Abstract
BACKGROUND: Data have been inconsistent regarding the association between TIMI frame count (TFC) and coronary function, with data suggesting that the TFC measured after pharmacological stress could correlate better with coronary physiology. OBJECTIVES: The purpose of this study was to evaluate the correlation of TFC after pharmacological stress with coronary function among women with suspected ischemia and no obstructed coronary arteries (INOCA). METHODS: Women with suspected INOCA enrolled in the WISE-CVD (Women's Ischemic Syndrome Evaluation-Coronary Vascular Dysfunction) study (NCT00832702) underwent coronary angiography with coronary function testing, to measure coronary flow reserve to adenosine, change in coronary blood flow and diameter in response to acetylcholine, and change in coronary diameter in response to nitroglycerine (ΔNTG). In a randomly selected subgroup, TFC was quantified at baseline and after pharmacological stress. The association of TFC (postpharmacological stress, rest-to-stress ratio, and percentage change from rest to stress) with measurements of coronary function was assessed with linear regression. RESULTS: TFC was quantified among 75 women, with a mean age of 54 ± 12 years. Among them, 29 (42%) had hypertension, 7 (10%) had diabetes, 34 (48%) had a previous smoking history, and 33 (49%) women had coronary atherosclerosis. Minor positive correlations were found linking higher TFC poststress with higher coronary flow reserve and higher ΔNTG (P < 0.05). Minor inverse correlations were found when using the TFC rest-to-stress ratio postacetylcholine and ΔNTG (P < 0.05). CONCLUSIONS: Among women with suspected INOCA, measuring the TFC poststress did not help in the identification of abnormal coronary physiology pathways. Other strategies should be developed to improve accessibility to coronary function testing in this population.