The Prevalence and Risk Factors of Sleep Disordered Breathing in a Heart Failure Program

The objective of this protocol is the evaluation of our clinical screening program for sleep disorders in patients with heart failure. These patients have very high prevalence of Sleep Disordered Breathing (SDB), including central and obstructive sleep apnea. There is also strong evidence that SDB, if unrecognized and untreated, will worsen heart failure and may leads to serious complications. Effective treatment of SDB results in improvement in heart failure and functional status. So far there are no guidelines in the area of screening in this patient population. The only test that would reliably rule out or confirm SDB is the polysomnography (PSG) this test is expensive and technically demanding. With the current approach to diagnosis and treatment of SDB, it routinely takes up to 5-6 months between the emergence of clinical suspicion of SDB and the initiation of appropriate treatment with CPAP. This delay and cost of this traditional approach, is a significant obstacle to providing highly needed care to this very vulnerable population. In OSU we have a state of the art Heart Failure Program and a Sleep Heart program that was created to develop an approach to prompt diagnosis and treatment of SDB in our heart failure patients. We designed an algorithm that employs validated questionnaires and FDA approved devices. We need, however to validate our algorithm against the gold standard: the PSG. Furthermore, we need to analyze the prevalence and risk factors of each sleep disorder in light of the recent changes in the management of heart failure, which may have influenced the risk factors and prevalence as we knew them. This protocol includes a combination of clinically indicated procedures, and others that are repeated for validation purposes. The accumulation and analysis of data is also done for research purposes.

Patients with systolic heart failure have higher prevalence of SDB than the general middle aged population \[1-3\]. There is strong evidence that treatment of OSA in the general population reduces fatal and non-fatal cardiovascular events\[4\]. In patients with underlying heart failure and OSA, treatment with CPAP improves ejection fraction and functional outcome\[5\]. In patients with heart failure and CSA, there is evidence of increased sympathetic activity \[6\], predisposition to dsyrrythmia \[7\] and increased mortality. However, to date systematic diagnostic approach of SDB in this vulnerable population is not part of the guidelines for management of heart failure. In patients with heart failure, the prevalence of Obstructive Sleep Apnea (OSA) was estimated at 24-37 % and Central Sleep Apnea (CSA) at 40%. The severity of CSA is shown to be directly related to the severity of the underlying heart failure\[8\]. Additionally, the management of heart failure has changed significantly since these original studies, to include b-blockade, aggressive hemodynamic targets, and device therapy\[9\]. Taken together, these observations call into question the applicability of this previous prevalence estimate of CSA in this patient population. Indeed, recent data suggest a decline in the incidence of CSA\[10, 11\]. Obstructive Sleep Apnea, on the other hand, is strongly associated with obesity. The rising incidence of obesity, and its strong association with cardiovascular disease, may suggest a rise in the incidence of OSA in this patient population. Did the recent changes in the management of heart failure change the prevalence and distribution of SDB? What is the most effective approach to diagnosis of this highly prevalent disorder in this very vulnerable patient population? A modern cost benefit analysis and comparison against the current slow inefficient and very expensive approach is needed. An approach that combines evaluation of risk factors and an abbreviated portable study may be adequate and certainly less expensive. Our program aims at providing every heart failure patient with clinically indicating and not otherwise available screening for SDB. Validated questionnaires and screening ambulatory sleep studies are provided to every patient. Additionally, this clinical operation has no risk to patients, rather a significant benefit. The sensitivity and specificity of this surveillance approach will need to be evaluated and validated. The validation operation will bring additional benefit to our future patients. The accumulation and analysis of the data will also enable us to determine the magnitude of the sleep co-morbidity in our heart failure patients and help educate clinicians who treat similar patients nationwide