TIMI grade 3 flow and reocclusion after intravenous thrombolytic therapy: a pooled analysis

Association of culprit lesion plaque characteristics with flow restoration post-fibrinolysis in ST-segment elevation myocardial infarction: an intravascular ultrasound-virtual histology study

Background

Not every patient achieves normal coronary flow following fibrinolysis in STEMI (ST-segment elevation myocardial infarction). The culprit lesion plaque characteristics play a prominent role in the coronary flow before and during percutaneous coronary intervention. The main purpose was to determine the culprit lesion plaque features by virtual histology-intravascular ultrasound (VH-IVUS) in patients with STEMI following fibrinolysis in relation to baseline coronary angiogram TIMI (thrombolysis in myocardial infarction) flow. Pre-intervention IVUS was undertaken in 61 patients with STEMI after successful fibrinolysis. After the coronary angiogram, they were separated into the TIMI1–2 flow group (n = 31) and TIMI 3 flow group (n = 30). Culprit lesion plaque composition was evaluated by VH-IVUS.

Results

On gray-scale IVUS, the lesion external elastic membrane cross-sectional area (EEM CSA) was significantly higher in the TIMI 1–2 groups as compared to the TIMI 3 group (15.71 ± 3.73 mm² vs 13.91 ± 2.94 mm², p = 0.041) with no significant difference in plaque burden (82.42% vs. 81.65%, p = 0.306) and plaque volume (108.3 mm³ vs. 94.3 mm³, p = 0.194). On VH-IVUS, at the minimal luminal area site (MLS), the fibrous area (5.83 mm² vs. 4.37 mm², p = 0.024), necrotic core (NC) area (0.95 mm² vs. 0.59 mm², p < 0.001), and NC percentage (11% vs. 7.1%, p = 0.024) were higher in the TIMI 1–2 groups in contrast to the TIMI 3 group. The absolute necrotic core (NC) volume (8.3 mm³ vs. 3.65 mm³, p < 0.001) and NC percentage (9.3% vs. 6.0%, p = 0.007) were significantly higher in the TIMI 1–2 groups as compared to the TIMI 3 group. Absolute dense calcium (DC) volume was higher in TIMI 1–2 groups with a trend towards significance (1.0 mm³ vs.0.75 mm³, p = 0.051). In multivariate analysis, absolute NC volume was the only independent predictor of TIMI 1–2 flow (odds ratio = 1.561; 95% CI 1.202–2.026, p = 0.001). Receiver operating characteristic curves showed absolute NC volume has best diagnostic accuracy (AUC = 0.816, p < 0.001) to predict TIMI 1–2 flow with an optimal cutoff value of 4.5 mm³ with sensitivity and specificity of 79% and 61%, respectively.

Conclusions

This study exemplifies that the necrotic core component of the culprit lesion plaque in STEMI is associated with the coronary flow after fibrinolysis. The absolute necrotic core volume is a key determinant of flow restoration post-fibrinolysis and aids in prognostication of less than TIMI 3 flow.

Development of myocardial microcirculation and metabolism in acute ST-elevation myocardial infarction evaluated with positron emission tomography

BACKGROUND

Early reperfusion is an established therapeutic objective in acute myocardial infarction (MI). The relationship of regional myocardial microcirculation and metabolism toward outcome in acute human MI is not well known.

METHODS AND RESULTS

In 8 patients, positron emission tomography (PET) was performed with oxygen 15-labeled water at 3 hours, 24 hours, and 3 weeks after the start of fibrinolytic treatment, with carbon 11 acetate at 3 hours and with fluorine 18 fluorodeoxyglucose at 24 hours and 3 weeks. Absolute quantification of perfusion and water-perfusable tissue fraction (PTF), metabolic activity, and substrate extraction in 4 regions of interest was performed. Coronary angiography was performed at 24 hours. Short-term outcome at 3 weeks was evaluated by contractile reserve with dobutamine stress echocardiography and lung water measurements with PET. Early regional perfusion, PTF, and extraction and utilization of oxygen and glucose decreased closer to the infarct region ( P < .001 for all). Infarct-related oxygen utilization and extraction of oxygen and glucose were closely related to outcome ( P < .01 for all). PTF improved significantly in the infarct-related regions over time in proportion to early oxygen extraction and utilization.

