Infarct vessel status after intravenous tissue plasminogen activator and acute coronary angioplasty: prediction of clinical outcome

Endovascular management of acute ischemic stroke: advances in patient and treatment selection

Selection of patients for acute-stroke therapy has traditionally been based on rigid time criteria in clinical trials. Recent advances in radiographic imaging have allowed clinicians to estimate brain physiology and thus utilize radiographic parameters to select patients for acute-stroke therapies. Both a better understanding and the quantification methods of salvageable tissue versus irreversibly injured tissue can help guide clinicians to which treatment modality to utilize. The evolution of endovascular techniques to treat acute stroke has resulted in treatment modalities that include mechanical and chemical methods to revascularize occluded cerebral arteries. Prior technical limitations to accessing distal-cerebral arteries have been partially overcome by modifications in technology. Patient and treatment-modality selection can help reduce hemorrhagic complication rates and also potentially increase revascularization rates, which may translate into improved clinical outcomes. We review the recent advances in radiographic imaging that have advanced patient selection in treating acute ischemic stroke and also consider current endovascular treatment options that are available to interventionalists performing these procedures.

ST variability during the first 4 hours of acute myocardial infarction predicts 1-year mortality

BACKGROUND

Early and complete myocardial reperfusion is the goal when treating a patient with acute myocardial infarction. To achieve this in each individual, an on-line, accurate, easily handled and preferably noninvasive technique to monitor flow alterations is needed. Recurrent ST-segment elevation has been shown to reflect cyclic disturbances in perfusion.

METHODS

We have retrospectively analyzed ST variability in 102 patients with acute myocardial infarction randomized to 100 mg of rt-Pa or placebo. Patients were monitored for 24 hours using vectorcardiography.

RESULTS

Patients alive at one year (86%) had significantly less ST variability during the first four hours: 4.3 versus 7.1 episodes, P = 0.007. Patients having six or more ST episodes showed a 31.3% one-year mortality as compared to no mortality in patients having no ST variability. Furthermore ST variability was reduced by fibrinolysis.

CONCLUSION

Early ST variability detectable in real time is associated with worse outcome.

Percutaneous coronary intervention: recommendations for good practice and training

Cardiologists undertaking percutaneous coronary intervention (PCI) are excited by the combination of patient and physician satisfaction and technological advance occurring on the background of the necessary manual dexterity. Progress and applicability of percutaneous techniques since their inception in 1977 have been remarkable; a sound evidence base coupled with the enthusiasm and ingenuity of the medical device industry has resulted in a sea change in the treatment of coronary heart disease (CHD), which continues to evolve at breakneck speed. This is the third set of guidelines produced by the British Cardiovascular Intervention Society and the British Cardiac Society. Following the last set of guidelines published in 2000, we have seen PCI activity in the UK increase from 33,652 to 62,780 (87% in four years) such that the PCI to coronary artery bypass grafting ratio has increased to 2.5:1. The impact of drug eluting stents has been profound, and the Department of Health is investigating the feasibility of primary PCI for acute myocardial infarction. Nevertheless, the changes in the structure of National Health Service funding are likely to focus our attention on cost effective treatments and will require physician engagement and sensitive handling if we are to continue the rapid and appropriate growth in our chosen field. It is important with this burgeoning development now occurring on a broad front (in both regional centres and district general hospitals) that we maintain our vigilance on audit and outcome measures so that standards are maintained for both operators and institutions alike. This set of guidelines includes new sections on training, informed consent, and a core evidence base, which we hope you will find useful and informative.

Clinical implications of early ST-segment variability. A report from the ASSENT 2 ST-monitoring sub-study

OBJECTIVES

Evolution of the ST-segment during acute myocardial infarction has been shown to yield more information on prognosis than invasive measurements. By continuous ST-monitoring even very occasional dynamic changes can be analysed. We have recently suggested these variations to be of prognostic importance and possibly reflect individual abilities to deal with a vascular event. We wanted to confirm these findings.

METHODS

Four hundred and forty-eight patients were included in the vectorcardiographic sub-study of the second Assessment of Safety and Efficacy of a New Thrombolytic (ASSENT 2) trial. Patients underwent 24 h of ST-monitoring. ST-trend curves were blindly analysed by two independent observers.

RESULTS

ST-variability, defined as an increase of the ST-segment shift of > or = 25 microV for 2 min or more, was found to predict death, reinfarction at 30 days or urgent revascularization. By combining variability with resolution of the ST-segment elevation we could identify a high-risk group with 9.9%, and a low-risk group with only 0.8% 30-day mortality. Hypertensive patients, suggested to have an impaired secretion of endogenous t-PA, expressed significantly more ST-variability, possibly a non-invasive marker of impaired capability of dissolving and preventing thrombi.

CONCLUSION

Small variations in ST-segment shift during the first 4 h of acute myocardial infarction predict worse outcome.

Prognosis of patients with a recurrent acute myocardial infarction before and in the reperfusion era--a national study

BACKGROUND

Patients with recurrent acute myocardial infarction (AMI) are at increased risk for morbidity and mortality. We compared the outcome of patients with recurrent AMI hospitalized in coronary care units in the prereperfusion and reperfusion eras.

METHODS

The study population comprised 2 large-scale cohorts with recurrent AMI: (1) 1415 (24%) of 5839 consecutive patients with AMI hospitalized in 1981 to 1983 (Secondary Prevention Reinfarction Israeli Nifedipine Trial [SPRINT] Registry) and (2) 1093 (25%) of 4317 patients with AMI from three national surveys performed in 1992 to 1996.

RESULTS

Patients in the 1990s had significantly lower rates of heart failure and cardiogenic shock. The 7-day mortality declined from 18% in 1981-1983 to 10% in 1992-1996 (adjusted odds ratio [OR] 0.57 [0.44-0.75]), the 30-day mortality rate from 26% to 16% (OR 0.56 [0.44-0.71]), and the 1-year mortality rate from 39% to 26% (adjusted hazard ratio [HR] 0.64 [0.54-0.75]), respectively. In the 1992-1996 cohort, the adjusted risk of 7-day, 30-day, and 1-year mortality for patients with recurrent AMI treated with thrombolysis in comparison to patients without thrombolysis was OR 1.69 (1.07-2.65), 1.52 (1.03-2.23), and HR 1.18 (0.90-1.55), respectively. The mortality rate among patients treated with early percutaneous transluminal coronary angioplasty/coronary artery bypass grafting was 3% versus 12% at 7 days (OR 0.36 [0.16-0.73]), 7% versus 18% at 30 days (OR 0.45 [0.25-0.77]), and 16% versus 29% at 1 year (HR 0.64 [0.46-0.96]), in comparison to patients without revascularization.

