Routine Angioplasty and Stenting After Fibrinolysis for Acute Myocardial Infarction

Background:

In Canada, most patients with acute myocardial infarction (AMI) present to hospitals without cardiac catheterization facilities. Thrombolytic therapy remains the standard-of-care in these centres. However, thrombolytic therapy achieves normal coronary flow and myocardial perfusion in less than 50% of patients, and is associated with reocclusion, reinfarction, and recurrent ischemia. Primary angioplasty results in more complete reperfusion and lower rates of reocclusion, reinfarction and recurrent ischemia, but is not available in most centres. Although patients can be transferred for primary angioplasty, long transport times are associated with worse outcomes. An alternative strategy, described as facilitated angioplasty, involves administration of thrombolytic therapy at the community hospital followed by immediate transport for angioplasty. This approach achieves the benefits of primary angioplasty without delaying treatment. A well-conducted, prospective, randomized trial is needed to compare this strategy of facilitated angioplasty with standard thrombolytic therapy.

Objectives:

To evaluate the safety, feasibility, and efficacy of routine transfer of patients with AMI to an angioplasty centre immediately after thrombolysis for coronary angiography and percutaneous coronary intervention (PCI).

Hypothesis:

A strategy of routine transfer of patients with AMI to an angioplasty centre immediately after thrombolysis for coronary angiography and percutaneous intervention is associated with a significantly lower incidence of the composite of death, reinfarction, recurrent ischemia, heart failure, and shock at 30 days compared with the conventional strategy of thrombolysis with transfer reserved for failed reperfusion and/or development of shock.

Research Plan:

Patients with ST-elevation myocardial infarction and high-risk characteristics presenting to community hospitals without cardiac catheterization facilities will receive thrombolysis with tenecteplase and heparin (unfractionated or low molecular weight heparin) and will then be randomized to one of two strategies: facilitated PCI or standard treatment (thrombolysis with provisional rescue PCI). In the facilitated PCI group, patients will be transferred immediately to an angioplasty centre for urgent cardiac catheterization, and PCI if appropriate. In the standard treatment group, patients will only undergo urgent angiography for evidence of failed reperfusion and/or development of cardiogenic shock. The primary endpoint will be the composite of death, reinfarction, recurrent ischemia, heart failure, and shock at 30 days.

Patients with ST-elevation myocardial infarction and high-risk characteristics presenting to community hospitals without cardiac catheterization facilities will receive thrombolysis with tenecteplase and heparin (unfractionated or low molecular weight heparin) and will then be randomized to one of two strategies: facilitated percutaneous coronary intervention (PCI) or standard treatment (thrombolysis with provisional rescue PCI). In the facilitated PCI group, patients will be transferred immediately to an angioplasty centre for urgent cardiac catheterization, and PCI if appropriate within 6 hours of thrombolysis. In the standard treatment group, patients will only undergo urgent angiography for evidence of failed reperfusion and/or development of cardiogenic shock.

Eligibility Criteria:
Inclusion Criteria:

1. Patients \>= 18 years old who present within 12 hours of symptom onset with more than 30 minutes of continuous symptoms of an acute myocardial infarction to a centre that does not perform primary PCI, with either:

* \>= 2 mm ST-segment elevation in 2 or more contiguous anterior leads
* \>= 1 mm ST-segment elevation in 2 or more contiguous inferior leads with at least one of the following high-risk features:

  * Systolic blood pressure \< 100 mm Hg
  * Heart rate \> 100/minute
  * Killip Class II-III
  * \>= 2 mm ST-segment depression in anterior leads
  * \>= 1 mm ST-segment elevation in right-sided lead V4 (V4R), indicative of right ventricular involvement

Exclusion Criteria:

1. Left bundle branch block
2. Cardiogenic shock (Killip Class IV requiring vasopressors or inotropic support to maintain a systolic blood pressure \> 90) prior to randomization
3. Active bleeding or known hemorrhagic diathesis
4. Availability of primary PCI with door-to-balloon time ≤ 60 minutes
5. Time from thrombolysis to initiation of consent process \> 30 minutes
6. Use of thrombolytic agent other than tenecteplase (TNK) for index event
7. Major surgery, biopsy of parenchymal organ, or significant trauma in the past 6 weeks
8. Systolic blood pressure \> 200 mm Hg or diastolic \> 110 mm Hg after arrival to the hospital and before enrollment
9. Concomitant use of oral anticoagulants (e.g. warfarin) with International Normalized Ratio (INR) of \> 2
10. Recent non-compressible vascular puncture
11. History of central nervous system structural damage (e.g. aneurysm, neoplasm, arteriovenous malformation, stroke) at any time, or transient ischemic attack within the last year
12. History of heparin-induced thrombocytopenia
13. Documented allergy to aspirin
14. Participation in other clinical research studies involving experimental therapies including drugs or devices within 7 days of enrollment or prior participation in this study
15. Inability to cooperate with the protocol or undergo cardiac catheterization
16. Other serious illness (e.g. active cancer, significant hepatic disease)
17. Serum creatinine \> 140 umol/L
18. Percutaneous coronary intervention within one month
19. Previous bypass surgery
20. Pregnancy
21. Use of enoxaparin (or other low molecular weight heparin) in last 12 hours in patient \> 75 years of age
22. Inferior ST-elevation myocardial infarction with none of the 5 high-risk features listed in the inclusion criteria