CONCLUSIONS

This pilot study indicates that PET might be useful in the evaluation of treatment efficacy and that restoration of oxidative metabolism is more closely related to myocardial damage recovery than perfusion in the early phase after MI.

Efficacy and safety of tenecteplase in combination with the low-molecular-weight heparin enoxaparin or unfractionated heparin in the prehospital setting: the Assessment of the Safety and Efficacy of a New Thrombolytic Regimen (ASSENT)-3 PLUS randomized trial in acute myocardial infarction

BACKGROUND

The combination of a single-bolus fibrinolytic and a low-molecular-weight heparin may facilitate prehospital reperfusion and further improve clinical outcome in patients with ST-elevation myocardial infarction.

METHODS AND RESULTS

In the prehospital setting, 1639 patients with ST-elevation myocardial infarction were randomly assigned to treatment with tenecteplase and either (1) intravenous bolus of 30 mg enoxaparin (ENOX) followed by 1 mg/kg subcutaneously BID for a maximum of 7 days or (2) weight-adjusted unfractionated heparin (UFH) for 48 hours. The median treatment delay was 115 minutes after symptom onset (53% within 2 hours). ENOX tended to reduce the composite of 30-day mortality or in-hospital reinfarction, or in-hospital refractory ischemia to 14.2% versus 17.4% for UFH (P=0.080), although there was no difference for this composite end point plus in-hospital intracranial hemorrhage or major bleeding (18.3% versus 20.3%, P=0.30). Correspondingly, there were reductions in in-hospital reinfarction (3.5% versus 5.8%, P=0.028) and refractory ischemia (4.4% versus 6.5%, P=0.067) but increases in total stroke (2.9% versus 1.3%, P=0.026) and intracranial hemorrhage (2.20% versus 0.97%, P=0.047). The increase in intracranial hemorrhage was seen in patients >75 years of age.

CONCLUSIONS

Prehospital fibrinolysis allows 53% of patients to receive reperfusion treatment within 2 hours after symptom onset. The combination of tenecteplase with ENOX reduces early ischemic events, but lower doses of ENOX need to be tested in elderly patients. At present, therefore, tenecteplase and UFH are recommended as the routine pharmacological reperfusion treatment in the prehospital setting.

Acute myocardial infarction complicated by early onset of heart failure: safety and feasibility of interhospital transfer for coronary angioplasty. Subanalysis of Killip II-IV patients from the PRAGUE-1 study

OBJECTIVE

The objective of this study is to assess the feasibility and safety of interhospital transfer (within up to 60 minutes) for primary/rescue coronary angioplasty of patients with myocardial infarction (AMI) complicated by an early onset of acute heart failure (AHF) admitted to a community hospital without PCI facilities.

DESIGN AND PATIENTS

From the multicenter randomized PRAGUE-1 study, a subgroup of 66 patients with AMI complicated by AHF on the first presentation to the community hospital were retrospectively analyzed. Group A patients (n = 21) were treated on site in community hospitals using thrombolysis (streptokinase), group B patients (n = 20) were transported with thrombolytic infusion to a PCI center for coronary angioplasty, and group C patients (n = 25) were immediately transported to a PCI center for primary angioplasty without thrombolysis.

RESULTS

No patient died during transportation. One group B patient developed ventricular fibrillation during transfer. The time delay from the onset of chest pain to reperfusion was > 142 minutes, and 253 and 251 minutes in groups A, B, and C, respectively. Hospital stay (16 vs 11 vs 10 days, P = NS) was shorter in the angioplasty groups. Transported patients (groups B, C) displayed a significant decrease in heart failure progression within the first 24 hours after treatment (48% vs 15% vs 8%, P < 0.05). The combined end point, i.e., mortality + nonfatal reinfarction (43% vs 25% vs 8%, P < 0.05), was significantly less frequent in the coronary angioplasty group.

CONCLUSIONS

Interhospital transfer for coronary angioplasty of patients with AMI complicated by an early onset of AHF is feasible and safe. Transport for angioplasty may even reduce the risk of heart failure progression and improve clinical outcome compared to immediate thrombolysis in the nearest community hospital.

