Obstructive sleep apnea severity and prevalent atrial fibrillation in a sleep clinic cohort with versus without excessive daytime sleepiness

BACKGROUND

Obstructive sleep apnea (OSA) is associated with atrial fibrillation (AF) in cardiac cohorts. Less is known regarding the magnitude of this association in a sleep clinic cohort with vs. without excessive daytime sleepiness (EDS).

OBJECTIVES

To explore the association of OSA severity with AF in a sleep clinic cohort stratified by EDS.

PATIENTS AND METHODS

All consecutive adults (n = 3814) admitted to the Skaraborg Hospital, Sweden between Jan 2005 and December 2011 were registered in a local database, and the follow-up ended in December 2018. OSA was defined as an apnea-hypopnea index (AHI) ≥5 events/h. Mild OSA was defined as AHI ≥5 & AHI<15 events/h; moderate OSA as AHI ≥15 & AHI<30 events/h; and severe OSA as AHI ≥30 events/h. EDS was defined as an Epworth Sleepiness Scale score ≥11. We conducted cross-sectional analyzes of the prevalent AF across the OSA severity categories and logistic regression analyzes stratified by EDS.

RESULTS

In all, 202 patients (5.3%) had AF at baseline, 1.6% in no-OSA, 3.9% in mild OSA, 5.2% in moderate OSA, and 7.6% in severe OSA, respectively (p < 0.001). The stratified analyzes revealed that patients with severe OSA without EDS had an increased risk for prevalent AF (OR 2.54, 95% CI 1.05-6.16; p = 0.039) independent of the confounding factors.

CONCLUSIONS

There was an independent dose-response relationship between OSA and prevalent AF among the non-sleepy phenotype in this sleep clinic cohort. Since adherence to OSA treatment is challenging in the absence of EDS, these patients may have increased risk for adverse cardiovascular outcomes.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Mechanism and prevention of atrial remodeling and their related genes in cardiovascular disorders

Atrial fibrillation (AF) is associated with profound structural and functional changes in the atrium. Inflammation mediated atrial fibrosis is one of the key mechanisms in the pathogenesis of AF. The collagen deposition in extracellular matrix (ECM) is mainly mediated by transforming growth factor β1 (TGF-β1) which promotes AF via controlling smads mediated-collagen gene transcription and regulating the balance of metalloproteinases (MMPs)/ tissue inhibitor of metalloproteinases (TIMPs). Although many processes can alter atrial properties and promote AF, animal models and clinical studies have provided insights into two major forms of atrial remodeling: Atrial tachycardia remodeling (ATR), which occurs with rapid atrial tachyarrhythmia's such as AF and atrial flutter, and atrial structural remodeling (ASR), which is associated with CHF and other fibrosis-promoting conditions. The mechanism of atrial remodeling such as atrial enlargement, ultra structural changes of atrial muscle tissue and myocardial interstitial fibrosis in AF is still unclear. At present, many studies focus on calcium overload, renin angiotensin aldosterone system and transforming growth factor β1, that effect on atrial structural remodeling. Recent experimental studies and clinical investigations have provided structural remodeling is important contributor to the AF. This paper reviews the current understanding of the progresses about mechanism of atrial structural remodeling, and highlights the potential therapeutic approaches aimed at attenuating structural remodeling to prevent AF. Now some recent advancements of this area are reviewed in this paper.

Detection of Common Arrhythmias by the Watch-PAT: Expression of Electrical Arrhythmias by Pulse Recording

BACKGROUND

The WatchPAT (WP) device was shown to be accurate for the diagnosis of sleep apnea and is widely used worldwide as an ambulatory diagnostic tool. While it records peripheral arterial tone (PAT) and not electrocardiogram (ECG), the ability of it to detect arrhythmias is unknown and was not studied previously. Common arrhythmias such as atrial fibrillation (AF) or premature beats may be uniquely presented while recording PAT/pulse wave.

PURPOSE

To examine the potential detection of common arrhythmias by analyzing the PAT amplitude and pulse rate/volume changes.

PATIENTS AND METHODS

Patients with suspected sleep disordered breathing (SDB) were recruited with preference for patients with previously diagnosed AF or congestive heart failure (CHF). They underwent simultaneous WP and PSG studies in 11 sleep centers. A novel algorithm was developed to detect arrhythmias while measuring PAT and was tested on these patients. Manual scoring of ECG channel (recorded as part of the PSG) was blinded to the automatically analyzed WP data.

