Obstructive Sleep Apnea and Atrial Fibrillation: A Call for Increased Awareness and Effective Management

Obstructive sleep apnea and cardiovascular disease, a story of confounders!

Obstructive sleep apnea (OSA) syndrome is increasingly common among middle aged and older adults and is frequently linked to most cardiovascular diseases (CVD). Sleep-disordered breathing and CVD share a number of common risk factors and comorbid conditions including obesity, male gender, advancing age, metabolic syndrome, and hypertension. OSA appears to be associated with worsened CVD outcomes, sleep-related symptoms, quality of life, and risk of motor vehicle accidents. Demonstrating a cause-and-effect relationship between CVD and OSA has been challenging due to shared comorbidities. Strong evidence demonstrating clinically significant benefit for OSA treatments on OSA-related CVD outcomes are limited. In this review, we evaluate potential pathophysiologic mechanisms that link OSA to CVD and focus on specific treatments for OSA, including positive airway pressure (PAP), dental devices, and surgeries with regard to OSA-related CVD outcomes.

Seasonal Variation in Paroxysmal Atrial Fibrillation: A Systematic Review

INTRODUCTION

A variety of cardiovascular diseases have been demonstrated to have seasonal variations with peaks in the winter and troughs in the summer. Studies regarding atrial fibrillation (AF) have had varying results and this review describes the current data regarding the seasonal variation of AF and mechanisms mediating this seasonal fluctuation.

METHODS

A systematic review was conducted of PubMed, EBSCO and OVID for manuscripts describing the association between seasonal variation and the occurrence of AF. Studies meeting eligibility criteria were assessed for quality and reporting bias. Data was extracted in regards to the following associations: seasonal variation and AF paroxysms, temperature and AFparoxysms, duration of daylight and AF paroxysms, barometric pressure and AF paroxysms, alcohol and AF paroxysms, as well as seasonal variation and AF related stroke.

RESULTS

A total of 15 studies were identified for inclusion. Of these, 11 studies assessed seasonal variation and the remaining 4 studies assessed seasonal variation in AF related stroke. AF paroxysms peaked in winter with a trough in summer. There was an inverse correlation between temperatures as well barometric pressure and the occurrence of AF paroxysms and a positive correlation with duration of daylight.

CONCLUSIONS

The rate of occurrence of paroxysmal AF varies by seasons and is greatest during winter and least in summer.

P wave duration and dispersion in Holter electrocardiography of patients with obstructive sleep apnea

PURPOSE

The underlying mechanisms of the association between obstructive sleep apnea (OSA) and atrial fibrillation (AF) remained unclear. We investigated P wave parameters as indicators of atrial conduction status among OSA patients.

METHODS

We studied 42 untreated OSA patients, categorized into mild (6), moderate (18), and severe (18) OSA based on the apnea/hypopnea index (AHI) and 18 healthy controls. Twenty-four-hour Holter electrocardiography was applied to measure P wave parameters including P wave duration and P wave dispersion; difference between the maximum (P-max) and minimum (P-min) measured P wave duration.

RESULTS

Mean P wave duration ranged from 110.2 ± 9.3 ms in mild OSA patients to 121.1 ± 15.4 ms in severe OSA patients and was 113.4 ± 10.0 ms in controls with no significant difference among the groups, P = 0.281. P wave dispersion and P-max were significantly longer in those with moderate OSA (68.0 ± 9.3 and 154.2 ± 9.3 ms) and those with severe OSA (71.6 ± 13.7 and 157.2 ± 13.3 ms) than controls (52.6 ± 15.3 and 142.1 ± 15.4 ms), P < 0.05. AHI was significantly correlated with P-max (r = 0.407, P = 0.012) and P wave dispersion (r = 0.431, P = 0.008). With linear regression analysis controlling for age, gender, and BMI, the AHI was independently associated with P wave dispersion (β = 0.482, P = 0.002).

CONCLUSIONS

Using Holter monitoring for measurement of P wave parameters, this study showed an association of OSA with prolonged P-max and P wave dispersion. These results indicate that patients with OSA have disturbances in atrial conduction associated with OSA severity. Repeating this study in a larger sample of patients is warranted.

Association of obstructive sleep apnea with risk of serious cardiovascular events: a systematic review and meta-analysis

BACKGROUND

The relationship between obstructive sleep apnea (OSA) and cardiovascular events remains unclear. We conducted a systematic review to determine the incident risk of cardiovascular events among patients with OSA.

METHODS AND RESULTS

We searched MEDLINE and EMBASE in January 2011 for prospective studies that followed up patients with OSA for incident ischemic heart disease, stroke, and cardiovascular mortality. Outcomes data were pooled using random effects meta-analysis and heterogeneity assessed with the I(2) statistic. Regression analysis was performed to evaluate the effects of different gradations of OSA severity based on apnea-hypopnea index. We identified 9 relevant studies from 1731 citations. OSA was associated with incident stroke in a meta-analysis of 5 studies (8435 participants), odds ratio (OR) 2.24; 95% confidence interval (CI), 1.57-3.19; I(2)=7%. A significant association was seen in studies that were predominantly on men; OR, 2.87; 95% CI, 1.91-4.31, whereas data on women were sparse. In the overall analysis of 6 studies (8785 participants), OSA was nonsignificantly associated with ischemic heart disease (OR, 1.56; 95% CI, 0.83-2.91), with significant findings in the 5 studies that recruited mainly men (OR, 1.92; 95% CI, 1.06-3.48). Substantial heterogeneity was noted (I(2)=74%). OSA was linked to cardiovascular death in 2 studies involving 2446 participants (OR, 2.09; 95% CI, 1.20-3.65, I(2)=0%). Regression analysis showed greater likelihood of stroke or cardiovascular events with increasing apnea-hypopnea index values.

CONCLUSIONS

OSA appears to be associated with stroke, but the relationship with ischemic heart disease and cardiovascular mortality needs further research.