary artery bypass surgery.

Dear Editor, In a recent study in the Journal, Steuer and colleagues¹ reportthat elevated biochemical markers after on-pump CABG correspondto the amount of peri-operatively infarcted myocardium as measuredby delayed-enhancement cardiac MRI (DE-MRI). They found that18 out of 23 (78%)     

Mortality in patients undergoing coronary artery bypass surgery after myocardial infarction

Data on 1,700 patients who underwent coronary artery bypass surgery without additional cardiovascular procedures at the Texas Heart Institute were analyzed, relating the interval between myocardial infarction and operation to early mortality (within 30 days after operation). Patients who underwent coronary artery bypass surgery after a recent infarction (within 2 months before operation) had a higher rate of early mortality (14.5 percent) than patients who had an old infarction (6.9 percent) or no previous infarction (4.1 percent). The interval between recent infarction and operation was most significant. Mortality in patients who underwent operation within the first 7 days after acute infarction (38.1 percent) was more than six times greater than in patients who were operated on 31 to 60 days after infarction (5.8 percent). Mortality of those operated on 8 to 30 days after infarction was 16.4 percent. Elective coronary artery bypass surgery after recent infarction is best accomplished after the first 30 days, when there is no increased risk to the patient. Emergency coronary artery bypass after complicated acute myocardial infarction may be a lifesaving procedure, but it is associated with increased early mortality and should be reserved for those whose condition has not responded to aggressive medical therapy.     

Angina preceding myocardial infarction and residual coronary narrowing after intracoronary thrombolysis

Thirty-six consecutive patients with evolving acute myocardial infarction underwent emergent coronary angiography and intracoronary thrombolysis with urokinase. Nineteen of the patients had had angina before the infarction (group A), whereas the infarction was unheralded in the remaining 17 (group B). Thirty-two vessels (88%) were patent at follow-up angiography performed after 3 to 4 weeks, and the residual stenosis was 87% +/- 14% in group A and 47% +/- 25% in group B (p less than 0.001). Coronary spasm was provoked by ergonovine maleate in four of 12 patients in group A (33%) and in three patients in group B (18%). Coronary revascularization was undertaken in nine patients in group A and three in group B. These results indicate that patients with angina preceding acute myocardial infarction are more likely to have significant stenosis even at the late follow-up stage and to have a more urgent need for subsequent coronary revascularization. It also seems apparent that thromboembolism in most patients and coronary spasm in a few patients without significant coronary narrowing play significant causal roles in the onset of acute myocardial infarction.     

Percutaneous transluminal coronary angioplasty after intracoronary streptokinase in evolving acute myocardial infarction

To achieve optimal myocardial revascularization and prevent rethrombosis of the infarct-related coronary artery, percutaneous transluminal coronary angioplasty (PTCA) was attempted in 18 patients with evolving acute myocardial infarction (9 anterior and 9 inferior) after administration of intracoronary streptokinase. PTCA was attempted 338 +/- 151 minutes after the onset of symptoms. After thrombolytic therapy, 11 patients had a severe residual stenosis and 7 a persistent total occlusion of the infarct-related coronary artery. PTCA was successful in 13 of 18 patients: in 9 of 11 with coronary stenoses and in 4 of 7 with total coronary occlusions. PTCA reduced the severity of the coronary lesion from 91 +/- 2% to 27 +/- 7% (p less than 0.001), and the transstenotic pressure gradient from 38 +/- 5 to 6 +/- 2 mm Hg (p less than 0.01). One patient in cardiogenic shock died during urgent coronary surgery after unsuccessful PTCA. After PTCA, all patients received heparin and antiplatelet agents. One patient had reinfarction with reocclusion of the infarct-related artery 5 days after PTCA. The other 12 patients had an uneventful hospital course, and cardiac catheterization before hospital discharge (8 to 17 days) revealed reocclusion of the infarct-related coronary artery in 3 and persistent patency in 9. Persistent patency of the infarct-related artery was associated with preservation of left ventricular end-diastolic volume (initial 86 +/- 6 ml/m2, follow-up 91 +/- 6 ml/m2), and improvement in left ventricular ejection fraction in some patients.     