CONCLUSION

The prognosis of patients with recurrent AMI improved significantly during the reperfusion era. Although thrombolysis may have a limited therapeutic effect among patients with recurrent AMI, an interventional approach seems more appropriate when indicated. A randomized trial of thrombolysis versus early revascularization is needed in patients with recurrent AMI.

Early, Complete Infarct Vessel Patency: Arriving at a Gold Standard for Future Clinical Investigation in Myocardial Reperfusion

Early clinical trials of thrombolytic therapy in the setting of acute myocardial infarction (AMI) demonstrated that early angiographic reperfusion correlated with improved survival. This supported the open-artery hypothesis that early reperfusion decreases infarct size, improves left ventricular function, and improves survival. Two subsequent comparative thrombolytic trials showed no difference in left ventricular function or survival between agents with different rates of reperfusion. Additionally, reduction in mortality was demonstrated without improvement in left ventricular function and with the late administration of thrombolytic therapy. Therefore, there was a real question as to the importance of infarct vessel patency, and its relation to clinical outcome. This article discusses the various markers of coronary artery patency, their relation to clinical outcome, and how they reflect perfusion at the tissue level. The coronary angiogram gives a snapshot view of the infarct-related artery (IRA) that does not reflect the dynamic process of vessel reocclusion and recanalization. The patent artery is therefore "open" at only a given time frame, and may undergo cyclic or complete reocclusion. Angiographically characterized flow has been demonstrated to be more clinically meaningful. The GUSTO-I trial was designed to test the open-artery hypothesis. This trial confirmed that improved early IRA patency and optimal (TIMI-3) flow correlated with improved survival. The presence of TIMI-3 flow in the IRA has consistently demonstrated significant improvement in patient morbidity and mortality, and conversely, less than optimal, but still "patent" (TIMI-2) flow in the IRA correlates with clinical outcomes observed in patients with occluded infarct vessels. Even TIMI-3 flow in the IRA does not always confirm perfusion of the myocardium at risk. Therefore, the "patent" IRA can be subsequently compromised by intermittent patency, reocclusion, less than TIMI-3 flow, and a "no-reflow" effect at the tissue level. The development of accurate, reliable non-invasive markers of IRA patency is crucial. This would allow a more selective application of invasive and interventional techniques to restore patency to the IRA. The merits and faults of these noninvasive markers are discussed. The ideal gold standard for establishing the adequacy of therapy in AMI is one that could detect rapid, complete, and sustained coronary reperfusion with adequate myocardial perfusion. Current technologic achievements allow an approach to this ideal; however, as of 1997, the coronary angiogram demonstrating TIMI-3 flow represents the clinically proven standard of optimal therapeutic efficacy.

Achieving Optimal Reperfusion without Adjunctive Antithrombotic Therapy: Novel Thrombolytic Dosing Strategies

There is firm evidence that reperfusion therapy, to be effective must establish and maintain coronary arterial blood flow at a level sufficient to allow myocardial perfusion. However, current thrombolytic regimens have clear limitations, including a relatively low capacity to achieve TIMI Grade 3 blood flow and an unacceptable incidence of coronary reocclusion. Although it has been assumed that the key to achieving optimal reperfusion lies with adjunctive antithrombotic therapy, it may be that novel thrombolytics and dosing strategies can address the problem adequately. This possibility is attractive and requires careful consideration.

Improving the Efficacy and Stability of Coronary Reperfusion Following Thrombolysis: Exploring the Thrombin Hypothesis

A major assumption in the treatment of patients with acute myocardial infarction (MI) implies that the speed of coronary arterial reperfusion correlates directly with the overall extent of myocardial salvage, and that the extent of mycardial salvage, in turn, determines the absolute reduction in patient mortality. While a growing experience has made it clear that myocardial salvage-independent (time-independent) mechanisms of benefit also exist, few would argue with the hypothesis that the greatest benefit derived from coronary thrombolysis occurs with early (time-dependent) treatment. Thus, improvements in the efficacy of reperfusion and the stability of reperfusion are likely to have considerable impact on patient outcome.

Abnormal coronary flow in infarct arteries 1 year after myocardial infarction is predicted at 4 weeks by corrected Thrombolysis in Myocardial Infarction (TIMI) frame count and stenosis severity

Because 24% to 30% of patent infarct-related arteries occlude in the year following thrombolytic therapy for acute myocardial infarction, angiographic factors including corrected Thrombolysis in Myocardial Infarction (TIMI) frame count which may predict abnormal infarct-artery flow, require definition. We examined changes in coronary flow and infarct-artery lesion severity by computerized quantitative angiography over 1 year in 154 patients with a patent infarct-related artery 4 weeks after myocardial infarction. These patients were randomized to receive either ongoing daily therapy of 50 mg aspirin and 400 mg dipyridamole, or placebo. All angiograms were interpreted blind in our core angiographic laboratory. Infarct-artery flow, assessed by corrected TIMI frame counts, was normal (< or = 27) in 46% and 45% of patients at 4 weeks and 1 year, respectively. At 4 weeks, patients with corrected TIMI frame counts < or = 27 had higher ejection fractions (60+/-11% vs 56+/-12%; p = 0.04) than those with corrected TIMI frame counts >27. On multivariate analysis, corrected TIMI frame count and stenosis severity were predictive of late abnormal infarct-artery flow (TIMI 0 to 2 flow, both p <0.01). Only stenosis severity at 4 weeks predicted reocclusion at 1 year (p <0.0001). Aspirin and dipyridamole had no effect on flow or reocclusion. Thus, corrected TIMI frame count and stenosis severity at 4 weeks was highly correlated with infarct-artery flow at 1 year.

The role of antegrade and collateral flow in relation to left ventricular function post-thrombolysis

The aim of the study was to analyze the relationship between antegrade and collateral flow degree to the "culprit" coronary artery, and between both variables and left ventricular systolic function. We analyzed five hundred patients with acute myocardial infarction, treated prospectively and consecutively within 6 h of evolution with intravenous streptokinase. The degree of antegrade (0-3) and collateral blood flow (0-3) were correlated with 18 other variables.

RESULTS

(a) By simple regression analysis, antegrade flow degree correlated positively (p < 0.0001), and collateral flow degree negatively (p = 0.0073) with left ventricular ejection fraction; (b) By multiple regression analysis, antegrade flow degree (p = 0.0032), but not collateral flow degree (p > 0.1), correlated independently with left ventricular ejection fraction; (c) In the subgroup of patients with occluded "culprit" coronary artery, the mean ejection fraction was significantly higher for those with collateral flow 3 (60.2% +/- 13.3 in relation to those with collateral flow < 3 (53.9% +/- 13.1, p = 0.032, 95% CI. 11.96 to (0.53%). In conclusion, antegrade coronary flow degree, but not collateral flow degree, correlated significantly and independently with left ventricular ejection fraction. However, in the subgroup of patients with occluded "culprit" coronary artery, collateral flow 3 led to better left ventricular systolic function, in relation to collateral flow < 3.

