Coronary Artery Disease
Early temporal changes in coronary flow velocity patterns in patients with acute myocardial infarction demonstrating the “no-reflow” phenomenon

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Abstract

Coronary flow velocity pattern in patients with acute myocardial infarction demonstrating no-reflow phenomenon is characterized with early systolic retrograde flow and rapid deceleration of diastolic flow velocity. In this study, we investigated the early temporal changes in microvascular function in patients with the no-reflow phenomenon. Among 144 patients with a first acute myocardial infarction, 33 exhibited sizable no-reflow phenomenon after coronary reperfusion with myocardial contrast echocardiography. We assessed temporal changes in coronary flow velocity patterns with the Doppler guidewire. The early systolic retrograde flow was observed ≤10 seconds after reperfusion in 16 patients (group A) or later in 17 patients (331 ± 327 seconds, group B). Diastolic deceleration rate was higher in group A than in group B at 1 minute after reperfusion. It gradually increased in group B and showed comparable value to group A 10 minutes later. Group A had longer elapsed time from symptom onset to reperfusion and a greater number of infarct Q waves before reperfusion than group B (14 ± 13 vs 5 ± 2 hours, p <0.01; and 3 ± 2 vs 2± 1, p <0.02). In contrast, the incidence of transient ST reelevation shortly after reperfusion was higher in group B (76% vs 25%, p <0.01). Thus, the characteristic coronary flow velocity pattern is either established at the moment of coronary reperfusion or progresses thereafter in patients with no-reflow phenomenon. This suggests different mechanisms of developing ischemic microvascular injury.

Section snippets

Study population

Between October 1993 and March 1996, 144 patients with first AMI underwent PTCA of an occluded coronary artery (Thrombolysis In Myocardial Infarction trial grade 0 or 1) and underwent MCE and Doppler guidewire examination in the catheterization laboratory. The diagnosis of AMI was based on chest pain prolonged for ≥30 minutes, ST-segment elevation of ≥2 mm in at ≥2 contiguous electrocardiographic leads, and a more than threefold increase in serum creatine kinase levels. Twenty-nine patients

Clinical backgrounds

We found MCE no reflow in 36 of 144 study patients (25%). The early systolic retrograde flow was observed at the end of Doppler guidewire study in patients with MCE no reflow with the exception of 1, who was excluded from further analysis. We could not record coronary blood flow velocity at the moment of coronary reperfusion in 2 patients, and these patients were also excluded. The remaining 33 patients with MCE no reflow were used for further analysis (median 61 ± 10 years; range 34 to 79), of

Discussion

Several possible mechanisms have been postulated to explain the development of ischemic microvascular dysfunction. In canine studies, Kloner et al8, 9 found that no-reflow phenomenon is located well within the areas of necrosis, and suggested that no-reflow phenomenon is the consequence of ischemic microvascular and myocardial damages and established in the infarct myocardium before reperfusion. On the other hand, there are some reports suggesting that no-reflow phenomenon may develop mainly

Acknowledgements

We greatly acknowledge the excellent technical assistance of Yuzo Sakagami, Masakazu Ueda, Naoki Jonishi, and Hideshi Shimokawa, and the excellent secretarial assistance of Hideko Masuda.

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