Tissue Doppler imaging for diagnosis of coronary artery disease: a systematic review and meta-analysis

Coronary artery disease (CAD) is responsible for one out of every six deaths in the United States. Each year, approximately 800,000 Americans have a new coronary event resulting in approximately one death per minute [1]. This extraordinary burden of disease necessitates early diagnosis and treatment.Non-invasive imaging tests like radionuclide imaging and stress echocardiography are frequently used in clinical practice for detection and evaluation of CAD [2]. Global and regional left ventricular (LV) systolic function is an important marker of CAD in stress echocardiography, which is conventionally assessed using two-dimensional echocardiography. In 1989, the technique of tissue Doppler imaging (TDI) emerged as a potential modality for assessing systolic and diastolic LV performance [3-5]. TDI visualizes myocardial velocities by measuring low-frequency, high-amplitude signals of myocardial motion. TDI is done using either the spectral pulsed-wave or the color-coded pulsed-wave technique. Spectral Doppler measures the instantaneous velocity in a sample volume of the region of interest, while color-coded Doppler allows simultaneous sampling of the entire ultrasound sector [6-8].Most of the studies of TDI have employed the technique for measuring LV diastolic function. Other investigators have applied TDI to measure resting or post-stress velocities of various myocardial segments of the LV as an adjunct tool in the diagnosis of regional wall motion abnormalities from CAD. However, there has not been a consensus on the value of these techniques in the diagnosis of CAD. In this paper, we perform a systematic review and meta-analysis to assess the efficacy of TDI indices in the diagnosis of CAD.We searched MEDLINE (inception to June 2012) and the Cochrane Library (inception to June 2012) using keywords and/or medical subject headings (MeSH) for TDI and CAD. The detailed search strategy for MEDLINE is presented in Table 1. Titles and abstracts of the references identified