Abstract 408: Prognostic Significance and Determinants of Myocardial Salvage Assessed by Cardiovascular Magnetic Resonance Imaging
Purpose: Myocardial salvage is the hallmark of successful reperfusion therapy and results in improved prognosis. Cardiovascular magnetic resonance (CMR) can visualize the extent of the salvaged area at risk and may serve as an important therapeutic target. So far the prognostic relevance and predictors of myocardial salvage assessed by CMR has not been evaluated appropriately.
Methods: This study analyzed 230 consecutive STEMI patients (158 male (69%); mean age 65±12) reperfused by primary PCI within 12 h after symptom onset. The following parameters were calculated using a 1.5 Tesla scanner:
area at risk=volume edema/volume left ventricular mass;
%infarct size=volume infarct/volume left ventricular mass;
myocardial salvage index (MSI)=area at risk-infarct size/area at risk.
Reperfusion times, 90min STR, TIMI-flow grades pre and post PCI, TIMI risk score and multiple clinical parameters such as cardiovascular risk factors, Killip-class, and infarct location were also assessed. Clinical endpoints were major adverse cardiovascular events within 6 months after randomization
Results: The median time between index event and MRI was 3±6 days. The median MSI was 50. In patients with pre PCI TIMI-flow 0–1 MSI was significantly higher in comparison to TIMI-flow 2–3 (44±24 vs. 59±26; p<0.001). The extent of STR 90min after primary PCI correlated with MSI (r=0.238; p<0.001). Anterior MI MSI was higher with 56±26 vs. 48±26 in inferior MI (p=0.02). In a stepwise multiple linear regression model the strongest predictors were pre PCI TIMI-flow, pain-to-balloon time, STR at 90min, infarct location and Killip class. There was a significant inversely correlation of symptom duration and MSI (r−0.265, p<0.001). Patients with an MSI ≥ the median had a 6-month major adverse cardiac event rate of 3%, significantly less than the 20% of patients with MSI < the median (p<0.001).
Conclusions: In patients with reperfused STEMI, CMR visualizes both reversible and irreversible injury. This allows for quantifying the extent of the salvaged area after revascularization as a reliable clinical parameter with important prognostic relevance.