Coronary Palmaz-Schatz stent implantation in acute myocardial infarction

OBJECTIVE

To investigate the feasibility of coronary stenting in acute myocardial infarction.

DESIGN

Prospective observational study.

PATIENTS

80 patients undergoing direct balloon angioplasty for acute myocardial infarction who had coronary Palmaz-Schatz stents implanted during a 3 year study period. Indications for stenting were abrupt reocclusion, large dissection with threatened reocclusion, and failure to achieve brisk flow of contrast by angioplasty alone.

INTERVENTIONS

After stenting, 50 patients were treated by conventional anticoagulation and 30 patients received antiplatelet therapy with aspirin and ticlopidine.

MAIN OUTCOME MEASURES

Death and subacute reocclusion within two weeks.

RESULTS

Coronary stenting fully restored vessel patency in 79 patients (98.8%). 10 of 14 patients with symptoms of Killip class IV on admission were discharged from hospital alive. Three of the 66 patients with symptoms of Killip classes I-III died in hospital. Repeat angiography in 59 of these patients, showed 3 symptomatic and 2 silent reocclusions (reocclusion rate 8.5%). No stent thromboses were detected in patients treated with ticlopidine.

CONCLUSIONS

Coronary stenting is a safe and effective treatment for complicated direct balloon angioplasty in acute myocardial infarction. In patients with symptoms of Killip classes I to III the risk of subacute reocclusion is comparable to that of bail-out stenting after elective balloon angioplasty.

Early hospital discharge after direct angioplasty for acute myocardial infarction

To determine the feasibility and safety of early hospital discharge after myocardial infarction, we reviewed a 3-yr experience with direct angioplasty: 204 patients had direct angioplasty with in-hospital mortality of 3.4%. Of these patients, 125 were discharged < 5 days after infarction and 98% of these were available for 30-day follow-up. There was one early death (0.8% mortality), two early readmissions without complications, and three late readmissions. Thus early hospital discharge a mean of 3.4 days after infarction can be achieved in > 60% of patients undergoing direct angioplasty with no significant early complications and excellent 30-day survival (99.2%).

Angiographic predictors of reocclusion after thrombolysis: results from the Thrombolysis in Myocardial Infarction (TIMI) 4 trial

OBJECTIVES

This study attempted to determine which lesion characteristics are associated with reocclusion by 18 to 36 h.

BACKGROUND

Reocclusion of the infarct-related artery after successful reperfusion is associated with significant morbidity and up to a threefold increase in mortality.

METHODS

Two hundred seventy-eight patients with acute myocardial infarction were randomized to receive either anisoylated plasminogen streptokinase activator complex (APSAC) or recombinant tissue-type plasminogen activator (rt-PA) or their combination. Culprit arteries were assessed for Thrombolysis in Myocardial Infarction (TIMI) flow grade, lesion ulceration, thrombus, collateral circulation and eccentricity. Minimal lumen diameter, percent diameter stenosis and lesion irregularity (power) were calculated using quantitative angiography.

RESULTS

Reocclusion was observed more frequently in arteries with TIMI 2 versus TIMI 3 flow (10.4% vs. 2.2%, p = 0.003), in ulcerated lesions (10.7% vs. 3.0%, p = 0.009) and in the presence of collateral vessels (18.2% vs. 5.6%, p = 0.03). Similar trends were observed for eccentric (7.3% vs. 2.3%, p = 0.06) and thrombotic (8.4% vs. 3.3%, p = 0.06) lesions. Reocclusion was associated with more severe mean percent stenosis (77.9% vs. 73.9%, p = 0.04). Lesion length, reference segment diameter and Fourier measures of lesion irregularity were not associated with reocclusion.

CONCLUSIONS

Several simply assessed angiographic variables, such as the presence of TIMI grade 2 flow, ulceration, collateral vessels and greater percent diameter stenosis at 90 min after thrombolytic therapy, are associated with significantly higher rates of infarct-related artery reocclusion by 18 to 36 h and may aid in identifying the subset of patients who are at significantly higher risk of early reocclusion and who potentially warrant further early pharmacologic or mechanical intervention.

A new look at coronary angiograms: plaque morphology as a help to diagnosis and to evaluate outcome

Characterization of plaque morphology can provide useful information beyond those generally yielded by the more traditional methods of interpretation of coronary angiograms based on assessment of severity of stenoses and number of diseased vessels. Focus on the culprit coronary lesion in acute myocardial infarction and in unstable angina allows recognition of the complex plaque and of presence of endoluminal thrombi that are closely associated to the mechanisms of the disease. Response to treatment in these clinical situations, and the healing process can be assessed by repeated opacifications of the lesion. The presence of a residual thrombus is associated with a worse clinical outcome and also a higher risk of complication if coronary angioplasty is performed. The prognostic information derived from the morphologic analysis extends to the chronic phase of the disease. The extent score of disease, defined as the sum of coronary artery segments showing a narrowing of any severity marks more severe disease and predicts future progression. Severity of stenosis is also a predictor. More severe lesions will occlude more frequently but most often without clinical consequences. Occlusion of less severe stenosis, on the other hand, leads to acute myocardial infarction or to the other manifestations of acute coronary syndromes. Other morphologic features are also associated with a higher risk of myocardial infarction. These include a geometry favoring blood flow separation and turbulence such as acute inflow and outflow angles of the stenosis and presence of a division within its vicinity. This new look at coronary angiograms may help orient therapy. Patients with angina and a significant stenosis will profit from a corrective intervention. Others with a high extent score should receive a comprehensive program for control of risk factors. Patients with a lesion of borderline significance at risk of activation should be closely monitored, and when clinical symptoms evolve, receive more intensive antithrombotic therapy. Quantification of the morphologic characteristics of the plaque, coupled to new techniques for endovascular imaging should lead in the future to better diagnostic and better risk stratification.

Culprit lesion morphology and stenosis severity in the prediction of reocclusion after coronary thrombolysis: angiographic results of the APRICOT study. Antithrombotics in the Prevention of Reocclusion in Coronary Thrombolysis

OBJECTIVES

In the APRICOT study (Antithrombotics in the Prevention of Reocclusion In Coronary Thrombolysis), we sought to determine whether angiographic characteristics of the culprit lesion could predict reocclusion after successful thrombolysis and to analyze the influence of three antithrombotic treatment regimens.

