Chest
Volume 133, Issue 4, April 2008, Pages 934-940
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Original Research
Sleep Medicine
Timing of Nocturnal Ventricular Ectopy in Heart Failure Patients With Sleep Apnea

https://doi.org/10.1378/chest.07-2595Get rights and content

Background

Ventricular ectopy is frequent in heart failure (HF) patients with sleep apnea. A previous report indicated that in HF patients, ventricular premature beats (VPB) occurred more frequently during episodes of recurrent central sleep apnea (CSA) than during normal breathing, and their frequency was greater during hyperpnea than during apnea. We hypothesized that, because respiratory stimuli that might provoke ventricular ectopy are stronger during obstructive apneas than during central apneas, in contrast to CSA, VPBs would be more frequent during apnea than hyperpnea in HF patients with obstructive sleep apnea (OSA).

Methods

HF patients in sinus rhythm who have OSA or CSA (apnea-hypopnea index, ≥ 15 events per hour) and with > 30 VPBs per hour were matched for severity of cardiac dysfunction and sleep apnea. The frequency of VPBs was then assessed during stage 2 sleep during the apneic and the hyperpneic phases of recurrent obstructive or central apneas.

Results

VPBs occurred more frequently during the apneic phase than during the hyperpneic phase in patients with OSA. In contrast, VPBs occurred more frequently during the hyperpneic phase than the apneic phase in patients with CSA. There was no difference in the degree of apnea-related oxygen desaturation between central and obstructive apneas.

Conclusions

In patients with HF, nocturnal ventricular ectopy oscillates in time with oscillations in ventilation, with VPBs occurring predominantly during apneas in patients with OSA, but during hyperpneas in patients with CSA. This difference in VPB timing between OSA and CSA may be attributable to the differences in timing of arrhythmic stresses in these patients.

Section snippets

Subjects

As part of an ongoing prospective epidemiologic study, all patients with HF who are newly referred to our HF clinic undergo overnight polysomnography. This protocol was approved by the University of Toronto Research Ethics Board, and subjects provided written informed consent before study entry. The inclusion criteria were as follows: (1) chronic HF (LV ejection fraction < 45%, as assessed by echocardiography) secondary to ischemic or nonischemic cardiomyopathy; (2) sinus rhythm on the ECG; (3)

Characteristics of the Subjects

Forty patients (20 subjects in each group) with HF met our inclusion criteria. The clinical and polysomnographic data are summarized in Tables 1 and 2, respectively. Patients had a moderate-to-severe degree of sleep apnea, as indicated by their AHI. Patients with OSA were younger and more obese than those with CSA. In all subjects, LV ejection fraction was moderately to severely depressed, and all subjects were receiving appropriate medical therapy for HF. Medical therapy for HF was similar in

Discussion

In a previous study,4 we observed that the frequency of VPBs was higher during hyperpnea than apnea in HF patients with CSA. The present findings confirm that observation. However, the timing of ventricular ectopy during sleep in HF patients with OSA had not been examined previously. In this study, we compared the timing of the occurrence of ventricular ectopy in HF patients with either CSA or OSA matched for LV ejection fraction, sex, and AHI. During stage 2 sleep in HF patients with OSA, we

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  • Cited by (0)

    Supported by operating grant MOP-11607 from the Canadian Institutes of Health Research (CIHR). Dr. Ryan was supported by a research fellowship from the Toronto Rehabilitation Institute, Dr. Leung was supported by a Clinician Scientist Award from the CIHR, and Dr. Bradley was supported by a Senior Scientist Award from the CIHR.

    The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

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