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Risk of Cardiovascular Disease in ART-Naive People Without Heart Symptoms, Carotid Artery Ultrasonography May Be Useful
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12th European AIDS Conference, November 11-13, 2009, Cologne, Germany
Mark Mascolini
People naive to antiretroviral therapy (ART) and without cardiovascular disease symptoms had a "vascular age" 7.6 years older than their actual age, according to results of 72-person, four-center Italian study [1]. Nearly one quarter of study participants with a low cardiovascular risk by the Framingham score and three other algorithms--and without metabolic syndrome--had evidence of atherosclerosis on carotid artery ultrasonography. But this study has a few important limitations.
Giuseppe De Socio (Santa Maria Hospital, Perugia) and colleagues from three other centers calculated the 10-year risk of cardiovascular disease and analyzed relations between predicted risk and subclinical carotid artery lesions in 72 people who had never taken antiretrovirals. They used the Framingham Risk Score, the Global Framingham Risk Score, the Progetto-Cuore method, and the SCORE algorithm to predict 10-year heart disease risk. The investigators devised a new model from the Global Framingham Risk Score to reckon vascular age, but De Socio did not offer details on this model in this brief presentation. The researchers based the diagnosis of metabolic syndrome on the National Cholesterol Education Program system and the International Diabetes Federation formula.
Carotid ultrasonography evaluated the central carotid artery, the bulb, and at least 2 cm of the internal and external carotid on both sides. De Socio and coworkers defined subclinical atherosclerosis as a carotid intima media thickness greater than 0.9 mm. An intima media thickness greater than 1.2 mm indicated plaques.
The study group had a median age of 41 years, and 57 participants (79%) were men. Median body mass index measured 23.4 kg/m(2) and median waist circumference 86.8 cm (34.2 inches). Median CD4 count measured 412 and median viral load 4.27 log (about 18,600 copies). Thirty-seven people (51%) smoked, and 6 (8%) were former smokers. Median blood pressure was 123/77 mm Hg, median triglycerides were 144 mg/dL, median total cholesterol measured 170 mg/dL, and median glucose was 87 mg/dL.
De Socio and colleagues calculated that study participants had a vascular age 7.6 years older than their chronological age. Vascular age, the Framingham Risk Score and the three other predictive algorithms, and five other factors correlated with subclinical atherosclerosis on ultrasonography:
· Older vascular age: 57.2 years with subclinical atherosclerosis, 43.4 years without, P = 0.0002
· Older actual age: 48.4 versus 36.7 years, P < 0.0001
· Greater body mass index: 24.8 versus 22.5 kg/m(2), P = 0.008
· Greater waist circumference: 92.1 versus 83.0 cm, P = 0.0002
· Higher total cholesterol: 189 versus 156 mg/dL, P = 0.001
· Metabolic syndrome by the International Diabetes Federation system: 9 versus
2, P = 0.004
Of the 72 study participants, 23% who were classified as having a low cardiovascular risk by the four risk algorithms and without metabolic syndrome had ultrasound evidence of atherosclerosis.
De Socio concluded that ultrasound-determined carotid intima media thickness may be valuable mainly in HIV-infected people with an intermediate 10-year cardiovascular risk, that is, between 6% and 20%. He proposed that carotid ultrasonography should be performed in HIV-infected people with a waist circumference of 94 cm or more for men and 80 cm or more for women (37 and 31.5 inches).
The investigators proposed a screening algorithm that starts with calculation of 10-year cardiovascular risk by Framingham or another score and a waist circumference measure. Then the following combinations can be interpreted as follows:
· 10-year risk under 6%, waist normal: low cardiovascular risk
· 10-year risk above 20%, waist normal or high: high cardiovascular risk
· 10-year risk under 6%, waist high OR 10-year risk 6% to 20%, waist normal or increased: perform carotid ultrasonography
· If intima media thickness < 1 mm: low cardiovascular risk
· If intima media thickness > 0.9 mm: high cardiovascular risk
One limitation of the study is its failure to analyze a comparison population of people without HIV. After De Socio's presentation, Patrick Mallon (University College Dublin) argued that recommending carotid intima media thickness screening in people with HIV remains tenuous because no HIV study has correlated ultrasound results with clinical outcomes [2].
References
1. De Socio GV, Mantinelli C, ,Ricci E, et al. Relations between cardiovascular risk estimates and subclinical atherosclerosis in naive HIV patients: results from the HERMES study. 12th European AIDS Conference. November 11-13, 2009. Cologne, Germany. Abstract PS11/4.
2. Mallon PWG. Limits of surrogate markers in predicting cardiovascular disease in patients living with HIV. Clinical Care Options. February 25, 2009. http://www.clinicaloptions.com/HIV/Journal%20Options/Articles/Kaplan_AIDS_2008/Commentary.aspx.
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