Cardiac troponin I in perioperative myocardial infarction after coronary artery bypass surgery

BACKGROUND AND AIMS: Myocardial infarction after coronary artery bypass grafting is a serious complication and one of the most common causes of perioperative morbidity and mortality. The present study was designed to determine the relevance of serum cardiac troponin I as a specific diagnostic marker for perioperative myocardial infarction. METHODS: A cohort of 64 patients undergoing coronary artery bypass grafting was enrolled for prospective study. Postoperative blood samples were extracted and analyzed for total creatine kinase (CK), CKMB and cardiac troponin I activity. Perioperative infarction was defined as the development of new Q waves in the postoperative electrocardiogram together with congruent regional wall motion abnormalities in the echocardiogram and CK values greater than 400 IU/l with MB fraction greater than 40 IU/l. RESULTS: Perioperative infarction occurred in 12 patients. Higher cardiac troponin I values were observed in patients experiencing perioperative myocardial infarction than in those without infarction (p < 0.001). Cardiac troponin I values higher than 12 ng/ml 10 h after release of the aortic clamp best detected the presence of perioperative myocardial infarction, with an area under the characteristic receiver operating curve of 0.91 (95% CI, 0.82-0.97), a sensitivity of 90.9%, and a specificity of 88.5%.The mean stay in the intensive care unit was significantly longer for patients who suffered perioperative myocardial infarction (6.5 8.6 days) than for patients without perioperative infarction (4.7 7.5 days) (p < 0.005). CONCLUSIONS: Cardiac troponin I elevation appears to be an early, specific marker for the diagnosis of perioperative myocardial infarction after coronary artery bypass grafting.     

Late thrombolysis with intracoronary streptokinase after myocardial infarction

This patient had a myocardial infarction 4 years after coronary bypass grafting. Catheterization 1 month later revealed occlusion of the graft to the posterior descending by what appeared to be a clot. On each of 3 successive days, infusion of streptokinase accomplished recanalization of the graft. After the third treatment, he showed marked symptomatic improvement. Recanalization may be successful as late as 1 month after occlusion and repeated infusions of streptokinase over a period of days can be carried out safely and without loss of effectiveness.     

Risk factors for myocardial infarction during coronary artery bypass graft surgery

Patients with a particular thrombotic profile may be at greaterrisk of myocardial infarction during coronary artery bypassgraft surgery. The thrombotic profile of 50 patients admitted to hospital withstable angina pectoris was determined prior to haemodynamicinvestigation. ECG results and determination of cardiac enzymesshowed that 12 patients had suffered a perioperative myocardialinfarction. These patients had a higher mean atheroscleroticscore (42.1 ± 10.5 vs 32.9 ± 13, P<0.02), alonger aortic cross clamp time (59 ± 15.2 vs 45.7 ±16.3 min, P < 0.05), lower serum levels of protein C (101.2±26vs 124.7+ 31.4%, P<0.05) and tissue plasminogen activator(322 ± 580 vs 2307±2830 IU ml^–1, P<0.01). There were no differences between the two groups in Jenkin'scoronary score, the number and type of grafts, ejection fraction,left ventricular end-diastolic pressure, lipid profile or levelsof markers of platelet release. In addition to a more severe distal coronary atheroma and alonger aortic cross-clamp time, patients with impaired endothelialfibrinolytic activity appeared to be at greater risk of myocardialinfarction during coronary artery bypass graft surgery.     

Electrocardiographic and serum enzyme changes of myocardial infarction after coronary artery bypass surgery

Serial preoperative and postoperative electrocardiograms were obtained in 50 patients undergoing coronary artery bypass surgery, 15 undergoing aortic valve replacement and 13 undergoing mitral valve surgery. Postoperative infarction was defined as the appearance of new Q waves on the postoperative electrocardiogram. Infarction occurred in 5 of 50 patients (10 percent) who underwent coronary artery bypass surgery. Age, preoperative hypertension or a pattern of left ventricular hypertrophy on the electrocardiogram did not correlate with infarction. Coronary disease was more severe in patients with than in those without infarction (mean of 3.2 vessels with 50 percent stenosis compared to 2.4 vessels). There was no correlation with bypass time or use of cross-clamping of the aorta during surgery. Postoperatively, 4 of 5 patients (80 percent) with infarction had serum values for glutamic oxaloacetic transaminase (SGOT) and creatine phosphokinase (CPK) of more than 200 and more than 2,000 international units, respectively, whereas 3 of 45 (7 percent) without infarction had this pattern (P < 0.001).Of patients undergoing aortic valve replacement, 3 of 15 (20 percent) had postoperative infarction. All 3 of these patients had a serum glutamic oxaloacetic transaminase value of more than 200 and a creatine phosphokinase value of more than 2,000 units, compared to 2 of 12 (17 percent) without infarction. None of the 12 patients who underwent mitral valve surgery had postoperative infarction, and none had a serum glutamic oxaloacetic transaminase value of more than 200 or a creatine phosphokinase value of more than 2,000 units.Myocardial infarction after coronary artery bypass surgery is more likely in patients with at least three-vessel disease but appears to be unrelated to pump time or aortic cross-clamping. Localized snaring or clamping of coronary arteries may be important. Postoperative serum glutamic oxaloacetic transaminase and creatine phosphokinase levels correlate with electrocardiographic evidence of infarction.     

