Obstructive Sleep Apnea and Cardiovascular Disease in Blacks
Obstructive Sleep Apnea and Cardiovascular Disease in Blacks
Several longitudinal studies such as the Sleep Heart Health Study, Wisconsin Sleep Cohort, Pennsylvania Sleep Cohort, Cleveland Family Study, and, recently, the Jackson Heart Study have demonstrated to some degree that OSA is an independent risk factor for adverse CV outcome.
Epidemiologic and clinical studies suggest that between 35% and 91% of patients with hypertension have OSA. Emerging evidence also indicates that the presence of OSA in hypertensive patients is associated with treatment resistance. In a cross-sectional analysis of the Sleep Heart Health Study, individuals with severe OSA (AHI >30 per hour) had a higher risk of hypertension compared with those without OSA (AHI <1.5 per hour). Among subjects who were followed for 4 years in the Wisconsin Sleep Cohort, the risk of hypertension increased with increasing baseline AHI. In the cohort with SDB followed for an average of approximately 7 years, a dose-response increase in the risks of incident nocturnal nondipping of systolic BP was observed.
A strong racial disparity exists in the prevalence and treatment of hypertension, and its relationship to OSA. Among hypertensive blacks, we previously reported a 91% prevalence of SDB. It is notable that hypertensive blacks had higher baseline BP, a greater number of oxygen desaturations, and higher AHI than their white counterparts. Obstructive sleep apnea may, in fact, be partly responsible for the higher prevalence of hypertension and treatment resistance in this group. Whether this link is mediated fully or in part via the strong association of obesity with OSA remains unclear. Of note, analysis of data from 2,470 participants of Sleep Heart Health Study revealed that much of the relationship between AHI and risk of incident hypertension in people with SDB was accounted for by obesity. In that study, SDB was not an independent risk factor for hypertension after adjusting for the effect of body mass index. However, in a recent study, weight gain over a decade did not appear to diminish the protective effect of CPAP therapy against development of new-onset hypertension in OSA.
The evidence linking OSA to CHD is rapidly increasing. A high prevalence (30%) of OSA was found among 223 patients with angiographically proven CHD. In addition, OSA of moderate severity (AHI >20) was independently associated with myocardial infarction. Data from the Sleep Heart Health Study also revealed a higher risk of self-reported CHD for individuals with high AHI, but subsequent longitudinal analyses of the study data indicate that the risk of incident CHD occurred primarily in men younger than 70 years. After percutaneous coronary intervention, the presence of OSA was associated with increased vessel remodeling and restenosis and increased incidence of major adverse cardiac events such as revascularizations and cardiac mortality. Studies evaluating the impact of race on the association of CHD with OSA are lacking.
A wide range of cardiac arrhythmias including atrial fibrillation, nonsustained ventricular tachycardia, and complex ventricular ectopies have been described in persons with SDB. In a study of patients with OSA, Guilleminault et al found that 48% had cardiac arrhythmias, including 2% with ventricular tachycardia, 11% with sinus arrest, 8% with second-degree atrioventricular block, and 19% with premature ventricular contractions. Subsequent tracheostomy in selected patients cured them of OSA and abolished their arrhythmias. Building on these earlier findings, Mehra et al report that individuals with severe SDB have up to 4-fold higher odds of complex arrhythmias than do those without SDB. Further detailing this SDB-arrhythmia risk, Monahan et al, in their recent study, showed a nearly 18-fold increase in the risk of nocturnal arrhythmia after the occurrence of apneas and hypopneas.
Among patients referred to a general cardiology practice, OSA was found in 49% of patients with atrial fibrillation, compared with 32% of those without atrial fibrillation The risk of incident atrial fibrillation was higher in younger patients (<65 years) and those with severe nocturnal hypoxemia. A recent meta-analysis showed that patients with OSA have a 25% greater risk of atrial fibrillation recurrence after catheter ablation than do those without OSA. The inadequate inclusion of blacks in most of these studies limits the generalizability of the findings. Particularly worrisome is the lack of OSA-related arrhythmia evidence in blacks in light of their higher sudden cardiac death rate and the possible operative role of the OSA–arrhythmia–sudden cardiac death connection.
