Diastolic dysfunction plays an important role in the pathophysiology of both coro- nary slow flow phenomenon and heart failure with preserved ejection fraction, which could be predicted by the H2FPEF score. We sought to investigate the association of H2FPEF score with coronary slow flow phenomenon in subjects undergoing coronary angiography for suspected stable ischemic heart disease. The study included 228 consecutive individuals [60.5% male, mean age 52.6 (10.1)]. Subjects with non-obstructive coronary artery disease were classified as coronary nor- mal flow (n = 112) and coronary slow flow (n = 116) after confirmation of coronary angiography results. H2FPEF score of each participant was calculated. Subjects with coronary slow flow phenomenon were more likely to be male (75% vs. 45.5%, P < .001) and have a higher body mass index than that of normal flow group [30.5 (2.9) vs. 29.3 (2.8), P=.001]. H2FPEF score was significantly higher in the former group [2 (2-4) vs. 0 (0-1), P < .001]. H2FPEF score was also positively correlated with mean corrected thrombolysis in myocardial infarction frame count (r = 0.725, P < .001). On multivariate logistic regression analysis, male gender [odds ratio: 4.580, 95% CI: 1.700-12.336, P = .003], current smoker [OR: 2.398, 95% CI: 1.064-5.408, P=.035], total cholesterol [OR: 1.011, 95% CI: 1.001-1.021, P=.026], and H2FPEF score [OR: 3.111, 95% CI: 2.160-4.480, P < .001] were found to be the independent predictors of coronary slow flow phenomenon. We found that the H2FPEF score, which is useful in demonstrating diastolic dysfunction, is independently associated with coronary slow flow pattern in suspected ischemic heart disease.