RESULTS

A total of 84 patients aged 57±16 (54 males) participated in this study. Their BMI was 30±5.7Kg/m2. Of them, 41 had heart failure (49%) and 17 (20%) had AF. The sensitivity and specificity of the WP to detect AF segments (of at least 60 seconds) were 0.77 and 0.99, respectively. The correlation between the WP derived detection of premature beats (events/min) to that of the PSG one was 0.98 (p<0.001).

CONCLUSION

The novel automatic algorithm of the WP can reasonably detect AF and premature beats. We suggest that when the algorithm raises a flag for arrhythmia, the patients should shortly undergo ECG and/or Holter ECG study.

Cardiorespiratory Polygraphy for Detection of Obstructive Sleep Apnea in Patients With Atrial Fibrillation

Background: Obstructive sleep apnea (OSA) is a modifiable risk factor of atrial fibrillation (AF) but is underdiagnosed in these patients due to absence of good OSA screening pathways. Polysomnography (PSG) is the gold standard for diagnosing OSA but too resource-intensive as a screening tool. We explored whether cardiorespiratory polygraphy (PG) devices using an automated algorithm for Apnea-Hypopnea Index (AHI) determination can meet the requirements of a good screening tool in AF patients.

Methods: This prospective study validated the performance of three PGs [ApneaLink Air (ALA), SOMNOtouch RESP (STR) and SpiderSAS (SpS)] in consecutive AF patients who were referred for PSG evaluation. Patients wore one of the three PGs simultaneously with PSG, and a different PG during each of three consecutive nights at home. Severity of OSA was classified according to the AHI during PSG (<5 = no OSA, 5–14 = mild, 15–30 = moderate, >30 = severe).

Results: Of the 100 included AF patients, PSG diagnosed at least moderate in 69% and severe OSA in 33%. Successful PG execution at home was obtained in 79.1, 80.2 and 86.8% of patients with the ALA, STR and SpS, respectively. For the detection of clinically relevant OSA (AHI ≥ 15), an area under the curve of 0.802, 0.772 and 0.803 was calculated for the ALA, STR and SpS, respectively.

Conclusions: This study indicates that home-worn PGs with an automated AHI algorithm can be used as OSA screening tools in AF patients. Based on an appropriate AHI cut-off value for each PG, the device can guide referral for definite PSG diagnosis.

Prevalence and Assessment of Sleep-Disordered Breathing in Patients With Atrial Fibrillation: A Systematic Review and Meta-analysis

BACKGROUND

In this study, we sought to estimate the prevalence of concomitant sleep-disordered breathing (SDB) in patients with atrial fibrillation (AF) and to systematically evaluate how SDB is assessed in this population.

METHODS

We searched Medline, Embase and Cinahl databases through August 2020 for studies reporting on SDB in a minimum 100 patients with AF. For quantitative analysis, studies were required to have systematically assessed for SDB in consecutive AF patients. Pooled prevalence estimates were calculated with the use of the random effects model. Weighted mean differences and odds ratios were calculated when possible to assess the strength of association between baseline characteristics and SDB.

RESULTS

The search yielded 2758 records, of which 33 studies (n = 23,894 patients) met the inclusion criteria for qualitative synthesis and 13 studies (n = 2660 patients) met the meta-analysis criteria. The pooled SDB prevalence based on an SDB diagnosis cutoff of apnea-hypopnea index (AHI) ≥ 5/h was 78% (95% confidence interval [CI] 70%-86%; P < 0.001). For moderate-to-severe SDB (AHI ≥ 15/h), the pooled SDB prevalence was 40% (95% CI 32%-48%; P < 0.001). High degrees of heterogeneity were observed (I² = 96% and 94%, respectively; P < 0.001). Sleep testing with the use of poly(somno)graphy or oximetry was the most common assessment tool used (in 22 studies, 66%) but inconsistent diagnostic thresholds were used.

CONCLUSIONS

SDB is highly prevalent in patients with AF. Wide variation exists in the diagnostic tools and thresholds used to detect concomitant SDB in AF. Prospective systematic testing for SDB in unselected cohorts of AF patients may be required to define the true prevalence of SDB in this population.

