The use of periinfarct contrast-enhanced cardiac magnetic resonance imaging for the prediction of late postmyocardial infarction ventricular dysfunction.

BACKGROUND: Although ejection fraction (EF) both perimyocardial infarction (MI) and late post-MI are important prognostic factors, only implantable cardioverter-defibrillator trials of post-MI patients with depressed late EF have shown improved survival. This may relate to imprecision of early EF because of post-MI stunning. We sought to determine if peri-MI infarct size, as measured by cardiac magnetic resonance (CMR), is superior to early EF to predict late post-MI EF.
METHODS: Seventy-three patients with ST-elevation MI had infarct size and EF quantified using CMR early (<1 week) and late (>3 months) post-MI.
RESULTS: Late EF was significantly correlated with early EF (R = 0.734, P < .001), and with infarct size (R = -0.661, P < .001), and both early EF and infarct size were significant predictors of late EF. Subgroup analyses showed that low late EF (<or=35%) was better predicted by infarct size than early EF. Half of the patients with early EF <or=35% had a late EF >35%. There was no difference in early EF between the subgroup with a late EF >35% compared to the subgroup with late EF </=35% (29.7% +/- 4.6% vs 28.0% +/- 4.9%, P = .414). There was, however, a significant difference between these 2 groups in infarct size (22.6% +/- 10.8% vs 34.7% +/- 7.8%, P = .011).
CONCLUSIONS: Infarct size as determined by CMR immediately post-MI is a significant predictor of late EF and is superior to early EF in patients with initially depressed EF. Further studies are warranted to assess whether infarct size estimation by CMR after acute MI can better identify patients who are at risk for sudden cardiac death than early EF.