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Early temporal changes in coronary flow velocity patterns in patients with acute myocardial infarction demonstrating
K Iwakura1, H Ito, N Nishikawa
1Division of Cardiology, Sakurabashi Watanabe Hospital, Osaka, Japan.
Insights
Patients with acute myocardial infarction and no-reflow phenomenon show distinct coronary flow patterns. Early systolic retrograde flow and diastolic deceleration changes reveal insights into microvascular injury mechanisms.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Interventional Cardiology
Background:
- The no-reflow phenomenon is a critical complication following acute myocardial infarction (AMI) reperfusion.
- Characterizing coronary flow velocity patterns is essential for understanding microvascular dysfunction.
- Early systolic retrograde flow and rapid diastolic deceleration are hallmarks of no-reflow.
Purpose of the Study:
- To investigate the early temporal changes in microvascular function in patients with AMI and no-reflow.
- To correlate coronary flow velocity patterns with clinical factors and reperfusion times.
- To elucidate the mechanisms underlying ischemic microvascular injury in no-reflow.
Main Methods:
- Myocardial contrast echocardiography to identify no-reflow in 144 AMI patients.
- Doppler guidewire assessment of coronary flow velocity patterns post-reperfusion.
- Categorization into early (<=10s) and late (>10s) systolic retrograde flow groups.
Main Results:
- Early systolic retrograde flow occurred within 10s in 16 patients (Group A) and later in 17 (Group B).
- Group A showed higher initial diastolic deceleration, while Group B's increased over 10 minutes.
- Group A had longer symptom-to-reperfusion times and more pre-reperfusion Q waves; Group B had higher transient ST elevation post-reperfusion.
Conclusions:
- The characteristic coronary flow velocity pattern in no-reflow is established at reperfusion or develops shortly after.
- Temporal changes in flow patterns suggest distinct mechanisms of microvascular injury.
- Understanding these patterns aids in diagnosing and managing no-reflow in acute myocardial infarction.
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 < or = 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.