Coronary perfusion during acute myocardial infarction with a combined therapy of coronary angioplasty and high-dose intravenous streptokinase

Intravenous thrombolytic treatment for acute myocardial infarction. Effects of early intervention and early examination

Intravenous thrombolytic treatment (streptokinase or anisoylated plasminogen streptokinase activator complex (APSAC) was given to 50 consecutive patients within 3 hours after onset of symptoms of acute myocardial infarction. Left heart catheterisation with coronary angiography and simultaneous double view left ventriculography were performed approximately 4 hours after start of thrombolytic treatment. This examination showed that the acute infarct-related coronary artery was open in 36 patients (72%) and closed in 14 patients (28%). A higher left ventricular ejection fraction was found among patients with open, than among patients with closed infarct-related artery (58.8% vs. 48.4%, p = 0.05). The group with open artery also had a lower score of regional left ventricular dysfunction (1.7 vs. 2.4, p less than 0.05, on a scale from 0-3). Single, double and triple vessel coronary heart disease was found in 22, 14 and 13 patients respectively. Mean age was lower in the group with single vessel disease as compared to double and triple vessel disease (48.4 years vs. 53.4 and 55.4 years, p less than 0.05 and p less than 0.005). Independently of whether the infarct-related artery was open or closed, there tended to be an inverse correlation between number of diseased vessels and preservation of left ventricular function (statistical significance only for single vessel versus triple vessel disease with respect to score of regional left ventricular dysfunction, 1.8 vs. 2.4, p less than 0.05). These findings suggest that early thrombolytic treatment within 3 hours of onset of symptoms may preserve myocardial tissue during the evolution of acute infarction. Furthermore, a presumably better collateralisation from adjacent coronary arteries without stenoses may be important for myocardial preservation. Finally, early angiographic examination can be performed safely and is a good support for determination of further treatment, which in the actual patients was coronary bypass surgery in 8 cases, transluminal angioplasty, PTCA, in 20 cases, and medical treatment alone in 22 cases.

Immediate angioplasty after thrombolysis: a systematic review

BACKGROUND

The role of immediate transfer for percutaneous coronary intervention (PCI) after thrombolysis for ST-segment elevation myocardial infarction remains controversial. We performed a systematic review of the related literature to determine whether thrombolysis followed by transfer for immediate or early PCI is safe, feasible and superior to conservative management.

METHODS

A systematic literature search of MEDLINE, EMBASE, the Cochrane Database for Systematic Reviews and Cochrane Central Register of Controlled Trials, and the American Heart Association EndNote 7 Master Library databases, was performed to 2004 for relevant published studies. The level of evidence and the quality of the study design and methods were rated by 2 reviewers according to a standardized classification. A quantitative meta-analysis was performed to assess the effect at 6-12 months on mortality of immediate or early PCI after thrombolysis.

RESULTS

We found 13 articles that were supportive of immediate or early PCI after thrombolysis and 16 that were neutral or provided evidence opposing it. The largest randomized trials and meta-analyses showed no benefit of routine PCI immediately or shortly after thrombolysis. The studies that were supportive were generally more recent and more frequently involved coronary stents. One large trial supported early PCI after thrombolysis for patients with myocardial infarction complicated by cardiogenic shock. Overall, the difference in mortality rates between the invasive strategy and conservative care was nonsignificant. The 3 stent-era trials showed a significantly lower mortality among patients randomly assigned to the invasive strategy (5.8% v. 10.0%, odds ratio 0.55, 95% confidence interval 0.32-0.92). Analysis of variance found a significant difference in treatment effect between stent-era and pre-stent-era trials.

INTERPRETATION

At present, there is inadequate evidence to recommend routine transfer of patients for immediate or early PCI after successful thrombolysis. Results of recent trials using contemporary PCI techniques, including coronary stents, appear more favourable but need to be confirmed in large randomized trials, which are currently in progress. Transfer for immediate PCI is recommended for patients with cardiogenic shock, hemodynamic instability or persistent ischemic symptoms after thrombolysis.

Combined revascularization strategy for acute myocardial infarction in patients with intracoronary thrombus: preceding intracoronary thrombolysis and subsequent mechanical angioplasty

Thrombus in the infarct-related artery is one of the limitations for flow restoration in primary percutaneous transluminal coronary angioplasty (PTCA) treatment for acute myocardial infarction (AMI). The present study investigated the benefit of preceding intracoronary thrombolysis (ICT) by retrospectively analyzing acute phase flow restoration in 80 AMI patients with intracoronary thrombus: 40 undergoing primary PTCA alone (primary PTCA group) and 40 treated with preceding ICT plus PTCA (combined group). Acute phase Thrombolysis in Myocardial Infarction (TIMI) grade flow was as follows: TIMI 0/1: 35.0% vs 12.5% for the primary PTCA group and the combined group, p=0.06; TIMI 2: 7.5% vs 15.0%, p=NS; TIMI 3: 57.5% vs 72.5%, p=NS). In the subgroup analysis, it was also less in the combined group among 33 patients with a left anterior descending coronary artery (LAD) lesion (42.1 % vs 7.1%, p=0.08), but not among the remaining 47 with either a right coronary artery or left circumflex artery lesion. The combined therapy may potentially provide better acute phase flow restoration in AMI patients with an intracoronary thrombus in a LAD lesion.

