Fig. 1

Illustrative examples of measurement of right atrial (RA) strain by fast long-axis method. Three anatomical points were selected at end-diastolic phase and automatically tracking was applied during the cardiac cycle. RA strain was calculated according to the Lagrange strain equation: (L_(t) – L₀) × 100/L₀. L_(t) is the distance between the mid-posterior point and the atrioventricular points at any time (t) during the cardiac cycle. L₀ is the distance at end-diastole phase. Patient A (upper) and patient B (lower) had similar RA empty fraction but with great difference in strain values, and they presented totally different prognosis. Patient A experienced heart failure death while patient B is still alive. ε_s: reservoir strain; ε_e: conduit strain; ε_a: booster strain