Influence of Sleep Apnea on Risk of Atrial Fibrillation
Condition: Sleep Apnea; Atrial Fibrillation
MeSH terms: Apnea; Sleep Apnea Syndromes; Atrial Fibrillation
Study type: Interventional

Summary: 
      The Elucidation of the Influence of Sleep Apnea on Risk of Atrial Fibrillation study.

      The study involves a case control design to investigate the extent to which there is an
      independent relationship of sleep disordered breathing (SDB) and paroxysmal atrial
      fibrillation (PAF). Cases will be defined as clinically identified patients with PAF and
      controls as those without AF. In order to rigorously address important biologic confounding
      influences, the cases and controls will be individually matched based upon age, gender, race,
      and body mass index. Those participants with both PAF and SDB (Apnea Hypopnea Index, AHI>=15)
      will be asked to return for a follow up exam after 3 months of SDB treatment in the Clinical
      Research Unit (CRU) for collection of the same measures collected at the baseline exam to
      observe for any significant changes with the purpose of collecting effect size data to inform
      future clinical trials.

      The total duration of the study is 4 years. The duration for any individual participant is up
      to from one to 13 weeks months, including a 3-month treatment period for those with moderate
      to severe SDB, i.e. AHI>15.
    

Detailed description: 
      Sleep-disordered breathing (SDB) is common in patients with cardiovascular disease and its
      attendant hypoxemia and autonomic dysfunction create a milieu that is likely to enhance AF
      propensity. Thus, SDB may represent a novel target for AF prevention and treatment
      strategies. Although our prior cross-sectional work has shown a 2-4 fold higher odds of AF
      related to SDB, these and other reports have not included cardiac structural data or
      autonomic/biochemical measures, and have addressed only arrhythmic events occurring during an
      overnight sleep study. In this proposal, we will examine paroxysmal AF (PAF), an early stage
      risk factor for persistent AF, and relevant to this proposal because it occurs prior to
      extensive cardiac electrical remodeling/fibrosis.

      OUTLINE OF STUDY VISITS Baseline Visit (SA 1 and 2). After informed consent, eligible
      participants will be scheduled to arrive for an overnight visit in the CRU. During the
      evening, participants will undergo questionnaire administration, blood pressure measurements,
      and anthropometry. They will be provided dinner and undergo polysomnography (PSG). In the
      morning, participants will undergo fasting venipuncture, overnight urine collection, ECHO, 6
      minute walk test, vascular measures and blood pressure measurements. For those with PAF
      (cases), hook-up for continuous ECG monitoring will be performed along with education
      regarding how to handle the device and bathing instructions, etc. All measurements in the
      DCRU/CRU will be performed blinded to PAF status. The only unblinded staff will be a
      dedicated research assistant who will perform the ECG monitoring hook-up. Blinded staff will
      collect and process data and perform data entry. After the baseline visit, participants with
      PAF (n=150) will undergo hook-up of the ECG monitor and an activity monitor at the baseline
      visit to wear for a 7-21 day period.

      Follow-Up Visit (SA3). Those with SDB (AHI>=15) without evidence of central apnea (central
      apnea index>5) or Cheyne Stokes Respirations via baseline visit PSG and who have PAF will
      undergo the following. A 5-7 day home-based auto-titration (APAP, Respironics Autopap System
      One with humidifier) to identify the optimal positive airway pressure (PAP) setting will be
      performed (with settings 4-20cm H2O). At the end of the 5-7 day titration, the goal will be
      to identify the pressure that results in an AHI<5 events/hour (optimally). The research
      assistant will re-set the device to deliver this optimal fixed pressure identified by the PI
      through the secure wireless web-site. An overnight DCRUCRU visit will be scheduled after 3
      months of wearing CPAP during which the same measures performed at the baseline visit will be
      collected.

      STUDY PROCEDURES 2-DIMENSIONAL DOPPLER ECHOCARDIOGRAPHY. Parasternal, apical and subcostal
      2-D views and apical 3D views will be obtained with transducer orientation and gain settings
      adjusted to optimally define endocardial surface of each cardiac chamber.

      POLYSOMNOGRAPHY (PSG). Procedure for PSG: Research PSG will be performed using the
      Compumedics E-series system (Abbottsford, AU) which will include 3 cortical encephalograms,
      bilateral electro-oculograms, a bipolar submental electromyogram, thoracic and abdominal
      respiratory inductance plethysmography, airflow (by nasal-oral thermocouple and nasal cannula
      pressure recording), oximetry (using highly sensitive finger pulse oximeter, sampling
      frequency 25Hz), electrocardiogram (ECG) at 250Hz (used to derive HRV measures of autonomic
      function); body position (mercury switch sensor), bilateral leg movements. EEGs are recorded
      at 125Hz. 3) 7-21 Day CONTINUOUS ECG MONITORING.

      Procedure: A 3-lead (2 channel), wireless, lightweight ECG monitoring device will be used to
      collect the ECG data over a 7-21 day period in those with PAF after the baseline and
      follow-up CRU visits.

      ACTIVITY MONITORING. Procedure: An accelerometer (GT3X+, Actigraph Co., Ft Walton Bch, Fl)
      will be used for 7-21 days, coincident with the time of continuous ECG monitoring.

      FASTING VENIPUNCTURE (52cc). Procedure: Phlebotomy will be performed the morning of the
      baseline and follow-up visits using standard techniques by trained research staff following
      written procedures. 6) DNA collection. Blood will be collected to extract RNA, which will be
      stored to test future hypotheses regarding genetic determinants of treatment response.

      OVERNIGHT URINE. Procedure: Overnight urine collection will be performed. ANTHROPOMETRY.
      Height (inches, cm), neck circumference (cm), waist circumference (cm), hip circumference
      (cm) will be obtained. Skinfolds are measured with calibrated metal calipers from 7 sites
      (chest, calf, thigh, calf, subscapular, midaxillary, suprailiac, abdominal).

      RESTING BLOOD PRESSURE (BP). BP will be measured after the participant has been sitting
      quietly for at least 5 minutes following standardized guidelines using a calibrated
      sphygmomanometer. Measurements will be repeated three times and recorded.

      QUESTIONNAIRES. The following will be collected: a) The Berlin Sleep Questionnaire, b)
      Epworth Sleepiness Scale, c) The Sleep Habits and Medical Condition Questionnaire d) The
      Medical Outcomes Survey-SF 36 (MOS-SF) e) Patient Health Questionnaire-9 (PHQ-9) f) Daily
      ECG/Activity Log g) Atrial Fibrillation Effect on Quality-of-life, a 20-item questionnaire
      that assesses the impact of atrial fibrillation on quality of life.

      6 Minute Walk Test. Baseline oxygen saturation and heart rate will be recorded. If oxygen
      saturation >90%, then proceed with protocol. Using the BORG Scale record rate the symptoms of
      breathlessness and leg fatigue after a 6 minute walk at usual pace.

      Arterial Applanation Tonometry: Radial artery measurements will be performed after
      sphygmomanometric pressure is obtained with use of an applanation tonometry probe with a
      minimum of two consecutive measurements to obtain pulse wave analysis results. For pulse wave
      velocity, lead II ECG will be performed along with cardotid and femoral applanation
      tomometry.
    

Intervention name(s): Continuous Positive Airway Pressure
Intervention type(s): Other
Intervention description(s): For cases, those found to have moderate sleep apnea (AHI >=15) will be place on CPAP therapy.
Allocation: Non-Randomized
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment