Heartbeat: Virtual histopathology after myocardial infarction

Inflammation plays a key role in outcomes after myocardial infarction yet we have few tools to directly visualise the cellular inflammatory response in clinical practice. In this issue of Heart , Stirrat and colleagues1 performed repeated MRI studies in 31 patients after myocardial infarction using ultra-small-super-paramagnetic particles of iron oxide (USPIO) to visualise macrophages within the myocardium. In combination with other MRI imaging sequences, this approach provides a virtual histopathologic view of the myocardium. In the infarcted myocardial segment, USPIO uptake peaked at 2–3 days and resolved by 10–16 days whereas myocardial oedema peaked later (day 3 to 9) and persisted for over 3 months. (figure 1) As the authors suggest: “This imaging technique holds promise as a non-invasive method of assessing and monitoring myocardial cellular inflammation with potential application to diagnosis, risk stratification and assessment of novel anti-inflammatory therapeutic interventions.” Figure 1 Examples of myocardial oedema and USPIO enhancement in the infarct zone after MI. Three examples of MI (1—anteroseptal, 2—lateral and 3—inferior) illustrating LGE, USPIO enhancement (R2* map) and oedema (T2 map) at early (up to 10 days) and late (3 months) time points. Early inflammation and oedema seen on R2* (dark region) and T2 maps (light region), respectively, have …