|Ahead of print publication
Prevalence of cardiac arrhythmias in patients of obstructive sleep apnea syndrome and changes after 6 months of continuous positive airway pressure therapy
Ankit Kakar1, R Ananthakrishnan2, Ajay Handa3, SK Joshi4, Rahul Tyagi5, Soumitra Mohanty6
1 Department of Medicine, INHS Asvini, Mumbai, India
2 Department of Cardiology, MH CTC, Pune, India
3 Senior Consultant (Pulmonary Medicine), Sakra World Hospital, Bangalore, India
4 Department of Cardiology, INHS Kalyani, Vizag, India
5 Department of Critical Care Medicine, AIIMS, New Delhi, India
6 Department of Cardiology, INHS Asvini, Mumbai, India
|Date of Submission||08-Apr-2020|
|Date of Decision||14-Apr-2020|
|Date of Acceptance||30-Aug-2020|
|Date of Web Publication||22-Mar-2021|
Department of Cardiology, MH CTC, Old Golibar Maidan Camp, Pune - 411 037, Maharashtra
Source of Support: None, Conflict of Interest: None
Obstructive sleep Apnoea (OSA) has generated lot of attention recently. The prevalence of OSA in adult Indian population is approximately 3.5% and the majority of these patients remain undiagnosed. OSA is associated with repeated episodes of hemoglobin desaturation and higher inspiratory effort, combined with repeated arousals during sleep. This causes repeated sympathetic and parasympathetic stimulation. This has been postulated to be associated with both electric and mechanical remodeling of the heart leading to cardiac arrhythmias. In this study, we try to find a correlation between OSA and cardiac arrhythmias and to find the type of arrhythmia as the secondary aim.This study was conducted over three year period at a tertiary care hospital in Mumbai. We screened 186 patients with proven OSA (Apnoea Hypopnea Index> 5). Among these, those with pre-existing structural heart disease or arrhythmia or those not consenting for the study were excluded. 121 subjects were taken up for the study. 01 was lost to follow up, leading to a final sample size of 120. These 120 patients with proven OSAand no pre- existing cardiac pathology were subjected to 24 hour ambulatory Holter monitoring to determine the prevalence of cardiac arrhythmias among this cohort. It was found that 30% of this population had some or the other arrhythmia. (n = 36). Various factors such as age, metabolic and endocrine ailments and others were also accounted for.In the follow up to this study, these 36 patients were advised to use CPAP. Following 06 months of effective CPAP use, these subjects underwent repeat 24 hour Holter examination. Unsurprisingly, significant reduction in prevalence of cardiac arrhythmia was noticed. Now, out of this cohort of 36 subjects, only 02 were found to have cardiac arrhythmia.
Keywords: Cardiac arrhythmia, continuous positive airway pressure, obstructive sleep apnea, obstructive sleep apnea syndromes
|How to cite this URL:|
Kakar A, Ananthakrishnan R, Handa A, Joshi S K, Tyagi R, Mohanty S. Prevalence of cardiac arrhythmias in patients of obstructive sleep apnea syndrome and changes after 6 months of continuous positive airway pressure therapy. J Mar Med Soc [Epub ahead of print] [cited 2021 Apr 23]. Available from: https://www.marinemedicalsociety.in/preprintarticle.asp?id=311699
| Introduction|| |
Obstructive sleep apnea syndrome (OSAS) is a modern age epidemic. The patient suffers repeated cortical or subcortical arousals due to a recurring sequence of the collapse of the upper respiratory tract and consequent airflow limitation. Physiologically, such cyclical events of a partial or full cessation of breathing during sleep are accompanied by hemoglobin desaturation and resultant arousal.
The prevalence of obstructive sleep apnea (OSA) is estimated between 0.3% and 5.1% by several studies world over. The limitation here being that available literature of the Western population may not completely juxtapose in the Indian setup. Various domestic epidemiological studies have estimated that the prevalence of OSA in India is approximately 3.5%. Major contributory factors include obesity and craniofacial anatomy. Based on clinical experience, it is believed that the majority of sleep apneics in India remain undiagnosed.,
OSA is now considered as a risk factor for cardiovascular morbidity and several diseases of the circulation have been associated with OSA. Examples include resistant hypertension, coronary artery disease, congestive cardiac failure, and arrhythmias.
Cardiac arrhythmias cause significant mortality and mortality and have drawn the interest of the medical community for decades. It is known that the heart rate varies cyclically with choking episodes in OSA syndromes. Hence, it is believed that rhythm disorders are common in OSA syndromes, but their true prevalence is understudied and elusive.
