September 17th, 2013
How Well Does Hypertensive Retinopathy Predict Stroke?
Mohammad Kamran Ikram, MD PhD
CardioExchange’s editor-in-chief Harlan Krumholz interviewed Mohammad Kamran Ikram about his research group’s investigation of the value of hypertensive retinopathy in predicting the long-term risk for stroke in patients with hypertension. The study is published in the journal Hypertension.
Researchers enrolled 2907 patients with hypertension (age 50 to 73 on initial examination) from the Atherosclerosis Risk in Communities study. All had gradable retinal photographs; no history of diabetes mellitus, stroke, or coronary heart disease at baseline; and available data on incident stroke. Mean follow-up was 13 years. After adjustment for potentially confounding risk factors, participants with moderate hypertensive retinopathy were significantly more likely than those with no retinopathy to experience stroke (hazard ratio, 2.37; 95% CI, 1.39–4.02). In participants with well-controlled hypertension while on treatment, mild and moderate hypertensive retinopathy were each associated with significantly increased risk for cerebral infarction.
Harlan Krumholz: You show that hypertensive retinopathy has prognostic importance beyond blood pressure. Please explain what you think the underlying mechanism might be.
Ikram: High blood pressure is one of the most important risk factors for stroke (caused by a blood clot in the brain), but predicting exactly which patients with hypertension will develop a stroke is still not possible. A simple blood pressure measurement cannot elucidate the underlying mechanisms, because the blood pressure we measure is the net result of many processes, including functional and structural changes. However, the presence of “hypertensive retinopathy” gives us specific information on structural damage to the small blood vessels.
Harlan Krumholz: You depend on retinal photographs. Might a routine retinal examination produce the same information?
Ikram: Routine retinal examination using fundoscopy has been shown to have low inter- and intrarater reliability. Hence, there is a need to obtain standardized images of the retina, which can then be evaluated by experienced graders. In our study, we tried to streamline this process by using a simplified Hypertensive Retinopathy Grading system. The first step was to demonstrate the link between retinal features and the development of stroke using a standardized method of assessing the retina. Future work must determine whether routine examination using fundoscopy provides the same sort of information about risk for stroke.
Harlan Krumholz: Should an evaluation for hypertensive retinopathy be part of every exam? What should we do if we find it in the absence of uncontrolled hypertension?
Ikram: It is too early to recommend changes in clinical practice. Other studies need to confirm our findings and show that retinal imaging provides additional information on predicting the risk for stroke in people with high blood pressure.
JOIN THE DISCUSSION
How useful do you think retinal photographic assessment of hypertensive retinopathy will become in predicting hypertensive patients’ risk for stroke?