Carotid Plaque Thickness Associated with Risk of Vascular Events in Hispanics

By Todd Neale
MIAMI, March 20 -- Hispanics with carotid plaque that is 1.9 millimeters thick or more have twice the risk of stroke, myocardial infarction, or other vascular events as people who are plaque-free, a cohort study revealed.
After adjustment for demographics and several cardiovascular risk factors, Hispanics had a hazard ratio of 2.22 (95% CI 1.30 to 3.78) for any vascular event, Tatjana Rundek, M.D., Ph.D., of the University of Miami, and colleagues, reported online in Neurology.
For the overall cohort (52% Caribbean Hispanic, 25% black, 15% white), the hazard ratio was 1.48 (95% CI 1.05 to 2.10), but the association was not significant among blacks or whites independently.
Dr. Rundek and colleagues showed in a previous study that Hispanics had a higher incidence of stroke compared with other ethnic groups.
"Taken together," they said, "these results may be of significant importance for the development of primary prevention programs for this vulnerable and the fastest growing minority population in the United States."
Although carotid atherosclerosis is a well-known risk factor for vascular disease, the risk associated with small, nonstenotic plaques is less clear, the researchers said.
High-resolution B-mode ultrasound may be an inexpensive, simple, and noninvasive means of measuring plaque thickness and identifying at-risk patients beyond conventional Framingham vascular risk factors, they said.
To examine the relationship between plaque thickness and risk of vascular events, Dr. Rundek and colleagues prospectively analyzed data from 2,189 participants (mean age 68 ± 10; 59.8% female) as part of the ongoing Northern Manhattan Study. All participants were stroke-free at enrollment and were followed up yearly by telephone.
The researchers used ultrasound to examine the carotid artery for plaque, which was defined as an area of thickening 50% greater than the thickness of the surrounding wall.
Plaque was present in 1,263 (58%) of participants and was more prevalent in those 65 and older, non-Hispanics, those with a history of hypertension, diabetes, or cardiac disease, current smokers, and those with an LDL cholesterol level of 130 or higher.
Mean maximum carotid plaque thickness was 1.1 ± 0.9 mm (range 0 to 8.0 mm).
Participants were divided into three categories, those with:
No plaque
Maximum carotid plaque thickness less than the 75th percentile of distribution within the cohort (<1.9 mm)
Maximum carotid plaque thickness of 1.9 mm or more
After a mean follow-up of 6.9 years, 121 participants had had an ischemic stroke, 118 had had an MI, and 166 had died from other vascular causes.
Overall, incidence rates for ischemic stroke, MI, or combined vascular events were highest for those participants with a maximum carotid plaque thickness of 1.9 mm or more (11.26, 13.42, and 34.59 per 1,000 person-years, in the three categories respectively).
The researchers noted that the incidence rate of ischemic stroke was noticeably higher than in previous studies. They suggested that the finding may be a consequence of a relatively higher age in their cohort.
When the participants were stratified by age, gender, and race/ethnicity, the association between a maximum carotid plaque thickness of 1.9 mm or more and an increased risk of any vascular event was significant only in Hispanics after adjusting for several factors. These included age, gender, race/ethnicity, education, hypertension, diabetes, LDL and HDL cholesterol levels, body mass index, smoking, alcohol consumption, and use of aspirin and lipid-lowering medication.
Presence of plaque may give physicians a better estimate of vascular risk than Framingham risk score alone, the researchers said.
"More than half of individuals in low and moderate [Framingham risk score] categories can be reclassified into the higher risk category if their information on presence of carotid plaque is available," they said.
Because their cohort consisted predominantly of Caribbean Hispanics, the results may not be generalizable to other Hispanic or racial/ethnic populations, the researchers noted.
They acknowledged other limitations, as well, including the lack of measurements on plaque area or volume, not evaluating the associations of maximum carotid plaque thickness with stroke subtype, and not accounting for the possibility that new vascular risk factors developed during follow-up.
"However," they said, "the prevalence of the risk factors such as hypertension and diabetes did not considerably change over time in our cohort."
The study was supported in part by the Gilbert Baum Memorial Grant and the Goddess Fund for Stroke Research in Women and by grants from the National Institute of Neurological Disorders and Stroke, the AHA, and the General Clinical Research Center.
The authors reported no conflicts of interest.
Primary source: NeurologySource reference:Rundek T, et al "Carotid plaque, a subclinical precursor of vascular events: The Northern Manhattan Study" Neurology 2008; DOI: 10.1212/01.wnl.0000303969.63165.34.

