PURPOSE: Obstructive sleep apnea (OSA) may increase the risk of cardiovascular disorders (CVD). However, despite extensive investigation, direct association of OSA with CVD remains to be established. Using 99m-Tc-PYP single photon emission computed tomography (SPECT) plus dobutamine stress test, we have studied the cardiac function and myocardial perfusion in patients with OSA who have apparently normal cardiac function.
METHODS: We studied 46 patients with documented OSA and 17 normal volunteers. We compared their SPECT (BP-SPECT) images before and after dobutamine stress test. The OSA patients were further grouped into mild (15), moderate (13), and severe (18) according to their Apneia Hypopnea Index (AHI). In the statistic analysis, significant difference (p< 0.05) was established using Chi-square test and Spearman’s and Pearson correlation analysis.
RESULTS: The patients were matched in age, sex, body mass index (BMI), and other CVD risk factors. At rest, the SPECT imaging revealed significant decreases in the Peak Ejection Rate (PER), Left Ventricle Ejection Fraction (LVEF), 1/3 Filling Fraction (1/3FF) and Peak Filling Ratio (PFR) in patients with severe OSA (P< 0.05 for all). On dobutamine stress, the compensatory increases in LVEF, PER, 1/3 FF, and PFR were significantly less in OSA patients. Meanwhile, myocardiac ischemia was detected in the OSA patients in the apical, inferior and septal area (P<0.01). Furthermore, there were significant correlations between the changes in 1/3FF and PER with the AHI, Tmax(The longest time of apnea, seconds), T< 90% (The duration of oxygen desaturation to < 90%, minutes) and lowest SaO2 (SaO2 minimal, %).
CONCLUSION: Our results showed that, despite apparent normal cardiac examinations, subtle compromises in ventricular function can be detected using SPECT in patients with severe OSA and are associated with myocardiac ischemia.
CLINICAL IMPLICATIONS: Patients with severe OSA should be screened for subtle cardiac ischemia and changes in ventricular function using sensitive technology such as SPECT.
DISCLOSURE: Bei Wang, No Financial Disclosure Information; No Product/Research Disclosure Information