BACKGROUND

After successful thrombolysis, reocclusion is a major problem. Prediction of reocclusion by angiographic data and choice of antithrombotic treatment would be important for clinical management.

METHODS

After thrombolysis, patients were treated with intravenous heparin until initial angiography was performed within 48 h. Patients with a patent infarct-related artery were eligible. Three hundred patients were randomly selected for treatment with coumadin, aspirin (300 mg once daily) or placebo. Patency on a second angiographic study after 3 months was the primary end point of the study.

RESULTS

Reocclusion rate was 25% with aspirin, 30% with coumadin and 32% with placebo (p = NS). Lesions with > 90% stenosis reoccluded more frequently (42%) than did those with < 90% stenosis (23%) (p < 0.01). Reocclusion rate of smooth lesions was higher (34%) than that of complex lesions (23%) (p < 0.05). In lesions with < 90% stenosis, the reocclusion rate was lower with aspirin (17%) than with coumadin (25%) or placebo (30%) (p < 0.01). In complex lesions, the reocclusion rate was lower with aspirin (14%) than with coumadin (32%) or placebo (25%) (p < 0.02). Multivariate analysis showed only stenosis severity > 90% to be an independent predictor of reocclusion (odds ratio 2.31, 95% confidence interval 1.28 to 4.18, p = 0.006).

CONCLUSIONS

Angiographic features of the culprit lesion after successful coronary thrombolysis significantly predict the risk of reocclusion: high grade (> 90%) stenoses reoccluded more frequently. Aspirin was effective only in complex and less severe lesions (< 90% stenosis). These findings should prompt investigation of the effects of an aggressive approach to patients with severe residual stenosis.

Bedside cardiology and thrombolysis

The study by Christian et al. (37) provides useful clinical information for the management of the patient with myocardial infarction with thrombolytic therapy. 1) Complete resolution of chest pain during the infusion of an intravenous thrombolytic agent suggests reperfusion and myocardial salvage. Initial conservative medical management should be considered in these patients especially if serial ECGs show a progressive and rapid downward defection of the ST segment. 2) Patients presenting within 6 h after the onset of infarction, who are pain free, may still benefit from thrombolysis if their ECGs show persistent ischemia. 3) In the remaining patients in whom chest pain does not resolve completely during thrombolytic therapy, management, whether continued medical or invasive strategy, should be individualized and dictated by the extent of myocardium at risk (i.e., by the number of ECG leads showing ST segment elevation), the response of the ST segment to thrombolysis and, most important, the clinical status of the patient.

Illusion of reperfusion. Does anyone achieve optimal reperfusion during acute myocardial infarction?

Thrombolytic therapy significantly improves the natural history of acute myocardial infarction, but recent data suggest that current reperfusion strategies have yet to realize the maximum potential for reduction of mortality and salvage of ventricular function. Coronary patency rates as high as 85% assessed by angiography 90 minutes after initiation of treatment greatly overestimate the efficacy of thrombolytic regimens, as this conventional angiographic "snapshot" view does not satisfactorily reflect the dynamic processes of coronary artery recanalization and reocclusion or the adequacy of myocardial perfusion. In fact, only the unusual patient appears to achieve optimal reperfusion for acute myocardial infarction, with a substantial deterioration of benefit in many patients due to insufficiently early or rapid recanalization, incomplete patency with TIMI grade 2 flow or critical residual coronary stenoses, absence of myocardial tissue reflow despite epicardial artery patency, intermittent coronary patency, subsequent reocclusion, or reperfusion injury. Recently developed techniques to critically assess the quality of reperfusion, coupled with the introduction of novel pharmacological agents and an improved understanding of the roles and mechanisms of existing thrombolytic and adjunctive drugs, have provided the opportunity to overcome many of the present limitations of reperfusion therapy. Emerging strategies to achieve optimal reperfusion are directed at enhancement of the velocity and quality of thrombolysis, amelioration of the adverse effects of reperfusion, and use of alternative pathways to myocardial salvage.

Emergency coronary angioplasty for acute myocardial infarction: predictors of early occlusion of the infarct-related artery after balloon inflation

THE FACTORS RESPONSIBLE FOR EARLY OCCLUSION OF THE INFARCT VESSEL AFTER emergency percutaneous transluminal coronary angioplasty (PTCA) were retrospectively examined in 191 patients with acute myocardial infarction. During the 24-hour period after the initial balloon inflation, 47 patients (25%) had occlusion of the vessel (occlusion group), whereas 144 did not (nonocclusion group). The former patients immediately underwent repeat PTCA, which was successful in 37. Univariate correlates of early occlusion were a shorter time interval between the onset of symptoms and PTCA (3.5 +/- 2.2 vs 4.5 +/- 2.9 hours, p = 0.025), right coronary artery involvement (53% vs 30%, p = 0.015), prior thrombolytic therapy (49% vs 32%, p = 0.035), and undersized inflation (43% vs 17%, p < 0.001). With multivariate analysis the three independent predictors were undersized inflation (p < 0.001), right coronary artery involvement (p = 0.004), and a shorter time interval until PTCA (p = 0.011). Thus patients undergoing early PTCA and having right coronary artery involvement appear to be at greater risk of having early occlusion. Thrombolytic agents and undersized inflation may also play an important role in its development.

Angiographic validation of bedside markers of reperfusion

OBJECTIVES

We sought to validate with coronary angiography several primary and ancillary markers of reperfusion.

BACKGROUND

The availability of bedside markers of reperfusion is of major importance in the thrombolytic therapy of acute myocardial infarction. However, the reliability of current markers is still controversial.

METHODS

Changes in chest pain, ST segment elevation and heart rate and rhythm were assessed every 5 to 10 min for up to 3 h after initiation of recombinant tissue-type plasminogen activator therapy in 82 patients with acute myocardial infarction. Coronary angiography was performed within 24 h.

RESULTS

At angiography, 69 of the 82 patients had a patent infarct-related artery with Thrombolysis in Myocardial Infarction trial (TIMI) grade 3 flow and a rapid and progressive decrease in chest pain and ST elevation. The pain resolved in 24 +/- 23 min (range 3 to 50). The ST elevation decreased by > or = 50% within 16 +/- 14 min (range 5 to 41). Accelerated idioventricular rhythm developed in 49% of patients and sinus bradycardia in 23%; conduction abnormalities and atrial fibrillation resolved. All markers appeared in close temporal proximity to the onset of an abrupt increase in plasma creatine kinase (CK) and CK-MB isoenzyme activity, a previously validated marker of the time of reperfusion. Before its final resolution, ST elevation transiently decreased and increased in 58% of patients. Comparison of one pretreatment and one posttreatment electrocardiogram significantly reduced the reliability of ST segment change as a marker of reperfusion. In 13 of 82 patients, the infarct-related artery demonstrated TIMI grade < or = 2 flow; in 9, pain and ST elevation did not lessen and CK and CK-MB activity showed no abrupt increase. The remaining four patients initially demonstrated a decrease in pain and ST elevation; however, within 3 h and before angiography, the recurrence of pain and ST elevation suggested reocclusion.