Stroke, one of the most debilitating diseases, especially in blacks, has a significant association with OSA. In patients with first-time strokes or transient ischemic attacks, SDB was frequently observed. An analysis of prospective data from the Sleep Heart Health Study indicates that severe SDB is an independent risk factor for stroke only in men. Similar findings were reported in the Wisconsin Cohort Study, although the fully adjusted odds ratio failed to reach statistical significance, likely because of inadequate study power.
The impact of race/ethnicity on the association of OSA with stroke is largely unknown. Mortality resulting from stroke is greater in blacks compared with whites. This finding, along with the aforementioned relationship between OSA and stroke, provides further compelling evidence of the need for more research in this area among blacks.
With regard to HF, a disease affecting almost 6 million people, a report from the Sleep Heart Health Study revealed a 2-fold increase in the risk of HF among subjects with OSA. A prospective study of patients with systolic HF revealed a high prevalence (49%) of OSA. Some studies evaluating the relationship between HF and SDB have focused on central sleep apnea (CSA)—a less common type of SDB characterized by intermittent sleep disruptions caused by impaired control of breathing by the brain that is more commonly encountered in patients with HF. Research has shown that CSA with Cheyne-Stokes respiration is associated with increased incidence of cardiac arrhythmia and higher mortality in patients with HF. However, preliminary analyses of data from the Sleep Heart Health Study indicate that men have an increased risk of incident HF as a consequence of SDB, even after exclusion of subjects with CSA.
Obstructive sleep apnea is common among patients with CVD (Figure 3). Studies investigating the role of OSA on CVD in the minority population are limited, and there are no adequately powered specific studies on the interaction of race on the association of OSA with increased CV risk or adverse outcomes.
(Enlarge Image)
Figure 3.
Prevalence of OSA in various CVDs.
Ethnic/Racial Differences in CV Risk Associated With OSA
Several longitudinal studies such as the Sleep Heart Health Study, Wisconsin Sleep Cohort, Pennsylvania Sleep Cohort, Cleveland Family Study, and, recently, the Jackson Heart Study have demonstrated to some degree that OSA is an independent risk factor for adverse CV outcome.
Obstructive Sleep Apnea and Hypertension
Epidemiologic and clinical studies suggest that between 35% and 91% of patients with hypertension have OSA. Emerging evidence also indicates that the presence of OSA in hypertensive patients is associated with treatment resistance. In a cross-sectional analysis of the Sleep Heart Health Study, individuals with severe OSA (AHI >30 per hour) had a higher risk of hypertension compared with those without OSA (AHI <1.5 per hour). Among subjects who were followed for 4 years in the Wisconsin Sleep Cohort, the risk of hypertension increased with increasing baseline AHI. In the cohort with SDB followed for an average of approximately 7 years, a dose-response increase in the risks of incident nocturnal nondipping of systolic BP was observed.
A strong racial disparity exists in the prevalence and treatment of hypertension, and its relationship to OSA. Among hypertensive blacks, we previously reported a 91% prevalence of SDB. It is notable that hypertensive blacks had higher baseline BP, a greater number of oxygen desaturations, and higher AHI than their white counterparts. Obstructive sleep apnea may, in fact, be partly responsible for the higher prevalence of hypertension and treatment resistance in this group. Whether this link is mediated fully or in part via the strong association of obesity with OSA remains unclear. Of note, analysis of data from 2,470 participants of Sleep Heart Health Study revealed that much of the relationship between AHI and risk of incident hypertension in people with SDB was accounted for by obesity. In that study, SDB was not an independent risk factor for hypertension after adjusting for the effect of body mass index. However, in a recent study, weight gain over a decade did not appear to diminish the protective effect of CPAP therapy against development of new-onset hypertension in OSA.