Relation between coronary thrombus and angiographic no-flow during primary angioplasty in patients with acute myocardial infarction

No flow is an unsolved issue in primary percutaneous transluminal coronary angioplasty (PTCA) for patients with acute myocardial infarction (AMI), and the pathophysiology of no-flow is undetermined. To evaluate the potential participation of coronary thromboembolism in no-flow during primary PTCA, the present study reviewed cinefilms of 256 consecutive patients who underwent primary PTCA for AMI within 24h after the onset of chest pain between January 1992 and June 1998, focusing on the thrombus size. Angiographic no-flow was defined as the cessation of flow into the distal coronary circulation of the treated vessel with a to-and-fro contrast movement, not attributable to high-grade stenosis or spasm of the original target lesion. The coronary thrombus size was determined by using the 2-cm balloon catheter as a reference after crossing the infarct-related occluded artery with a guide wire. Angiographic no-flow was observed in 37 patients (37/256, 14%): 14 of 29 cases (48%) with a large thrombus (> or =2cm) versus 23 of 227 cases (9%) with a small thrombus (<2cm, 14/29 vs 23/227, p<0.01). Among 37 patients who experienced angiographic no-flow, overt distal emboli were observed in 14 patients. A thrombolytic agent was used through a guiding catheter in 102 cases prior to or after balloon dilatation to prevent or attenuate distal embolism, particularly in all those cases with a large thrombus (29/29 100%), and angiographic no-flow was seen in 27 cases of this subgroup (27/102, 26%). It is suggested that distal thromboembolism plays an important role in the mechanism of angiographic no-flow during primary PTCA performed for AMI.

Percutaneous transluminal coronary angioplasty, alone or in combination with urokinase therapy, during acute myocardial infarction

To investigate the effect of pre-treatment of a thrombus with a low dose of urokinase on establishing patency in a persistent infarct-related artery (IRA) during direct percutaneous coronary angioplasty (PTCA), the frequency of acute restenosis during direct PTCA, alone, or in combination with the intracoronary administration of urokinase, was examined in a consecutive nonrandomized series of patients with acute myocardial infarction (AMI). Two hundred and seventy-two successful PTCA patients (residual stenosis <50%) were divided into 2 groups: 88 patients received pre-treatment with intracoronary urokinase following PTCA (combination group); 184 received only direct PTCA without thrombolytic therapy (PTCA group). In the present study, after achievement of a residual stenosis of less than 50%, IRA was visualized every 15 min to assess the frequency of acute restenosis, which was defined as an acute progression of IRA with more than 75% restenosis after initially successful PTCA. In the patients with a large coronary thrombus, the frequency (times) of acute restenosis was significantly lower in the combination group than in the PTCA group (0.98+/-0.19 vs 2.92+/-0.32, p<0.0001). On the other hand, in the patients with a small coronary thrombus, the frequency of acute restenosis showed no difference in either group. The present study indicates that in patients with AMI, PTCA combined with pre-treatment of a low dose of urokinase is much more effective than PTCA alone, especially for those patients who have a large coronary thrombus.

Survival following cardiogenic shock caused by acute left main coronary artery total occlusion. A case report and review of the literature

The authors describe a fifty-five-year-old Japanese man with an acute extensive anterior myocardial infarction associated with a total occlusion of the left main coronary artery. The patient suffered cardiogenic shock and was treated successfully with rescue percutaneous transluminal coronary angioplasty and an intraaortic balloon pump (IABP) after unsuccessful intracoronary thrombolysis. Ten days after admission, he was weaned from IABP, and recovery-phase coronary angiography revealed no significant coronary artery stenosis and an ejection fraction of 32% by left ventriculography. The patient was discharged from the hospital without any ischemic findings.

A pooled analysis of coronary arterial patency and left ventricular function after intravenous thrombolysis for acute myocardial infarction

Individual studies of patency rates and left ventricular (LV) function after thrombolysis have generally been limited by small numbers of observations, wide confidence intervals, and limited numbers of time points. To obtain a more reliable estimate of patterns of patency and LV ejection fraction, a systemic overview of angiographic studies was performed after intravenous thrombolytic therapy. A total of 14,124 angiographic observations from 58 studies evaluating patency after no thrombolytic agent, streptokinase, standard dose tissue-type plasminogen activator (t-PA), accelerated dose t-PA, or anistreplase (anisoylated plasminogen streptokinase activator complex [APSAC]) were included. At 60 and 90 minutes, streptokinase had the lowest patency rates of 48% and 51%, respectively, standard dose t-PA and APSAC had similar intermediate rates of approximately 60% and 70%, and accelerated t-PA had the highest patency rates of 74% and 84%. By 2 to 3 hours and longer, the patency rates were similar for the various regimens. Reocclusion rates in studies including 1,172 patients randomized to t-PA versus a nonfibrin-specific agent were higher after t-PA (13.4% vs 8.0%, p = 0.002). Ten studies enrolling 4,088 patients treated with thrombolytic therapy versus control demonstrated a modest improvement in mean LV ejection fraction in the thrombolytic group at each of the times after thrombolytic therapy: hour 4, day 1, day 4, day 7 to 10, and day 10 to 28 after thrombolysis. By 4 days, mean ejection fraction was 53% versus 47% (thrombolytic vs control therapy, p < 0.01); by 10 to 28 days it was 54.1% and 51.5%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic information from on-line vectorcardiography in acute myocardial infarction

The present study assesses the prognostic information from continuous on-line vectorcardiography in patients with acute myocardial infarction (AMI). A series of 203 patients with AMI were studied. Vectorcardiographic (VCG) recordings were obtained continuously for 24 hours. Analysis was performed on-line with the commercial system MIDA CoroNet. QRS vector difference (QRS-VD), ST change vector magnitude (STC-VM), and ST vector magnitude (ST-VM) were monitored. Patients were followed for 538 +/- 220 days. During follow-up, 36 patients died from cardiac causes and 38 patients had reinfarction. A significantly higher occurrence of transient VCG changes (QRS-VD, STC-VM, and ST-VM; p < 0.001) was seen in patients who died from cardiac causes or experienced either cardiac death or reinfarction at follow-up. The end value for QRS-VD was higher in patients who died from cardiac causes and correlated with the maximal value for creatine kinase when all patients were considered (r = 0.66; p < 0.001). Significantly lower mortality was seen in patients with VCG trend curves suggestive of coronary reperfusion (p < 0.01). In multivariate analysis, occurrence of transient changes in STC-VM, high QRS-VD end value, and VCG trend curves not suggestive of reperfusion gave additional prognostic information beyond that of age, gender, maximal creatine kinase value, heart size on chest x-ray, occurrence of ventricular fibrillation during hospitalization, and the inability to perform exercise tests. VCG monitoring during the first 24 hours of hospitalization for an AMI is a promising method for early detection of patients with increased risk for subsequent cardiac death or reinfarction.

