Limitations
RECURRENCE
The main limitation of this study was the relatively small sample size, in part determined by the availability of good quality echocardiographic images for all relevant time points and less so the presence of sinus rhythm during follow-up to measure contractile function. High-quality images were essential for LA strain measurements due to respiratory motion artifact and unfavourable body habitus. Consequently, the cutoff value of LA strain found to predict AF recurrence in LSPAF proposed in this study may not be robust and larger studies are required to explore this further. Our proposed cutoff value only represents a LSPAF cohort, as studies of paroxysmal AF show better contractile function. Three-dimensional echocardiography may have provided more accurate LA volume measurements but is technically challenging, requires very high-quality images, and would almost certainly have led to further exclusions from our study. It is important to acknowledge that the measurement of LA volume is a part of the minimum dataset for transthoracic echocardiography in routine clinical practice, whereas assessment of LA strain remains a research tool with a need for further standardization of techniques and improved reproducibility.