Contractile reserve and contrast uptake pattern by magnetic resonance imaging and functional recovery after reperfused myocardial infarction

OBJECTIVE We hypothesized that contrast-enhanced and dobutamine tagged magn etic resonance imaging (MRI) could investigate microvascular integrity and contractile reserve of reperfused myocardial infarction (MI) in one examina tion. BACKGROUND In reperfused MI, microvascular integrity and contractile reserv e are important determinants of functional recovery. METHODS Twenty-three patients with a reperfused first MI were studied. On d ay 3 +/- 1 after MI, patients underwent tagged MRI at baseline and during i nfusion of 5 anh to mug/kg/min of dobutamine followed by contrast-enhanced MRI (first pass and delayed imaging) after a bolus infusion ofgadolinium-di ethylenetriaminepenta-acetic acid. Tagged MRI nas performed 9 +/- 1 weeks l ater (follow-up). Eighty-four transmural regions with hyperenhancement on d elayed contrast-enhanced images were defined as COMB (first pass hypoenhanc ement) or HYPER (normal first pass signal enhancement). Percent circumferen tial segment shortening was measured within the subendocardium and subepica rdum of each region of HYPER or COMB at baseline, peak dobutamine and follo w-up. RESULTS Shortening improved in COMB regions from 4 +/- 1% at baseline to 10 1% at peak dobutamine and 10 +/- 1% at follow-up, respectively (p < 0.0003 vs, baseline for both). The HYPER regions likewise improved from 10 +/- 1% at baseline to 16 +/- 1% and 17 +/- 1%, respectively (p < 0.0004 vs. basel ine for both). Function within COMB regions was less than that of HYPER at baseline, peak dobutamine and follow-up (p < 0.0003 for all). CONCLUSIONS Dobutamine magnetic resonance tagging and contrast enhanced MRI are complementary in assessing functional recovery after reperfused MI. Re gions of delayed contrast hyperenhancement demonstrate both contractile res erve and late functional recovery. However, if these regions demonstrate fi rst pass contrast hypoenhancement, they are associated with greater myocard ial damage. (C) 2000 by the American College of Cardiology.