Fast assessment of left ventricular systolic function in obstructive sleep apnea patients with automated function imaging: Comparison with mitral annular plane systolic excursion

Background: Early cardiovascular impairment in obstructive sleep apnea (OSA) patients is often overlooked, leading to irreversible outcome. Left ventricular (LV) global longitudinal strain (GLS) derived from automated function imaging (AFI) echocardiography provides a fast tool to assess global longitudinal function. We therefore aimed to compare the feasibility and reproducibility of AFI with mitral annulus plane systolic excursion (MAPSE) as obesity is common in OSA. Methods: A comprehensive echocardiographic examination was done in 186 consecutive patients having polysomnography for suspected OSA in this prospective study. MAPSE was measured by using M-mode. AFI was derived by offline analysis of three long-axis views that semi-automatically detects LV endocardial boundary, which is adjusted manually as necessary. Variability of AFI and MAPSE were compared among the different subgroups and further tested in BMI subgroups. Results: Despite a relatively high obesity rate (42.9%), AFI was feasible in 94% (175/186) patients and MAPSE could be recorded in all patients. Although more segments were measured with AFI it showed excellent correlation (r=0.882) superior to MAPSE (r=0.819) between the expert and beginner. Intra- and inter- observer variability of AFI were comparable with MAPSE in Bland-Altman analysis, 5.5% and 6.5% for AFI, 6.2% and 8.8% for MAPSE, respectively. In repeated measurements, AFI showed higher intra-class correlation (ICC=0.95) than MAPSE (ICC=0.87). Furthermore, analysis showed that AFI was feasible even in more obese patients (BMI≥28kg/m2). Conclusions: Even in obese patients with OSA, AFI-GLS is feasible and more reliable for less expert operators than MAPSE for detecting LV longitudinal dysfunction.