Impact of intracoronary reteplase during primary percutaneous coronary intervention on infarct size in large anterior myocardial infarction: rationale and design of the RECOVER II trial

Background: Thrombus embolization and microvascular obstruction during percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction (STEMI) is commonly detected, which causes inadequate myocardial perfusion and elevated infarct size. An approach with low-dose intracoronary fibrinolytic treatment for reducing distal embolization and improving myocardial reperfusion in high-risk STEMI cases remains controversial. Methods: The RECOVER II study represents a multicenter, randomized, double-blind, parallel-group trial assessing low-dose adjunctive intracoronary reteplase during primary PCI in individuals with large anterior myocardial infarction and thrombus determined by angiography. The trial will enroll 306 cases who present within 12 h following STEMI for proximal or mid left anterior descending artery occlusion undergoing primary PCI. Cases will be randomized to receive a bolus intracoronary reteplase at 9 mg or 18 mg vs. placebo. The drug will be delivered over 2 minutes proximal to culprit lesions with an intracoronary catheter early after wire-crossing and before thrombus aspiration or balloon dilation. Results: The primary outcome will be infarct size assessed by late gadolinium-enhanced magnetic resonance imaging (MRI) (% of left ventricular mass) on day 7 after enrollment. Secondary outcomes will include the amount of microvascular obstruction and myocardial salvage index examined via MRI on day 7, angiographic measures of reperfusion [Thrombolysis in Myocardial Infarction (TIMI) coronary flow grade, TIMI frames count and myocardial blush grade], incidence of complete ST-segment resolution at 2 hours after reperfusion, area under the curve for troponin T, and rates of major adverse cardiovascular events at 30 days. Conclusions: RECOVER II will determine whether the addition of low-dose intracoronary reteplase early after wire-crossing as an adjunct to reperfusion treatment reduces infarct size in individuals with large anterior myocardial infarction. Trial Registration: ClinicalTrials.gov Identifier: NCT04571580.