ASSESSMENT OF MICROVASCULAR NO-REFLOW PHENOMENON USING TC-99M MACROAGGREGATED ALBUMIN SCINTIGRAPHY IN PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION

Objectives. The aim of this study was the scintigraphic evaluation of clinical no reflow phenomenon, Background. In patients with acute myoc ardial infarction, the relationship of the severity of reduction of mi crovascular reflow to the ischemia time or to the secondary extension of myocardial necrosis is poorly understood, and we accordingly conduc ted a scintigraphic evaluation of clinical no reflow phenomenon, Metho ds. The group studied consisted of 25 consecutive patients viith their first acute myocardial infarction. After recanalization, each patient received intracoronary injections of technetium-99m macroaggregated a lbumin (MAA). Results. Eight patients (32%) had absent tracer uptake ( scintigraphic no-reflow phenomenon). Fourteen patients shelved ab sent or moderately reduced MAA uptake (group 1) and 11 showed slightly red uced or normal uptake (group 2). The time to recanalization was signif icantly longer in group 1 than in group 2 (290.4 +/- 130.6 min vs, 177 .3 +/- 93.5 min; p = 0.0238), In chronic phase, the thallium-201 (TI-2 01) defect score index was significantly larger (p < 0.01) and regiona l ejection fraction was significantly lower (p < 0.01) in group 1 comp ared with corresponding values in group 2, No significant deterioratio n from acute phase to chronic phase in either TI-201 defect score inde x or regional ejection fraction was found in either group (two-way rep eated measures analysis of variance), Conclusions. These findings sugg est that scintigraphic no reflow phenomenon occurs in a subgroup of pa tients without angiographic no-reflow phenomenon, that the myocardial damage depends on the severity of microvascular damage and that prolon ged ischemia time may increase the likelihood of ''microvascular no-re flow phenomenon.'' (C) 1998 by the American College of Cardiology.