Coronary hemodynamics in acute myocardial infarction

Microvascular dysfunction in the setting of ST-segment elevation myocardial infarction (STEMI) plays an important role in long-term poor clinical outcome. Microvascular dysfunction in the heart may exist despite successful primary PCI of the epicardial coronary occlusion. Intracoronary derived coronary flow characteristics can be used to evaluate the coronary microcirculation.
In our studies we evaluated the time course of the microvascular function as reflected by alterations in microcirculatory physiological parameters in the infarct-related and the noninfarct-related arteries immediately after reperfusion and during follow-up in STEMI patients.
Our studies revealed the following results:
• Coronary flow reserve and flow capacity in the infarct and noninfarct-related coronary artery were reduced following reperfusion therapy for STEMI;
• Microvascular vasodilation, assessed by Doppler derived coronary flow velocity reserve immediately after primary PCI for anterior myocardial infarction, was associated with left ventricular function recovery;
• The Doppler flow guidewire may identify patients with apparently restored epicardial flow but impaired microvascular reperfusion;
• A low coronary flow reserve in the non-culprit reference vessel after reperfusion for anterior STEMI was associated with a 4-fold increase in cardiac mortality at 10 years follow-up;
• Persistent impairment of coronary flow reserve in the non-infarct related coronary artery, due to enhanced baseline blood flow velocity at 6-month follow-up, was associated with a 10-fold increase in 10-year cardiac mortality hazard; furthermore, elevated admission glucose levels in the setting of STEMI were associated with impaired microvascular function in non-culprit vessels.