Poststroke Blood Pressure and Outcomes in Ischemic Stroke (page 54)
When stroke occurs, the blood pressure (BP) often rises because of various factors. BP after acute ischemic stroke may also be elevated because of impaired autoregulation or compensatory efforts to maximize cerebral perfusion to ischemic brain tissue. A high BP is beneficial to maintain the blood flow in the ischemic brain, but it may be detrimental with regard to the brain edema and hemorrhagic transformation. Although several studies have reported a relationship between the poststroke BP and clinical outcomes in patients with ischemic stroke, the results are still conflicting. In this issue of Hypertension, results from the Fukuoka Stroke Registry, a large-scale prospective registry of acute stroke, indicate that the higher poststroke BP levels during the 48 hours after onset are associated with a lower probability of a good neurological recovery and elevated risks of neurological deterioration and a poor functional outcome in patients with acute ischemic stroke. The multivariate-adjusted odds ratio in the highest quintile of systolic BP (versus the lowest quintile as a reference) was 2.51 for a poor functional outcome (Figure). Similar associations were still observed in patients with atherothrombotic infarction. These findings suggest that a high poststroke BP is associated with unfavorable clinical outcomes after acute ischemic stroke.
Heart Rate Variability and Cognition (page 181)
Heart rate variability (HRV) is a measure of the beat-to-beat alterations to the sinus rhythm resulting from the interactions between sympathetic and parasympathetic activity. Reduced HRV is a hallmark of cardiac autonomic dysfunction and a predictor of hypertension, diabetes mellitus, depression, cardiovascular events, and mortality. The association of HRV with cognitive function independently of traditional cardiovascular risk factors remains relatively unexplored, especially for minority populations. Mexican Americans are an understudied ethnic group with a high-risk cardiovascular risk factor profile, especially type-2 diabetes mellitus. We examined whether HRV was associated with cognitive performance in a total of 869 elderly Mexican Americans who were recruited as part of the Sacramento Area Latino Study on Aging. In our cohort, a lower quartile of HRV was associated with higher prevalence of stroke, diabetes mellitus, hypertension, depression, and dementia. A lower quartile of HRV was associated with worse cognitive performance, adjusted for traditional cardiovascular risk factors. Our cross-sectional findings highlight the subclinical cardiovascular pathogenesis of cognitive impairment in a population with poor cardiovascular prognosis. This is relevant for targeted screening and early preventive strategies to delay the progression of cognitive impairment. Our findings build on prior knowledge and provide motivation for future work from longitudinal studies investigating the predictive role of HRV and its role as a prognostic factor for risk stratification and management of cognition.
Neonatal Oxygen Leads to Cardiac Dysfunction (page 143)
Eight to 12% of infants are born preterm (<37 weeks of gestation), and since the mid-1980s, nearly 90% of these infants survive, including the most premature ones. Preterm infants have lower and less inducible antioxidant defenses and are prematurely exposed on birth to high concentrations of O2 compared with intrauterine life. This relative hyperoxic injury results in classical prematurity-related short-term vascular complications, such as retinopathy and bronchopulmonary dysplasia; in the long term, preterm born individuals display higher blood pressure and changes in cardiac shape with impaired systolic and diastolic function.
The heart is in active development in the last trimester of gestation in humans (≤2 weeks after birth in rodents). The current study shows that transient high O2 exposure of newborn pups leads to dilated cardiomyopathy in adults. Importantly, cardiac remodeling and left ventricular dysfunction occurred before blood pressure elevation, indicating a direct effect of O2 on the developing myocardium. When challenged with pressure overload, a rapid progression to heart failure was observed in O2-exposed rats. The study also shows that O2 exposure triggered renin–angiotensin system activation, profibrotic factors, and premature cardiac senescence. This study is relevant for the growing proportion of adults born preterm who might be at higher risk of cardiac dysfunction when faced with increased vascular resistance associated with hypertension, vascular diseases, or aging.
- © 2013 American Heart Association, Inc.