Should every patient undergo cardiac catheterization after myocardial infarction?

During the past few decades, management of patients with myocardial infarction has dramatically evolved. High-risk patients are now identified by a variety of noninvasive tests, and aggressive use of reperfusion strategies has improved clinical outcomes. Despite the benefits of reperfusion, only a few patients are eligible to receive thrombolytic therapy. Mortality rates among patients excluded from thrombolytic trials (15% to 20%) have been far greater than those eligible for treatment (3% to 10%). Because most deaths occur within the first few days of infarction, interventions designed to reduce mortality should be performed acutely. Immediate catheterization allows identification of high-risk anatomy that may benefit from surgery and allows coronary angioplasty to be performed as a reperfusion strategy (when appropriate). Furthermore, catheterization allows documentation of ejection fraction, vessel patency, number of diseased vessels, and residual stenosis, all of which have been predictive of prognosis. Conversely, frequently repeated noninvasive diagnostic tests are associated with increased cost, are generally performed in low-risk patients, and 60% to 80% of patients with myocardial infarction ultimately require catheterization anyway. It is possible that early catheterization and percutaneous transluminal coronary angioplasty when indicated may effectively risk stratify patients (eliminating the need for noninvasive testing), may reduce morbidity and mortality, and shorten the length of hospital stay.

The open artery: beyond myocardial salvage

Despite the potential limitations, the available data suggest the importance of the open artery as a marker of survival following infarction. Perhaps the most important, although as yet unanswered, question is when is it too late to reopen an artery? Further, is reperfusion by interventional techniques preferable to reperfusion by lytic therapy alone? Although a reduction in mortality has not been demonstrated for thrombolysis beyond 12 hours (other than the Second International Study of Infarct Survival, ISIS-2), improvements in ventricular function (which might translate into a survival benefit) have been demonstrated even for very delayed reperfusion. It is hoped that future work will allow us to answer better when such therapy might be preferable.

An overview of the patency and stroke rates following thrombolysis with streptokinase, alteplase, and anistreplase used to treat an acute myocardial infarction

The results of an overview of early (90-240 min) and late (24 hours or more) patency and of stroke rates for each of the three commercially available thrombolytic agents, streptokinase, alteplase, and anistreplase are presented. Studies included in this analysis are all those published between 1985 and March 1992 and focus on the licensed dosage regimens of each agent. The rates of early and late patency for streptokinase were 64.7% and 80.8%; for alteplase, 66.6% and 73.7%; and for anistreplase, 72.1% and 84.5%. The rates of total and hemorrhagic stroke for streptokinase were 0.69% and 0.17%; for alteplase, 1.27% and 0.50%; and for anistreplase 0.91% and 0.38%. These results provided evidence that the rates of early and late patency appeared to be greatest for anistreplase and that the rates of stroke are within "acceptable" ranges for all three thrombolytic agents with streptokinase affording the lowest rate.

Specificity of an immunochemical reagent for quantifying the isoforms of creatine kinase-MB

Fractionation of the creatine kinase-MB isoforms is promising for use in diagnosing acute myocardial infarction and for monitoring myocardial perfusion status after thrombolytic therapy. An immunochemical reagent intended for use in fractionating the MB1 and MB2 isoforms of creatine kinase-MB was examined before and after immunoextraction, qualitatively by visually examining electrophoresis separation of various MB1 and MB2 mixtures, and quantitatively by comparing the observed and predicted enzymatic activity of various MB1 and MB2 mixtures. Qualitatively the reagent showed greater reactivity for MB1 than for MB2, as demonstrated by a marked decrease in the MB1 electrophoretic region following immunoextraction. Quantitatively, the reagent consistently eliminated about 75% of MB1 activity; however, the assay also eliminated about 40% of MB2 activity from isoform mixtures. Although the performance of the immunochemical reagent was not ideal, the greater reactivity for MB1 may have clinical use.

Prognosis in cardiogenic shock after acute myocardial infarction in the interventional era

OBJECTIVES

The purpose of this study is to describe the outcome in cardiogenic shock treated with aggressive reperfusion therapy and to identify factors predictive of in-hospital and long-term mortality.

BACKGROUND

Cardiogenic shock is the most common cause of death in patients admitted to the coronary care unit. Although studies have reported lower mortality rates in shock treated with angioplasty, few studies have described a cohort of patients with shock who were not selected because they were most likely to benefit from reperfusion therapy.

METHODS

A consecutive series of 200 patients admitted with acute myocardial infarction complicated by cardiogenic shock were studied.

RESULTS

The in-hospital mortality rate was 53%. Variables with significant univariable association with in-hospital death included patency of the infarct-related artery, patient age, lowest cardiac index, highest arteriovenous oxygen difference and left main coronary artery disease. The most important independent predictors of in-hospital death were patency of the infarct-related artery, cardiac index and peak creatine kinase, MB fraction. The mortality rate in patients with patent infarct-related arteries was 33% versus 75% in those with closed arteries and 84% in those in whom arterial patency was unknown. Patients who survived to hospital discharge were followed up for a median of 2 years, with a mortality rate of 18% after 1 year. The best descriptors of the relation between these variables and postdischarge mortality included age, peak creatine kinase, ejection fraction and patency of the infarct-related artery.

CONCLUSIONS

In a large consecutive series of patients with cardiogenic shock with complete follow-up, patency of the infarct-related artery was most strongly associated with in-hospital and long-term mortality. This finding supports an aggressive interventional strategy in patients with cardiogenic shock.

