Background: Newly developed 2-dimensional speckle tracking imaging allows quantitative assessment of global circumferential strain (GCS) and left ventricular (LV) torsion as well as global longitudinal strain (GLS). To detect clinical significance of GCS and LV torsion in exercise echocardiography, we observe responses of parameters of strain and LV torsion on maximal oxygen consumption, VO2 max and double product before and after dynamic exercise in normal healthy subjects. Methods: The study group included 48 participants (24 men and 24 women, mean age 41.7±2.0 years, range 19 to 68 years) with normal resting LV function and no detectable structural heart disease confirmed by echocardiography and exercise treadmill test. Two-dimensional echocardiographic examinations were performed at rest and immediately after exercise treadmill test. Postexercise image acquisition was completed within 3 minutes. 3 cardiac cycles from each baseline and postexercise recording were digitized and analyzed. Double product was calculated as multiplication of peak heart rate and peak systolic blood pressure. Results: Participants showed normal LV systolic functions (EF=65.5±0.8%). Participants exercised for an average of 11 min 3 sec and achieved 99.2 ± 2.0% of maximally predicted for age with a mean peak heart rate 176±3 bpm. After exercise, GCS, GLS and mid-LV torsion increased -2.3±1.0 sec-1, -1.6±0.5 sec-1 and 2.4±0.6 degrees, respectively (p=0.03, p=0.03 and p=0.00, respectively). Interestingly, the change of global circumferential strain rate showed significant correlations with VO2 max, double product and age (r=-0.53 and p=0.02, r=-0.41 and p=0.02 and r=0.35 and p=0.03, respectively). As we expected, the change of GLS showed significant correlations with double product (r=0.38 and p=0.03). And also time to peak untwist of mid-LV torsion significantly correlates with VO2 max (r=-0.49 and p=0.03). Conclusions: GCS, GLS and LV torsion after exercise increased and contributes to maximal exercise capacity. And these parameters may be a promising new index in exercise capacity as well as intuitively assessing wall motion abnormality like myocardial ischemia during exercise echocardiography.
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