Myocardial first pass perfusion assessed by cardiac magnetic resonance and coronary microvascular dysfunction in women with angina and no obstructive coronary artery disease.

Coronary microvascular dysfunction (CMD) is associated with a poor prognosis even in absence of obstructive coronary artery disease. CMD can be assessed as a myocardial blood flow reserve by positron emission tomography (PETMBFR) and as coronary flow velocity reserve by transthoracic Doppler echocardiography (TTDECFVR). Impaired first-pass perfusion assessed by cardiac magnetic resonance (CMR) is an early sign of ischemia. We aimed to investigate the association between CMD and CMR first-pass perfusion. Women (n=66) with angina pectoris and an invasive coronary angiogram (<50% stenosis) were assessed by TTDECFVR and in a subgroup of these (n=54) also by PETMBFR. Semi-quantitative evaluation of first-pass perfusion at rest and adenosine stress was assessed by gadolinium CMR in all 66 women. Four measures of CMR perfusion reserve were calculated using contrast upslope, maximal signal intensity and both indexed to arterial input. Mean (standard deviation) age was 62 (8) years. Median (interquartile range) TTDECFVR was 2.3 (1.8;2.7) and PETMBFR was 2.7 (2.2;3.1). Using a cut-off of 2.0 for TTDECFVR and 2.5 for PETMBFR, 25 (38%) and 21 (39%) had CMD, respectively. CMR myocardial perfusion reserve from contrast upslope (CMR_MPRupslope) showed moderate but significant correlation with PETMBFR (R=.46, p<.001) while none of the other CMR variables were associated with CMD. A CMR_MPRupslope cut-off of 0.78 identified CMD, area under the curve 0.73 (p=.001). The results indicate that CMR_MPRupslope may be associated to PETMBFR; a measure of CMD. Further research is needed to validate and implement the use of CMR first pass perfusion in this population.