Evidence of increased platelet activation after thrombolysis in patients with acute myocardial infarction

OBJECTIVE

To assess platelet activation after thrombolysis in patients with acute myocardial infarction.

DESIGN

Platelet function was assessed by measurement of the in vivo synthesis of thromboxane by gas chromatography-mass spectrometry of thromboxane's major urinary metabolite, 2,3-dinor-thromboxane-B2.

SETTING

Coronary care unit of Huddinge University Hospital.

SUBJECTS

30 patients with acute myocardial infarction given either streptokinase 1.5 million units intravenously over one hour + 500 mg aspirin (n = 10), 500 mg aspirin (n = 10), or neither thrombolysis nor aspirin (n = 10).

RESULTS

Patients treated by thrombolysis had a 20-fold increase in thromboxane formation during thrombolysis compared with control patients not treated by thrombolysis (p = 0.0001). Until two days after thrombolysis thromboxane production in patients treated with streptokinase did not decrease to a value comparable with patients treated with aspirin but not given thrombolysis.

CONCLUSION

Thromboxane production increased considerably during thrombolysis, possibly reflecting greatly enhanced platelet activation. The slow decrease in thromboxane formation after treatment with aspirin suggests that the efficacy of thrombolysis might be improved by more efficient antiplatelet treatment.

A patency-oriented strategy for early management of acute myocardial infarction using emergency coronary angiography and selective coronary angioplasty

From June 1988 to March 1991, an unselected cohort of 150 consecutive patients with acute myocardial infarction (AMI) (less than 6 hours) was managed according to a strategy designed to ensure early patency of the infarct-related artery in the maximum number of patients. The following procedures were used: (1) intravenous thrombolysis, which was the usual treatment (n = 103), followed in 98 cases by emergency coronary angiography 90 minutes after the beginning of thrombolysis. This identified 31 thrombolysis failures (32%) and led to 19 rescue angioplasties (18 successes). All patients were then scheduled for predischarge angiography. (2) Direct angioplasty, which was performed in 40 patients because of contraindications to thrombolysis (n = 23), cardiogenic shock (n = 3), diagnostic doubt (n = 7) or "ideal" conditions for direct angioplasty (n = 7). Success (defined as Thrombolysis in Myocardial Infarction [TIMI] flow greater than 1, with a residual stenosis less than 50% in the infarct-related artery) was achieved in 36 of 40 patients (90%). (3) The 7 remaining patients were given conventional medical treatment because of advanced age, contraindications to thrombolysis and angioplasty, or spontaneous reperfusion (confirmed by emergency angiography). In all, emergency angioplasty was performed in the acute phase in 39% of the 150 patients in this nonselected cohort.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of early death despite thrombolytic therapy: Experience from the Thrombolysis in Myocardial Infarction Phase II (TIMI II) study

Mechanisms of death among patients who died within 18 h of enrollment in the Thrombolysis in Myocardial Infarction Phase II (TIMI II) study were analyzed. Of 3,339 patients enrolled, 32 died within the 1st 4 h and 31 died within the subsequent 14 h. Thirteen of the 63 patients had shock at enrollment; 22 had advanced hemodynamic compromise without shock and 28 initially had minimal to no compromise. Prior infarction was present in 16 patients (25%). Pump failure was responsible for 39 early deaths (62%), ventricular rupture for 10 (16%), arrhythmia for 8 (13%) and complications of therapy for 6 (10%). Nine of 720 patients randomized to immediate intravenous beta-adrenergic blocking agent therapy had an early death compared with 6 of 714 assigned to deferred beta-blocker therapy. Thus, mortality is highest in the early hours after myocardial infarction, even in patients treated with thrombolytic therapy and is most frequently due to pump failure. These results imply that efforts to reduce mortality during this critical time period should be directed at prevention, limitation or palliation of early pump failure.

Percutaneous transluminal coronary angioplasty in patients with cardiogenic shock

In cardiogenic shock complicating acute myocardial infarction, percutaneous transluminal coronary angioplasty has been reported to significantly improve the modest survival benefits afforded by emergency surgical revascularization and thrombolytic therapy. The records of all patients who underwent angioplasty for acute myocardial infarction complicated by cardiogenic shock were retrospectively reviewed to determine whether coronary angioplasty improves survival. Of the 45 patients, 28 (group 1, 62%) had successful dilation of the infarct-related artery and 17 (group 2, 38%) had unsuccessful angioplasty. The groups were similar in extent of coronary artery disease, infarct location, incidence of multivessel disease and hemodynamic variables. The overall hospital survival rate was 56% (71% in group 1 and 29% in group 2). Group 1 patients had more left main coronary artery disease, and group 2 patients were older and had a higher incidence of prior myocardial infarction. Multivariate analysis showed that the survival advantage in patients with successful angioplasty was statistically significant (p = 0.014) when these factors were taken into account. At a mean follow-up interval of 2.3 years (range 1 month to 5.6 years), there were five deaths (four cardiac and one noncardiac), for a 2.3-year survival rate of 80% in patients surviving to hospital discharge. During the follow-up period, 36% of hospital survivors had repeat hospitalization for cardiac evaluation, 8% had myocardial infarction, 8% had coronary artery bypass surgery and 24% had angina.

