NEW YORK (Reuters Health) – It is well established that sleep disordered breathing increases the risk of heart disease. It now appears that incident cardiovascular disease is associated with worsening sleep-disordered breathing.
As Dr. Daniel J. Gottlieb told Reuters Health by email, “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 apnea increases the risk of a heart attack, having a heart attack is associated with an increase in the severity of sleep apnea.”
In the March 29th issue of Circulation, 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 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 2 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 apnea-hypopnea index between polysomnograms than did those without this outcome.
These findings, say the investigators, “suggest that not only is sleep-disordered breathing a risk factor for cardiovascular disease, but cardiovascular disease can potentially exacerbate sleep-disordered breathing.”
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, Drs. S. F. Paul Man and Don D. Sin observe that “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.”