부산대학교 도서관

Background: Pharmacologic stress echocardiography is a useful diagnostic technique for coronary artery disease (CAD) One of its main limitations is subjective analysis of regional left ventricular (LV) systolic function. We assessed the changes of longitudinal strain and strain rate between baseline and peak stage of high-dose dobutamine test (DT) in group with negative stress echocardiography and normal coronary arteries and patients with proved CAD and contractility impairment during dobutamine examination.Methods: Dobutamine test was performed in 120 patients with recording of 2D high frame-rate apical views for the analysis with speckle tracking software (Echopac 6) to calculate peak longitudinal systolic strain and strain rate in 12 basal and medial LV segments. This analysis includes 38 subjects with EF at baseline > 50%. We compared the regional deformation parameters measured at baseline and during peak dobutamine infusion between subjects with negative stress test (20 subjects, mean age 58±8, 12 F confirmed by normal coronary angiogram or angio CT) and patients with positive stress and angiographic significant stenosis in RCA or Cx artery (18 patients, mean age 63±10, 7 F).Results: Mean dose of dobutamine was 40 μg/kg/min in controls and 35 μg/kg/min in CAD group, resulting in heart rate increase from 64±9 to 146±9 in controls and 63 ±7 to 128±28 in CAD patients. Baseline deformation values were comparable. Regional peak systolic strain did not change significantly during infusion as opposed to strain rate which increased in both groups. Mean values for systolic strain did not differ between control and CAD patients at peak. Strain rate measured during peak stage of dobutamine test was significantly lower in patients with CAD in the following segments: basal inferior -2.28±0.79 vs -2.97±1.2, p<0.05, medial inferior -2±0.61 vs -2.55±0.9, p< 0.05, basal septum -2.02±0.77 vs -2.67±0.68, p<0.01, medial septum -2±0.68 vs -2.56±0.8, p<0.05, basal lateralis -2.04±0.77 vs -2.64±0.8, p<0.05, medial posterior -1.75±0.37 vs -2.17±0.72, p<0.05, medial anteroseptalis -1.6±0.58 vs -2.45±0.83, p<0.001, basal anteroseptalis -1.53±0.42 vs -2.28±1.6, p<0.01. Thus, lower strain rate was observed mainly in segments perfused by stenosed RCA/Cx arteries, e.g. on inferior but not anterior wall in 2 chamber view but also in anterior septum.Conclusions: Speckle-tracking derived longitudinal systolic strain rate but not strain value during peak dobutamine dose allows quantification of myocardial function and differentiation of normal and ischemic segments perfused by stenosed right coronary / circumflex artery.