CONCLUSIONS

A rapid and progressive decrease in pain and ST elevation is a reliable marker of reperfusion with TIMI grade 3 flow. Because ST elevation and pain often fluctuate before undergoing final resolution with reperfusion, frequent or continuous monitoring of ST elevation is essential for reliable recognition of the fact and time of reperfusion. Accelerated idioventricular rhythm and episodes of sudden sinus bradycardia, although specific to reperfusion, do not occur in all patients with reperfusion.

Invasive versus conservative strategy after thrombolytic therapy for acute myocardial infarction in patients with antecedent angina. A report from Thrombolysis in Myocardial Infarction Phase II (TIMI II)

OBJECTIVES

This study was designed to assess the possibility that a subgroup of patients at high risk for recurrent ischemia and reinfarction after thrombolytic therapy might benefit from early intervention.

BACKGROUND

The Thrombolysis in Myocardial Infarction Phase II (TIMI II) study recently concluded that an obligatory invasive strategy after thrombolytic therapy offered no advantage over a more conservative strategy.

METHODS

Data from the 3,534 patients enrolled in the TIMI II trial were analyzed to determine whether a history of antecedent angina before myocardial infarction identifies patients at high risk for subsequent ischemia and whether these patients might benefit from an invasive strategy.

RESULTS

Within the TIMI II population, antecedent angina identified patients at increased risk for recurrent chest pain in the hospital (32.3% vs. 22.1%, p < 0.001) and recurrent infarction during the 1st year of follow-up (11.2% vs. 7.9%, p = 0.001) compared with that of patients without antecedent angina. Among patients assigned to the invasive strategy, coronary arteriography revealed that those with antecedent angina had a more severe residual stenosis of the infarct-related artery after thrombolytic therapy (77.1 +/- 0.7% vs. 73.0 +/- 0.9%, p < 0.001) and more multivessel disease (37.9% vs. 26.4%, p < 0.001). The clinical outcome of the patients with antecedent angina assigned randomly to either the invasive or the conservative strategy were compared. The invasive strategy patients had a slightly lesser incidence of recurrent chest pain in the hospital (29.9% vs. 34.8%, p = 0.13) and more negative (normal) findings on exercise tolerance tests (24.7 vs. 18.9%, p = 0.003), but there was no difference between the treatment strategies in the end point variable of recurrent myocardial infarction or death.

CONCLUSIONS

These data demonstrate that antecedent angina identifies patients at increased risk for recurrent ischemic events after thrombolytic therapy. However, similar to the results for the overall population, the invasive strategy does not alter the risk of reinfarction or death compared with the conservative approach.

Recombinant tissue plasminogen activator in acute myocardial infarction in the Chinese in Hong Kong

Eighty-nine consecutive Chinese patients (69 males, 20 females) with acute myocardial infarction treated by 100 mg recombinant tissue plasminogen activator (7 intracoronarily, 82 intravenously) at 3.7 +/- 1.0 h after onset, and intravenous heparin or dipyridamole therapy started at 3 h, were studied prospectively. Their mean age was 59.6 +/- 10.6 yr. Forty-six patients (51.7%) had anterior and 39 patients (43.8%) had inferior infarcts. Clinical evidence of reperfusion were seen in 63 patients (70.8%), while new complications included hypotension (5.6%), heart failure (6.7%), cardiac arrhythmias (76.4%) majority of which are related to reperfusion and self-remitting, haematoma around vascular access sites (23.6%), melaena (3.3%) and cerebral infarction (2.2%). Maximal changes in coagulation profiles were seen at 3 h, including a decrease in fibrinogen by 64.2% and an increase in fibrin degradation products by 47 times. The changes in haemostatic variables were not related to body weight or bleeding complications. Nine patients (10.1%) had recurrence of angina and 6 patients (6.9%) died due to pump failure and reinfarction. Angiogram at 14 days confirmed TIMI 2 or 3 patency of infarct-related arteries in 63 out of 73 (86.3%) patients, with a mean global ejection fraction of 52.5 +/- 12.4%. Nearly all survivors could maintain class I-II functional status after discharge. The safety and promise of recombinant tissue plasminogen activator for acute myocardial infarction in the Chinese were confirmed.

Changes in myocardial echo amplitude during reversible ischaemia in humans

OBJECTIVE

This study investigated the changes in regional myocardial ultrasonic backscatter, measured as myocardial echo amplitude, that occur during reversible myocardial ischaemia in humans.

DESIGN

Left anterior descending coronary angioplasty was used to produce reversible myocardial ischaemia in human subjects. Regional myocardial echo amplitude was studied in the interventricular septum and left ventricular posterior free wall before, during, and after coronary occlusion with the angioplasty balloon. Wall motion analysis of the left ventricle was performed from simultaneous cross sectional echocardiographic imaging. Patients were studied prospectively.

PATIENTS

Six patients (mean age 56 (SD 11), range 46 to 69 years) with single vessel, left anterior descending coronary artery stenoses, were investigated during elective coronary angioplasty. A total of 11 balloon inflations were studied.

SETTING

All patient studies were performed at Harefield Hospital. Echo amplitude analysis was performed at the Royal Brompton Hospital.

INTERVENTIONS

Angioplasty was performed by the usual procedure at Harefield Hospital for elective coronary angioplasty. All routine medication including beta blockers and calcium antagonists were continued. Inflation pressures were up to 12 atm (1212 kPa) and mean inflation time ranged from 30 to 120 (86 (31)) s. In four studies the first inflation was examined, in three the second, in two the third, and in one each the fourth and fifth inflations. Echo amplitude and cross sectional echo-cardiographic studies were recorded with a 3.5 MHz Advanced Technology Laboratories (ATL) (720A/8736 series) mechanical sector scanner and an ATL Mark III (860-1 series) echocardiograph system with 45 dB logarithmic grey scale compression.

MAIN OUTCOME MEASURES

Regional echo amplitude was examined in four regions of the left ventricle--namely, the basal and mid-septum, and basal and mid-posterior wall. Consecutive end diastolic and end systolic frames were analysed and cyclic variation was determined as the difference between the level of echo amplitude at end diastole and at end systole. Measurements were made before balloon inflation, at peak inflation, and after balloon deflation. Regional wall motion and systolic wall thickening were analysed qualitatively.