Obstructive sleep apnoea testing and management in atrial fibrillation patients: a joint survey by the European Heart Rhythm Association (EHRA) and the Association of Cardiovascular Nurses and Allied Professions (ACNAP)

Obstructive sleep apnoea (OSA) is highly prevalent in atrial fibrillation (AF) patients and associated with reduced response to rhythm control strategies. However, there is no practical guidance on testing for OSA in AF patients and for OSA treatment implementation. We sought to evaluate current practices and identify challenges of OSA management in AF. A descriptive cross-sectional study was performed with a content-validated survey to evaluate OSA management in AF by healthcare practitioners. Survey review, editing, and dissemination occurred via the European Heart Rhythm Association and the Association of Cardiovascular Nursing and Allied Professions and direct contact with arrhythmia centres. In total, 186 responses were collected. OSA-related symptoms were ranked as the most important reason to test for OSA in AF patients. The majority (67.7%) indicated that cardiologists perform 'ad-hoc' referrals. Only 11.3% initiated systematic testing by home sleep test or respiratory polygraphy and in addition, 10.8% had a structured OSA assessment pathway in place at the cardiology department. Only 6.7% of the respondents indicated that they test >70% of their AF patients for OSA as a component of rhythm control therapy. Various barriers were reported: no established collaboration between cardiology and sleep clinic (35.6%); lack in skills and knowledge (23.6%); lack of financial (23.6%) and personnel-related resources (21.3%). Structured testing for OSA occurs in the minority of AF patients. Centres apply varying methods. There is an urgent need for increased awareness and standardized pathways to allow OSA testing and treatment integration in the management of AF.

Should we incorporate obstructive sleep apnea in CHA2DS2-VASc score?

Atrial fibrillation (AF) is considered a significant challenge in cardiovascular medicine related to significant morbidity and mortality. Obstructive sleep apnea (OSA) is associated with stroke and constitutes an important risk factor for AF. However, it is still ambiguous whether OSA is independently related to stroke or systemic embolism in AF patients, and whether or not OSA should be included in CHA2DS2-VASc score. In a recent study, the presence of OSA in patients with AF was associated with higher rates of adverse events, namely stroke and systemic embolism. Patients with OSA have higher CHA2DS2-VASc scores and mean CHA2DS2-VASc scores that increase with OSA severity. The addition of OSA to CHA2DS2-VASc resulted in improved discrimination, but this improvement was modest and clinically non-significant. However, cardiovascular risk factors that accompany OSA and not OSA per se might be responsible for the increased thromboembolic risk in these patients. It is noteworthy that patients with OSA with CHA2DS2-VASc <2 had a higher incidence of stroke compared to those without. Unfortunately, the event rates for stroke in these patients were too low to reach statistically validated conclusions. Therefore, it seems reasonable to suggest that in borderline stroke risk patients (CHA2DS2-VASc <2), the presence of OSA should be taken into account in the treatment decision. More studies are needed to elucidate whether or not OSA should be incorporated in CHA2DS2-VASc score.

Watch-PAT is Useful in the Diagnosis of Sleep Apnea in Patients with Atrial Fibrillation

BACKGROUND

Early diagnosis and treatment of sleep apnea in patients with atrial fibrillation (AF) is critical. The WatchPAT (WP) device was shown to be accurate for the diagnosis of sleep apnea; however, studies using the WatchPAT device have thus far excluded patients with arrhythmias due to the potential effect of arrhythmias on the peripheral arterial tonometry (PAT) amplitude and pulse rate changes.

PURPOSE

To examine the accuracy of the WP in detecting sleep apnea in patients with AF.

PATIENTS AND METHODS

Patients with AF underwent simultaneous WP and PSG studies in 11 sleep centers. PSG scoring was blinded to the automatically analyzed WP data.

RESULTS

A total of 101 patients with AF (70 males) were recruited. Forty-six had AF episodes during the overnight sleep study. A significant correlation was found between the PSG-derived AHI and the WP- derived AHI (r=0.80, p<0.0001). There was a good agreement between PSG-derived AHI and WP-derived AHI (mean difference of AHI: -0.02±13.2). Using a threshold of AHI ≥15 per hour of sleep, the sensitivity and specificity of the WP were 0.88 and 0.63, respectively. The overall accuracy in sleep staging between WP and PSG was 62% with Kappa agreement of 0.42.

