Alternation in the coronary blood flow velocity pattern in patients with no reflow and reperfused acute myocardial infarction

Background: Experimental and clinical evidence indicates that myocardial ischemia often damages the coronary microvasculature ('no-reflow' phenomenon). In this study, we examined the effect of this phenomenon on the coronary blood flow velocity pattern in patients with reperfused acute myocardial infarction. Methods and Results: We measured coronary blood flow velocity after coronary angioplasty in 42 patients with acute myocardial infarction using a Doppler guidewire. Myocardial contrast echocardiography (MCE) was also performed before and after angioplasty. Thirty-one patients showed good contrasts reperfusion (MCE reflow), whereas the other 11 showed no reflow (MCE no reflow). Peak velocity and duration of systolic coronary flow were significantly less in patients with MCE no reflow than in those with MCE reflow (8±4 versus 17±10 cm/s and 207±79 versus 289±55 ms, respectively; P<.01). Early systolic retrograde flow was frequently observed in patients with MCE reflow, whereas it was observed in only 1 patients among those with MCE reflow (95% versus 3%; P<.001). Although peak diastolic flow velocity was similar between the two subsets, diastolic deceleration rate was significantly higher in patients with MCE no reflow than in those with MCE reflow (107±76 versus 56±31 cm/s², P<.01). Conclusions: The coronary flow velocity pattern in patients with the no-reflow phenomenon was characterized by the appearance of systolic retrograde flow, diminished systolic integrate flow, and rapid deceleration of diastolic flow. Thus, the Doppler guidewire allows us to assess the presence of microvascular dysfunction in AMI.