Myocardial ischemia in the absence of obstructive coronary lesion: The role of post-stress diastolic dysfunction in detecting early coronary atherosclerosis

Background: The interactions between non-obstructive coronary atherosclerosis (<50% stenosis) and myocardial perfusion and functional parameters on myocardial perfusion imaging (MPI) have never been evaluated. Methods and Results: One-hundred and ninety-five patients were submitted to stress-rest MPI and invasive coronary angiography. The presence of obstructive coronary lesions (>50% stenosis) was excluded. The summed stress score (SSS) was calculated in every patient. Moreover, the left ventricular (LV) ejection fraction (EF) and peak filling rate (PFR) were computed from gated MPI images as measures of systolic and diastolic functions. Sixty/195 patients (31%) showed the presence of non-obstructive atherosclerosis (>20% and <50% diameter reduction). Interestingly, they presented a higher SSS than those with normal coronary arteries (P < 0.001) despite a similar myocardial scar burden. If compared to patients with normal coronary arteries, those with non-obstructive atherosclerosis showed more abnormal post-stress PFR values (2.5 ± 0.9 vs 2.9 ± 0.8, P = 0.004), despite a similar EF. On multivariate analysis, the presence non-obstructive atherosclerosis was the only significant predictor (P = 0.026) of post-stress LV diastolic impairment, independently from perfusion parameters. Conclusions: In patients without anatomically significant coronary lesions, the development of post-stress LV diastolic dysfunction on MPI associates with the presence of non-obstructive atherosclerosis on coronary angiography