Effect of Ischemia Duration and Door-to-Balloon Time on Myocardial Perfusion in ST-Segment Elevation Myocardial Infarction An Analysis From HORIZONS-AMI Trial (Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction)

OBJECTIVES This study sought to investigate the effect of treatment delay on microvascular reperfusion in ST-segment elevation myocardial infarction (STEMI) patients from the large, multicenter, prospective HORIZONS-AMI (Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction) trial. BACKGROUND Despite restoration of epicardial blood flow during primary percutaneous coronary intervention (PCI), one-third of patients do not obtain myocardial perfusion due to impairment in the microvascular circulation. METHODS We examined the effect of symptom onset-to-balloon time (SBT) and door-to-balloon time (DBT) on myocardial reperfusion during primary PCI in STEMI, utilizing resolution of ST-segment elevation (STR) and the myocardial blush grade (MBG). The primary analysis was the relationships between SBT <= 2, >2 to 4, and >4h and DBT <= 1, >1 to 1.5, >1.5 to 2, and >2 h with MBG and STR. Clinical risk was assessed using a modified version of the Thrombolysis In Myocardial Infarction risk score for STEMI. RESULTS In 2,056 patients, absent microvascular perfusion (MBG 0/1) and STR (STR <30%) after primary PCI was significantly more common in patients with longer SBT, in patients with both low and high clinical risk profiles. By multivariable analysis, SBT (p < 0.0001), anterior infarction (p < 0.0001), reference vessel diameter (p - 0.005), lesion minimum lumen diameter (p < 0.0001), hyperlipidemia (p = 0.03), and current smoking (p = 0.001) were independent predictors of MBG 0/1, whereas SBT (p = 0.007), anterior infarction (p < 0.0001), and history of renal insufficiency (p = 0.0002) were independent predictors of absent STR. DBT (p < 0.0001) was an independent predictor of MBG 0/1. MBG 0/1 and STR <30% identified patients with increased 3-year mortality. CONCLUSIONS The present study suggests that delay in mechanical reperfusion therapy during STEMI is associated with greater injury to the microcirculation. (C) 2015 by the American College of Cardiology Foundation.