Concomitant use of echocardiographic strain analysis and treadmill stress testing to predict coronary artery disease

CONCOMITANT USE OF ECHOCARDIOGRAPHIC STRAIN ANALYSIS AND TREADMILL STRESS TESTING TO PREDICT CORONARY ARTERY DISEASE The sensitiviy and specificity of treadmill exercise test in the detection of coronary artery disease (CAD) are 68% and 77% respectively. As a result false-positive results occure in a considerable number of patients. Traditionally, wall motion and wall thickening are evaluated visually with echocardiography to decide about global and regional contraction. However, in recent years new methods have been developed for accurate quantification of regional and global left ventricular contractions, and strain imaging is one of them. This study is planned to test the hypothesis that a combined non-invasive approach with concommitent use of strain imaging and treadmill exercise testing could increase the accuracy of patient selection for coronary angiography. A total of 77 patients with positive treadmill stress testing who were assigned to coronary angiography (CAG) were included in the study. Patients were devided into 2 groups: Those having mild-moderate CAD vs severe CAD. Mild CAD was defined as; normal coronary arteries or at least one coronary artery with < 50% stenosis, moderate CAD as; at least one coronary artery with 50-70% stenosis and severe CAD as; at least one coronary artery with 70% stenosis or more or left main coronary artery stenosis 50% or more. The extent of CAD was assessed by using the Gensini score. Echocardiographic evaluation was performed within ±12 hours from the time of CAG. Strain analysis were made with speckle tracking method by using the EchoPac BT 13.0 (GE, Horten Norway) software. The average age of the patients was 56.4±10.8 years. According to the CAG results 56 patients (73%) had severe CAD, 21 patients (27%) had non-severe CAD. Epicardial, endocardial and myocardial strain measurements were significantly lower in patients with severe CAD than patients without severe CAD (Patients with and without severe CAD, respectively GLS endocardial: -20.6±2.4 ve -26.3±3.1, p<0.001; GLSmyocardial: -17.5±2.1 ve -22.1±2.5, p<0.001; GLSepicardial: -14.9±1.9 ve -18.7±2.2, p<0.001). GLS also positively correlated with the Gensini score. Significant percentage of the patients with preserved strain despite a positive exercise test had non-severe CAD (73%). The approach of adding strain evaluation to positive exercise stress test reached a sensitivity of 81% and a specificity of 89%. As a result, the addition of the strain evaluation to the positive stress test had a higher sensitivity and specificity in detecting significant CAD compared to the exercise stress test alone. These results suggest that patients with positive exercise stres test and preserved strain are rather be tested with advanced non-invasive anatomical or functional imaging modalities before deciding about coronary angiography Key words: Tredmill stress test, echocardiography, strain, coronary artery disease