Coronary Microvascular Dysfunction After ST-Segment–Elevation Myocardial Infarction
Local or Global Phenomenon?
Variable degrees of coronary microvascular dysfunction occur at the time of ST-segment–elevation myocardial infarction (STEMI) correlating with infarct size and long-term prognosis. Angiographic methods for assessing microvascular dysfunction in the cardiac catheterization laboratory at the time of STEMI include thrombolysis in myocardial infarction flow grade, thrombolysis in myocardial infarction frame count, and thrombolysis in myocardial infarction myocardial perfusion grade.1 More recently, coronary wire-based methods measuring Doppler-derived parameters, such as the coronary flow velocity reserve (CFVR), or measuring thermodilution-derived parameters, such as the index of microcirculatory resistance, have been shown to be more powerful predictors of acute left ventricular dysfunction, myocardial viability, and subsequent adverse outcomes.2,3
Article see p 207
Although it is widely accepted that the degree of microvascular dysfunction occurring in the myocardium subtended by the infarct-related vessel correlates with infarct size and prognosis, there has been some debate on whether more global microvascular dysfunction, involving myocardial regions not supplied by the infarct-related vessel, is present at the time of STEMI. For example, Uren et al4 performed positron emission tomography imaging in 13 patients with STEMI and found a decreased coronary flow reserve in the noninfarct-related vessel, which improved at 6-month follow-up. However, Ntalianis et al5 measured fractional flow reserve in a nonculprit vessel at the time of STEMI in 75 patients and again 1 month later and found no significant difference in fractional flow reserve or in index of microcirculatory resistance, which was measured in a subgroup, suggesting that the microvascular dysfunction resulting from STEMI is limited to the territory supplied by the infarct-related artery.
In this issue of Circulation: Cardiovascular Interventions, van de Hoef et al6 report long-term follow-up in 100 patients presenting with STEMI, in whom they measured Doppler wire-derived CFVR, diastolic deceleration time, and systolic flow reversal …