Residual FlowtotheInfarct Zoneas a Determinant ofInfarct Size After Direct Angioplast

arteries isoften present before reperfusion therapy. Thepurposeofthis study was toassesstheinfluence ofantegrade flow intheinfarct-related artery and/or collateral flow totheinfarct zonebefore successful direct angioplasty on infarct size andmyocardial salvage inpatients withacuteevolving myocardial infarction. Methods andResults. Sixty patients withacuteevolving myocardial infarction underwent direct successful angioplasty without prior thrombolytic therapy. Themyocardium atrisk ofinfarction, thefinal infarct size, andmyocardial salvage were measured bytomographic perfusion imaging with""Tc sestamibi. Antegrade flowintheinfarct-related artery before intervention was graded according tothe Thrombolysis inMyocardial Infarction (TIMI) study groupclassification. Collateral flowtotheinfarct zonebefore angioplasty was alsograded (0through 3,0being no collateral flow). Thepresenceofeven minimal antegrade flowbefore angioplasty (TIMIgrade1)intheinfarct-related artery compared with absent flow was associated with asignificant reduction infinal infarct size (9±17% versus23±19%ofleft ventricle, P=.02)anda significant increase inmyocardial salvage (23±16% versus14±13%ofleft ventricle, P=.05) after angioplasty. Whenantegrade flowintheinfarct-related artery was absent before angioplasty, thepresenceofcollateral flowbefore angioplasty resulted ina significantly smaller final infarct size(P=.01) andmore myocardial salvage (P=.05) after angioplasty. Bothantegrade infarctrelated artery flowandcollateral flowtotheinfarct zonehadsignificant independent ability topredict infarct size after angioplasty. Whencollateral grade andTIM grade wereaddedtoprovide an estimate ofresidual flow, amodelincluding residual flow, myocardium atrisk, andtheinteraction ofresidual flow andinfarct site explained 83%ofthevariability ininfarct size after angioplasty. Conclusions. Thepresenceofantegrade flowintheinfarct-related artery and/or collateral flowtothe infarct zonebefore direct angioplasty inacuteevolving infarction results ina smaller infarct size after direct successful angioplasty. (Circulation. 1993;88[part 11:1527-1533.)