8 Myocardial haemorrhage after acute reperfused st-elevation myocardial infarction: temporal evolution, relation to microvascular obstruction and prognostic significance

Abstract

Background: The success of emergency coronary reperfusion therapy in STelevation myocardial infarction (STEMI) is commonly limited by failed tissue perfusion. Purpose: To perform a longitudinal clinical study of myocardial haemorrhage in a large cohort of reperfused STEMI survivors and assess the temporal relationship between intramyocardial haemorrhage (IMH) versus microvascular obstruction (MVO) early after reperfusion in a serial cardiac magnetic resonance (CMR) sub-study. Methods: We performed a prospective single centre cohort study in reperfused STEMI patients who underwent CMR 2 days (n=286) and 6 months post-MI. IMH was taken to represent a hypointense infarct core with a T2∗ value <20 ms. 30 STEMI patients underwent serial CMR at 4 time points: 4 to 12 hours, 3 days, 10 days and 6-7 months post reperfusion. Adverse remodeling was defined as an increase in left ventricular end-diastolic volume (LVEDV) ≥20% at 6 months. Results: 245 STEMI patients had evaluable T2∗ data and 101 (41%) patients had IMH. In multivariable regression, IMH was independently associated with initial TIMI coronary flow grade, ECG evidence of reperfusion injury and Killip class (all p<0.03). 133 (51%) patients had MVO. All of the patients with IMH had MVO. IMH was multivariably associated with adverse remodeling, independent of baseline LVEDV (odds ratio (95% CI): 2.64 (1.07, 6.49); p=0.035). IMH was also multivariably associated with cardiovascular (CV) death or heart failure hospitalisation post-discharge (hazard ratio (95% CI): 12.9 (1.6, 100.8); p=0.015). In the serial imaging subgroup, IMH occurred in 7 (23%), 13 (43%), 11 (33%), and 4 (13%) patients at 4-12 hours, 3 days, 10 days and 7 months, respectively. The amount of MVO was greatest 4-12 hours post-reperfusion, then fell progressively over time. In contrast, the amount of IMH increased dynamically from 4-12 hours with a peak at 3 days and then a decrease at 10 days. MVO resolved by day 10 in 8 patients (44%), 2 (25%) of which had evidence of IMH. Whereas MVO persisted in 10 patients (56%), all (100%) of which had evidence of IMH. Conclusion: IMH is independently associated with adverse remodeling at 6- months and CV death or heart failure hospitalisation post-discharge. The severity of MVO affects its degree of persistence and T2∗ imaging differentiates persistent, structural microvascular injury from functional, potentially reversible MVO. Haemorrhage occurs in primary and secondary phases within the first 10 d…