Thrombolytic therapy: adjuvant mechanical intervention for acute myocardial infarction

Following successful pharmacologic thrombolysis, early coronary angiography frequently shows a tight residual stenosis in the infarct-related artery at the site of recent occlusion. Approaches to the management of the residual stenosis have undergone a gradual evolution from an aggressive strategy of immediate balloon dilation to a more conservative approach. Randomized, controlled trials have indicated that immediate percutaneous transluminal coronary angioplasty (PTCA) is associated with no greater recovery in regional or global left ventricular function, and a tendency toward an increased incidence of complications, including the need for emergency coronary artery surgery and blood transfusion. The role of immediate rescue PTCA for failed thrombolysis has not been as rigorously investigated, but selected patients, including those with evidence of ongoing myocardial ischemia or hemodynamic instability, may benefit from this approach. A major source of current controversy is the value of routine coronary angiography after uncomplicated myocardial infarction. Two carefully conducted trials have indicated that a conservative strategy of clinically indicated, predischarge cardiac catheterization may be associated with an increased need for readmission and late, elective cardiac catheterization when compared with a more invasive strategy of routine coronary angiography, but that the conservative approach is not associated with an increased incidence of death or reinfarction. Provision was not made in these studies, however, for evaluating the positive economic and psychologic impact of early coronary angiography, early hospital discharge, and early return to work of patients with a favorable postinfarction prognosis. It is concluded that early mechanical revascularization following thrombolysis should be considered for ongoing myocardial ischemia, but should otherwise be deferred pending the results of predischarge functional studies. For most patients, routine coronary angiography is likely to remain an important diagnostic tool and an integral component of the management of the convalescent phase of acute myocardial infarction.

Clinical benefits of thrombolytic therapy in acute myocardial infarction

The value of coronary artery reperfusion resulting from pharmacologically induced fibrinolysis in patients with evolving myocardial infarction has been rigorously evaluated. Improved left ventricular function and even more impressive improvements in survival rates have been demonstrated consistently in controlled studies. Benefit is related to the restoration of myocardial blood flow. Maximal benefit is achieved with early and sustained restoration of coronary artery patency. Benefits observed during initial hospitalization are sustained for at least 1 year in the majority of patients, even without subsequent mechanical revascularization. To date, analysis of subgroups has not identified a population of patients with evolving infarction that should routinely be excluded from consideration for thrombolysis. As with many potent pharmacologic agents, activators of the fibrinolytic system are associated with a degree of risk whenever they are administered to a patient. Therefore, patients must be assessed carefully prior to initiating treatment, especially for potential bleeding hazards, and appropriate follow-up evaluation and concomitant therapy needs to be planned. However, given the overwhelming body of data now available regarding its benefits and relative safety, thrombolysis should be considered as conventional therapy for patients with acute evolving myocardial infarction (AMI).

Comparative safety of thrombolytic agents

Three available thrombolytic agents, streptokinase, alteplase, and anistreplase, have been shown to have similar effects on preservation of left ventricular function and mortality reduction after acute myocardial infarction (AMI). The agents are, however, quite different with respect to their safety profiles. Clinical trials to date suggest that alteplase (tissue plasminogen activator) or anistreplase administration is associated with a high incidence of cerebral hemorrhage. In contrast, streptokinase is associated with a low rate of cerebral hemorrhage. Streptokinase and anistreplase are associated with a higher risk of allergic reaction when compared with alteplase. Hypotension is also more common with streptokinase and anistreplase, but occurs significantly with alteplase as well. Alteplase is associated with a lower reinfarction rate when compared with streptokinase and anistreplase. The Third International Study of Infarct Survival (ISIS-3), a direct comparison of 3 thrombolytic agents (streptokinase, anistreplase, and duteplase), may provide some insight regarding the safety of these agents. Because these agents have been shown to be equally effective, selection of an appropriate agent for an individual patient may depend more on assessment of the likelihood of an adverse event or other factors, such as cost or convenience of administration, rather than assessment of the probability of greater benefit with a particular agent.

Dynamic QRS complex and ST segment vectorcardiographic monitoring can identify vessel patency in patients with acute myocardial infarction treated with reperfusion therapy

Reperfusion therapy has lowered the mortality in patients suffering acute myocardial infarction. Failure to reperfuse is associated with significantly higher risk of short- and long-term mortality. Detection of reperfusion is thus important. In a prospective pilot study, we used continuous on-line computerized vectorcardiography to monitor 21 patients with acute myocardial infarction treated with reperfusion therapy to noninvasively detect coronary patency. By using trend analysis of QRS vector difference, we were able to correctly blindly identify 15 of 16 patients with a perfused infarct-related artery and four of six patients with a persistently occluded artery at an early angiogram. The present results are based on a limited number of patients, but suggest that QRS complex and ST segment monitoring with continuous on-line vectorcardiography has substantial potential for monitoring patients with acute myocardial infarction treated with reperfusion therapy.

Effect of age on use of thrombolytic therapy and mortality in acute myocardial infarction. The MITI Project Group

The findings in 3,256 consecutive patients hospitalized for acute myocardial infarction were tabulated to assess the history, treatments and outcome in the elderly; 1,848 patients (56%) were greater than 65 years of age, including 28% who were aged greater than or equal to 75 years. The incidence of prior angina, hypertension and heart failure (only 3% of patients less than 55 years of age had a history of heart failure compared with 24% greater than or equal to 75 years old) was found to increase with age. Twenty-nine percent of patients less than 75 years of age were treated with a systemic thrombolytic drug compared with only 5% of patients older than 75 years. Mortality rates increased strikingly with advanced age (less than 2% in patients less than or equal to 55, 4.6% in those 55 to 64, 12.3% in those 65 to 74 and 17.8% in those greater than or equal to 75 years). Both the incidence of complicating illness and a nondiagnostic electrocardiogram (ECG) increased with age. In a multivariate analysis of outcome in older patients (greater than or equal to 65 years), adverse events were related to both prior history of heart failure (odds ratio 3.9) and increasing age (odds ratio 1.4 per each decade of age). Outcome was not improved by treatment with thrombolytic drugs, but these agents were prescribed to only 12% of patients greater than 65 years of age, thereby reducing the power for detecting such an effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraaortic balloon pumping as the postangioplasty strategy in acute myocardial infarction

To assess the usefulness of intraaortic balloon pumping (IABP) in acute myocardial infarction (AMI), 114 patients with anterior AMI undergoing emergency percutaneous transluminal coronary angioplasty (PTCA) for total occlusion of the left anterior descending artery were studied. After successful PTCA 66 patients were treated with conventional therapy (group I), and 48 patients were treated with IABP for 25 +/- 8 hours (group II). The reocclusion rate was significantly lower in group II (2.4% vs 17.7% p less than 0.05). An increase in ejection fraction in group II compared with group I was marginally significant (4.5 +/- 12.2% vs 9.2 +/- 13.0%, p = 0.08). Vascular complications occurred in two patients, but there were no deaths from IABP. These results suggest that after successful PTCA for acute myocardial infarction, IABP prevents reocclusion and may add strength to reperfusion in the improvement of left ventricular function.

