Administration of low-dose intracoronary alteplase during primary percutaneous intervention (PCI) may not reduce microvascular obstruction by 3 months in patients with acute ST-segment elevation myocardial infarction (STEMI). These findings were reported in a new edition of JAMA.

A total of 440 patients with acute STEMI who were seen at 11 hospitals in the United Kingdom within 6 hours of symptom onset were enrolled. Investigators randomly assigned patients to either placebo (n=151), 10 mg alteplase (n=144), or 20 mg alteplase (n=145) by manual infusion over 5 to 10 minutes.

Administration of the assigned therapies occurred early during the patients’ primary PCI procedure and following reperfusion of the infarct-related coronary artery. Additionally, therapies were administered prior to implanting the stent.

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At 3-month follow-up, researchers examined the amount of microvascular obstruction as shown by contrast-enhanced cardiac magnetic resonance imaging (MRI).

There was no difference between the 20-mg alteplase and placebo groups in terms of mean microvascular obstruction (% left ventricular mass) at 3 months (3.5% vs 2.3%, respectively; estimated difference, 1.16%; 95% CI, −0.08% to 2.41%; P =.32).

Additionally, the investigators found no difference between the 10-mg alteplase and placebo groups for the same primary outcome (2.6% vs 2.3%, respectively; estimated difference, 0.29%; 95% CI, −0.76% to 1.35%; P =.74).

A similar proportion of major adverse cardiac events (cardiac death, nonfatal myocardial infarction, unplanned hospitalization for heart failure) occurred in the placebo group (10.1%), the 10-mg alteplase group (12.9%), and the 20-mg alteplase group (8.2%).

Limitations of the study include its short follow-up duration as well as its enrollment of only patients attending UK-based hospitals.

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“Contemporary practice guidelines call for more research to identify new treatments for microvascular obstruction,” the researchers concluded. As for the use of low-dose intracoronary alteplase during primary PCI in [patients with] acute STEMI, the researchers indicate that their “study findings do not support this treatment.”

Disclosures: Several study authors report potential conflicts of interest. Please refer to original reference text for full list of author disclosures.


McCartney PJ, Eteiba H, Maznyczka AM, et al; T-TIME Group. Effect of low-dose intracoronary alteplase during primary percutaneous coronary intervention on microvascular obstruction in patients with acute myocardial infarction: a randomized clinical trial. JAMA. 2019;321(1):56-68.