Abstract 16142: Grad 3-Ischemia (QRS Complex Distortion) as a Predictor of Myocardial Damage as Assessed by Cardiac Magnetic Resonance Imaging and Clinical Prognosis in Patients With ST-Elevation Myocardial Infarction

Abstract

Introduction: Predicting the extent of myocardial damage on early electrocardiographic (ECG) findings could be helpful for improved risk stratification in patients with acute reperfused ST-elevation myocardial infarction (STEMI). Distortion in the terminal portion of the QRS complex (so called grade 3 ischemia, G3I) has been associated with adverse outcomes in STEMI patients. The correlation of G3I with infarct size and microvascular injury is not well defined. Objective: To studied the relation of G3I with myocardial damage as assessed by CMR and the association of G3I with adverse clinical outcomes in a STEMI population treated by primary percutaneous coronary intervention (PCI). Methods: We analyzed the ECGs of 572 consecutive STEMI patients regarding the presence or absence of G3I. G3I was defined as: 1) complete loss of S waves in 2 adjacent leads with typical Rs configuration (i.e. V1-V3), or 2) ST-J point to R wave amplitude ratio >0.5 in other leads with qR configuration. CMR was performed within 1 week after infarction for comprehensive assessment of myocardial damage using a standardised protocol. The primary clinical end-point was major adverse cardiac events (MACE) defined as death, reinfaction and readmission for congestive heart failure within 12 months after the index event. Results: G3I was present in 186 (32%) patients. The presence of G3I was associated with larger infarct size (18.3%LV [10.4 to 27.6] versus 16.5%LV (8.2 to 23.5), p=0.01), late microvascular obstruction (0.4%LV [0 to 2.7] versus 0%LV [0 to 1.5], p= 0.05, presence of intramyocardial hemorrhage (41 versus 32%, p=0.04) and less myocardial salvage (47 [28 to 64] versus 53 (35 to 68), p=0.01). G3I was associated with a significant higher incidence of MACE (p=0.01) and was identified as an independent predictor of MACE in Cox regression analysis (Hazard ratio 2.19 [1.10 to 4.38], p=0.03). Conclusions: This largest study to date correlating G3I on the admission ECG with CMR markers of myocardial damage demonstrates that G3I is significantly associated with infarct size, myocardial salvage and reperfusion injury in a STEMI population reperfused by primary PCI. Moreover, G3I was independently associated with MACE.