Assessment of coronary microvascular obstruction by CMR

Assessment of coronary microvascular obstruction by CMR

Contrast enhanced cardiac magnetic resonance imaging is an important modality for assessment of coronary microvascular obstruction. Magnetic resonance imaging of the heart is obtained ten to fifteen minutes after injecting a gadolinium-based contrast. Infarcted tissue is seen as a region of hyper enhancement. A dark core of hypoenhancement within the infarct tissue is taken as a region of coronary microvascular obstruction [1].

One study checked the relation between IMR or Index of Microvascular Resistance with microvascular obstruction and myocardial injury. They included a broad range of patients with ST segment elevation myocardial infarction undergoing emergency percutaneous coronary intervention. CECMR cannot be done in the acute phase, but IMR is a simple invasive measure of microvascular function available at the time of emergency PCI. They enrolled 57 patients with STEMI of which 53  underwent CECMR in 2 days and 47 had CECMR 30 days following myocardial infarction. Hypoenhancement of microvascular obstruction was noted within the hyperenhanced infarct.

Though positron emission tomography is often considered the gold standard for diagnosing microvascular abnormalities, CMR and CT have been demonstrated as emerging modalities for assessment of microcirculation [2]. These modalities are also useful for characterization of patients with chest pain having no epicardial coronary artery disease, the typical scenario of microvascular disease [2].

References

  1. Ross McGeoch, Stuart Watkins, Colin Berry, Tracey Steedman, Andrew Davie, John Byrne, Stewart Hillis, Mitchell Lindsay, Stephen Robb, Henry Dargie, Keith Oldroyd. The index of microcirculatory resistance measured acutely predicts the extent and severity of myocardial infarction in patients with ST-segment elevation myocardial infarction. JACC Cardiovasc Interv. 2010 Jul;3(7):715-22.
  2. Tonet E, Pompei G, Faragasso E, Cossu A, Pavasini R, Passarini G, Tebaldi M, Campo G. Coronary Microvascular Dysfunction: PET, CMR and CT Assessment. J Clin Med. 2021 Apr 23;10(9):1848. doi: 10.3390/jcm10091848. PMID: 33922841; PMCID: PMC8123021.