BACKGROUND:
Increased myocardial injury visualized by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) portends worse outcomes in patients with acute coronary syndromes (ACS). Although non ST-segment acute coronary syndromes (NSTE-ACS) comprise 70% of all ACS and 1-year mortality rates are similar to the more readily-diagnosed and uniformly-treated ST-elevation myocardial infarction, ischemic changes and treatment strategies in NSTE-ACS are not well-defined, Studies have shown that T2-weighted (T2W) cardiac magnetic resonance (CMR) may be a marker of acute myocardial injury in ACS. We hypothesized that the presence of at-risk myocardium, identified by T2W CMR at presentation, predicts increased subsequent myocardial injury by LGE beyond traditional risk predictors in NSTE-ACS.
METHODS & RESULTS:
48 patients enrolled in a prospective study of NSTE-ACS underwent CMR with short tau inversion recovery (T2W STIR) imaging and LGE prior to intervention and repeat CMR 61 ± 27 days later. Baseline presence/absence of increased myocardial signal intensity by T2W STIR was determined by consensus of two expert reviewers blinded to other data. In 13 patients (27%), follow-up LGE images showed more extensive injury compared to baseline. Peak troponin at time of event, baseline TIMI risk score and baseline LGE score did not predict subsequent LGE score increase (p=0.13, p=0.48, p=0.55, respectively). Conversely, a much higher proportion of patients with vs. without increased T2W STIR SI at baseline demonstrated increased myocardial injury by LGE at follow-up (12/31 vs. 1/17, p<0.01; Figure).
CONCLUSION:
Myocardium at-risk by T2-weighted STIR CMR in patients with NSTE-ACS predicts subsequent myocardial injury, more so than clinical predictors or extent of baseline myocardial damage. Prospective studies that intensify care for patients with at-risk myocardium may help identify strategies to improve myocardial salvage and reduce mortality in NSTE-ACS.
Area at risk assessed by 123 I-MIBG SPECT: prospective study in 35 patients admitted for acute STEMI and comparison to cardiac magnetic resonance