CONCLUSION

WP can detect sleep apnea events in patients with AF. AF should not be an exclusion criterion for using the device. This finding may be of even greater importance in the era of the COVID19 epidemic, when sleep labs were closed and most studies were home based.

Impact of severe OSA on pharmacoinvasive treatment in ST elevation myocardial infarction patients

PURPOSE

The negative association between obstructive sleep apnea (OSA) and adverse cardiovascular outcomes in patients undergoing percutaneous coronary intervention (PCI) is well documented. However, little is known about the influence of OSA on fibrinolytic therapy. The aim of this study was to evaluate the impact of severe OSA on pharmacoinvasive treatment in ST elevation myocardial infarction (STEMI) patients.

METHODS

We enrolled consecutive STEMI patients without previous vascular disease, heart failure, or OSA diagnosis. All patients underwent either a pharmacoinvasive therapy or primary PCI. Syntax score (SS) was calculated for all patients, and a full bedside polysomnography was performed in the first 72 h of admission. In-hospital events and 30 days readmissions were analyzed.

RESULTS

The sample included 116 patients, 87 men. Patients with severe OSA were older (p = 0.01), had higher neck and abdominal circumferences (p < 0.01), and had higher BMI (p < 0.01). They also had lower reperfusion rates post-fibrinolysis (20 vs. 65%; p = 0.001), higher SS (20.2 ± 11.2 vs. 14.6 ± 10.6; p = 0.03), lower left ventricle ejection fraction (45 ± 8 vs. 51 ± 10%; p = 0.02), and a higher incidence of atrial arrhythmias (4 vs. 21%; p = 0.02). STEMI patients with severe OSA presented with threefold increase in the risk for at least one adverse outcome. Regression analysis showed that both severe OSA and hypertension were independent predictors of higher SS.

CONCLUSION

Severe OSA was associated with a poor outcome after pharmacoinvasive treatment in STEMI patients.

Sleep Disorders and Atrial Fibrillation: Current Situation and Future Directions

Atrial fibrillation (AF) is a growing health problem worldwide. In recent years, there has been a rising interest in the relationship between sleep disorders and AF. Several studies have reported higher prevalence and incidence rates of AF in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). However, some believe that OSAHS is not a risk factor for AF; but AF, by itself, is regarded as one of the possible triggers for OSAHS. In this study, the related literature investigating the association between OSAHS and AF was reviewed, and then the possible mechanisms of this interplay were discussed. To conclude, recommendations for further research in this field were presented to researchers and some points were highlighted for physicians.

Cardiac effects of CPAP treatment in patients with obstructive sleep apnea and atrial fibrillation

PURPOSE

Obstructive sleep apnea (OSA) has been recognized as an independent risk factor for the development and progression of atrial fibrillation (AF). We aimed to investigate the changes in heart rate and atrial and ventricular ectopy after continuous positive airway pressure (CPAP) treatment in patients with OSA and AF.

METHODS

Consecutive patients with AF underwent ambulatory sleep monitoring, and OSA was defined as an Apnea-Hypopnea-Index (AHI) ≥ 5/h. Treated patients completed in-laboratory CPAP titration study. A 24-h ECG Holter was performed at baseline and at 3 and 6 months after CPAP treatment.

RESULTS

One hundred patients (70% males) with AF were included in the final analysis. OSA was diagnosed in 85% of patients. There were no significant changes in mean 24-h heart rate in patients with paroxysmal or permanent AF at 3 and 6 months of treatment compared to baseline. In patients with paroxysmal AF (n = 29), atrial and ventricular ectopy counts/24 h significantly decreased at 3 months compared to baseline (median (IQR) 351 (2049) to 57 (182), P = 0.002; 68 (105) to 16 (133), P = 0.01 respectively). At 6 months follow-up, the atrial ectopy count/24 h significantly decreased in patients with paroxysmal AF compared to baseline (median (IQR) 351 (2049) to 31 (113), P = 0.016, n = 14). In patients with permanent AF (n = 15), there was a significant reduction in ventricular ectopy count/24 h at 3 months compared to baseline (median (IQR) 100 (1116) to 33 (418), P = 0.02).

