Background: Assessment of myocardial blood flow is important for identification and monitoring of microvascular effects of glycoprotein IIb/IIIa inhibitors. Magnetic resonance imaging is a novel noninvasive method providing complementary information on myocardial blood flow and cardiac function.
Methods and results: Patients (n = 53) admitted within 12 (mean, 5.8) hours after onset of symptoms were randomized to tirofiban or standard therapy before primary percutaneous coronary intervention (PCI) with stenting. Myocardial blood flow was graded by measurement of corrected Thrombolysis in Myocardial Infarction frame counts and by semiquantitative analysis of signal intensity curves from first-pass contrast-enhanced magnetic resonance perfusion. Pretreatment with tirofiban proved safe and resulted in a significantly lower corrected Thrombolysis in Myocardial Infarction frame counts (21 vs 34, P = .008) indicating improved myocardial blood flow. Magnetic resonance imaging revealed higher normalized peak signal intensities (2.19 vs 1.63, P = .046) and a trend to steeper upslopes (0.79 vs 0.48, P = .1). Cardiac left ventricular wall motion analysis resulted in a significantly lower number of myocardial segments with abnormal wall thickening (6.4 vs 8.5, P = .025).
Conclusions: Pretreatment with tirofiban appears safe and improves myocardial flow after primary PCI with stenting. Magnetic resonance imaging proved useful as a complementary method for noninvasive assessment of myocardial blood flow and cardiac function in patients with ST-segment elevation myocardial infarction undergoing primary PCI.