Intra- and Inter-observer Variability
The intra- and inter-observer variability were calculated as the intraclass correlation coefficient (ICC) for measures of PALS and PACS in 2- and 4-chamber views across 8 randomly selected patients. Intra-observer variability was calculated based on repeated LA strain measures by the same echocardiographer blinded to prior measurements, and interobserver variability was performed by a second echocardiographer blinded to prior measurements.