Noninvasive detection of reperfusion in acute myocardial infarction based on plasma activity of creatine kinase MB subforms

Successful thrombolytic therapy is associated with an accelerated release of creatine kinase (CK) MB from necrotic myocardium. With use of a previously validated assay, the plasma kinetics of the myocardial subform (MB2) and the plasma-modified subform (MB1) were determined in blood samples obtained from 56 patients with acute Q wave myocardial infarction: 33 patients who received thrombolytic therapy (group A) and 23 patients managed conservatively (group B). Plasma MB2 activity increased more rapidly in the group A patients, but there was substantial overlap with group B. Plasma MB1 activity did not differ significantly between the two groups. The MB2/MB1 ratio was significantly higher in group A patients than in group B patients between 2 and 10 h after the onset of infarction. Among group A patients, the ratio increased from 2.4 +/- 1.6 to 4.6 +/- 2.0 in the 1st h after therapy (p less than 0.001). The peak ratio was 6.3 +/- 2.5 in group A patients and 3.1 +/- 1.2 in group B patients. Twenty-seven of the 33 group A patients had a peak ratio greater than 3.8 versus 5 of the 23 group B patients (p less than 0.001). In seven group A patients, the ratio was greater than 3.8 before plasma CK MB activity was out of the normal range. Angiography was performed at 5.0 +/- 3.5 days in 39 patients. Eighteen (90%) of 20 patients with a patent infarct-related artery had a peak ratio greater than 3.8; 17 (89.5%) of 19 patients with an occluded infarct-related artery had a ratio less than 3.8 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Relation between flow grade after thrombolytic therapy and the effect of angioplasty on left ventricular function: a prospective randomized trial

Recent intervention trials during myocardial infarction demonstrated no benefit from emergency angioplasty after thrombolytic therapy when compared with either delayed percutaneous transluminal coronary angioplasty (PTCA) or a conservative strategy. However, it is possible that subgroups of patients may benefit from early intervention with angioplasty. We performed a prospective randomized trial in patients with a patent infarct-related artery after thrombolytic therapy to determine whether initial flow grade is related to infarct-zone function and whether patients with ineffective reperfusion (greater than 90% stenosis or Thrombolysis in Myocardial Infarction [TIMI] flow less than or equal to 2) might benefit from immediate PTCA. Thrombolytic therapy was administered to 170 patients at a mean of 2.1 +/- 0.5 hours after onset of myocardial infarction. A patent infarct-related artery that was suitable for angioplasty was present in 89 patients who comprised the study group; after randomization, 47 of 50 patients with a patent infarct-related artery had successful emergency PTCA 3.8 +/- 1.5 hours after onset of symptoms, and 39 were scheduled for delayed (18 to 48-hour) PTCA. Reocclusion occurred before the scheduled (delayed) procedure in eight patients (20.5%), and was symptomatic in six. Infarct-region function (by the centerline method) measured initially, before discharge, and at 4 months was similar in both groups; improvement was significant (p less than 0.001) at discharge when compared with initial values with no further change at 4 months. However, patients with ineffective reperfusion had greater hypokinesia initially (p less than 0.05) compared with those with effective reperfusion (less than or equal to 90% stenosis plus TIMI flow 3). Moreover, independent of the timing of PTCA, improvement was greater before discharge in patients with ineffective reperfusion (p less than 0.05) with a trend also evident at 4 months. Importantly, 42 of 51 patients (82%) with a residual lumen less than 0.4 mm after thrombolysis had some improvement in function at discharge; this compared with a previous study in which patients with a similar degree of stenosis (without PTCA) had no improvement. Moreover, reocclusion occurred before scheduled (delayed) PTCA in 37% of patients with greater than 90% stenosis compared with only 5% in those with less than or equal to 90% stenosis (p = 0.02). Thus flow grade is an important determinant of myocardial function in patients with a patent artery after thrombolytic therapy and is predictive both of improvement in wall motion after PTCA and early reocclusion.(ABSTRACT TRUNCATED AT 400 WORDS)

The unstable ST segment early after thrombolysis for acute infarction and its usefulness as a marker of recurrent coronary occlusion

To investigate the incidence of early recurrent ST elevation after intravenous thrombolytic therapy for acute myocardial infarction, 12-lead electrocardiograms were continuously monitored for 571 +/- 326 minutes in 31 patients presenting within 4 hours of symptom onset. The study group comprised 9 women and 22 men (mean age +/- standard deviation 53 +/- 12 years), with ST elevation (anterior in 15, inferior in 16) on the initial electrocardiogram, who were given either tissue plasminogen activator (22 patients) or streptokinase (9 patients). Angiography was performed in 30 of 31 patients at 7 to 10 days. Early (less than 3 hours) resolution of ST elevation occurred in 19 patients (61%) at a median of 94 minutes (interquartile range 57 to 113) after thrombolysis, whereas 12 (39%) had no or late (greater than 6 hours) resolution. Eleven of the 19 with early resolution (58%) had either transient (5 patients) or sustained (6 patients) recurrences of ST elevation. Recurrent ST elevation was equal to or more than the initial peak elevation in 9 of 11 patients, and greater than 75% of initial peak in 2. A total of 25 episodes of recurrent ST elevation were observed in the 11 patients (19 transient and 6 sustained episodes), of which 8 (32%) were silent. The proportion of silent episodes was similar for transient (35%) and sustained (33%) recurrences. All patients with sustained recurrent ST elevation had at least 1 preceding transient recurrence. The median duration of transient recurrent ST elevation was 43 minutes (28 to 63).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of heparin on coronary arterial patency after thrombolysis with tissue plasminogen activator in acute myocardial infarction

