Phenomena of microvascular myocardial injury in patients with primary ST-segment elevation myocardial infarction: prevalence and association with clinical characteristics

Aim. The aim of this study was to evaluate the prevalence of microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH), their combination, and relationship to the clinical and anamnestic characteristics in patients with primary STEMI after coronary reperfusion.Material and Methods. A single-center observational cohort study comprised a total of 60 patients with primary STEMI and successful coronary reperfusion within 12 hours of the onset of symptoms. All patients were studied using a contrast-enhanced cardiac magnetic resonance imaging (CE-MRI) at day 2 after STEMI. The study protocol was registered on ClinicalTrials.gov (Identifier: NCT03677466).Results. The total occurrence rate of MVO and IMH phenomena was 68.3% including MVO only in 17% of patients, IMH only in 15% of cases, combination of MVO and IMH in 36% cases, and without a microvascular myocardial injury in 32% of cases. The patients with MVO only and combination of MVO and IMH experienced a longer time of ischemia versus patients without these conditions: 205 (140-227) and 193 (95-400) versus 130 (91-160) min (p = 0.049). On the contrary, the time of myocardial ischemia did not differ between patients with IMH only (113 min) and patients without it. Then, patients were assigned to the group of pharmaco-invasive strategy of coronary reperfusion (PIS) (n = 39) and the group of primary percutaneous intervention (PPCI) (n = 21). The incidence of MVO only and IMH only was equal in PIS and PPCI groups: 17.9% versus 14.2% and 12.8% versus 19.1% in PIS and PPCI groups, respectively. The tendency to a decrease in the incidence of combined MVO and IMH was observed in PIS group compared to PPCI group: 30.8% versus 47.6% (p = 0.09).Conclusion. The combination of MVO and IMH phenomena in patients with primary STEMI after coronary reperfusion developed more often than each of these phenomena separately. The development of MVO only and combination of MVO and IMH was associated with a longer duration of myocardial ischemia. A total frequency of combination of MVO and IMH phenomena in patients with primary STEMI after coronary reperfusion was as high as 68.3%. Combination of these phenomena developed more frequently than each of them separately: 36% versus 17% (MVO only) and 15% (IMH only). No difference was observed in the duration of myocardial ischemia between the groups with MVO only and without it. The thrombolysis did not increase the occurrence of IMH in PIS group compared with PPCI group. There was a tendency to a decrease in the incidence of combination of MVO and IMH in PIS group compared to PPCI group: 30.8 versus 47.6% (р = 0.09).