Erstwhile studies have identified that OSA patients have a higher prevalence of arrhythmias such as atrial fibrillation, ventricular tachycardia, sinus arrest, second-degree atrioventricular conduction block, and premature ventricular contractions., Some studies have proven that symptomatic OSA is a risk factor for hypertension and vascular diseases. It has also been causally linked to cardiac arrhythmias and sudden cardiac death. Cross-sectional studies have suggested a high prevalence of arrhythmia in OSA patients and vice versa.,
To add to the dilemma, the exact pathophysiologic link between OSA and arrhythmias is unclear. Several theories have been propounded by clinical researchers. The most convincing mechanism postulates that the persistent repeated negative intrathoracic pressure generated due to strong inspiratory effort made against a collapsed airway leads to several autonomic, hemodynamic and endocrinal consequences. Individually or synergistically these mechanisms may lead to rhythm disturbances and probably other maladies of the cardiovascular system., Despite the emergence of new evidence, controversy still prevails whether or not OSA is a primary risk factor for cardiac rhythm disorders. As a corollary to this theory, it is also unclear if timely intervention in proven OSA cases can avert cardiovascular afflictions and consequent mortality.,
The aim of our study presented here is to study the prevalence of cardiac arrhythmias in patients of OSAS. The secondary objective is to study the types of arrhythmias that occur in these patients. We further attempt to see the change in arrhythmia prevalence by repeating Holter examination after 6 months of continuous positive airway pressure (CPAP) therapy in all these patients.
| Methods|| |
This observational study was conducted during September 2016 – August 2019 at a tertiary care hospital at Mumbai. Inclusion criteria was - Age of patients >18 years, Apnea-Hypopnea Index (AHI) >5, and those agreeing to consent. Exclusion criteria were a known case of arrhythmia, coronary artery disease or previous pacemaker implanted cases and pregnancy.
Ethical clearance was obtained from the authority appointed by the institution (ethics committee). Patients were interviewed as per protocol with appropriate history, examination and necessary investigations.
Overnight polysomnography proven OSA cases with AHI > 5 were included in the study. Baseline echocardiography (Echo) recording and ECG was performed in all patients to evaluate the presence of structural heart diseases and to document the left ventricular function, pulmonary arterial hypertension and regional wall motion abnormalities. These patients then underwent a Holter study to diagnose the occurrence of arrhythmia during a 24 h period. Basal rhythm, lowest heart rate, maximum heart rate, occurrences of various brady and tachyarrhythmias were recorded and documented. Sinus bradycardia (<30 bpm), sinus tachycardia (>100 bpm), >10/h supraventricular premature beats (SVPBs), >10/h ventricular premature beats (VPBs), or >250/24 h VPBs were considered significant. Other arrhythmias such as various AV blocks, atrial fibrillation, and sustained/nonsustained VT were also studied as per the existing criteria of the European Heart Rhythm Association.
The patients were then advised to use a CPAP machine daily and the correct procedure of use and strict adherence was advised. After 6 months of CPAP use, a 24 h Holter test was repeated in the patients and any changes in the prevalence of arrhythmia were studied.
All the data were noted down in a predesigned study proforma. Association between qualitative variables was calculated by the Chi-square test or Fisher's exact test (for 2 × 2 tables). Quantitative data was represented using mean ± standard deviation and median and interquartile range. Quantitative data was assessed using an unpaired t-test if data passed “Normality test” and by Mann–Whitney test if otherwise. Significance was determined by P < 0.05. Finally, logistic regression analysis was applied to evaluate the predictors of the occurrence of cardiac arrhythmia. SPSS Version 20 (IBM SPSS software version 20- Statistical Product and Service Solutions, Manufactured by IBM) was used for statistical analysis and Microsoft Excel 2010 for graphical representation.
Based on the study by Guilleminault et al., the prevalence of rhythm disturbances in patients of OSA was approximately 48%. Considering 10% of patients lost to follow-up, the final sample size was taken as 120 diagnosed patients of OSA.
| Results|| |
After screening 186 patients, 121 were included, 01 lost to follow-up, therefore 120 patients were analyzed. Majority of our study patients (28.3%) were in the age group of 41–50 years followed by 51–60 years (25%), 31–40 years (23.3%), >60 years (15.1%) and 21–30 years (8.3%). The mean age was 46.5 ± 11.91 years. 52.5% of patients were male and 47.5% were female. The sex ratio was 1.10:1. The most common symptom at presentation was snoring (80%) followed by weight gain (69.2%), daytime sleepiness (55%), fatigue during daytime (34.2%), nocturia (29.2%), memory loss (25%), choking at night (21.7%), and morning headache (15.8%). Interview with a bed partner was conducted wherever feasible.