Coffee Has No Effect on CV Events Post-MI

December 10, 2007 — A new analysis of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico (GISSI)-Prevenzione trial shows that moderate coffee intake does not appear to have any effect on future cardiovascular events in patients who have already had an myocardial infarction (MI) [1]. Dr Maria Giuseppina Silletta (Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy) and colleagues report their results online December 3, 2007 in Circulation.
Silletta stressed to heartwire, however, that the findings can really be applied only to patients eating a Mediterranean diet who drink coffee prepared in the Italian way. Most of the participants in this study drank mocha or espresso coffee, which is unfiltered — the ground coffee beans are in contact with hot water for only a very short time, Silletta explained.
"We will tell patients that it is no problem for them to drink a moderate amount of coffee (two to four cups per day) after a heart attack, there is no cause for concern," she said. But she noted that her team could not draw conclusions about very high coffee intake because of the small number of patients included in this category.
First to evaluate effects of coffee on a large prospective cohort of CHD patients
The Italian researchers explain that many studies have looked at the association between coffee consumption and risk of cardiovascular disease (CVD), "but the issue remains controversial." Case-control studies suggest a harmful effect of coffee drinking on the risk of coronary heart disease (CHD), whereas prospective cohort studies show conflicting findings. And more recent studies have shown that coffee consumption may lower the risk of type 2 diabetes, they say.
But evidence is scarce on the association between coffee drinking and cardiovascular events among patients with documented CVD, they point out. Hence they decided to analyze data from a large cohort of patients who had had an MI and were enrolled in the GISSI-Prevenzione trial.
In their analysis, they included 11,231 patients with recent MI (within past three months), the majority of whom were male (n=9584). Usual dietary habits were assessed at baseline and updated at 0.5 and 1.5 years. Coffee consumption was categorized as never/almost never, low (less than two cups per day), moderate (two to four cups per day), or high (more than four cups per day).
The main outcome measure was the cumulative incidence of cardiovascular events (cardiovascular death, nonfatal MI, and nonfatal stroke). A total of 1167 events occurred during the three-and-a-half-year follow-up, with no significant differences found between the various categories of coffee drinker.
a. The total number of subjects does not add up to 11,231 because of the time-dependent use of collected data. This means that the same subject can be counted in the table more than once, but the habit more recently associated with the event is considered to be "responsible" for the events. However, such "responsibility" is in some way "weighted" for the amount of time of the exposure.b. Compared with abstainers (never/almost-never drinkers). Adjusted for age, gender, smoking, time from MI to enrollment, prior MI previous to index MI, body-mass index (BMI), history of hypertension, history of diabetes, peripheral vascular disease, electrical instability, results of exercise stress testing, left ventricular ejection fraction (LVEF), New York Heart Association (NYHA) class, Canadian Cardiovascular Society angina symptoms, revascularization procedures, n-3 polyunsaturated fatty-acid use, vitamin-E use, antiplatelet-agent use, angiotensin-converting enzyme (ACE)-inhibitor use, lipid-lowering-medication use, beta-blocker use, and intake of cooked vegetables, raw vegetables, fruit, fish, olive oil, butter, cheese, and wine.
And when they analyzed stroke, MI, and sudden cardiac death separately, they also found no significant differences in CV events between the different levels of coffee drinkers. The findings on sudden death are of particular interest, they say, because there has been concern that drinking coffee might increase fatal arrhythmias.
"The present study is the first to evaluate the effects of coffee consumption on a large prospective cohort of patients with established CHD. Ultimately, coffee consumption did not change the risk of CHD events, stroke, and sudden death," the researchers note.
Coffee and CVD: A controversial issue
Silletta et al go on to discuss why the issue of coffee and CVD is so controversial. For example, two recent studies showed, respectively, a J-shaped association between coffee intake and the risk of CHD and a U-shaped association, they note.
"Can the discrepancies between the results from different studies ever be reconciled or explained?" they wonder. They discuss several factors that may have affected the conclusions of various studies, particularly the earlier ones, such as recall and selection bias, inadequate adjustment for confounding factors, and publication bias.
Other difficulties in interpreting results include variations in cup size, brewing methods for coffee preparation, amount of caffeine contained in coffee beans, and the multitude of biologically active substances that are contained in coffee — "all could contribute to misclassification of exposure and may in part explain some conflicting results."
In addition, the development of tolerance to the effects of caffeine among habitual drinkers "adds to the complexity of the effects of coffee" and may make it hard to extrapolate short-term metabolic studies to long-term use of coffee, they conclude.
The GISSI-Prevenzione trial was supported by grants from Bristol-Myers Squibb, Pharmacia-Upjohn, Societá Prodotti Antibiotici, and Pfizer. The study authors have disclosed no relevant financial relationships.

Source
Silletta M, Marfisi R, Levantesi G, et al. Coffee consumption and the risk of cardiovascular events after acute myocardial infarction. Results from the GISSI-Prevenzione Trial. Circulation. 2007 doi: 10.1161/CIRCULATIONAHA .107.712976.