Speckle Tracking Echocardiography-Based Correlation Between Left Atrial Strain and Functional Capacity in Patients With Hypertrophic Cardiomyopathy

Introduction: The left atrium (LA) dilates and its function decreases as a chronic secondary change in hypertrophic cardiomyopathy (HCM). LA strain is a more sensitive measure of LV filling pressure than LA volume and can be used to predict the functional capacity in HCM. Objective: To analyze LA strain in patients with HCM and its correlation with exercise tolerance. Methods: A total of 113 patients with HCM were enrolled. All patients underwent detailed clinical evaluation, 24-h Holter monitoring, exercise stress testing, two-dimensional echocardiography with LA strain analysis using speckle tracking imaging. Assessment of functional capacity was done in terms of metabolic equivalents (METs). HCM patients with METS >6.0 were included in Group A while those with METS <= 6.0 were included Group B. Correlation of various parameters of LA strain (left atrial reservoir strain [LASr], left atrial conduit strain [LAScd], and left atrial contraction strain [LASct]) was done with functional capacity. Results: The mean age of the study population was 47 +/- 10.77 years with the majority of them being males (71.9%). Group B patients had significantly lower LASr (12.95% +/- 8.61% vs. 22.16% +/- 16%; p < 0.001), LAScd (-7.28% +/- 6.29% vs. -12.74% +/- 8.40%; p < 0.001), and LASct (-7.44 +/- 4.46 vs. -11.19 +/- 6.53; p < 0.001). Multivariable linear regression analysis reported LASr to be an independent predictor of METs and had a quadratic relationship with log-odds with negative linear and positive quadratic coefficients. LASr was the strongest echocardiographic predictor of reduced METS with an AUC of 0.78 (95% confidence interval [CI]: 0.68-0.88), sensitivity of 71.8%, and specificity of 82.9%. Conclusion: LA strain parameters are associated with functional capacity in patients with HCM with lower LA strain values being associated with poor functional capacity.