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CMR Microvascular Obstruction Prognosis — EECC MCQ

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HardCoronary Artery DiseaseCMR Microvascular Obstruction PrognosisEECC

A 58-year-old man with acute STEMI is treated with primary PCI. His post-PCI ECG shows persistent ST elevation despite TIMI 3 flow. CMR at day 5 shows a large area of microvascular obstruction (MVO) within the infarct zone. What is the prognostic significance?

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Correct answer: B — MVO on CMR (appearing as a dark zone within the bright LGE area on early gadolinium imaging) is the strongest CMR predictor of adverse LV remodelling, HF, and mortality after STEMI — it indicates irreversible microvascular damage despite successful epicardial reperfusion

Microvascular obstruction (MVO) on CMR represents severe microvascular injury within the infarct core where capillary beds are destroyed and gadolinium cannot penetrate (appearing as a dark/hypointense zone within the bright LGE region). MVO is present in 40-60% of STEMI patients post-primary PCI and is the strongest independent CMR predictor of: (1) adverse LV remodelling (progressive LV dilatation); (2) LV thrombus formation (stagnant blood in the MVO zone); (3) arrhythmic events; (4) all-cause mortality — superior to infarct size alone. The extent of MVO correlates with clinical severity and is associated with failed ST-segment resolution despite angiographic TIMI 3 flow (the 'no-reflow' phenomenon at the microvascular level). The 2023 ESC ACS Guidelines acknowledge CMR-detected MVO as prognostically important. Strategies to prevent MVO (optimal timing, pharmacological adjuncts) are areas of active research.

Reference: ESC (2023): ACS Guidelines; SCMR Recommendations