Abstract 3136: Depressed Myocardial Contractile Reserve in Patients with Obstructive Sleep Apnea Assessed by Tissue Doppler Imaging with Dobutamine Stress Echocardiography
Background: It has been suggested that hypoxia itself impairs myocardial contractility, although no data are available with regard to this relationship in the clinical setting. This study sought to examine whether myocardial contractile reserve, as determined by tissue Doppler imaging with dobutamine stress echocardiography (TDDS), might be depressed in patients with obstructive sleep apnea (OSA).
Methods: Thirty patients with suspected OSA (25 men and 5 women) underwent an overnight polygraphic study and TDDS. Peak myocardial systolic velocities (Sm) in the 12 myocardial segments of the left ventricular (LV) walls were averaged, and the mean Sm was compared at each TDDS stage between patients with apnea-hypopnea index (AHI) <15 (Group I, n=13) and those with AHI ≥ 15 (Group II, n=17). The myocardial contractile reserve was calculated by the difference between resting and peak mean Sm during TDDS.
Results: There were no significant differences between the groups with regard to age (50±11 years vs. 53±11 years), LV mass index (85±13 g/m2 vs. 95±20 g/m2), or resting LV ejection fraction (59±6% vs. 60±7%). In both groups, the mean Sm progressively increased from rest to peak TDDS stage. However, the relative increase in the mean Sm was significantly lower in Group II, resulting in a lower value of myocardial contractile reserve (5.5±1.2 cm/s vs. 7.4±1.3 cm/s, p<0.001). Myocardial contractile reserve correlated significantly with AHI (r=0.67, p<0.0001) and body mass index (r=0.46, p<0.02).
Conclusions: OSA can affect myocardial contractile reserve, implying an etiologic contribution from repetitive hypoxic events.