From the Guidelines

Alteplase in STEMI trials show that primary PCI is superior to fibrinolysis with alteplase in reducing mortality and morbidity.

The DANAMI-2 trial 1 demonstrated a statistically significant reduction in the primary endpoint of death, reinfarction, and stroke at 30 days for patients treated with primary PCI (8.0% for primary PCI vs. 13.7% for fibrinolysis, p < 0.001).
A meta-analysis involving six randomized trials 1 compared the strategy of transfer for primary PCI versus on-site thrombolysis, and found that the combined end point of death, reinfarction, or stroke was reduced by 42% favoring the transfer for PCI strategy (p < 0.001).
The PRAGUE-2 study 1 showed that the primary end point of 30-day mortality was 10% in the streptokinase group compared with 6.8% in the PCI group (p 0.12), and death/reinfarction/stroke at 30 days was 15.2% in the streptokinase group versus 8.4% in the PCI group (p < 0.003).

The FINESSE trial 1 showed that neither PCI preceded by abciximab and reteplase nor PCI preceded by abciximab alone was superior to abciximab used at the time of PCI among patients presenting within 4 hours of medical contact.
The CARESS-in-AMI trial 1 studied 600 STEMI patients and found that high-risk STEMI patients treated at non-PCI hospitals with a preparatory pharmacological strategy of half-dose fibrinolytic therapy, abciximab, heparin, and ASA have improved outcomes when transferred immediately to a PCI facility rather than when medical therapy is continued with transfer for rescue PCI only if there is evidence of failed reperfusion.

Primary PCI is the preferred treatment for STEMI patients if it can be performed in a timely manner by an experienced team.
Alteplase can be used as a fibrinolytic agent in patients who are not candidates for primary PCI or in whom primary PCI is not available.
Transfer for primary PCI should be considered for high-risk STEMI patients treated at non-PCI hospitals with a preparatory pharmacological strategy.

From the Research

The efficacy and safety of Alteplase in patients with STEMI have been evaluated in several studies 2, 3, 4, 5.
A phase 3, double-blind, randomized trial compared the efficacy and safety of Altelyse (bio-similar Alteplase) versus Actilyse (brand name Alteplase) in patients with STEMI, and found that Altelyse was non-inferior to Actilyse with respect to total ST-segment resolution after 90 min 2.
The EARLY-MYO trial compared the efficacy and safety of a pharmaco-invasive strategy with half-dose Alteplase versus primary angioplasty in patients with STEMI, and found that the pharmaco-invasive strategy was non-inferior (and even superior) to primary angioplasty for the primary endpoint of complete epicardial and myocardial reperfusion 3.
A study compared coronary flow and bleeding complications in patients with STEMI after administration of Alteplase or streptokinase, and found that Alteplase provided higher coronary flow (TIMI-3) and lower frequency of hypotension, with no significant difference in major bleeding 4.
A randomized clinical trial evaluated the effect of low-dose intracoronary Alteplase during primary percutaneous coronary intervention on microvascular obstruction in patients with acute myocardial infarction, and found that adjunctive low-dose intracoronary Alteplase did not reduce microvascular obstruction 5.

The studies suggest that Alteplase is effective in achieving coronary reperfusion and reducing microvascular obstruction in patients with STEMI 2, 3, 4.
However, the results of the study on low-dose intracoronary Alteplase during primary percutaneous coronary intervention suggest that this treatment strategy may not be effective in reducing microvascular obstruction 5.

The studies suggest that Alteplase is generally safe and well-tolerated in patients with STEMI, with a low risk of major bleeding and other adverse events 2, 3, 4, 5.
However, the study on low-dose intracoronary Alteplase during primary percutaneous coronary intervention found that this treatment strategy was associated with a higher risk of major adverse cardiac events 5.