INTRODUCTION: Myocardial bridging (MB) is a congenital anomaly characterized by the intramyocardial course of one or more coronary arteries that provokes endothelial dysfunction and can generate myocardial ischemia with its pathological consequences. Because of the dynamic nature of the ischemic mechanism, a high-sensitivity myocardial perfusion stress test is often needed to decide on the correct management of the patient, mainly single photon emission computed tomography (SPECT). As an alternative to SPECT, our center offers the possibility of performing a dynamic stress-rest cCT-MPI (cardiac computed tomography – myocardial perfusion imaging).
HYPOTHESIS: To compare the feasibility of performing cCT-MPI for the functional evaluation of MBs.
METHODS: All cases underwent cCT (192-slice dual-source Somatom Force CT scanner, Siemens Healthcare, Germany), cCT-MPI with administration of a standard intravenous dose of 0.4 mg of regadenoson (Rapiscan®, GE Healthcare), and SPECT with physical stress (the latter not performed in one case of a minor patient, in favor of a coronary angiography with functional tests). Image processing was performed using Siemens Syngo® software, which can provide perfusion maps of myocardial blood flow (MBF) and volume (MBV) in a planar and 17 segments Bull ‘s eye view. The interpretation of the results was performed toghether by an expert radiologist and cardiologist, both on a qualitative (color map) and quantitative basis (MBF ratio).
RESULTS: From May 2022 to September 2023, 15 cases of MB with otherwise intact coronary arteries were collected, all involving the LAD and with anatomical characteristics considered ‘dangerous’, i.e. length >2.5 cm and depth >2 mm. The investigations carried out revealed two relevant results: the first is that, despite all the selected MBs had anatomical features of complexity, a reversible perfusion defect related to MB was detected in only 2 cases (13%), one of which was confirmed by SPECT investigation and the other by functional tests during coronary angiography; the second is the high positive and negative concordance between cCT-MPI with pharmacological stress and SPECT with physical stress.
CONCLUSION: Myocardial bridging is an increasing finding detected through cCT investigations, but in a minority of cases it carries hemodynamic consequences. cCT followed in the same session by cCT-MPI with regadenoson administration constitutes two stages of the same exam.