Preexisting comorbidities were also accounted for. Hypertension and diabetes were the most prevalent comorbidities present in 41.7% and 35.8% of patients, respectively, while 20% of patients had hypothyroidism and 16.7% had asthma/COPD. It was observed that 36 (30%) patients consumed alcohol while 24 (20%) patients were smokers.
Twenty-four (20%) patients had body mass index (BMI) in the normal range, whereas 59 (49.2%) and 37 (30.8%) patients were overweight and obese, respectively. The mean BMI of patients was 28.3 ± 3.62 kg/m2. Waist to hip ratio (WHR) was high in 79.4% of males and their mean WHR was 0.91 ± 0.06, while 80.7% of female patients had high WHR and their mean WHR was 0.84 ± 0.07.
Mean neck circumference was 37.65 ± 2.75 cm and the mean systolic blood pressure and diastolic blood pressure values were 151.44 ± 19.84 mmHg and 81.45 ± 7.24 mmHg respectively. The average total recording time was 365.02 ± 14.49 min while the mean total sleep time was 252.63 ± 14.84 min. The mean SpO2 was 92.68% ±8.96%. Thirty-nine (32.5%) patients had mild OSA (AHI of 5–14) while 29 (24.2%) and 52 (43.3%) patients had moderate OSA (AHI 15–29) and severe OSA (AHI of 30 or more), respectively.
It was observed that arrhythmia (atrial or ventricular) was observed in 36 (30%) patients. Among all the arrhythmia events, the most common was sinus bradycardia (<30 bpm) (30.5%) followed by atrial fibrillation (27.8%), sinus tachycardia (22.2%), >10/h VPBs/>250/24 h (VPBs) in 11.1%, SVPBs (2.8%), Sustained/Non-sustained VT (2.8%) and AV blocks (2.8%) in this order [Flow Chart 1].
We used the Chi-square test for logistic regression to evaluate the predictors of the occurrence of cardiac arrhythmia. It showed that age (31–40 years), sex (female), hypertension, and diabetes mellitus were independently associated with the occurrence of cardiac arrhythmia [Table 1].
|Table 1: Multivariate analysis for predictors of the occurrence of cardiac arrhythmia|
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After 6 months of CPAP use, a significant reduction in the prevalence of arrhythmia was observed. Of the 36 patients who had various arrhythmias initially, only 02 persisted to have an arrhythmia, (one had SVPBs and the other one had runs of atrial fibrillation) without any other therapeutic intervention. Thus, 94.4% reduction in the prevalence of cardiac arrhythmias was noticed on the institution of CPAP in cases of OSA with Holter confirmed arrhythmia.
| Discussion|| |
Despite years of research, the exact mechanisms leading to an association between OSA and cardiac arrhythmias and other cardiovascular ailments remain elusive. Several hypothesis proposed by generations of researchers includes autonomic dysfunction, hypoxia, and oxidative stress. The result is cyclical sympathetic and counter-regulatory parasympathetic stimulation, altered cardiac excitability, and vasoconstriction. The variations in intrathoracic pressure may also contribute by mechanical stress on the myocardium leading to altered excitability and also probable anatomic remodeling. The repeated compensatory parasympathetic over activation has been speculated to cause awake autonomic dysfunction also.
The results of this study are in conformity with other similar studies. Kufoy et al. in 2012 demonstrated that patients with significant OSA showed a reduction in heart rate variability after CPAP initiation. Ryan et al. conducted an RCT in 2005 studying the effects of OSA treatment over VPBs. They proved a reduction of 58%. Simantirakis et al. in 2004 showed 91% reduction in bradyarrhythmia prevalence after 6 months of CPAP therapy. Harbison et al. in 2000 proved 88% reduction in rhythm events after CPAP therapy. Becker et al. in 1995 showed 95% reduction in cardiac rhythm disturbances after CPAP therapy.
Despite the sizeable clinical evidence to incriminate sleep-disordered breathing as an independent risk factor for rhythm disorders, the exact pathophysiology is still a matter of deliberation. Future research based on molecular analysis or artificial intelligence models may lead to the development of further sophisticated interventions in these patients.
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Conflicts of interest
There are no conflicts of interest.
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