Relationship between microvascular resistance and perfusion in patients with reperfused acute myocardial infarction.
Despite its prognostic importance, accurate assessment of microvascular perfusion in patients with ST elevation acute myocardial infarction (STEMI) is difficult. As a new tool, the index of microvascular resistance (IMR) measurement provides us a new opportunity for interrogating microvascular condition after STEMI. In this study, we measured IMR in infarct-related artery (IRA) and explored its relation with other indices which have been suggested to evaluate microvascular perfusion in patients with reperfused STEMI.


METHODS
Forty-two patients with STEMI treated successfully with primary percutaneous coronary intervention (pPCI) were prospectively included. After 48 hours following pPCI, patients were recatheterized and IMR, coronary flow reserve (CFR), systolic and mean coronary wedge pressures (CWPs and CWPm) pressure-derived collateral flow index (CFIp) were measured in IRA by using intracoronary pressure-temperature sensor tipped guide wire. Myocardial blush grade was assessed from the second angiogram. Coronary flow velocity pattern (diastolic deceleration time: DDT) was examined with transthoracic echocardiography 48 hours after pPCI. Percentage of ST-segment recovery was calculated from surface ECG (STR%).


RESULTS
IMR well correlated with CWPs (r = 0.70, P < 0.001), CWPm (r = 0.59, P < 0.001), CFIp (r = 0.65, P < 0.001), CFR (r =-0.50, P = 0.001), and DDT (r =-0.59, P = 0.001). Correlations of IMR to non/semiinvasive indices like myocardial blush grades (MBG) (r =-0.42, P = 0.007) and STR (r =-0.37, P = 0.024) are somewhat weaker.


CONCLUSIONS
Given its simplicity of measurement, independence from the presence of an epicardial stenosis, and good correlation with all measures of microvascular obstruction used in this study, IMR may prove to be a valuable modality for evaluating the microcirculation.
Sezer
Murat
M
Department of Cardiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey. sezerm@istanbul.edu.tr
Umman
Berrin
B
Okcular
Irem
I
Nisanci
Yilmaz
Y
Umman
Sabahattin
S
D000208:Acute Disease; D015906:Angioplasty, Balloon, Coronary; D000077144:Clopidogrel; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000503:physiopathology*; D003331:Coronary Vessels; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology*; D015425:Myocardial Reperfusion; D009206:Myocardium; D010477:Perfusion; D011446:Prospective Studies; D012720:Severity of Illness Index; D013988:Ticlopidine / Q000031:analogs & derivatives
D000077144:Clopidogrel; D013988:Ticlopidine