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It now appears that incident cardiovascular disease is associated with worsening sleep-disordered breathing, according to a new study published in the 29 March issue of Circulation.
As Dr Daniel J. Gottlieb said, "Prior studies have demonstrated that sleep apnea is a cause of coronary heart disease. This study shows that the relationship is bi-directional: while sleep apnoea increases the risk of a heart attack, having a heart attack is associated with an increase in the severity of sleep apnoea."
Dr Gottlieb of Boston University School of Medicine and colleagues report that they came to this conclusion after studying data from 2721 Sleep Heart Health Study participants.
The study
The mean age of this group was 62 years and they were recruited from several ongoing cohort studies of cardiovascular and obstructive pulmonary diseases. None had cardiovascular disease at baseline.
They were given two polysomnograms 5 years apart. During this period, 95 of the subjects demonstrated incident cardiovascular disease. After adjustment for factors including age, sex, race and body mass index, those with such disease showed significantly larger increases in apnoea-hyperpnoea index between polysomnograms than did those without.
Dr Gottlieb concluded that "the reason for this is not yet clear, but it is thought to reflect impaired control of ventilation as a result of reduced cardiac function."
In an accompanying editorial, Dr S. F. Paul Man and Dr Don D. Sin observe, "The evidence to support the widespread use of sleep studies to diagnose sleep-disordered breathing in everyone with recent onset of heart failure or heart attack is certainly not substantiated; this approach also is not practical."
Nevertheless, the researchers from the University of British Columbia, Vancouver, point out "the diagnostic possibility of sleep-disordered breathing in those patients who have not responded to optimal treatment for their underlying cardiac disease." (Reuters Health/ April 2011)
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