title: The impact of cardiac resynchronization therapy on obstructive sleep apnea in heart failure patients: a pilot study.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) has been shown to improve cardiac function and reduce Cheyne-Stokes respiration but has not been evaluated in patients with obstructive sleep apnea (OSA). In this pilot study, we investigated the impact of both CRT and CRT plus increased rate pacing in heart failure (ie, congestive heart failure [CHF]) patients with OSA. We hypothesized that through increased cardiac output CRT/pacing would reduce obstructive events and daytime symptoms of sleepiness.
  
  
  METHODS
  Full polysomnograms were performed on CHF patients who were scheduled for CRT, and those patients with an apnea-hypopnea index (AHI) of > 5 events per hour were approached about study enrollment. Patients had a pre-CRT implant baseline echocardiogram and an echocardiogram a mean (+/- SEM) duration of 6.6 +/- 1.4 months post-CRT implant; polysomnography; and responded to the Minnesota Living with Heart Failure questionnaire, the Epworth sleepiness scale, and the Functional Outcomes of Sleep Questionnaire. An additional third polysomnography was performed combining CRT with a pacing rate of 15 beats/min above the baseline sleeping heart rate within 1 week of the second polysomnography. Assessments for the change in cardiac output during the polysomnography were performed using circulation time to pulse oximeter as a surrogate.
  
  
  RESULTS
  Twenty-four patients were screened, and 13 patients (mean age, 68.6 years; body mass index, 28.7 kg/m(2)) had evidence of OSA. The mean AHI decreased from 40.9 +/- 6.4 to 29.5 +/- 5.9 events per hour with CRT (p = 0.04). The mean baseline ejection fraction was 22 +/- 1.7% and increased post-CRT to 33.6 +/- 2.0% (p < 0.05). The reduction in AHI with CRT closely correlated with a decrease in circulation time (r = 0.89; p < 0.001) with CRT. Increased rate pacing made no additional impact on the AHI or circulation time. CRT had a limited impact on sleep architecture or daytime symptom scores.
  
  
  CONCLUSIONS
  CRT improved cardiac function and reduced the AHI. Reduced circulatory delay likely stabilized ventilatory control systems and may represent a new therapeutic target in OSA.
authors.affiliation: Pulmonary, Critical Care, and Sleep Medicine Division, Rhode Island Hospital, 1285 South County Trail, East Greenwich, RI 02818, USA. mstanchina@lifespan.org
authors.forename: Michael L
authors.initials: ML
authors.lastname: Stanchina
authors.forename: Kristin
authors.initials: K
authors.lastname: Ellison
authors.forename: Atul
authors.initials: A
authors.lastname: Malhotra
authors.forename: Maria
authors.initials: M
authors.lastname: Anderson
authors.forename: Malcolm
authors.initials: M
authors.lastname: Kirk
authors.forename: Michael E
authors.initials: ME
authors.lastname: Benser
authors.forename: Christine
authors.initials: C
authors.lastname: Tosi
authors.forename: Carol
authors.initials: C
authors.lastname: Carlisle
authors.forename: Richard P
authors.initials: RP
authors.lastname: Millman
authors.forename: Alfred
authors.initials: A
authors.lastname: Buxton
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology; D010092:Oximetry; D010865:Pilot Projects; D017286:Polysomnography; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D013318:Stroke Volume / Q000502:physiology*; D011795:Surveys and Questionnaires