[Comparison between treadmill exercise test and stress-rest myocardial perfusion imaging in myocardial bridge with...

To evaluate the feature and difference between treadmill exercise test (TET) and myocardial perfusion imaging (MPI) in myocardial bridge patients with symptoms.

The data from 97 patients, who underwent 256-slice CT coronary angiography (CTCA) on TET and MPI, were collected and analyzed retrospectively. The patients were divided into an incomplete MB group (n=41) and a complete MB group (n=56). They were also divided into three groups according to the narrow degree of mural coronary artery (MCA) during the cardiac systolic period (Nobel grade): a Nobel 1 grade group (n=44), a Nobel 2 grade group (n=42), and a Nobel 3 grade group (n=11). Besides, the abnormal TET and MPI patients were divided into a TET abnormal group (n=21) and a MPI abnormal group (n=31). The results of TET and MPI were compared among the total, the different MB type groups and the different Noble grade groups, while the complete MB thickness and length were also compared between the abnormal TET group and the MPI abnormal group.

The positive rate of MPI (39/97) was higher than that of TET (26/97) in total (χ2=8.048, P<0.01). But there was no significant difference in the positive rate of TET (5/41) and MPI (8/41) in the incomplete group (χ2=1.000, P>0.05). There was a significant difference in the positive rate of TET (21/56) and MPI (31/56) in the complete MB group (χ2=8.333, P<0.01). There were significant difference in the positive rate of TET (6/44) and MPI (12/44) in the Noble 1 grade group (χ2=4.500, P<0.05), or TET (11/42) and MPI (18/42) in the Nobel 2 grade group (χ2=5.444, P<0.05). But there was no difference in Nobel 3 grade group (P>0.05). The complete MB thickness was (3.4±0.6) and (2.9±0.8) mm between the TET abnormal group and the MPI abnormal group, with statistically difference (t=2.229, P<0.05). But the MB length was (16.6±5.5) and (15.7±7.1) mm, with no statistical difference (t=0.489, P>0.05).

MPI is more sensitive than TET in myocardial ischemia in patients with MB, especially to complete MB and mild-to-moderate systolic narrowing of MCA. The positive rate is low to incomplete MB, and it is highly sensitive to severe systolic narrowing of MCA. There is difference in the MB thickness between the two methods, but there is no difference in the MB length between the two methods.