CONCLUSIONS

There is a significant decrease in atrial and ventricular ectopy count/24 h in patients with AF and OSA at 3 and 6 months of CPAP treatment compared to baseline.

A review of factors associated with maintenance of sinus rhythm after elective electrical cardioversion for atrial fibrillation

Atrial fibrillation is the most common heart-rhythm disorder, affecting about 1.5% to 2% of the population with an increased risk of mortality and morbidity due to stroke, thromboembolism, and heart failure. If the conversion back to sinus rhythm does not happen spontaneously, pharmacological or electrical cardioversion (ECV) is the next available treatment options for some patients. However, the long-term success following ECV is variable. This review describes the factors that are associated with maintenance of sinus rhythm following ECV and proposes a clinical strategy based on the available evidence.

Impact of obstructive sleep apnea and continuous positive airway pressure therapy on outcomes in patients with atrial fibrillation-Results from the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF)

BACKGROUND

Obstructive sleep apnea (OSA) is common in patients with atrial fibrillation (AF). Little is known about the impact of OSA on AF treatment and long-term outcomes. We studied whether patients with OSA have a greater likelihood of progressing to more persistent forms of AF or require more hospitalizations and/or worse outcomes compared with patients without OSA.

METHODS

A total of 10,132 patients were enrolled between June 2010 and August 2011 in the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF) and followed for up to 2 years. The prevalence of OSA and continuous positive airway pressure (CPAP) treatment was captured at baseline. The association between OSA and major cardiovascular outcomes was analyzed using multivariable hierarchical logistic regression modeling and Cox frailty regression model.

RESULTS

Of the 10,132 patients with AF, 1,841 had OSA. Patients with OSA were more symptomatic (22% vs 16% severe/disabling symptoms; P < .0001) and more often on rhythm control therapy (35% vs 31%; P = .0037). In adjusted analyses, patients with OSA had higher risk of hospitalization (hazard ratio [HR], 1.12; 95% CI, 1.03-1.22; P = .0078), but no difference in the risks of death (HR, 0.94; 95% CI, 0.77-1.15; P = .54); the composite of CV death, myocardial infarction, and stroke/transient ischemic attack (HR, 1.07; 95% CI, 0.85-1.34; P = .57); major bleeding (HR, 1.18; 95% CI, 0.96-1.46; P = .11); or AF progression (HR, 1.06; 95% CI, 0.89-1.28; P = .51). Patients with OSA on CPAP treatment were less likely to progress to more permanent forms of AF compared with patients without CPAP (HR, 0.66; 95% CI, 0.46-0.94; P = .021).

CONCLUSION

Compared with those without, AF patients with OSA have worse symptoms and higher risks of hospitalization, but similar mortality, major adverse cardiovascular outcome, and AF progression rates.

CLINICAL TRIAL REGISTRATION

NCT01165710 (http://www.clinicaltrials.gov).

The mechanical fibrillation pattern of the atrial myocardium is associated with acute and long-term success of electrical cardioversion in patients with persistent atrial fibrillation

BACKGROUND

Electrophysiological studies demonstrate that a short atrial fibrillation cycle length (AFCL) is related with poor outcome of electrical cardioversion (ECV) of atrial fibrillation (AF). We found previously that the mechanical AFCL (AFCL-tvi) and atrial fibrillatory velocity (AFV-tvi) may be determined noninvasively using color tissue velocity imaging (TVI) and closely relates to the electrophysiological AFCL.

OBJECTIVE

To evaluate the relation between AFCL-tvi, AFV-tvi, and success of ECV in patients with AF.

METHODS

We prospectively studied 133 patients with persistent AF by performing echocardiography before ECV and measured the AFCL-tvi and AFV-tvi in the right atrium and left atrium. Recurrent AF was monitored.

RESULTS

Nineteen (14%) patients had failure of ECV, 42 (32%) remained in sinus rhythm after 1-year follow-up, and 72 (54%) had a recurrence of persistent AF. Patients with immediate ECV failure had a lower median AFV-tvi measured in the right atrium than did patients with a successful ECV: 0.7 cm/s (0.2-1.0 cm/s) vs. 1.7 cm/s (0.9-2.8 cm/s) (P = .008). Patients with maintenance of sinus rhythm after 1 year had a longer AFCL-tvi measured in the left atrium than did patients with recurrence of AF (150 ms vs 137 ms; P = .017) and had a higher AFV-tvi in both atria (1.4 vs. 0.9 cm/s in the left atrium; P = .013 and 2.2 vs 1.4 cm/s in the right atrium; P = .011). Multivariate analyses showed that all atrial TVI parameters were independently associated with the maintenance of sinus rhythm after 1 year.