Infarct artery patency rates at 90 minutes after coronary thrombolysis using recombinant tissue-type plasminogen activator (rt-PA) with and without concurrent heparin anticoagulation have been shown to be comparable. The contribution of heparin to efficacy and safety after thrombolysis with rt-PA is unknown. In this pilot study, 84 patients were treated within 6 hours of onset of acute myocardial infarction (mean of 2.7 hours) with the standard dose of 100 mg of rt-PA over 3 hours. Forty-two patients were randomized to receive additionally immediate intravenous heparin anticoagulation (5,000 U of intravenous bolus followed by 1,000 U/hour titrated to a partial thromboplastin time of 1.5 to 2.0 times control) while 42 patients received rt-PA alone. Coronary angiography performed on day 3 (48 to 72 hours, mean 57) after rt-PA therapy revealed infarct artery patency rates of 71 and 43% in anticoagulated and control patients, respectively (p = 0.015). Recurrent ischemia or infarction, or both, occurred in 3 (7.1%) anticoagulated patients and 5 (11.9%) control patients (difference not significant). Mild, moderate and severe bleeding occurred in 52, 10 and 2% of the group receiving anticoagulation, respectively, and 34, 2 and 0% of patients in the control group, respectively (p = 0.006). These data indicate that after rt-PA therapy of acute myocardial infarction, heparin therapy is associated with substantially higher coronary patency rates 3 days after thrombolysis but is accompanied by an increased incidence of minor bleeding complications.

Results of primary angioplasty for acute myocardial infarction in patients with multivessel coronary artery disease

The influence of multivessel coronary artery disease on the outcome of reperfusion therapy for myocardial infarction has not been fully characterized. Direct coronary angioplasty without antecedent thrombolytic therapy was performed during evolving myocardial infarction in 285 patients with multivessel coronary artery disease at 5.2 +/- 4.2 h after the onset of chest pain. Two vessel disease was present in 163 patients (57%) and three vessel disease in 122 (43%). An anterior infarct was present in 123 patients (43%), cardiogenic shock in 33 (12%) and age greater than or equal to 70 years in 59 (21%). Angioplasty of the infarct-related vessel was successful in 256 patients (90%), including 92% with two vessel and 88% with three vessel disease (p = NS). Emergency bypass surgery was needed in six patients (2%). In-hospital death occurred in 33 patients (12%), including 13 with two vessel and 20 with three vessel disease (p less than 0.05). The mortality rate was only 4% in the subgroup of 101 patients who met entry criteria for thrombolytic trials. The in-hospital mortality rate was 45% in patients in shock and 7% in patients not in shock (p less than 0.01). Logistic regression analysis identified shock and age greater than or equal to 70 years as independently associated with in-hospital death. In 135 patients who underwent predischarge left ventriculography, global ejection fraction increased from 50% to 57% (p less than 0.001) and regional wall motion in the infarct zone improved in 59% of patients. Follow-up data were available in 251 patients (99%) at a mean of 35 +/- 19 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of the patient following coronary thrombolysis

Myocardial salvage can be maximized by the early institution of thrombolytic therapy and aspirin. Certain patients may benefit from the administration of intravenous heparin, beta blockers, or nitroglycerin. The routine use of percutaneous transluminal coronary angioplasty (PTCA) or calcium-channel blockers does not appear to be warranted. Recurrent myocardial ischemia should be vigorously treated with medical therapy and there may be value in cardiac catheterization, followed by PTCA or bypass surgery, depending upon the extent of myocardium at risk and the underlying coronary anatomy. Long-term morbidity and mortality may be reduced by instituting aspirin and beta blockers as well as by modifying risk factors. There is no evidence for the long-term benefit from any calcium-channel blocker. Oral anticoagulation may be warranted in those patients with a mural thrombus, congestive heart failure, or atrial fibrillation. ACE inhibitors may be of value in the presence of left ventricular dysfunction and certainly in the presence of symptomatic congestive heart failure. Antiarrhythmic therapy is generally indicated only for symptomatic or life-threatening arrhythmias. Residual myocardial ischemia should be sought by exercise testing, and those patients with poor exercise tolerance generally warrant cardiac catheterization in consideration for revascularization.

Successful direct PTCA on LAD after first episode of acute myocardial infarction: does it improve cardiac function?

Patients who received direct percutaneous transluminal coronary angioplasty (PTCA) after acute mycardial infarction and maintained potency but with unimproved cardiac function were studied. In 15 patients, the first episode of acute myocardial infarction was caused by a left anterior descending branch lesion; 11 had an ejection fraction of 50% or more in the left ventriculogram in the follow-up period (improved group), and 4 patients had ejection fraction of less than 50% (unimproved group). There was so significant difference between the groups in the mean time between the onset of infarction and revascularization (improved group, 259.3 +/- 76.9 min; unimproved group, 168.0 +/- 101.6 min) or in the sigma Q. which was the sum of the Q wave depth of V2, V3, and V4 at the time of admission (improved group, 12.1 +/- 15.6 mm; unimproved group 29.8 +/- 13.4 mm). The maximum creatine kinase concentration was significantly higher in the unimproved group (improved group 2670 +/- 893 IU/L; unimproved group, 7243 +/- 1928 IU/L, p less than 0.05), and the time taken from the onset to reach its peak was significantly shorter in the unimproved group (improved group, 13.0 +/- 5.1 hr; unimproved group, 6.8 +/- 1.3 hr, p less than 0.05.) These results suggest the probability of sudden deterioration of myocardium, and factors other than microcirculatory thromboembolism should be considered as the cause of unimproved cardiac function after successful direct PTCA.

