Clinical outcome and correlates of coronary microvascular obstruction in latecomers after acute myocardial infarction

Aims Microvascular obstruction (MVO) is associated with a worse prognosis in patients with ST-elevation myocardial infarction (STEMI) treated by primary percutaneous coronary intervention (PCI). However, data about incidence, clinical outcome and correlates of MVO in latecomers after STEMI are still lacking. Methods We prospectively enrolled consecutive patients that were latecomers after STEMI (symptoms onset > 12 h) undergoing PCI. We performed an angiographic analysis to assess the occurrence of MVO [defined as TIMI flow grade ≤ 2 or 3 with a myocardial blush grade < 2]. Moreover, we performed a clinical and echocardiographic follow-up to assess the occurrence of major adverse cardiovascular events (MACE), defined as the composite of cardiac death, myocardial infarction and rehospitalization for heart failure, and to evaluate left ventricle remodelling. Results Seventy-eight patients were enrolled [mean age 67.58 ± 11.72 years, 57 (73%) male; mean time of symptom onset 23.14 ± 16.06 h] with a mean follow-up time of 29.7 ± 14.1 months. MVO occurred in 39 (50%) patients. Patients with MVO had a higher rate of MACE [18 (46%) vs. 3 (8%), p < 0.001] and LV remodelling [25 (64%) vs. 6 (15%), p < 0.001] compared with patients without MVO. By multivariable Cox regression MVO and left anterior descending artery were independent predictors of MACE. Conclusions Latecomers after STEMI have a high risk to develop MVO that is related to an adverse prognosis. Appropriate management and follow-up strategies should be implemented in such high-risk patients group.