Risk score for early risk prediction by cardiac magnetic resonance after acute myocardial infarction.

Background: Cardiac magnetic resonance (CMR) performed early after ST-segment elevation myocardial infarction (STEMI) can improve major adverse cardiac event (MACE) risk prediction. We aimed to create a simple clinical-CMR risk score for early MACE risk stratification in STEMI patients.

Methods: We performed a multicenter prospective registry of reperfused STEMI patients (n = 1118) in whom early (1-week) CMR-derived left ventricular ejection fraction (LVEF), infarct size and microvascular obstruction (MVO) were quantified. MACE was defined as a combined clinical endpoint of cardiovascular (CV) death, non-fatal myocardial infarction (NF-MI) or re-admission for acute decompensated heart failure (HF).

Results: During a median follow-up of 5.52 [2.63-7.44] years, 216 first MACE (58 CV deaths, 71 NF-MI and 87 HF) were registered. Mean age was 59.3 ± 12.3 years and most patients (82.8%) were male. Based on the four variables independently associated with MACE, we computed an 8-point risk score: time to reperfusion >4.15 h (1 point), GRACE risk score > 155 (3 points), CMR-LVEF <40% (3 points), and MVO >1.5 segments (1 point). This score permitted MACE risk stratification: MACE per 100 person-years was 1.96 in the low-risk category (0-2 points), 5.44 in the intermediate-risk category (3-5 points), and 19.7 in the high-risk category (6-8 points): p < 0.001 in multivariable Cox survival analysis.

Conclusions: A novel risk score including clinical (time to reperfusion >4.15 h and GRACE risk score > 155) and CMR (LVEF <40% and MVO >1.5 segments) variables allows for simple and straightforward MACE risk stratification early after STEMI. External validation should confirm the applicability of the risk score.