Retreatment with alteplase for early signs of reocclusion after thrombolysis. The European Cooperative Study Group

High-frequency electrocardiogram as a supplement to standard 12-lead ischemia monitoring during reperfusion therapy of acute inferior myocardial infarction

BACKGROUND

Resolution of ST-segment elevation in the electrocardiogram (ECG) is used as a reperfusion sign during thrombolytic therapy in acute myocardial infarction. Analysis of high-frequency QRS components (HF-QRS) might provide additional information. The study compares changes in HF-QRS (150-250 Hz) to ST-segment changes in the standard ECG during thrombolytic therapy.

METHODS

Twelve patients receiving intravenous thrombolytic therapy were included. A continuous 12-lead ECG recording was acquired for 4 hours.

RESULTS

After 1 hour of therapy, 3 patients showed ST-elevation resolution as well as an increase in HF-QRS. These changes in ST and HF-QRS occurred simultaneously. No other patient showed significant changes in ST or HF-QRS after 1 hour. After 2 and 4 hours, there was less concordance between the standard and high-frequency ECGs.

CONCLUSIONS

In patients with early ST-elevation resolution, the standard and high-frequency ECGs show similar results. Later changes are more disparate and may provide different clinical information.

Management of failed thrombolysis after acute myocardial infarction: An overview of current treatment options

Thrombolytic therapy remains the most commonly administered revascularization strategy for patients with ST-elevation myocardial infarctions (STEMI). However, many patients fail to have patent arteries or ST-segment resolution after these therapies. Multiple strategies have been examined to treat these patients with "failed thrombolysis." We examined the existing medical literature regarding treatment of failed thrombolysis including strategies testing repeat thrombolytic therapy and rescue percutaneous coronary intervention. Additional, we reviewed the literature regarding the efficacy of transferring patient for rescue percutaneous intervention and coronary stenting. The impact of contemporary antiplatelet strategies, cardiogenic shock, and coronary bypass surgery was examined. Overall, the management of patients with acute STEMI in whom thrombolytic therapy failed remains a challenging problem. As a result, many different strategies are currently in use. Among these therapeutic interventions, rescue PCI with coronary stenting appears to be superior when it is done in a timely manner by an experienced center.

[The clinical management guidelines of the Sociedad Española de Cardiología in acute myocardial infarct]

In the recent years, new possibilities have emerged in the diagnosis and management of acute myocardial infarction with ST segment elevation and its complications. Moreover, a deep transformation has taken place in the health care system organization, particularly in aspects related to care of patients presenting non-traumatic chest pain, both in pre-hospital and hospital areas. All these issues warrant a consensus document in Spain dealing with the role that these important changes should play in the whole management of myocardial infarction patients. This document revises and updates all the main clinical issues of acute myocardial infarction patients from the moment they contact with the health care system outside the hospital until they return home, after staying at the coronary care unit and the general hospitalization ward. All those aspects are considered not only in the uncomplicated myocardial infarction but also in the complicated one. This review also includes a set of recommendations on structural and organisational aspects, mainly referred to the prehospital and emergency levels.

A study of biochemical markers of reperfusion early after thrombolysis for acute myocardial infarction. The PERM Study Group. Prospective Evaluation of Reperfusion Markers

BACKGROUND

In acute myocardial infarction (AMI), early noninvasive identification of patients with occluded infarct-related arteries (IRAs) after thrombolysis has important prognostic and therapeutic implications. The aims of this study were to evaluate biochemical methods for the early diagnosis of patency after thrombolysis prospectively and to establish the optimal diagnostic criteria retrospectively.

