Diagnostic Value of Strain Rate Imaging by Tissue Doppler in Patients with Suspected Coronary Artery Disease

Background: Strain Rate Imaging (SRI) is a new diagnostic technique. Objectives: The present study aimed to determine the diagnostic value of SRI in detection and localization of coronary lesions in patients with chest pain, but without apparent wall motion abnormalities. Patients and Methods: This study was conducted on 91 patients with suspicion of stable angina or unstable angina selected through simple random sampling. SRI was done using Tissue Doppler Imaging (TDI) prior to coronary angiography. All the patients had normal electrocardiograms and normal wall motion in echocardiography. Longitudinal strain was obtained for 18 segments in the Left Ventricle (LV). Then, peak longitudinal systolic strain (epsilon(sys)), post systolic shortening, and its characteristics were assessed in normal and abnormal segments. Significant coronary lesion was considered if stenosis was above 70%. Results: The results showed that 40 patients with heterogeneous strains and 2 patients with constant strains had significant coronary stenosis. Besides, 31 patients with constant strains and 18 ones with heterogeneous strains had normal or minimal coronary lesions. Moreover, epsilon(sys) was lower in ischemic than in normal segments (P < 0.001). Receiver Operator Characteristic (ROC) analysis for epsilon(sys) yielded the following results: Area Under Curve (AUC) = 0.86 [95% CI (0.84 - 0.88)]. Additionally, the cutoff point of -11.4 had the highest sensitivity and specificity (69.55% and 87.23%, respectively). The gold standard for ROC analysis was the catheter result. Furthermore, post systolic shortening was found more in ischemic compared to normal segments (64.5% vs. 22.6%, P < 0.001). The magnitudes of epsilon(pss), epsilon(pss) /epsilon(sys) (PSI), and epsilon(pss)/epsilon(max) were significantly larger (P < 0.001) and T epsilon(pss) was longer (P < 0.001) in ischemic segments. Conclusions: SRI is a new non-invasive diagnostic tool that could be used for detecting coronary stenosis in patients with chest pain, but without apparent wall motion abnormalities on echocardiography.