Increased TIMI frame count of coronary arteries in patients with myocardial bridging

Objectives: Myocardial bridging (MB) is associated with recurrent chest pain and cardiovascular events. Recently it has been proposed that MB has the features of vasospastic coronary artery characterized with reduced coronary flow reserve and endothelial dysfunction. In this study, an evaluation was made of the angiographic Thrombolysis in Myocardial Infarction (TIMI) frame counts (TFCs) of patients with normal angiogram and those with MB. Methods: The study was conducted as a retrospective analysis of the demographic, laboratory, and angiographic features of consecutive patients who underwent coronary angiography between January 2014 and December 2017 in Necip Fazıl City Hospital and Sütçü Imam University, Kahramanmaraş, Turkey. Results: The except for age (51.1 ± 11.6 years vs 56.8 ± 11.4 years) (p = 0.011), no difference was determined between the groups in respect of laboratory parameters and demographic features. TFCs of LAD (42.9 ± 6.1 vs 54.5 ± 11.5. p < 0.001), Cx (19.4 ± 4.5 vs 24.4 ± 7.1, p < 0.001), and RCA (26.8 ± 6.2 vs 32.5 ± 8.9, p < 0.001), and corrected TFC of LAD artery (25.2 ± 3.6 vs 32.0 ± 6.8, p < 0.001) were observed to be significantly increased in patients with MB compared to patients with normal coronary flow. Multiple regression analysis revealed that MB was the only determinant of increased corrected TFC of LAD artery (r=0.537, Adjusted r=0.281, p < 0.001). Conclusions: Patients with MB had abnormally slow coronary flow demonstrated by increased TFC. This finding may explain the recurrent angina and cardiovascular events of patients with MB. It may also explain the reversible myocardial perfusion defects which are associated with recurrent cardiovascular events in patients with MB.