RESULTS

Before balloon inflation, cyclic variation in echo amplitude was noted in all regions (basal septum, 2.4 (SD 1.1) dB; mid-septum, 2.5 (1.1) dB; basal posterior wall, 3.3 (2.1) dB; mid-posterior wall, 3.9 (1.6) dB). During balloon inflation there was a significant fall in cyclic variation to 0.4 (0.9) dB (p < 0.0002) in the mid-septum. This was predominantly owing to an increase in end systolic echo amplitude from 5.4 (2.0) dB to 9.3 (1.9) dB (p < or = 0.01). This was associated with the development of severe hypokinesis or akinesis in the mid-septum. No significant changes in echo amplitude occurred in the three other regions examined. Changes were completely reversed after balloon deflation.

CONCLUSIONS

These results suggest a causal relation between occlusion of the supplying coronary artery and blunting of myocardial echo amplitude cyclic variation. It is suggested that balloon occlusion produced myocardial ischaemia. The resultant impairment of myocardial contraction then caused a blunting of cyclic variation in echo amplitude. The results of this study provide further data about the ability of quantitative studies of ultrasonic backscatter to identify alterations in the myocardium during injury.

Pharmacokinetics of tissue-type plasminogen activator during acute myocardial infarction in men. Effect of a prostacyclin analogue

BACKGROUND

Coronary reocclusion complicates the thrombolytic therapy of acute myocardial infarction despite the routine use of aspirin. This is consistent with experimental studies demonstrating that multiple agonists, in addition to thromboxane A2, mediate the platelet activation underlying reocclusion. Consequently, a more potent antiplatelet therapy with a broader spectrum of activity than aspirin may be required in this setting. Prostacyclin and its more stable analogue, iloprost, inhibit platelet aggregation to all known agonists and exert an additional effect over aspirin alone. Experiments in animal models have demonstrated, however, that iloprost increases the clearance of tissue-type plasminogen activator (t-PA) and impairs thrombolysis in vivo. This study examines whether a similar interaction occurs in humans.

METHODS AND RESULTS

Twelve patients with acute myocardial infarction received t-PA intravenously, 60 mg in the first hour and a maintenance infusion of 13.3 mg/hr for 3 hours. Patients were assigned in a double-blind fashion to iloprost (2 ng/kg/min) or placebo following the initial 90 minutes of the maintenance infusion of t-PA. Iloprost decreased mean arterial blood pressure (-10 +/- 2.9 mm Hg, p less than 0.05) but did not alter heart rate. Steady-state plasma iloprost concentration was 591 +/- 64 pmol/l. At this concentration, iloprost markedly inhibited platelet aggregation in vitro, particularly in the presence of aspirin. Steady-state clearance of t-PA was unchanged by iloprost (454 +/- 65 versus 443 +/- 136 ml/min in controls, p = NS). Furthermore, neither elimination kinetics nor plasma protein binding of t-PA was altered by iloprost.

CONCLUSIONS

At plasma levels that exert a potent antiplatelet effect, iloprost did not alter the pharmacokinetics of t-PA in men. Prostacyclin analogues may prove useful as an adjunct to plasminogen activators, particularly in patients at high risk for thrombotic reocclusion.

Thrombolysis, anticoagulation, and reocclusion

Based on apparent higher recanalization rates of the infarct-related artery, preferential use of thrombolytic agents with high clot specificity has been proposed for treating patients with acute myocardial infarction. In the Thrombolysis in Myocardial infarction (TIMI-I) and European Cooperative Group studies, higher reperfusion rates were observed with alteplase compared with streptokinase, causing many to assume that the former would achieve a greater reduction in early hospital mortality. However, the Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico (GISSI-2) and its associated International Study Group failed to show any differences in 15-day mortality between these agents in more than 20,000 patients. This apparent lack of correlation between reperfusion rates and early mortality may be explained in part when one considers that recanalization or patency rates measured at a given point in time, such as 90 minutes after onset of therapy, fail to define the subsequent vessel status. Early reocclusion is the major reason for this and is a major limitation to the clinical efficacy of thrombolytic drugs. Following recanalization, residual fibrin-bound thrombin adherent to the site of arterial injury from plaque rupture strongly promotes rethrombosis. Although antiplatelet and antithrombin agents such as aspirin and heparin help to decrease rethrombosis, these agents are far from ideal. Thrombolytic agents that produce a significantly prolonged systemic thrombolytic state, such as streptokinase and anistreplase, are likely to result in less rethrombosis. Therefore, a systemic fibrinolytic state would appear to be an advantage rather than a disadvantage, particularly because the incidence of intracerebral hemorrhage does not appear to be greater with their use compared with agents producing less systemic fibrinolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet activation in the pathogenesis of unstable angina: importance in determining the response to plasminogen activators

Unstable angina is a clinical syndrome of recurrent myocardial ischemia. In some cases, this reflects episodic platelet activation and coronary thrombosis. Thus, the biosynthesis of thromboxane A2, which is largely derived from activated platelets, is increased, often coincident with chest pain. The major role of platelets in unstable angina may influence the response to plasminogen activators. Platelets increase the resistance of thrombi to lysis, by inducing clot retraction and cross-linking and by releasing inhibitors. Thus, coronary thrombi in unstable angina may be resistant to lysis. Furthermore, both t-PA and streptokinase cause platelet activation and thrombin formation in vivo, possibly via plasmin. Plasmin can activate platelets and factor V directly. These prothrombotic effects of plasminogen activators may limit their activity in unstable angina. At the very least, their therapeutic efficacy may be highly dependent on the coadministration of potent antiplatelet agents and anticoagulants.

A prospective, randomized trial comparing combination half-dose tissue-type plasminogen activator and streptokinase with full-dose tissue-type plasminogen activator. Kentucky Acute Myocardial Infarction Trial (KAMIT) Group

BACKGROUND

The potential benefits of combination thrombolytic agents in the treatment of myocardial infarction remain uncertain. In a small pilot study, we demonstrated that combining half-dose tissue-type plasminogen activator (t-PA) with streptokinase (SK) achieved a high rate of infarct vessel patency and a low rate of reocclusion at half the cost of full-dose t-PA.

