Streptokinase Improves Microvascular Perfusion After Primary PCI

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Streptokinase Improves Microvascular Perfusion After Primary PCI

A small trial yields provocative results.

In acute MI patients, the use of fibrinolytics before primary percutaneous coronary intervention (PCI) generally worsens outcomes (Journal Watch Cardiology Mar 16 2006). Now researchers in Turkey have conducted a pilot study to determine how low-dose streptokinase given after PCI affects microvascular perfusion.

Forty-one patients who underwent PCI with stent implantation <12 hours after onset of MI symptoms were randomized to receive either 250 kU of streptokinase (infused for 3 minutes through the guiding catheter) or no additional therapy. All patients received aspirin, clopidogrel, intracoronary heparin, tirofiban, and post-procedure low-molecular-weight heparin for 48 hours. Investigators used intracoronary hemodynamic and angiographic measures to assess microvascular perfusion 2 days after PCI.

In multivariate analysis, the microvascular resistance index in the streptokinase group was 11.7 U versus 29.1 U in controls (P<0.001), and coronary flow reserve was 2.3, versus 1.7 in controls (P=0.002). Other measures of microvascular perfusion, including collateral-flow index, coronary wedge pressure, and corrected TIMI frame count, also showed significant improvement with streptokinase compared with controls. Although there was a trend toward higher percent ST segment resolution 60 minutes after PCI in the streptokinase group, there were no significant differences in infarct size or LV function between the two groups at 6 months.

Comment: In this pilot study, low-dose streptokinase immediately after primary PCI improved intracoronary measures of microvascular perfusion at 48 hours but had no effect on clinical endpoints or infarct size at 6 months. Some investigators were aware of participants’ group assignments, and the study’s size may have been too small to adjust adequately for differences between the groups. Based on the lack of improvement in infarct size and the previously established detrimental effect of higher-dose fibrinolytic agents during PCI, we cannot recommend these investigators’ approach unless a large clinical trial confirms their findings.

— Howard C. Herrmann, MD

Published in Journal Watch Cardiology May 2, 2007