A Study of the Usefulness of Tissue Doppler Imaging for the Diagnosis of Coronary Artery Disease in Patients with Left Bundle Branch Block

Abstract

In patients with left bundle branch block (LBBB), the diagnosis of ischemia by noninvasive modalities is cumbersome. Most of them such as stress tests, nuclear imaging, and magnetic resonance imaging have limitations in the detection of ischemia in this subset. The postsystolic motion (PSM) during the isovolumetric relaxation period on tissue Doppler imaging (TDI) is a sensitive and specific marker of ischemia. We aimed to see whether the TDI parameters can detect coronary artery disease (CAD) in patients with LBBB. Patients with LBBB (n = 64) who underwent coronary angiography were divided into two groups. Group A (n = 30) included patients with left anterior descending (LAD) artery stenosis of ≥70%, and group B (n = 34) included patients without LAD stenosis. All patients underwent TDI and various myocardial tissue velocity parameters were analyzed to detect the presence of CAD. P < 0.05 was considered significant. The TDI of the mid-interventricular septum showed a higher delayed amplitude of PSM (>100 ms after aortic valve closure), lower myocardial systolic (Sm), and early diastolic (Em) velocities, and a higher late diastolic (Am) velocity in group A when compared to group B (all were significant, P < 0.0001). Both the ratios Sm/PSM and Em/Am were significantly lower in group A compared to group B (P < 0.0001). On receiver operating characteristic curve analysis to predict the presence of significant LAD stenosis, the value of Sm/PSM ratio <0.8 showed the best combination of sensitivity (78%) and specificity (96%) with an area under the curve of 0.936. TDI, a noninvasive imaging modality, is reliable and effective in identifying myocardial ischemia in patients with LBBB.