Association of left atrial strain and exercise capacity among patients with hypertension: a single center study

Abstract Introduction Hypertension has been identified as one of the leading risk factors for developing cardiovascular disease in the Philippines. 1 The long term increase in afterload causes the progressive decline in both the systolic and diastolic function of hypertensive patients. There has been an increasing recognition in the role of left atrial function in the pathophysiology of several cardiac diseases, including hypertension. Purpose For patients with hypertension, exercise capacity is reduced by 30%.2 As exercise capacity is a known prognostic marker for adverse cardiovascular outcomes, identifying patients with hypertension with impaired left atrial reservoir strain may also improve cardiovascular risk stratification. With the use of two-dimensional (2D) speckle tracking echocardiography, left atrial strain can now be utilized in the evaluation of left atrial reservoir, conduit, and contractile function. Left atrial strain (LA strain) can now serve as a biomarker of adverse cardiovascular outcomes, including the exercise capacity of patients. Another goal of the study is to identify other clinical and echocardiographic factors that may affect exercise capacity Methods A single center, retrospective cross sectional study was conducted in a tertiary hospital to validate the association of left atrial strain with exercise capacity in terms of metabolic equivalent (METs) achieved during treadmill exercise echocardiography of patients diagnosed with hypertension. The primary objective of this study is to determine the left atrial strain cutoff that reliably discriminates poor, fair, average, good, or high exercise capacity. Data was obtained by conducting a chart and echocardiography review of adult patients from January 2023 to April 2023. The independent association of LA strain with METs was studied with regression analysis. Results were considered significant at p≤0.05 at 95% confidence interval. Receiver-operating characteristic curve analysis was utilized to determine the strength of the LA strain to discriminate between the different exercise capacities. Results A total of 136 patients were included in the study. LA strain, particularly the reservoir, can discriminate exercise capacity, specifically to discriminate good to high capacity from fair to average as their AUC is 0.678 (95% CI 0.58 to 0.77, p=.0001). The best cut-off is 30.2 which resulted to 80% sensitivity (95% CI 66.3 to 90) while specificity is only 51.16% (95% CI 40.1 to 62.1). Spearman rank correlation analysis showed that LA reservoir is significantly correlated with E/A and E/e’. The relationships are linear and positive. Among the other 2D echo parameters, only EDV, E/a and E/e’ were found to have a linear relationship or correlation with METS. Conclusion The study revealed that there is moderate correlation of LA reservoir strain in terms of METS achieved during treadmill stress echocardiography (rs=0.3196, p=0.0001).LA reservoir strain AUCLA strain and other echo parameters