Objective: Evaluation of the coronary flow reserve in cardiac syndrome X patients (patients with coronary microvascular disease, CMVD; patients with chest pain, positive exercise ECG and normal coronary angiograms) non-invasively using transthoracic Doppler echocardiography (TTDE) and mitral annular plane systolic excursion (MAPSE) marker.
Methods: This prospective study included 90 patients with suspected CAD (60 patients with cardiac syndrome X as a patient group and 30 patients as a control group), who were referred for treadmill exercise ECG, dobutamine stress echocardiography and TTDE.
Results: Coronary flow velocity reserve (CFVR) measured by TTDE, showed that the patient group had lower hyperaemic coronary flow reserve than control group.
Treadmill exercise ECG data showed that patient group who have exercise time <6 minutes, ST segment depression >1.5 mm and post recovery time >6 minutes are high-risk patients with obstructive coronary diseases.
Using the MAPSE marker in the detection of CMVD showed that the patient group has lower MAPSE than control group.
The correlation between CFVR and contractile reserve is a linear relation, as the patient group has lower CFVR so they have also low contractile reserve.
Phamacotherapy: According to 2019 ESC guidelines, we should use:
- Calcium channel blockers (non dihydropyridine CCBs).
- Angiotensin-converting enzyme inhibitors.
Conclusion: TTDE is a good non-invasive tool for assessment of CFVR. MAPSE marker is the future for assessment of CMVD.