Myocardial Rupture, Microvascular Obstruction, and Infarct Expansion
Elucidation by Cardiac Magnetic Resonance
A 75-year-old man was hospitalized for frequent, severe chest pressure over 2 days. Cardiac enzymes were elevated, and electrocardiography showed 3-mm anterior ST elevation. He developed severe pleuritic chest pain, dyspnea, rales, and a pericardial friction rub. Cardiac MRI (CMRI, Figure 1) showed mid-septal to distal septal and mid-apical to distal anteroapical and inferoapical myocardial thinning, no systolic wall thickening, and dyskinesis. Gadolinium infusion showed profound microvascular obstruction, indicated by very dark myocardium (Figure 2, arrows). The patient died suddenly 6 days after admission. An autopsy showed complete occlusion of the left anterior descending coronary artery, with inferoapical myocardial rupture and microvascular obstruction from platelet-fibrin thrombus (Figure 3).
CMRI demonstrates its unique ability here to define patients at risk of myocardial rupture. CMRI detected the rare combination of myocardial thinning early after infarction and predicted the severe microvascular obstruction found on microscopic examination. It thus showed the infarct to be recent (rather than old and scarred) and documented infarct expansion by thinned, unperfused myocardium. Infarct expansion, thinning, and microvascular obstruction in combination set up the lethal circumstances leading to myocardial rupture.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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