Authors:
Y.Ma, S.Sun

Reference:
Sleep Medicine Volume 14, Supplement 1, December 2013, Pages e188-e189

Objectives:
It has been proven that ECG-derived respiration signal is highly correlated with the actual respiration waveforms. Cardiopulmonary coupling (CPC) analysis is derived from an estimation of the coupling between the autonomic and respiratory drives, using heart rate and respiratory modulation of QRS amplitude, respectively. This dual information can be extracted from a single channel of ECG, and is highly correlated with the actual respiration waveforms. High frequency coupling (HFC) is the marker of stable sleep, and low-frequency coupling (LFC) is the marker of unstable sleep. Fragmented sleep is characterized by coupled low-frequency behaviors across numerous sleep based physiological stream. There have been an increasing number of papers evaluating CPC or using CPC as a clinical measurement.

Conclusions:
Using data derived from ECG can be used as clinical screen or post-treatment follow-up. This review confirmed the association between sleep physiology and sleep spectrums analyzed by cardiopulmonary coupling. As sleep problems are of growing concern, easier access of overnight ECG data can be used broadly when sleep monitor is necessary. With the techniques of cardiopulmonary analysis, a portable monitor for sleep can be effective by collecting enough data for sleep analysis, meanwhile be more convenient and cost-effective. Furthermore, adding actigraphy and/or oximetry will be recommended for clinical applications.

Practical Significance:
46 relevant English articles were found, 29 (63%) was cardiopulmonary coupling. 9 (19.6%) articles explain mechanism, 30 (65.2%) articles are studies on SDB, and 7 (15.2%) articles relate to other sleep disorders or comorbidities. The methods of CPC analysis as a measurement of sleep evaluation has been compared with conventional PSG or PTT. While most of the articles are about sleep apnea, sleep quality, detecting central and obstructive, and evaluating effects of PAP therapies, studies have covered sleep quality study in sleep apnea, insomnia, hypertension, chronic heart failure, diabetics, fibromyalgia, as well as healthy subjects.

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Authors:
Thomas RJ, Weiss MD, Mietus JE, Peng CK, Goldberger AL, Gottlieb DJ.

Reference:
SLEEP 2009;32(7):897-904

Objectives:
The ECG-based sleep spectrogram generates a map of CPC based on heart rate variability and respiration derived from QRS amplitude variations. A distinct spectrographic type, designated as elevated Low Frequency Coupling Narrow Band (e-LFCNB), has been associated with central apneas and periodic breathing and predicts failure of CPAP therapy. This study assesses, at a population level, the associations of this spectrographic biomarker with prevalent cardiovascular disease using the Sleep Heart Health Study (SHHS)-I dataset.

Conclusions:
An ECG derived spectrographic marker related to low frequency is associated with greater sleep apnea severity. Whether this biomarker is solely a sign of more severe disease or whether it reflects primary alterations in sleep apnea pathophysiology, which may either cause or result from sleep apnea, is unknown. This ECG-based spectral marker is associated with a higher prevalence of hypertension and stroke.

Practical Significance:
The presence of e-LFCNB represents for the first time a biomarker for sleep disordered breathing independent of age, sex and body mass has been described.

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Authors:
Woohyeun Kim, Jin Oh Na

Reference:
American Heart Assn. Circulation. 2017;136:A19496

Objectives:
Sleep instability is highly prevalent in patients with cardiovascular disease (CVD) and evidence supports a causal association of sleep instability with CVD. We investigate the impact of radio-frequency catheter ablation (RFCA) on sleep instability in patients with paroxysmal atrial fibrillation (pAF) and the effect of sleep stability on recurrence of AF.

Conclusions:
Sleep quality was improved after RFCA in patients with pAF. Furthermore, the recurrence rate was significantly lower after RFCA in patient who had pre-RFCA sleep instability(LFC≥50.3%). These results suggest that RFCA can influence sleep quality and sleep quality assessment by analyzing routine 24-hr Holter study can be a predictable marker of recurrence after RFCA in patients with pAF.

Practical Significance:
Sleep stability was significantly improved six-month after RFCA. HFC (marker of stable sleep) and VLFC (REM/wakefulness marker) was increased (29.84% to 36.15%, p<0.001, 26.20% to 28.76%, p=0.002, respectively) while LFC, unstable sleep marker, was decreased (41.25% to 32.13%, p<0.001) after RFCA. In the patients with pre-RFCA LFC<50.3%, the recurrence rate was higher than patients with pre-RFCA LFC≥50.3%. After adjusting for baseline characteristics (including age, CHA2DS2-VASC score, LAVI, creatinine, etc.), pre-RFCA LFC<50.3% remained a significant predictor of recurrence of AF (HR 8.24 (1.88-36.06), p=0.005) during 46.4 months of median follow-up.

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Authors:
W Kim, J Na, W Jang, E Park, J Choi, C Choi, J Kim, E Kim, S Rha, C Park, H Seo, H Lim

Reference:
Sleep, Volume 41, Issue suppl_1, April 2018, Page A327

Objectives:
This retrospective observational study was performed in pAF patients who underwent RFCA between October 2007 and January 2017. Of the total 445 patients, 24-hr Holter study was performed in 218 patients before and 6 months after RFCA. Sleep stability was assessed by 24-hr Holter study using cardiopulmonary coupling (CPC) analysis. We compared CPC parameter (high-frequency coupling[HFC], low frequency coupling[LFC], very low frequency coupling[VLFC], narrow band[NB], broad band[BB]) before and after RFCA. Sleep stability was significantly improved six-month after RFCA. HFC (marker of stable sleep) and VLFC (REM/wakefulness marker) was increased (29.84% to 36.15%, p<0.001, 26.20% to 28.76%, p=0.002, respectively) while LFC, unstable sleep marker, was decreased (41.25% to 32.13%, p<0.001) after RFCA. After multivariate Cox regression analysis, LFCpreRFCA<50.3% (hazard ratio 8.2; 95% confidence interval 1.88–36.06; P=0.005) were associated with AF recurrences during the follow-up period.

Conclusions:
Sleep quality was improved after RFCA in patients with pAF. Furthermore, the recurrence rate was significantly lower after RFCA in patient who had pre-RFCA sleep instability(LFC≥50.3%). These results suggest that RFCA can influence sleep quality and sleep quality assessment by analyzing routine 24-hr Holter study can be a predictable marker of recurrence after RFCA in patients with pAF.

Practical Significance:
Sleep instability is highly prevalent in patients with cardiovascular disease (CVD) and evidence supports a casual association of sleep instability with CVD. We investigate the impact of radio-frequency catheter ablation (RFCA) on sleep instability in patients with paroxysmal atrial fibrillation (pAF) and the effect of sleep stability on recurrence of atrial fibrillation.

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