Long-term prognosis after myocardial infarction in patients with previous coronary artery bypass surgery

A group of 205 patients hospitalized with myocardial infarction 2 to 162 months (mean 66) after bypass surgery and 205 control patients with myocardial infarction were compared and followed up for 34 +/- 25 months after hospital discharge. At baseline the postbypass group contained more men (p less than 0.03) and more patients with previous myocardial infarction (p less than 0.06), but the groups were otherwise comparable. Indexes of infarct size were lower in postbypass patients: sum of ST elevation, QRS score, peak serum creatine kinase (CK) (1,115 +/- 994 versus 1,780 +/- 1,647 IU/liter) and peak MB CK (all p less than or equal to 0.001). Postmyocardial infarction ejection fraction was 45 +/- 15% in the postbypass group and 43 +/- 15% in the control group (p = NS); in-hospital mortality rate was 4 and 5%, respectively (p = NS). When patent grafts were taken into account, the two groups were comparable in extent of coronary artery disease. At 5 years after discharge, cumulative mortality was similar in the postbypass and control groups (30 versus 25%, respectively, p = NS). However, postbypass patients had more reinfarctions (40 versus 23%, p = 0.007), more admissions for unstable angina (23 versus 18%, p = 0.04) and more revascularization procedures (34 versus 20%, p = 0.04) than did control patients. The total for these events at 5 years was 70% in the postbypass group and 49% in the control group (p = 0.001). Thus, although patients with previous bypass surgery who develop acute myocardial infarction have a smaller infarct, their subsequent survival is no better than that of other patients with acute myocardial infarction. They experience more reinfarctions and unstable angina. Previous bypass surgery is an important clinical marker for recurrent cardiac events after myocardial infarction.     

急性心肌梗死急诊冠脉溶栓后行冠脉搭桥术12例分析

目的探讨部分急性心肌梗死（AMI）急诊不适合行PC]的患者行急诊冠脉溶栓术后再行急诊或择期冠脉搭桥术的效果。方法回顾分析12例AMI急诊冠脉溶栓后行急诊或择期冠脉搭桥术患者的临床资料。结果12例中梗死相关血管再通并达到TIMIⅡ～Ⅲ级血流10例,TIMIⅢ级血流9例,TIMIⅡ级血流1例。2例应用血栓抽吸装置抽吸血栓后达到TIMIⅢ级血流。2例行急诊冠脉搭桥术,10例行择期冠脉搭桥术。结论对于部分急诊不适合行PCI术的AMI患者,先行急诊冠脉溶栓术,然后根据病情及冠脉病变特点行急诊或择期冠脉搭桥术,是一种比较好的临床治疗方法。     

Significance of silent myocardial ischemia after coronary artery bypass surgery.

The prevalence and prognostic significance of transient myocardial ischemia after coronary artery bypass grafting (CABG) were evaluated. In 3 studies, ischemia was found in an average of 24% of patients by ambulatory electrocardiographic monitoring at 3-12 months after CABG. An average of 36% of patients in 3 other studies experienced ischemic ST-segment depression during exercise testing at 4-50 months after CABG. Of the ischemic episodes, 77% were silent during exercise testing. In the Coronary Artery Surgery Study (CASS) randomized patient subsets, survival at 12 years was significantly lower for patients who had either silent or symptomatic ischemia during exercise testing at 6 months after CABG compared with those who had no ischemia.     

Perioperative myocardial infarction after coronary artery bypass surgery. Clinical significance and approach to risk stratification

The clinical significance of perioperative myocardial infarction (MI) after coronary artery bypass surgery is not known. Therefore, strategies for the risk stratification of these patients do not exist. This study was undertaken to define the effect of perioperative MI on prognosis after discharge from the hospital and to develop an approach to the risk stratification of these patients. Fifty-nine patients with and 115 patients without perioperative MI were observed for 30 months for the development of cardiac events (death, nonfatal MI, and admission to hospital for unstable angina or congestive heart failure). Patients with perioperative MI were significantly more likely than patients without to have a cardiac event (31% versus 12%, p less than 0.01) and multiple events (19% versus 1%, p less than 0.001). Cox regression analysis identified two independent predictors of cardiac events other than perioperative MI (relative risk, 2.7): inadequate revascularization (relative risk, 3.5) and depressed (less than 40%) postoperative ejection fraction (EF) (relative risk, 2.1). Event-free survival rate of patients with perioperative MI varied markedly depending on the number of other negative prognostic variables present. Patients with perioperative MI who were adequately revascularized and had a postoperative EF greater than 40% had an event-free survival rate similar to patients without a perioperative MI (92% versus 87%, p = NS). Patients with perioperative MI who were inadequately revascularized and had depressed postoperative EF had an event-free survival rate of 13% (p less than 0.001 versus all other subsets). Event-free survival rate was intermediate (68%) in patients with perioperative MI and with only one of the other two variables (p less than 0.001 versus other subsets). In conclusion, perioperative MI adversely affects prognosis. Patients can be stratified into low, high, and intermediate risk subsets based on a simple assessment of the adequacy of revascularization and a determination of residual left ventricular function.