The Importance of Speckle Tracking Echocardiography Evaluating of Nonobstructive Coronary Artery Stenosis and Its Correlation with Microvascular Angina

This study aims to evaluate patients with limited state of changes in coronary arteries detected by coronary angiography, the dynamics of these changes over the two years, identify the relevant diagnostic criteria, and assess the efficacy of applied treatment by using speckle tracking echocardiography. Peak radial and circumferential strain and SR (systolic, early, and late diastolic strains) were measured based on the short-axis view; peak longitudinal strain and SR were measured from the apical side of four- two- and three-chamber views. Radial, longitudinal (GLS), circumferential global and regional strains were calculated as an average of measurements. All patients (n - 146) were assigned to normal (control) and CAD groups according to cardiac angiography results. 128 of them were evaluated repeatedly after two years. Depending on angiography findings, LAD (85.83%) stenosis predominate, when subsequently fewer instances of RCA (52.5%) or LCX (40.83%) were observed. Most (about 80%) of the patients had one or two-vessel disease and only 20% had systemic all three-vessel disease. Analysis of STE data in groups during a two-year study period showed statistically reliable differences associated with a particular coronary artery. In the control group: RCA-myocardial circumferential strain (p - 0.037); LAD-no changes; LCX-early (p - 0.013) and late diastolic longitudinal (p - 0.033) strains. Subsequently, in the CAD group: RCA-diastolic circumferential strain rate (p - 0.007); LAD-myocardial longitudinal strain (p - 0.006), systolic longitudinal (p - 0.038) and circumferential strain (p - 0.012) rates, early diastolic circumferential (p - 0.008) and late diastolic longitudinal (p - 0.037) strain rates; LCX-myocardial longitudinal (p - 0.049) strain. Between groups, we detected significant changes in such circumferential strain rates, respectively: RCA- systolic (p=0.037), early diastolic (p=0.019), and late diastolic (p=0.024) strain rates; LAD-no changes; LCX-early diastolic longitudinal strain (p - 0.004). The clinical condition of our patients over the two years has improved both in control and CAD groups, according to GLS. We hold the opinion that microvascular angina (MVA) may be responsible for such an improvement because the main diagnostic criteria and common treatment with ACE inhibitors, statins, beta-blockers, antithrombotic, and nitrates was typical and effective for MVA treatment.