Patients with hypertensive retinopathy have an increased long-term risk of stroke, according to findings from the Atherosclerosis Risk in Communities study.
Of a subset of 2,907 participants with hypertension who were part of the prospective population-based study, 1,354 had mild hypertensive retinopathy, 146 had moderate hypertensive retinopathy, and 1 had severe hypertensive retinopathy; 165 developed incident stroke, including 146 with cerebral infarction and 15 with hemorrhagic stroke, during a mean of 13 years of follow-up. After adjustment for age, sex, blood pressure, and other risk factors such as body mass index, smoking, and alcohol consumption, those with moderate hypertensive retinopathy were found to have a significantly greater risk of stroke than those without retinopathy (adjusted hazard ratio, 2.37), Yi-Ting Ong of the National University of Singapore and colleagues reported online Aug. 12 in Hypertension.
The increased stroke risk persisted even when the patients’ hypertension was well controlled medically. In the subset of all patients with well-controlled hypertension, the stroke risk in those with mild and moderate/severe hypertensive retinopathy was significantly increased compared with patients without retinopathy (adjusted HR for mild retinopathy, 1.96, and for moderate/severe retinopathy, 2.98), the investigators reported (Hypertension 2013 Aug. 12 [doi: 10.1161/hypertensionaha.113.01414]).
Atherosclerosis Risk in Communities (ARIC) study participants were aged 49-73 years at a baseline examination between 1993 and 1996. Those with prevalent hypertension in the absence of prevalent stroke or coronary heart disease for whom gradable retinal photographs were available were included in the current analysis. Excluded were people with diabetes mellitus at the time of the photographs.
The findings suggest that "the presence of these retinal microvascular changes is indicative of additional vascular risk beyond that conferred by traditional cardiovascular risk factors," the investigators said.
The findings also suggest that retinal photography – which is widely available in clinics, hospitals, and optical shops – is a potential clinical tool for stroke risk assessment.
"Histopathologic studies suggest that these hypertensive retinopathy lesions result from small vessel arteriosclerosis, and continued elevated blood pressure results in retinal ischemia and breakdown of the blood-retina barrier. They parallel hypertensive microvascular changes described in the brain, such as concentric thickening of the arterial wall, intimal thickening, medial hyperplasia, and increased vessel permeability attributable to blood-brain barrier breakdown, suggesting that retinal photography is a potential clinical tool to indirectly assess potential microvascular damage in the cerebral vasculature," they explained.
The simplified three-grade system used in this study to classify hypertensive retinopathy (mild, moderate, severe) also appears useful, as it is easily implementable in both clinical and research settings, they said.
Of note, while clinical guidelines strongly recommend the lowering of blood pressure to reduce stroke risk, patients with retinal hypertension in this study remained at increased risk of stroke despite good blood pressure control.
"This suggests that closely monitoring blood pressures and medication compliance may not be sufficient for stroke prevention in patients with hypertension. Retinal assessment may be useful especially in those with good control of hypertension," they said.
In a press statement, lead author Dr. Mohammad Kamran Ikram, also of the National University of Singapore, said it would be premature to recommend changes in clinical practice based on the findings.
"Other studies need to confirm our findings and examine whether retinal imaging can be useful in providing additional information about stroke risk in people with high blood pressure," he said.
ARIC is supported by the National Heart, Lung, and Blood Institute. Dr. Ikram received funding from the Singapore Ministry of Education Academic Research Fund and the Singapore Ministry of Health’s National Medical Research Council. The authors reported having no other disclosures.