Heart disease in Ethnocultural Patients
By Dr. Shafiq Qaadri, MD
What are the main risk factors for heart disease?
The main risk factors for heart disease includes obesity, hypercholesterolemia, diabetes, hypertension.
Fortunately, these main risk factors of heart disease are modifiable. So with education and counselling, we can address some of these issues by getting our patients to partner with us. Non-modifiable risk factors such as advancing age and family history of CVD are also important, and do contribute their share of the risk burden.
Does disease in one vascular bed, causing for example Erectile Dysfunction, lead one to suspect disease in other vascular beds?
In general, diseases affecting one vessel usually affect other vascular beds.
This is an important concept. It tells us that the vascular system is a global system, interconnected and interdependent. So disease, say, peripherally, may be a marker, an early warning system, of either established disease, or impending disease, more centrally.
Organs need a constant, uninterrupted, adequate blood supply. The vessels are part of the delivery system. Compromise in one area frequently does point to disease elsewhere. Manifestation of the disease depends on end organ damage. Vascular disease of the heart such as a completed myocardial infarct may point to a future cerebrovascular event such as stroke.
How are primary care doctors doing in terms of cardiovascular risk factor management?
Primary care physicians are doing well in terms of risk factor management, but tend to miss target goals for BP and cholesterol. With the help from the research experts and leading specialists like Dr. Liao, guidelines are developed and delivered to the primary care physicians through CHE and journal publications. Guidelines are evidence-based and change according to published research data. Reviews and new guidelines are evolving; medicine is forever moving forward to improve human life. There is always room for improvement. Every effort is aimed at following the moving target in a primary care setting.
Of course, one of the challenges is that with the constantly revised guidelines, our practice goals change, or should change. But this makes it all the more important to know the changes, as well as try to aggressively approach the targets.
Does Framingham data, which is so often cited, underestimate cardiovascular risk?
Yes, because Framingham does not factor in family history, which is probably the greatest of all risk factors for heart disease and stroke.
As more research data become available, more risk factors in detail will be identified and quantified for clinical application. For example, in metabolic syndrome, 2 of the 5 criteria--namely abdominal obesity and fasting glucose--also play a significant role in cardiovascular risk. We are also learning more about the ethnocultural differences affecting risk profiles. Race matters.
In terms of cholesterol management, do diet and exercise work?
Diet works for the hyperabsorber or patients who ingest large amounts of cholesterol. However, because 65-70% of cholesterol comes from the liver, at most, diet could reduce cholesterol by 20%. In order to achieve >20% reduction in cholesterol, a statin must be used. Exercise lowers TG and increases HDL, but has little effect on cholesterol. Cholesterol is a steroid, not fat. So, exercise burns off fat, not steroid.
If diet could decrease cholesterol by 20%, it would still be beneficial to reduce cardiovascular risk. Dietary intervention may also help to control obesity and diabetes. Regular exercise not only burns off calories but also helps to enhance cardiovascular status. Though we know that diet and exercise can improve cardiovascular health, it is so difficult to implement and to maintain healthy lifestyle modification.
What is the cardiometabolic syndrome?
This is metabolic syndrome with cardiovascular consequences. One of the criteria for metabolic syndrome is abdominal obesity. Waist circumference measurement is recommended as a new vital sign in the 2006 guidelines for global cardiometabolic risk management.
Please explain your objectives in conducting and publishing the review called “Safety and Efficacy of Statins in Asians” recently published in the American Journal of Cardiology.
To determine whether statins are safe in Asians and to determine how efficacious statins are in the Asian population. Most efficacy trials were performed in the Caucasian population.
In this review, he addresses the issue of safety and efficacy of statins in Asians. He points out that despite noted higher plasma levels of statin in Asians, no particular safety issues are identified. However, heightened response to statin in Asians warrants prescribing lower statin doses.
This is part of the newer information that we are learning with regard, as I mentioned earlier, the ethnocultural differences.
What are the genetic factors at the root of the racial differences, higher risk profiles, differential response to therapies, etc?
Genes regulate basal HMG-CoA reductase enzyme activity, and thus patients may have different response to statins. Also, metabolism of drugs differ between ethnic groups. As stated in Dr. Liao’s review: “Genetically based differences in the metabolism of statins, in Asians, indicate that lower statin doses achieve lipid improvements comparable with those observed with higher doses in Caucasians. Few clinical trials have examined the effects of statins in various ethnic and racial groups.” Further studies are anticipated.
How has the cholesterol risk changed in ethnic communities, such as Asian? How does it now compare to Westerners?
I think that Asians are starting to appreciate that they need more aggressive lipid lowering. However, the standards and perception still lag behind Westerners.
In his review, Dr. Liao also noted that: “Recent studies have confirmed that the prevalence of the metabolic syndrome in Asians is comparable with that in Western populations.” Asians are exposed to the same risks comparable to the Western population. It is on the rise.
You spoke about Asian patients’ responses to statins vs. other populations. Can you explain this?
Taking Caucasians as the mean, Asians tend to be more sensitive to LDL lowering with statins. In contrast, African-Americans tend to be more resistant to LDL lowering effects of statins. Hispanics are about the same as Caucasians.
And how do we define risk levels for Asians (or other ethnic groups) with various risk factors? What should be the target for Asians?
We are all different, yet we are exposed to similar cardiovascular risks.
How does the effect of statin therapy differ in the Asian population vs. the Western population?
The responses to statins are different. However, the toxicity rate is about the same.
Heightened response without any identifiable safety issues.
Does the safety of statins change when treating someone of Asian descent?
No. So far so good. “Research on this subject continues”.
Does it make clinical sense for physicians to prescribe low-dose statin therapy to Asians?
Yes, because of increase efficacy or sensitivity to LDL lowering with statins in Asians. But it is not because of toxicity issues. While it still safe to prescribe equivalent dose of statin to Asians, a lower dose is warranted because of heightened response.
Recent changes in the Ontario formulary have been made with regard to cholesterol-lowering medications. Is this important for Asian patients?
Rosuvastatin 5 mg (Crestor) was recently covered by the Ontario formulary. It is important especially in the Greater Toronto Area, where there is a large Asian population and some of the Asian residents, e.g. elderly > 65y.o. It gives both the patient and the physician a choice. It may even benefit the non-Asian patient when a lower dose is indicated.
I think that this is the appropriate starting dose for Asians. For LDL lowering, this would be comparable to 10 mg rosuvastatin in Caucasians.
What is your final message?
Monitor your patients, screen them as appropriate. Make sure you do a global cardiovascular risk assessment, which should include all the parameters that we’ve discussed. Know the appropriate targets for blood pressure, cholesterol, sugar, waist measurement, and so on, and ease your patients towards them. Probably we will, for example, need combination therapies to reach, say, our blood pressure targets, and possibly other targets also.
Dr. Shafiq Qaadri is a Toronto family physician and Continuing Medical Education lecturer. www.doctorQ.ca
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