CONCLUSION

Higher atrial fibrillatory wall velocities and longer AFCLs determined by echocardiography are associated with acute and long-term success of ECV.

The role of obesity and sleep apnea in atrial fibrillation

PURPOSE OF REVIEW

To discuss the relationship between obesity and obstructive sleep apnea as they relate to the growing atrial fibrillation epidemic, and to discuss possible mechanistic links and implications for treatment of atrial fibrillation.

RECENT FINDINGS

Increasing BMI plays an important role in development of atrial fibrillation in both men and women. Sleep-disordered breathing contributes to cardiac chamber enlargement, which may be responsible for increasing atrial fibrillation in this population. Patients with obstructive sleep apnea and/or obesity have less freedom from atrial fibrillation recurrence after catheter ablation for atrial fibrillation.

SUMMARY

BMI is a strong predictor of future development of atrial fibrillation and should be considered as a risk factor for atrial fibrillation. Patients with obstructive sleep apnea and/or obesity have high atrial fibrillation recurrence rates following atrial fibrillation ablation.

Predictors of recurrence in patients undergoing cryoballoon ablation for treatment of atrial fibrillation: the independent role of sleep-disordered breathing

INTRODUCTION

In patients with atrial fibrillation (AF) undergoing pulmonary vein isolation, cryoballoon technique (cryoPVI) has been adopted in many centers. This study aimed to evaluate predictors of AF recurrence including impact of sleep-disordered breathing (SDB).

METHODS AND RESULTS

In 82 patients consecutively assigned to cryoPVI cardiorespiratory screening for SDB, assessment of medical history, ECG, echocardiography, standard laboratory measurement, and blood gas analysis were performed prior to intervention. After a 3-month blanking period, a 7-day Holter ECG was performed at 3, 6 and then every 6 months to determine AF recurrence. Seventy-five patients (69 paroxysmal AF, 6 persistent AF, 22 female, age 60 ± 9 years) completed at least 6-month follow-up. Median follow-up of 12 months (interquartile range 6-18 months) confirmed maintenance of sinus rhythm in 69.4% of these patients. Stepwise forward regression model revealed moderate to severe SDB (cut-off apnea-hypopnea-index (AHI) ≥ 15 per hour; Hazard Ratio (HR) 2.95, P = 0.04), early recurrence of AF (HR 8.74, P < 0.001), persistent AF (HR 7.16, P < 0.001), preprocedural class III-antiarrhythmic drug treatment (HR 3.63, P = 0.02), but not SDB per se (AHI ≥ 5 per hour) as independent predictors for AF recurrence.

CONCLUSION

Moderate to severe SDB is a treatable condition that independently predicts AF recurrence in patients undergoing cryoPVI. Screening for SDB and adequate treatment may improve long-term success of cryoPVI.

C-Reactive Protein and The Risk of Atrial Fibrillation: A Systematic Review and Meta-Analysis

There is increasing evidence linking C-reactive protein (CRP) and atrial fibrillation (AF). Despite the abundance of literature, confusion exists regarding this association because of inconsistent results. MEDLINE and Cochrane Controlled Trials Register databases were carefully searched through July, 2009 combining the following terms "C-reactive protein" and "atrial fibrillation". Reference lists of selected articles and reviews were also screened to identify additional relevant studies. Of the 129 studies initially identified, 8 studies with 7507 subjects (719 with AF) were included in the meta-analysis. Analysis yielded a relative risk of 1.63 (1.43, 1.86) for occurrence of AF when CRP level was above a cut off of 3-3.5 mg/l. When 3 studies with data on a higher cut off of 4.5-5.0 mg/l were analyzed separately, the relative risk was 4.03 (3.1, 5.25). Our study suggests that elevated CRP is associated with increased risk for AF. The risk appears incremental with higher CRP levels conferring proportionately increased risk. There is an urgent need for further large scale, well designed prospective studies to assess the relationship between CRP and AF.