METHODS AND RESULTS

In 97 patients with AMI treated with thrombolytic agents < or = 6 hours after the onset of symptoms, myoglobin, troponin T, creatine kinase, the MB isoenzyme and MM isoforms of creatine kinase were measured just before thrombolysis began and 90 minutes later. IRA patency was assessed by means of 90-minute coronary angiography. For each marker, compared with the expected sensitivity and specificity based on published thresholds for the diagnosis of patency, the observed values were consistently lower but were markedly improved in a subset of patients treated > 3 hours after the onset of symptoms. With receiver-operator characteristic curve analysis of the slopes of increase and relative increases in each marker over 90 minutes, the best diagnostic performance was achieved by use of the relative increase in myoglobin, troponin T, and MM3/MM1 creatine kinase isoforms in patients treated > 3 hours after onset (areas under the curve of 0.84, 0.83, and 0.85, respectively).

CONCLUSIONS

Effective early noninvasive diagnosis of patency after thrombolysis is possible in patients treated > 3 hours after symptom onset by use of criteria derived from the relative increase over 90 minutes in plasma markers, particularly myoglobin, troponin T, and MM3/MM1 creatine kinase isoforms. The diagnostic performance of the relative increase in myoglobin appears to be less susceptible to small changes in the diagnostic threshold value.

Acute myocardial infarction. Reperfusion strategies

Acute myocardial infarction is the result of an acute interruption of myocardial blood flow resulting in ischemic myocardial necrosis. The pathogenesis of this phenomenon nearly always involves acute thrombosis superimposed on a disrupted atherosclerotic plaque. Thrombolytic agents have been conclusively shown to reduce mortality in many patient subgroups with myocardial infarction, including the elderly, patients with inferior myocardial infarction, and patients with systolic hypertension. Nearly all patients with acute myocardial infarction of less than 6 h in duration with S-T segment elevation should receive thrombolysis unless significant contraindications exist and outweigh the potential benefits. Aspirin should be given to almost all patients regardless of whether they receive thrombolysis. Angioplasty and coronary artery bypass surgery are useful as primary or secondary modes of reperfusion in selected patients with infarction.

Repeat thrombolysis

Since 20% of patients with myocardial infarction (MI) have had a previous infarction, and reinfarction within one year after infarction occurs in 9% of cases, it is important to clarify the role of repeat thrombolysis. After streptokinase (SK) administration, IgG antibodies rise to a peak at two weeks and slowly fall over the next 12 months, but 50% of patients still have antibody levels sufficient to neutralise a standard dose of SK up to four years after initial SK administration. On this evidence, SK or anistreplase should not be readministered, except perhaps in the first two to three days after initial treatment. The efficacy of tissue plasminogen activator (t-PA) and urokinase is not affected by prior treatment with SK.

Tailored thrombolytic therapy. A perspective

BACKGROUND

In contrast with current standard regimens, it seems more appropriate to tailor thrombolytic therapy to individual patient characteristics. A proposed model for such tailored therapy is based on individual assessment of benefits and risks of thrombolytic therapy, taking into account the response of individual patients to the therapy given.

METHODS AND RESULTS

Potential benefits of thrombolysis in individual patients can be predicted by use of demographic patient characteristics (age, sex, history of previous infarction) together with indicators of the ischemic area at risk (total ST segment deviation) and treatment delay. Using these parameters, the number of "lives saved" by thrombolytic therapy for specific patient characteristics can be estimated. Similarly, the risk of intracranial hemorrhage during thrombolytic therapy can be estimated from the patient's age, blood pressure at admission, and body weight. Depending on benefit/risk estimates, a choice can be made between regimens with high, medium, or modest thrombolytic efficacy. Continuous multilead ECG ischemia monitoring and rapid assays of myocardial proteins in serum can be used to assess the occurrence or absence of reperfusion and to detect signs of reocclusion. Such data help to decide whether thrombolytic therapy should be continued or intensified or might be discontinued in individual patients before the total standard dose has been administered. Such tailored reduction of the total thrombolytic dose will reduce the risk for bleeding complications in some of the patients.

CONCLUSIONS

The concept of tailoring thrombolytic therapy and the models presented for benefit/risk assessment should be tested in clinical studies and may subsequently help the physician to select the optimal approach in individual patients.