高血压性视网膜病变可预测卒中风险

《高血压》杂志(Hypertension)8月12日在线发表的社区动脉粥样硬化风险(Atherosclerosis Risk in Communities，ARIC)研究结果表明，高血压性视网膜病变患者发生远期卒中的风险增加(Hypertension 2013 Aug. 12 [doi: 10.1161/hypertensionaha.113.01414])。

这项前瞻性人群研究由新加坡国立大学的Yi-Ting Ong及其同事进行，纳入1993年至1996年基线检查时年龄49~73岁的患者。分析的对象是无卒中或冠心病的高血压患者，这些患者具有可分级的视网膜照片。排除照相时患有糖尿病的患者。

在入组的2907例高血压患者中，1354例具有轻度高血压性视网膜病变，146例具有中度高血压性视网膜病变，1例具有重度高血压性视网膜病变；在平均13年随访期间，165例发生偶发性卒中，包括146例脑梗死和15例出血性卒中。校正年龄、性别、血压和其他危险因素(如体重指数、吸烟和饮酒)后，发现中度高血压性视网膜病变患者的卒中风险显著高于无视网膜病变的患者[校正风险比(HR) 2.37]。

在高血压经药物治疗得以良好控制的患者中仍持续观察到卒中风险增加的情况。在所有高血压得以良好控制的患者中，轻度和中度/重度高血压性视网膜病变患者的卒中风险显著高于无视网膜病变的患者(轻度视网膜病变，校正HR 1.96，中度/重度视网膜病变，校正HR 2.98)。

研究者表示，研究结果表明这些视网膜微血管改变引起的血管风险高于传统心血管危险因素引起的血管风险。此外，结果也表明，视网膜照相是临床上潜在的卒中风险评估工具。该研究中使用的简化3级高血压性视网膜病变分级系统(轻度、中度、重度)在临床和研究中均可容易实施，是一套有用的分级系统。

需指出的是，虽然临床指南强烈建议通过降低血压来降低卒中风险，但该研究中的高血压性视网膜病变患者在血压得以良好控制的情况下，卒中风险仍增加。这表明密切监测血压和药物依从性可能不足以预防高血压患者发生卒中。对高血压获得良好控制的患者进行视网膜评估可能特别有用。

在一份媒体声明中，该研究的第一作者Mohammad Kamran Ikram医生表示，目前基于该研究结果建议改变临床实践为时尚早。未来需进行其他研究证实该研究结果，并探讨视网膜影像学检查是否有助于提供高血压患者的额外卒中风险信息。

ARIC研究获美国国立心肺血液研究所支持。Ikram医生从新加坡教育部学术研究基金会和新加坡卫生部全国医学研究理事会获得资金。研究者声明无其他经济利益冲突。

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By: SHARON WORCESTER, Cardiology News Digital Network

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.