Feasibility and Contribution of Global and Regional 2D Strain during Exercise Stress Echocardiography

pp. 110-117

Abstract

Introduction: The feasibility of longitudinal 2D strain analysis during exercise and the contribution of the information provided to detect ischemia at elevated heart rate are not well established. Although pharmacologic stress echocardiography has been used to evaluate ischemia and viability in several studies, the use of longitudinal 2D strain for the diagnosis of myocardial ischemia during exercise stress echocardiography has not been analyzed.
Objectives: The goal of this study was to determine the feasibility of analyzing longitudinal 2D strain and to evaluate its performance during exercise stress echocardiography.
Methods: Between February and March 2012, 93 consecutive patients (59 men, 54.9%), with mean age 58.8 ± 11.8 years, underwent supine exercise stress echocardiography in 150 kgm stages. Wall motion was visually evaluated using a semi-quantitative analysis at baseline, peak exercise, and immediately after exercise. Longitudinal 2D deformation was analyzed in 16 segments at rest and immediately after exercise using a tracking algorithm of acoustic markers (AFI: automatic functional images, GE). Symptoms, 12-lead electrocardiogram, and blood pressure were simultaneously evaluated in each stage.
Results: Baseline heart rate was 76 ± 18 bpm, increased to 133 ± 25 bpm during peak exercise, and was 117 ± 15 bpm immediately after exercise. The target heart rate was achieved in 64 (68.8%) of the 93 patients evaluated; in the 29 patients who did not achieve target heart rate, 9 tests were positive and 20 were negative for coronary artery disease. Twenty-one patients (22.5%) developed ischemia diagnosed as transient regional assynergies during exercise stress echocardiography: 7 patients in the anterior, septal, and/or apical territories; 7 in the inferior, posterior, and/or lateral territories; and 7 in segments corresponding to both territories. These patients were older (63.5 ± 8.7 vs. 57.4 ± 12.2 years; p = 0.03) and the prevalence of previous myocardial infarction (14.3% vs. 7%; p = 0.01) and myocardial revascularization surgery (14.3% vs. 2.77%; p = 0.04) was higher compared to those without ischemia. There were no significant differences in the history of hypertension, diabetes, dyslipidemia, or smoking habits. The value of longitudinal 2D strain in the apical segments increased in 79 (85%) of the 93 patients evaluated: only 3 of these patients (3.8%) developed new wall motion abnormalities in the same region. In the 14 patients in whom longitudinal 2D strain did not increase or decreased, 11 (78.6%) presented apical ischemia in the visual analysis (sensitivity 79%, specificity 96%; p = 0.0001). Among the 53 patients presenting increased longitudinal 2D strain in the inferior, posterior, and/or lateral segments, 6 (11.3%) presented wall motion abnormalities in the same sites, whereas in the 40 patients in whom longitudinal 2D strain did not increase, 8 (20%) presented transient dyssynergias which were visually detected in the same region (sensitivity 43%, specificity 41%). Longitudinal 2D strain could be evaluated in 1472 of 1488 segments at rest (feasibility 99%), in 1452 after exercise (feasibility 97.5%), and in 1147 of 1488 (77%) during peak exercise (this stage was not considered for the analysis).
Conclusions: The analysis of longitudinal 2D strain is feasible immediately after exercise. The lack of increase or decrease in longitudinal 2D strain in the apical segments was consistent with the presence of visually detected ischemia. Elevated heart rates were responsible for the lack of specificity in the inferior, posterior, and lateral basal and mid segments. Thus, longitudinal 2D strain would only help to analyze the territory irrigated by the left anterior descending coronary artery.