Relationship between QRS score and microvascular obstruction after acute anterior myocardial infarction

Background: The QRS score on electrocardiogram (ECG) in patients with myocardial infarction (MI) reportedly reflects the severity of myocardial damage. The presence of microvascular obstruction (MO) assessed by cardiac magnetic resonance (CMR) imaging is associated with irreversible myocardial damage. MO assessed by CMR is known to be a predictor for adverse clinical outcome after ST-elevation MI. The aim of the present study was to examine the relationship between QRS score and MO in acute anterior MI patients. Methods: Sixty-two patients with first acute anterior MI who successfully underwent primary percutaneous coronary intervention (PCI) were enrolled. The QRS score after PCI on admission ECG was calculated by a Selvester-Wagner QRS scoring system. CMR imaging was performed at 11.4 ± 3.9 days after MI. MO was defined as delayed enhancement with contrast-devoid core. Patients were divided into two groups as follows: 37 patients who showed MO (MO group) and 25 patients who did not show it (non-MO group). Results: The QRS score was significantly greater in the MO group than in the non-MO group. The QRS score significantly correlated with MO volume (r = 0.418, p = 0.010). Multivariate analysis showed that the QRS score (odds ratio 1.362, 95% CI: 1.038-1.951, p = 0.024) and the peak creatine kinase levels (odds ratio 1.001, 95% CI: 1.000-1.002, p < 0.001) were independent predictors for MO. Conclusions: Our results indicate that the QRS score derived from simple and widely available ECG may be a useful parameter for assuring the presence of MO.