Coronary vasodilator reserve: a clue to the explanation of (201)Tl redistribution patterns early after successful primary stenting for acute myocardial infarction.

OBJECTIVES We sought to assess the mechanism and significance of different (201)Tl redistribution patterns after successful primary stenting following acute myocardial infarction (AMI). BACKGROUND The mechanism of (201)Tl reverse redistribution and the impact of different redistribution patterns on the recovery of contractility after successful reperfusion therapy for AMI remain unclear. METHODS We studied 41 consecutive patients with successful primary stenting for a first AMI. Patients underwent predischarge and six-month follow-up dipyridamole stress-reinjection single photon emission tomography (SPECT), coronary and left ventricular angiography. Intracoronary Doppler assessment of coronary flow reserve (CFR) was performed before discharge. RESULTS Four patient groups were identified according to predischarge SPECT: patients with I: nonreversible defects (n = 8), II: redistribution (n = 7), III: reverse redistribution (n = 21), IV: no defect (n = 5). At follow-up contractility recovery increased in a stepwise fashion from groups I to IV (19 +/- 41%, 40 +/- 53%, 70 +/- 28%, 78 +/- 33%, p = 0.01). Compared with patients with redistribution, those with reverse redistribution had lower infarct-related artery (IRA) CFR (2.2 +/- 0.5 vs. 2.8 +/- 0.9, p = 0.03) but higher contractility recovery. CONCLUSIONS Variable (201)Tl redistribution patterns, early after successful stenting for AMI, may predict different degrees of late contractility recovery. The lower IRA CFR and the higher contractility recovery in areas with reverse redistribution suggest more severe microvascular dysfunction and less severe myocardial injury in such areas compared with those with redistribution.