METHODS AND RESULTS

We designed a prospective trial in which 216 patients were randomized within 6 hours of myocardial infarction to receive either the combination of half-dose (50 mg) t-PA with streptokinase (1.5 MU) during 1 hour or to the conventional dose of t-PA (100 mg) during 3 hours. Acute patency was determined by angiography at 90 minutes, and angioplasty was reserved for failed thrombolysis. Heparin and aspirin regimens were maintained until follow-up catheterization at day 7. Acute patency was significantly greater after t-PA/SK (79%) than with t-PA alone (64%, p less than 0.05). After angioplasty for failed thrombolysis, acute patency increased to 96% in both groups. Marked depletion of serum fibrinogen levels occurred after t-PA/SK compared with t-PA alone at 4 hours (37 +/- 36 versus 199 +/- 66 mg/dl, p less than 0.0001) and persisted 24 hours after therapy (153 +/- 66 versus 252 +/- 75 mg/dl, p less than 0.0001). Reocclusion (3% versus 10%, p = 0.06), reinfarction (0% versus 4%, p less than 0.05), and need for emergency bypass surgery (1% versus 6%, p = 0.05) tended to be less in the t-PA/SK group. Greater myocardial salvage was apparent in the t-PA/SK group as assessed by infarct zone function at day 7 (-1.9 SD/chord versus -2.3 SD/chord after t-PA alone, p less than 0.05). In-hospital mortality (6% versus 4%) and serious bleeding (12% versus 11%) were similar between the two groups.

CONCLUSIONS

These results suggest that a less expensive regimen of half-dose t-PA with SK yields superior 90-minute patency and left ventricular function and a trend toward reduced reocclusion compared with the conventional dose of t-PA.

The use of intraaortic balloon pumping as an adjunct to reperfusion therapy in acute myocardial infarction. The Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) Study Group

To assess the risk and possible benefits of use of the percutaneous IABP in patients given thrombolytic therapy as treatment for acute myocardial infarction, we prospectively evaluated 810 consecutive patients entered into the TAMI trials. During hospitalization the 85 patients treated with the IABP had more cardiac risk factors, were slightly older (58 vs 56 years), and more often had anterior infarction (62% vs 38%). At acute cardiac catheterization, patients treated with the IABP also had more multivessel coronary disease (67% vs 43%), more frequent TIMI grade 0 or 1 flow (44% vs 28%), lower global ejection fraction (40% vs 52%), and worse regional infarct (-3.2 vs -2.5 SD/chord) and noninfarct (-0.67 vs +0.36 SD/chord) zone function. Although mortality rates (32% vs 4%) and in-hospital complications were greater in patients treated with the IABP, a greater improvement in global (delta ejection fraction: +1.9% vs +0.7%) and noninfarct zone (delta SD/chord: +0.11 vs -0.09) left ventricular function was observed in patients treated with the IABP at 1-week follow-up angiography. In addition, no reinfarction or reocclusion of the infarct-related artery occurred while patients were being treated with the IABP. These results suggest that the IABP may have a specific role after thrombolytic therapy in treating patients at high risk for reocclusion or at high risk for hemodynamic deterioration because of large infarction or critical stenoses in coronary vessels supplying the noninfarct zone.

Prediction of degree of residual stenosis in coronary thrombolysis

In order to predict the residual stenosis in coronary thrombolysis, the factors easily obtained from clinical history--age, gender, history of angina before acute myocardial infarction (AMI), family history, hypertension, diabetes, hypercholesterolemia, smoking, and interval between onset of AMI and recanalization--were observed in 114 patients with successful coronary thrombolysis. In 55 patients with angina before AMI, 29 patients had residual stenosis greater than or equal to 75% and 26 patients had residual stenosis less than 75%. In 59 patients without angina before AMI, 15 patients had residual stenosis greater than or equal to 75%, and 44 patients had residual stenosis less than 75%. The presence or absence of angina before AMI was the main variable that discriminated the groups of residual stenosis of more or less than 75%, which was the only significant independent variable to predict the residual stenosis. These data suggest that the presence of angina pectoris before AMI is likely to be associated with a significant degree of residual stenosis after thrombolysis.

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)

Critically ischemic myocardium in clinically stable patients following thrombolytic therapy for acute myocardial infarction: potential implications for early coronary angioplasty in selected patients

The utility of post-thrombolysis, rest-redistribution thallium (TI)-201 scintigraphy was studied in 32 patients with a first myocardial infarction who were clinically stable following reperfusion. Day 1 scintigraphy obtained 5 +/- 4 hours (range 1 to 16) after thrombolysis revealed an average perfusion defect of 6.5 +/- 2.6 segments (range 1 to 11). There was a total of 208 abnormal segments, 137 of which were nonreversible at 4 hours, 50 of which were fully or partially reversible, and 21 of which had a reverse redistribution pattern. Repeat TI-201 scintigraphy on day 10 revealed significantly smaller perfusion defects of 4.9 +/- 2.4 segments (range 0 to 9) with improvement predominantly of the day 1 reversible segments, and the improvement in segmental perfusion correlated with better regional left ventricular function. Twenty-nine (58%) of the 50 reversible segments normalized by day 10, and 11 (22%) improved, whereas only 16 (12%) of 137 nonreversible segments had normalized by day 10, only 9 had (6%) improved and 112 (82%) were unchanged (p less than 0.001 reversible versus nonreversible). There was no significant change in segments with a pattern of reverse redistribution. The improvement of reversible segments was greater in the 16 patients who underwent coronary angioplasty (PTCA) during the interval between the two scintigrams than in the 16 who did not. All 24 reversible segments in the PTCA group improved or normalized by day 10 compared with 16 (62%) of 26 reversible segments in the No PTCA group (p less than 0.001). Furthermore, 8 of the 10 reversible segments in the No PTCA group that did not improve actually deteriorated and became nonreversible by day 10. The minor improvement of nonreversible segments was not related to PTCA. Consistent with the findings in individual segments, the 19 patients with a reversible component on the day 1 TI-201 scintigram had significantly greater improvement in perfusion defect by day 10 than the 13 patients without a reversible component (37 +/- 33% versus 7 +/- 22% decrease in perfusion defect severity, p less than 0.05), and this improvement was greatest in the 10 patients with a reversible component who underwent PTCA. In contrast, PTCA had no impact on the perfusion defect in the 13 patients without a reversible component. Our data suggest that following thrombolytic therapy for acute myocardial infarction, viable myocardium in the reperfused zone may remain ischemic, as manifested by a reversible pattern of TI-201 redistribution at rest, and thus may be in jeopardy of gradual progression to necrosis.(ABSTRACT TRUNCATED AT 400 WORDS)

After coronary thrombolysis and reperfusion, what next?

