Assessment of coronary microvascular obstruction by CMR
Assessment of coronary microvascular obstruction by CMR: Contrast enhanced cardiac magnetic resonance (CMR) imaging is considered to be the gold standard for assessment of coronary microvascular obstruction. Magnetic resonance imaging of the heart is obtained ten to fifteen minutes after injecting a gadolinium-based contrast at a dose of 0.1 mmol/kg. 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 . The study checked the relation between IMR (Index of Microvascular Resistance) with MVO (Microvascular Obstruction) and myocardial injury. This was evaluated by CECMR (Contrast enhanced cardiac magnetic resonance) imaging. They included a broad range of patients with ST segment elevation myocardial infarction (STEMI) patients undergoing emergency PCI (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 (93%) underwent CECMR in 2 days and 47 (82%) had CECMR 30 days following myocardial infarction. Hypoenhancement of MVO was noted within the hyperenhanced infarct with 10 to 15 minutes following injection of intravenous gadolinium,
- 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.