Evolution of 5 cardiovascular magnetic resonance-derived viability indexes after reperfused myocardial infarction.

Background: The objective of this study was to evaluate the simultaneous evolution of 5 cardiovascular magnetic resonance-derived myocardial viability indexes.

Methods: We studied 72 patients with a first ST-elevation myocardial infarction and sustained TIMI 3 flow. In the first week and in the sixth month of the study, using cardiovascular magnetic resonance imaging, we determined wall thickening (WT) and the following viability indexes: wall thickness, WT with low-dose dobutamine, microvascular perfusion in first-pass imaging, microvascular obstruction in late-enhancement imaging, and transmural extent of necrosis.

Results: In 250 dysfunctional segments, the evolution outcomes for the viability indexes were as follows: (1) wall thickness thinned (8.6 +/- 2.9 versus 7.7 +/- 3 mm, P < .001), (2) WT with low-dose dobutamine improved (1.5 +/- 1.9 versus 2.6 +/- 3 mm, P < .001), (3) the number of segments showing abnormal microvascular perfusion in first-pass imaging decreased (22% versus 7%, P < .001), (4) the number of segments showing microvascular obstruction in late-enhancement imaging decreased (14% versus 2%, P < .001), and (5) the transmural extent of necrosis remained stable throughout follow-up (56% +/- 40% versus 54% +/- 39%, P = .3).

Conclusions: After reperfused myocardial infarction, dynamic changes in wall thickness, contractile reserve, microvascular perfusion, and microvascular obstruction take place. These changes may affect their accuracy as viability indexes early after myocardial infarction. The transmural extent of necrosis does not vary, however.