PURPOSE: Nocturnal hypoxia, which can precipitate cardiac arrhythmias, can be detected by overnight polysomnography(POLY) or overnight oximetry (OOS). POLY is comprehensive, measuring apnea/hypopnea and oxygen saturation among other variables; OOS is inexpensive, measuring oxygen saturation. This study evaluates the use of OOS as a screening test for sleep related breathing disorders (SRBD) in patients with cardiac arrhythmias.
METHODS: Records of patients from an outpatient Cardiology Electrophysiology clinic who underwent OOS and POLY for chronic fatigue, snoring, excessive daytime sleepiness, or unrestful sleep were reviewed. A positive OOS was defined as an arterial oxygen (oxyhemoglobin) saturation at or below 88% for at least 5 minutes cumulative. A positive POLY was defined as an apnea/hypopnea index of >5.0/hour.
RESULTS: Fifty-two patients underwent OOS and POLY. Seventeen (32%) were female. The mean age was 65.3± 12 and the average BMI was 39.1 kg/m2. Cardiac risk factors included hypertension in 26 (50%), hyperlipidemia in 32 (61.5%), diabetes in 11 (21%), and tobacco abuse in 3 (6%) patients. Known coronary artery disease was present in 28 (54%), 8 (15.4%) patients had a pacemaker, 8 (15.4%) had an implantable cardioverter-defibrillator and 2 (3.8%) had both. Twenty-one (40.4%) patients had atrial fibrillation. The sensitivity of OOS as a screen for SRBD in patients with cardiac arrhythmias was 88.9% and the specificity was 31.2%. The positive predictive value was 74.4% and the negative predictive value was 55.6%.
CONCLUSION: Nocturnal hypoxia is common in patients with cardiac arrhythmias and a clinical suspicion of SRBD. A positive OOS was predictive of a positive POLY, but a negative OOS did not identify all patients with SRBD. Considering the cost associated with POLY and the high sensitivity of OOS, OOS is a reasonable screening tool for SRBD.
CLINICAL IMPLICATIONS: Nocturnal hypoxia has a deleterious effect on morbidity of patients health. Using OOS as a screening test, offers a simple, cost-effective measure to evaluate for SRBD, a known modifiable factor that impacts chronic disease.
DISCLOSURE: Kimberly Delcour, No Financial Disclosure Information; No Product/Research Disclosure Information