Thrombolytic therapy for the removal of intravascular thrombi was introduced when streptokinase was first given to humans 40 years ago, the same year the American College of Cardiology was founded. Streptokinase was first administered to patients with acute myocardial infarction in 1959. Today, thrombolytic therapy has been established to offer significant benefits to patients with acute myocardial infarction provided they are brought to medical attention early enough after the onset of symptoms. The two major agents, streptokinase and recombinant tissue-type plasminogen activator (rt-PA), have been shown to result in reperfusion of infarct-related arteries, to salvage ischemic myocardium, to improve myocardial performance and to reduce mortality. In spite of these impressive gains, this novel therapy has shortcomings. The interval from the start of thrombolytic treatment to coronary reperfusion varies significantly from patient to patient and may, at times, be too long to produce a real benefit in terms of salvage of ischemic myocardium. The rate of reocclusion lies somewhere between 10% and 20% and appears not to be influenced by concomitant heparin anticoagulation. The rate of bleeding complications even with the "fibrin-specific" rt-PA is higher than anticipated and may range from 10% to 30%. As a consequence, intensive efforts are being directed at the development of improved thrombolytic agents and for adjunctive therapy evaluating better anticoagulants than heparin and better antiplatelet agents than aspirin. This review is a status report summarizing where we are in thrombolytic therapy in acute myocardial infarction, where we need to improve treatment results and what is being done mainly at the preclinical level to bring about such improvements.

A new thrombolytic regimen for acute myocardial infarction using combination half dose tissue-type plasminogen activator with full dose streptokinase: a pilot study. KAMIT Study Group

Because a previous study utilizing a combination of recombinant tissue-type plasminogen activator (rt-PA) and urokinase demonstrated reduced reocclusion rates compared with rates obtained with rt-PA alone, this study was conducted to determine whether the combination of rt-PA and streptokinase might achieve similar results at reduced cost. Forty patients with acute myocardial infarction were treated with a 1 h infusion of rt-PA (50 mg) and streptokinase (1.5 million U) administered within 6 h (mean 3.6 +/- 1.2) of symptom onset. Emergency coronary arteriography revealed patency of the infarct-related artery in 30 (75%) of 40 patients. With the addition of coronary angioplasty in those who had unsuccessful thrombolytic reperfusion, the early patency rate was increased to 98%. In-hospital mortality rate (2.5%) and the incidence of significant bleeding requiring transfusion (15%) were low. Angiographically documented reocclusion of the infarct vessel occurred in 3 (8%) of 37 patients by day 7. Regional wall motion of the infarct zone improved by 0.9 +/- 0.9 SD/chord (p less than 0.0005), and ejection fraction increased 3.6 +/- 8% units (p less than 0.05) between immediate and day 7 studies. In contrast to the price of full dose rt-PA ($2,300) or rt-PA with urokinase ($3,500), the cost of this regimen was $1,230. This pilot study demonstrates that at half the cost, a combination of half dose rt-PA with full dose streptokinase offers high infarct vessel patency, recovery of ventricular function, a low rate of reocclusion and few bleeding complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Antecedent angina: a predictor of residual stenosis after thrombolytic therapy

Patients with a significant residual stenosis after thrombolytic therapy are believed by many to be at increased risk for repeat ischemic events and may be candidates for prompt angiography and revascularization. To test the hypothesis that patients with antecedent angina (Canadian classes I to IV, greater than or equal to 24 h before myocardial infarction) are more likely to have a significant residual stenosis (greater than or equal to 60% diameter reduction) than are those without antecedent angina, the coronary angiograms of 82 consecutive patients undergoing routine angiography after thrombolytic therapy were reviewed. Compared with the patients without antecedent angina, the group with antecedent angina had an increased mean stenosis (74% versus 58%) and more multivessel disease (44% versus 5%). The sensitivity and specificity of a clinical history of antecedent angina predicting the presence of a significant residual stenosis were 75% and 96%, respectively; the positive predictive accuracy was 98%. These data suggest that antecedent angina can be used to identify a high risk subgroup whose condition may warrant routine coronary angiography.

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.

Primary percutaneous coronary angioplasty: a protagonist's view

The wide variety of reperfusion strategies now available has led to confusion regarding the optimal therapy of patients with acute myocardial infarction. In assessing the comparative efficacy of reperfusion strategies, safety factors, recanalization rates, reocclusion rates, myocardial salvage and improvement in survival must be compared. In this analysis, primary percutaneous transluminal coronary angioplasty (PTCA) compares favorably to intravenous thrombolytic therapy or combination PTCA and thrombolytic therapy as a reperfusion strategy. Primary PTCA has not been reported to cause intracerebral hemorrhage, whereas thrombolytic strategies are associated with an incidence of a 0.2 to 1.4% rate of intracerebral bleeding. Strategies using PTCA have recanalization rates of only 33 to 75%. Disappointingly, a major failure of all reperfusion strategies (including primary PTCA) is a high rate of reocclusion and reinfarction. Primary PTCA is associated with a 7 to 16% increase in global ejection fraction. Similar improvement in ejection fraction has not been demonstrated in patients treated with thrombolytic therapy alone. Although in-hospital mortality is improved, a substantial 1-year mortality persists for intravenous thrombolytic therapy. Long-term survival is greater when PTCA therapy is used. In addition, PTCA does favorably improve survival in high-risk patients with cardiogenic shock. Although it is unlikely that most patients with acute myocardial infarction will have primary PTCA as a treatment option, this therapy remains extremely attractive for centers where primary PTCA is readily available.

The risk of reperfusion strategies in the treatment of patients with acute myocardial infarction

Coronary reperfusion early after the onset of acute myocardial infarction can restore vessel patency, improve ventricular function and reduce short- and long-term mortality. A number of reperfusion methods have been used to achieve vessel patency in acute myocardial infarction, but each strategy varies considerably in its risk to the patient. Intravenous thrombolysis is associated with an 8% risk of major or minor bleeding and a less than 0.5% risk of intracranial bleeding. This latter risk has been reported to be 1.5% when 150 rather than 100 mg of intravenous recombinant tissue-type plasminogen activator (rt-PA) is used. Invasive procedures such as cardiac catheterization, coronary angioplasty and intraaortic balloon pumping significantly increased the risk of major bleeding at the vascular entry site (from 20 to 40%). Clinical factors such as older age, female gender, lower body weight and hematologic variables including nadir fibrinogen levels and fibrin degradation products also relate to an increased risk. Coronary angioplasty performed alone without thrombolysis is not associated with an excess risk of bleeding and appears to have complications similar to those reported for angioplasty in patients undergoing elective procedures. Systemic anticoagulation has a low (less than 2%) incidence of bleeding, and serious bleeding is rare. These risks must be considered in the decision to institute a treatment strategy in patients with acute myocardial infarction.