“The association between sleep disordered breathing and left ventricular function: a cross-sectional analysis of the ECHO-SOL Ancillary Study”

Dear editor:

We thank Dr. Yeow and colleagues for their interest in our work on the relationship between sleep disordered breathing (SDB) and subclinical measures of left ventricular structure and function.¹ Yeow et al. note that our results contrast with the recent findings by D’Andrea et al.,² who report that a clinical population of sleep apnea patients had impaired global longitudinal strain (GLS) compared to healthy controls. We believe there are several explanations for this difference. Besides presence of SDB, the groups studied by D’Andrea et al. also had differences in obesity; our analyses adjusted for body mass index. A second difference is that D’Andrea et al. focused on a select population referred for clinical care, whereas we studied a population-based cohort. Compared to a population-based cohort, the cardiovascular impact of SDB may be greater in a symptomatic cohort as suggested by a recent latent class analysis.³ These differences noted, our results and those of D’Andrea et al. are not actually so disparate. In their analysis, which was unadjusted, they observed reduced GLS and no difference in left ventricular ejection fraction (LVEF). In our unadjusted analysis (our table 1), we also observed a poorer GLS with more severe SDB, but no differences in LVEF. Our results showing no differences in GLS come from multivariable models. In the D’Andrea paper, multivariable models were only applied to exercise values.

Rather than focus on the differences, we think the similarities are impressive: both studies show that SDB is associated with diastolic dysfunction. We also agree with Dr. Yeow and colleagues that more longitudinal and interventional research is needed to fully understand the impact of SDB on cardiac function.