Obstructive Sleep Apnea and CHD
The evidence linking OSA to CHD is rapidly increasing. A high prevalence (30%) of OSA was found among 223 patients with angiographically proven CHD. In addition, OSA of moderate severity (AHI >20) was independently associated with myocardial infarction. Data from the Sleep Heart Health Study also revealed a higher risk of self-reported CHD for individuals with high AHI, but subsequent longitudinal analyses of the study data indicate that the risk of incident CHD occurred primarily in men younger than 70 years. After percutaneous coronary intervention, the presence of OSA was associated with increased vessel remodeling and restenosis and increased incidence of major adverse cardiac events such as revascularizations and cardiac mortality. Studies evaluating the impact of race on the association of CHD with OSA are lacking.
Obstructive Sleep Apnea and Arrhythmia
A wide range of cardiac arrhythmias including atrial fibrillation, nonsustained ventricular tachycardia, and complex ventricular ectopies have been described in persons with SDB. In a study of patients with OSA, Guilleminault et al found that 48% had cardiac arrhythmias, including 2% with ventricular tachycardia, 11% with sinus arrest, 8% with second-degree atrioventricular block, and 19% with premature ventricular contractions. Subsequent tracheostomy in selected patients cured them of OSA and abolished their arrhythmias. Building on these earlier findings, Mehra et al report that individuals with severe SDB have up to 4-fold higher odds of complex arrhythmias than do those without SDB. Further detailing this SDB-arrhythmia risk, Monahan et al, in their recent study, showed a nearly 18-fold increase in the risk of nocturnal arrhythmia after the occurrence of apneas and hypopneas.
Among patients referred to a general cardiology practice, OSA was found in 49% of patients with atrial fibrillation, compared with 32% of those without atrial fibrillation The risk of incident atrial fibrillation was higher in younger patients (<65 years) and those with severe nocturnal hypoxemia. A recent meta-analysis showed that patients with OSA have a 25% greater risk of atrial fibrillation recurrence after catheter ablation than do those without OSA. The inadequate inclusion of blacks in most of these studies limits the generalizability of the findings. Particularly worrisome is the lack of OSA-related arrhythmia evidence in blacks in light of their higher sudden cardiac death rate and the possible operative role of the OSA–arrhythmia–sudden cardiac death connection.
Obstructive Sleep Apnea and Stroke
Stroke, one of the most debilitating diseases, especially in blacks, has a significant association with OSA. In patients with first-time strokes or transient ischemic attacks, SDB was frequently observed. An analysis of prospective data from the Sleep Heart Health Study indicates that severe SDB is an independent risk factor for stroke only in men. Similar findings were reported in the Wisconsin Cohort Study, although the fully adjusted odds ratio failed to reach statistical significance, likely because of inadequate study power.
The impact of race/ethnicity on the association of OSA with stroke is largely unknown. Mortality resulting from stroke is greater in blacks compared with whites. This finding, along with the aforementioned relationship between OSA and stroke, provides further compelling evidence of the need for more research in this area among blacks.
Obstructive Sleep Apnea and HF
With regard to HF, a disease affecting almost 6 million people, a report from the Sleep Heart Health Study revealed a 2-fold increase in the risk of HF among subjects with OSA. A prospective study of patients with systolic HF revealed a high prevalence (49%) of OSA. Some studies evaluating the relationship between HF and SDB have focused on central sleep apnea (CSA)—a less common type of SDB characterized by intermittent sleep disruptions caused by impaired control of breathing by the brain that is more commonly encountered in patients with HF. Research has shown that CSA with Cheyne-Stokes respiration is associated with increased incidence of cardiac arrhythmia and higher mortality in patients with HF. However, preliminary analyses of data from the Sleep Heart Health Study indicate that men have an increased risk of incident HF as a consequence of SDB, even after exclusion of subjects with CSA.
Obstructive sleep apnea is common among patients with CVD (Figure 3). Studies investigating the role of OSA on CVD in the minority population are limited, and there are no adequately powered specific studies on the interaction of race on the association of OSA with increased CV risk or adverse outcomes.
(Enlarge Image)
Figure 3.
Prevalence of OSA in various CVDs.