Brachial approach to emergency cardiac catheterization during thrombolytic therapy for acute myocardial infarction. TAMI Study Group

The use of the brachial approach to acute coronary intervention has not been previously studied. In the course of the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) trials, we used the transbrachial approach to cardiac catheterization with or without angioplasty in 202 of 704 (28.6%) patients. The baseline characteristics of age, sex, risk factors, medical history, time from symptom onset to therapy, and left ventricular function were similar for the 2 different approaches. Time from therapy to coronary angiography was not delayed by the brachial approach compared with the femoral approach: 97.1 +/- 26 min vs. 99.9 +/- 133.8 min, respectively. Chemical patency was established in 78 vs. 73% of patients and technical success with acute PTCA with the brachial approach was 89% vs. 78% with the femoral approach. Clinical outcomes were quite similar with respect to death (6 vs. 6%), reocclusion (10 vs. 14%), and emergency coronary bypass surgery (5 vs. 6%). Baseline hematocrit was 43.9 +/- 4.4 and 43.5 +/- 4.8, respectively with a nadir of 32.9 +/- 5.6 vs. 33.0 +/- 5.4. The need for vascular repair occurred in 1% vs. 3% of patients and retroperitoneal hemorrhage was documented in 1% vs. 1% of patients. This study indicates that in the hands of experienced operators the transbrachial approach to acute coronary intervention in the acute phase of treatment with thrombolytic therapy can be used with equal risks and efficacy as the femoral approach.

Reinfarction after thrombolytic therapy for acute myocardial infarction followed by conservative management: incidence and effect of smoking

A group of 456 consecutive patients seen less than or equal to 6 h after the onset of acute myocardial infarction associated with ST segment elevation received thrombolytic therapy and were followed up for 12 months. Intravenous streptokinase was given to 315 patients and recombinant tissue-type plasminogen activator (rt-PA) to 141 patients. Reinfarction rate and risk factors for reinfarction were assessed. Management after thrombolysis was conservative; revascularization procedures were reserved for patients with symptoms refractory to medical therapy or for those with left main coronary artery stenosis. Coronary artery surgery or angioplasty was performed in only 3.7% of patients during the first 30 days after thrombolysis and in only 8.6% by 1 year. Most patients (79%) underwent coronary arteriography. Twenty-six patients (5.7%) exhibited signs of threatened reinfarction at 1 month after thrombolytic therapy as did 43 patients (9.4%) by 1 year. Reinfarction was prevented in four of these patients by early readministration of thrombolytic therapy. Multivariate analysis of possible risk factors for reinfarction identified at the time of initial infarction showed current cigarette smoking to be the only predictive factor (reinfarction occurred in 12.5% of smokers versus 6.3% of nonsmokers, p = 0.04). A second analysis of risk factors identified 3 weeks after initial infarction, including the severity of residual stenosis at coronary arteriography and exercise test variables, again showed continued cigarette smoking to be the only factor predictive of reinfarction. Twenty percent of patients who continued to smoke developed reinfarction compared with 5.1% of those who stopped (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Reperfusion therapy in acute myocardial infarction: present status and controversy

Coronary thrombolysis revolutionized the treatment of acute myocardial infarction. Most of the experience was obtained with intravenous use of streptokinase and tissue-type plasminogen activator, the latter being superior to streptokinase in regard to coronary recanalization. Numerous other promising thrombolytic agents are being investigated. Both streptokinase and tissue-type plasminogen activator decreased mortality in large trials; comparison studies in terms of efficacy are presently being performed (GISSI 2). Aspirin is an important adjunct to thrombolytic therapy; it decreased mortality by itself (ISIS 2). Heparin is conventionally used together with thrombolysis. Its efficacy is under study (GISSI 2). Intracranial hemorrhage is the most devastating complication of thrombolysis. With the present dosage regimens, the incidence is approximately 0.5%. Percutaneous transluminal coronary angioplasty in conjunction with thrombolysis accomplished frequent and persistent recanalization of the infarct artery with low mortality, including high risk patients. The TIMI IIB study demonstrated that the results of a "conservative strategy" with aggressive management of recurrent ischemic events were comparable to those of an "invasive strategy." Subgroup analysis should, however, be awaited. High risk patients with low ejection fraction or with shock benefit by early mechanical coronary recanalization. The role of thrombolysis in the "late" stage of transmural myocardial infarction or in the acute ischemic syndrome (unstable angina/non-Q-wave myocardial infarction) is unclear and presently under investigation.

Coronary angioplasty after intravenous streptokinase in acute myocardial infarction: influence of restenosis on clinical outcome and left ventricular function

The importance of recurrence of stenosis on clinical outcome and left ventricular function was studied in a consecutive series of patients with acute evolving myocardial infarction (maximal duration of pain 4 h) and thrombolysis (1.5 x 10(6) units of streptokinase intravenously over 60 min) with recanalized single-vessel disease and subsequent successful coronary angioplasty. Coronary angioplasty was performed in 76 patients between 24 hours and 8 days (mean interval 3.3 days) after thrombolysis and was successful in 86% (65/76). The in-hospital reinfarction rate was 5.2% (2 acute and 2 in-hospital reinfarctions). Repeat angiography after a mean interval of 5.9 months revealed a 39% (24/62) restenosis rate (21 restenoses, 3 reocclusions). Restenoses were associated with significantly more clinical complaints (21% vs. 62%; p less than 0.001). Left ventricular function analysis showed significant improvement in the mean global ejection fraction (6.6 +/- 6.0%; p less than 0.001) and mean regional wall motion of the infarct zone (6.2 +/- 8.2%; p less than 0.01) only in patients without restenosis. Recovery of left ventricular function was more evident in inferior than in anterior wall infarctions. In contrast, patients with restenosis had no change in left ventricular function. Thus, the present study demonstrates the adverse influence of restenosis on recovery of left ventricular function and clinical outcome.