Pharmacologic reperfusion therapy for acute myocardial infarction

Acute myocardial infarction (MI) remains a significant problem in terms of morbidity, mortality and healthcare costs. Pharmacologic reperfusion therapies for MI are becoming increasingly complex. This review therefore places contemporary pharmacologic MI developments into perspective. An historical overview of pharmacologic reperfusion therapy for MI is provided, followed by an analysis of current limitations, treatment options, and present and likely future pharmacologic therapies. Adjunctive percutaneous and other treatments are also discussed, to clarify what is becoming a rapidly changing field.

Influence on coagulation activity by subcutaneous LMW heparin as an adjuvant treatment to fibrinolysis in acute myocardial infarction

In this study, which includes 101 patients with acute ST segment-elevated myocardial infarction, we investigated the influence on the increased coagulation activity after streptokinase treatment by adding low-molecular-weight (LMW) heparin or placebo and the relation between the coagulation activity and ischemic episodes, coronary patency, and mortality. The expected increase of prothrombin fragment 1+2 (F1+2), thrombin-antithrombin (TAT), and D-dimer were significantly attenuated at 2, 6, and 18 h (D-dimer only at 18 h) in the dalteparin group compared to placebo. Ischemic episodes during the first 24 h appeared significantly more often in patients with F1+2 levels above the median at 18 h. There was a tendency to a lower frequency of Thrombolysis In Myocardial Infarction Trial (TIMI) grade 3 flow in the infarct-related artery in patients with TAT and D-dimer levels above the median at 18 h. F1+2, TAT, and D-dimer were significantly higher after 18, 6, and 18 h, respectively, in the deceased compared to surviving patients. Also, the lack of reduction of the levels of F1+2 between 6 and 18 h was related to a raised mortality. In conclusion, adjuvant treatment with LMW heparin to streptokinase attenuates increased coagulation activity. This might be of importance as remaining high coagulation activity is associated with signs of early reocclusion and raised mortality.

Low molecular weight heparin (dalteparin) as adjuvant treatment of thrombolysis in acute myocardial infarction--a pilot study: biochemical markers in acute coronary syndromes (BIOMACS II)

OBJECTIVES

This randomized, double blind, placebo-controlled pilot trial evaluated the effect of dalteparin as an adjuvant to thrombolysis in patients with acute myocardial infarction regarding early reperfusion, recurrent ischemia and patency at 24 h.

BACKGROUND

Low-molecular-weight heparin, given subcutaneously twice daily without monitoring, might be an attractive alternative to conventional intravenous heparin in the treatment of acute myocardial infarction.

METHODS

In 101 patients dalteparin/placebo 100 IU/kg was given just before streptokinase and a second injection 120 IU/kg after 12 h. Monitoring with continuous vector-ECG was done to obtain signs of early reperfusion and later ischemic episodes. Blood samples for myoglobin were obtained at start and after 90 min to evaluate signs of reperfusion. Coronary angiography was performed after 20-28 h to evaluate TIMI-flow in the infarct-related artery.

RESULTS

Dalteparin added to streptokinase tended to provide a higher rate of TIMI grade 3 flow in infarct-related artery compared to placebo, 68% versus 51% (p = 0.10). Dalteparin had no effects on noninvasive signs of early reperfusion. In patients with signs of early reperfusion, there seemed to be a higher rate of TIMI grade 3 flow, 74% versus 46% (myoglobin) (p = 0.04) and 73% versus 52% (vector-ECG) (p = 0.11). Ischemic episodes 6-24 h. after start of treatment were fewer in the dalteparin group, 16% versus 38% (p = 0.04).

CONCLUSIONS

When dalteparin was added as an adjuvant to streptokinase and aspirin, there were tendencies for less ECG monitoring evidence of recurrent ischemia and better patency at 24 h, warranting further study.

Analysis of vessel wall morphology, blood flow velocity, and the hemostatic system in a patient with a large intracoronary thrombus

A patient with AMI caused by a large thrombus in the proximal LAD was successfully treated with PTCA and an intracoronary lysis combined with the platelet-receptor antagonist c7E3. Analysis of cellular hemostasis after 1 and 6 months revealed a sustained platelet activation despite combined anti-platelet therapy with ASA and ticlopidine. A progredient slow-flow phenomenon appeared during control angiographies, confirmed by intracoronary Doppler examination.