Assessment of the relationship between coronary flow rates and myocardial perfusion abnormality in patients with nonobstructive coronary artery disease: an observational study in cardiac syndrome X and coronary slow flow.

OBJECTIVES

In this study, we evaluated and compared the level of myocardial ischaemia caused by cardiac syndrome X (CSX) and coronary slow flow (CSF) with single photon emission computed tomography myocardial perfusion imaging (SPECT-MPI), and determined if changes in the level of myocardial ischaemia exist in CSF and CSX cases according to thrombolysis in myocardial infarction frame count (TFC).

MATERIALS AND

METHODS

The study population consisted of 66 patients with CSF and 78 angiographically normal patients (36 of them with CSX and 42 of them healthy controls). The coronary flow rates of all patients were documented using TFC. Subsequently, all patients were evaluated with SPECT-MPI and categorized into the following groups according to their results: patients with CSF, patients with CSX, and patients with normal coronary arteries. Finally, we investigated whether a relationship existed between the SPECT-MPI and TFC results from these three groups.

RESULTS

All ischaemia scores for MPI were significantly higher in the CSF group than in the CSX and control groups (P < 0.05). TFC was significantly associated with the severity of ischaemia in the CSF patients. There was a significant positive correlation between the summon difference score (SDS) and mean TFC value (P < 0.05) as well as between the SDS and each individual coronary TFC value in the CSF patients (P < 0.05). The number of vessels involved in CSF was positively correlated with the SDS.

CONCLUSION

CSF is associated with more severe myocardial ischaemia than CSX. The level of myocardial ischaemia on SPECT-MPI was correlated with the TFC and the number of affected coronary vessels in patients with CSF. These results suggest that CSF is a more serious clinical entity than CSX, and that the clinical severity of CSF appears to increase as the coronary flow rate decreases.