Abstract 17497: Ischemic Grade on the Admission ECG of a First St-Elevation Myocardial Infarction Predicts Microvascular Damage and Impaired Functional Recovery
Background: Prediction of recovery of systolic function after STEMI remains challenging. Microvascular obstruction (MVO) is a known predictor of negative remodeling after reperfusion therapy, but can only be diagnosed on cardiovascular magnetic resonance (CMR). We sought to evaluate the relationship between ischemic grade on the presentation ECG on MVO severity at baseline and functional recovery after 4 months.
Methods: We prospectively enrolled 134 patients with a first STEMI undergoing successful PCI followed by state-of-the-art postinfarction medical treatment, and quantified MVO at day 3-4, and LV functional and structural remodeling after 4 mo follow-up using 1.5 T CMR and TTE. Ischemic grade was defined as ST elevation with distortion of the terminal portion of the QRS on ECG. Grade 2 and 3 ischemia represented the ST J amplitude greater or smaller than 50% criterion or presence or absence of an S wave or any Q in V2 and V3.
Results: Patients with grade 2 (n=77) and 3 (n=57) ischemia had comparable pre- and peri-procedural medication and cardiovascular risk profiles, except for age. Patients with gr 3 ischemia were older than those with gr 2 (60±12 vs 57±11y, P<0.05), had a longer delay between symptom onset and PCI (4.7±2.7 vs 4.1±3.1 hours, P<0.05) and a trend for a greater proportion of TIMI 0 flow before PCI (p=0.058). Infarct-related artery and TIMI flow after PCI were similar. Troponin and CK levels at admission were similar, but significantly higher after 24 h in patients with gr 3 ischemia (P<0.001). Patients with gr 3 ischemia had significantly more MVO (4±6 vs 10±13 g, P<0.01), greater area at risk (44±23 vs 34±20 g, P<0.01) and larger infarct volumes both at baseline and at 4 mo (23±14 vs 14±10%LV mass and 15±13 vs 11±7% respectively, P<0,001 for both), and smaller myocardial salvage index (p<0.003). LVEF at admission and after 4 mo measured by TTE was lower in gr 3 ischemia (52±12 vs 54±11, P<0.01 and 53±11 vs 61±9, P<0.001). Serial CMR confirmed impaired global LV systolic function recovery in patients with gr 3 ischemia (P<0.001).
Conclusion: Gr 3 ischemia in STEMI is a valuable predictor of extensive myocardial microvascular damage on CMR imaging, and is closely associated with impaired functional and structural recovery after successful PCI for STEMI.
- © 2011 by American Heart Association, Inc.