Obstructive Sleep Apnea Destabilizes Myocardial Repolarization Homogeneity
Obstructive Sleep Apnea Destabilizes Myocardial Repolarization Homogeneity
Literature shows that patients with obesity and Obstructive Sleep Apnea (OSA), both occurring
 independently, are more likely to develop cardiovascular diseases and sudden cardiac death
 (SCD). Assuming that ventricular depolarization is more stable than repolarization then QT
 interval parameters may be used for heart muscle repolarization assessment for those groups
 of patients.

 There were 121 patients included in the study, both - women and men, aging from 35-65 with
 visceral obesity. Only healthy patients were included - the ones who were not treated for any
 chronic disease, taking QT elongating drugs, or were not treated with Continuous Positive
 Airway Pressure (CPAP) therapy at that time.
The current study was a prospective, observational clinical trial performed between September
 2016 and August 2019 at a single-center institution specializing in treatment of patients
 with obstructive sleep apnea. The inclusion criteria were as follows: (1) gender: female or
 male, (2) age 35-65 years old, (3) visceral obesity, (4) lack of acute or chronic diseases
 that may have an influence on rhythm or conduction disorders, (5) not undergoing Continuous
 Positive Airway Pressure therapy (CPAP) or taking drugs that have or may have an influence on
 QT interval duration [according to Credible Meds list (Woosley et al, 2019)], (6) not
 consuming grapefruits or grapefruit juice for at least 2 weeks before Holter-ECG examination.
 Patients, who met all inclusion criteria, underwent subject and physical examination, an
 over-night Holter-ECG, polygraphy and laboratory biochemical tests (sodium, potassium,
 calcium, magnesium concentration and fasting glyceamia.

 Enrolled patients were asked questions about general frame of mind, daytime and nighttime
 symptoms that may suggest OSA [according to Epworth Sleepiness Scale
 (https://epworthsleepinessscale.com/about-the-ess/ access date 08 May 2020)]. All patients
 were fully physically examined. Neck and waist circumference were measured according to
 STEPwise Approach to Surveillance (STEPS) by WHO
 (https://www.who.int/ncds/surveillance/steps/en/. [access date 23 April.2019]. Upon subject
 examination (snoring and choking feeling during the sleep) a corrected neck circumference was
 calculated.

 Polygraphy was conducted using MED Recorder device by Infoscan company according to AASM
 guidelines (American Academy of Sleep Medicine, International classification of sleep
 disorders, 2016). The device registered blood saturation, heart rate, airflow, chest and
 abdomen movements, body position, snoring and single lead ECG. OSA was diagnosed according to
 AASM definition (American Academy of Sleep Medicine, Sleep-related breathing disorders in
 adults, 1999): in every patient with Respiratory Disturbance Index (RDI) ≥ 5/hour and with
 concomitant OSA sings (Epworth Sleepiness Scale ≥ 11 pts) or with RDI ≥ 15/hour. The minimum
 time of analyzed data without artifacts had to last at least 6 h.

 A Holter-ECG examination was conducted using DMS 300-3A device by Oxford company suitable for
 Cardioscan 10 system. Registration was made simultaneously with polygraphy, during the night.
 Chosen QT interval assessment parameters were evaluated upon partially automatically analyzed
 fragments of ECG records. Only nighttime ECG records were analyzed due to maximum
 comparability (similar patient's physical activity and minimized, because of limited body
 movements, artifacts). Moreover, the study aimed to assess a heart's activity simultaneous to
 sleep breathing disorders. Only ECG strips with constant heart rate, optimally within
 50-70/min limits, were chosen due to the minimum impact of such heart rate on QT interval
 correction formula. QTc data was calculated upon Bazett's formula. QTV and QTVi were
 calculated upon Berger's formula.

 After getting all results they were checked against the following exclusion criteria: 1)
 revealing that information about patient's chronic illness or drugs therapy was obfuscated,
 revealing increased fasting serum glucose concentration or ionic disturbances. It was
 strongly recommended to every patient to visit their GP for further diagnostics, 2) revealing
 any important deviation in physical examination i.a. blood pressure taken twice at the visit
 ≥140/ ≥90 mmHg, 3) revealing, upon Holter ECG examination, tachycardia or too numerous
 artifacts making QT interval assessment incredible, 4) too short total sleep time (< 6 hours)
 registered on polygraphy.

 Out of 187 consecutive patients meeting the inclusion criteria, 66 patients met at least one
 exclusion criterion, leaving 121 patients for the study analyses.
Inclusion Criteria:

 -  gender: female or male,

 -  age 35-65 years old,

 -  visceral obesity,

 -  lack of acute or chronic diseases that may have an influence on rhythm or conduction
 disorders,

 -  not undergoing Continuous Positive Airway Pressure therapy (CPAP) or taking drugs that
 have or may have an influence on QT interval duration [according to Credible Meds list
 (Woosley et al, 2019)],

 -  not consuming grapefruits or grapefruit juice for at least 2 weeks before Holter-ECG
 examination.

 Exclusion Criteria:

 -  revealing that information about patient's chronic illness or drugs therapy was
 obfuscated, revealing increased fasting serum glucose concentration or ionic
 disturbances. It was strongly recommended to every patient to visit their GP for
 further diagnostics,

 -  revealing any important deviation in physical examination i.a. blood pressure taken
 twice at the visit ≥140/ ≥90 mmHg,

 -  revealing, upon Holter ECG examination, tachycardia or too numerous artifacts making
 QT interval assessment incredible,

 -  too short total sleep time (< 6 hours) registered on polygraphy.