Abstract
The success of coronary reperfusion therapy in ST-segment-elevation myocardial infarction (MI) is commonly limited by failure to restore microvascular perfusion. We performed a prospective cohort study in patients with reperfused ST-segment-elevation MI who underwent cardiac magnetic resonance 2 days (n=286) and 6 months (n=228) post MI. A serial imaging time-course study was also performed (n=30 participants; 4 cardiac magnetic resonance scans): 4 to 12 hours, 2 days, 10 days, and 7 months post reperfusion. Myocardial hemorrhage was taken to represent a hypointense infarct core with a T2* value of <20 ms. Microvascular obstruction was assessed with late gadolinium enhancement. Adverse remodeling was defined as an increase in left ventricular end-diastolic volume ≥20% at 6 months. Cardiovascular death or heart failure events post discharge were assessed during follow-up. Two hundred forty-five patients had evaluable T2* data (mean±age, 58 [11] years; 76% men). Myocardial hemorrhage 2 days post MI was associated with clinical characteristics indicative of MI severity and inflammation. Myocardial hemorrhage was a multivariable associate of adverse remodeling (odds ratio [95% confidence interval]: 2.64 [1.07-6.49]; P=0.035). Ten (4%) patients had a cardiovascular cause of death or experienced a heart failure event post discharge, and myocardial hemorrhage, but not microvascular obstruction, was associated with this composite adverse outcome (hazard ratio, 5.89; 95% confidence interval, 1.25-27.74; P=0.025), including after adjustment for baseline left ventricular end-diastolic volume. In the serial imaging time-course study, myocardial hemorrhage occurred in 7 (23%), 13 (43%), 11 (33%), and 4 (13%) patients 4 to 12 hours, 2 days, 10 days, and 7 months post reperfusion. The amount of hemorrhage (median [interquartile range], 7.0 [4.9-7.5]; % left ventricular mass) peaked on day 2 (P<0.001), whereas microvascular obstruction decreased with time post reperfusion. Myocardial hemorrhage and microvascular obstruction follow distinct time courses post ST-segment-elevation MI. Myocardial hemorrhage was more closely associated with adverse outcomes than microvascular obstruction. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02072850.
Highlights
ObjectivesWe aimed to (1) detect myocardial hemorrhage using T2* mapping in a large relatively unselected segment–elevation myocardial infarction (STEMI) population and re-evaluate its pathophysiology and prognostic significance, (2) study the temporal evolution of myocardial hemorrhage with serial cardiac magnetic resonance (CMR) early after reperfusion, and (3) assess the temporal relationships between myocardial hemorrhage versus microvascular obstruction
The success of coronary reperfusion therapy in ST-segment–elevation myocardial infarction (MI) is commonly limited by failure to restore microvascular perfusion
Myocardial hemorrhage was a multivariable associate of adverse remodeling
Summary
We aimed to (1) detect myocardial hemorrhage using T2* mapping in a large relatively unselected STEMI population and re-evaluate its pathophysiology and prognostic significance, (2) study the temporal evolution of myocardial hemorrhage with serial CMR early after reperfusion, and (3) assess the temporal relationships between myocardial hemorrhage versus microvascular obstruction
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