Author(s): Dr. Sajan Ahmad Z
BACKGROUND Strain imaging by speckle tracking is a well-established method to assess left ventricular function. The objective of this study was to define the utility of strain imaging in predicting obstructive coronary artery disease (CAD) in a subset of patients who do not have regional wall motion abnormality (RWMA) on routine 2D echocardiography. METHODS This is a prospective study. Consecutive patients with no RWMA scheduled to undergo coronary angiography (CAG) for clinical indications were included in the study. Longitudinal strain imaging by speckle tracking using automated functional imaging (AFI) was done by a single investigator prior to CAG. All angiograms were reported by a second investigator who was blinded to the strain imaging findings. Obstructive CAD was defined as ≥ 70% luminal stenosis of epicardial coronary arteries and/or ≥ 50% luminal stenosis of LMCA. RESULTS 129 patients were enrolled over a 7 month period (mean age 56.07±10.7, males 69%, females 31%). For detecting obstructive CAD, strain imaging had a sensitivity of 97% for LAD, 90.69% for RCA, 91.6% for LCX, a negative predictive value of 81.81% for LAD, 91.3% for RCA, 92.3% for LCX, a specificity of 15.2% for LAD, 13.9% for RCA, 22.8% for LCX and a positive predictive value of 57.6% for LAD, 34.5% for RCA and 21.3% for LCX territories. Patients with obstructive CAD had a lower global strain value of -18.37 ± 4.13 as compared to -21.18 ± 3.81 in patients who did not have obstructive CAD (p value <0.01). CONCLUSIONS Peak longitudinal strain imaging by speckle tracking is a very sensitive (ranging from 90.69% to 97.14%) test with a high negative predictive value (ranging from 75% to 92.3%) for identifying obstructive coronary artery lesions on coronary angiography. These properties make strain imaging a good screening test to rule out significant CAD, especially when the pre-test probability is low.