A series of papers in a special issue of Circulation is highlighting
new data on cardiovascular disease in Asians specifically. The
researchers stress that the presentation of disease there is often
different from that seen in the West, and responses to treatment can
also differ, necessitating separate study in Asian populations. And
given that it is now widely acknowledged that 85% of cardiovascular
deaths worldwide will soon occur in low- and middle-income countries,
there is a pressing need for such research, they note.

Dr Hirotsugu Ueshima (Shiga University of Medical Science, Otsu,
Japan) and colleagues review the whole subject of cardiovascular
disease and risk factors in Asia in the December 16, 2008 issue of
Circulation [1]. They note that many countries in Asia have greater
mortality and morbidity from stroke than from coronary heart disease
(CHD), "whereas the opposite is true in Western countries," and they
emphasize the high prevalence of hypertension in some Asian nations.
They also point out that, in most Asian countries, mean levels of
total cholesterol are lower than those found in Western countries.

In fact, a new report from the INTERHEART study, published separately
in the January 20, 2009 issue of the Journal of the American College
of Cardiology, has found that the low-density lipoprotein cholesterol
(LDL-C) threshold for treatment may be lower in Asians, perhaps
necessitating a rethinking of treatment targets there [2].

In an editorial accompanying the Circulation papers [3], Dr Shigetake
Sasayama (Doshisha University, Kyoto, Japan) says: "It is our hope
that this issue provides a clear exposition of the current state of
cardiovascular disease in Asia and provides readers with a better
understanding of some of these diseases, with an emphasis on therapy
and insight into specific problems that face patients suffering from
cardiovascular disease in Asia."

Stroke on the Rise in India, on the Wane in Japan

Two of the new papers in Circulation detail the current picture on
stroke in India and Japan, respectively, and another discusses the
situation with regard to hypertension in China.

In their paper [4], Indian physicians Drs Shyamal Kumar Das and Tapas
Kumar Banerjee (Bangur Institute of Neurosciences and Psychiatry,
Kolkata, India) say, "The data accumulated so far are sufficient for
us to declare that stroke in India is very much on the rise," and
they note that in the past decade in particular, some critical data
on stroke in India have become available.

"Management of hypertension, the most important risk factor in the
community, is far from satisfactory," they point out, noting that a
high prevalence of cerebral hemorrhage has been documented in eastern
India. "Similar studies need to be conducted in different parts of
India to develop a national stroke registry . . . that would define
criteria, dietary, and risk factors because India is a multiethnic
and multicultural country."

Data on long-term outcome of stroke, the influence of socioeconomic
factors on its occurrence, and an estimate of the economic burden of
the condition are also essential to allow for adequate allocation of
resources by healthcare planners, they note.

And finally, there is "an urgent need for undertaking health
education . . . about the awareness of risk factors and early warning
signs of stroke in the community," they stress.

Meanwhile, in Japan, new data show that the incidence of ischemic
stroke has declined significantly over the past 40 years, say Dr
Michiaki Kubo (Center for Genomic Medicine, RIKEN, Yokohama,
Kanagawa, Japan) and colleagues [5].

They examined three cohorts of people over the age of 40 in 1961,
1974, and 1988 in the Japanese community of Hisayama. Morphological
exams by autopsy or brain imaging were performed on most of the
ischemic-stroke cases in these cohorts. When 13-year follow-up data
were compared, the age-adjusted incidence of ischemic stroke and
lacunar infarction declined significantly from the first to the third
cohort for both sexes, whereas the incidences of atherothrombotic and
cardioembolic infarction did not change during this period.

They believe that improved control of hypertension would largely have
influenced this declining trend: the age-adjusted and sex-adjusted
hazard ratio of hypertension decreased from 3.25 in the first cohort
to 1.83 in the third cohort.

But they warn that hypertension "still makes a large contribution to
the development of ischemic stroke, [and] there is a need for greater
primary-prevention efforts in the treatment of hypertension and
metabolic disorders."

Hypertension Remains a Huge Problem in China

Meanwhile, Dr Yanfeng Wu (Peking University of Public Health,
Beijing, China) and colleagues, in their report [6], attempt to
provide accurate estimates of the prevalence, awareness, and control
of hypertension in adults in China. Despite evidence to the contrary,
the figures suggest that the ratio of controlled to treated
hypertension has remained largely unchanged, at 1:4, over the past
decade, they note.

Using data obtained from the China National Nutrition and Health
Survey 2002, they discovered that around one in six Chinese is
hypertensive, equating to around 153 million adults, but only one-
quarter are aware of their condition.

The prevalence of hypertension was higher among men than women (20%
vs 17%; p<0.001) and was higher in successive age groups. The
prevalence of hypertension was also higher in urban compared with
rural areas for both sexes.

"National hypertension programs must focus on improving awareness in
the wider community, as well as treatment and control, to prevent
many tens of thousands of cardiovascular-related deaths," they
conclude.

Reduce Salt Consumption, Smoking in Asia

In wrapping up the Circulation issue, Ueshima and colleagues make
some important observations. While total cholesterol intake has
traditionally been low in Asia, the recent Westernization in many
countries there is beginning to change this, resulting in the
prevalence of obesity and diabetes increasing, they note. As in the
West, management of the traditional risk factors for CVD is just as
important for prevention in Asian nations, they stress.

And specifically, "reduction in salt consumption in East Asian
countries . . . is important for the reduction of CVD, especially
stroke. Prevention of smoking is also an important strategy for
reducing CVD in most Asian countries, especially for men," they
conclude.

New INTERHEART Analysis Shows Mean LDL-C Lower in Asians

The new analysis from the INTERHEART study may help illuminate the
picture further with regard to cholesterol and Asian populations.

Dr Ganesan Karthikeyan (McMaster University, Hamilton, ON) and
colleagues recruited 5731 cases of a first AMI and 6459 control
subjects from 65 centers in Asia. They obtained plasma levels of
lipids and apolipoproteins in the different Asian subgroups (South
Asians, Chinese, Southeast Asians, and Japanese) and correlated these
with the risk of AMI.

Among both cases and controls, mean LDL-C levels were about 10-mg/dL
lower compared with non-Asians, and HDL-C levels were slightly lower
among Asians compared with non-Asians.

But despite these differences in absolute levels, the risk of AMI
associated with increases in LDL-C and decreases in HDL-C was similar
for Asians and non-Asians. And in South Asians in particular, changes
in apolipoprotein predicted risk better than HDL-C (South Asians were
much more likely than other Asians to have low HDL-C).

"Although Asian patients are likely to benefit from lowering LDL-C,
the threshold for treatment initiation and the treatment targets are
conceivably lower than for Caucasians. These thresholds and targets
need to be determined in future studies," say Karthikeyan et al.

Also, in South Asians--given their lower levels of HDL-C--approaches
to increasing HDL-C may also be beneficial, they conclude.

The INTERHEART study was funded by unrestricted grants from several
pharmaceutical companies, which are listed in the paper.


Ueshima H, Sekikawa A, Miura K, et al. Cardiovascular disease and
risk factors in Asia. A selected review. Circulation 2008; 118: 2702-
2709. Abstract
Karthikeyan G, Teo KK, Islam S, et al. Lipid profile, plasma
apolipoproteins, and risk of a first myocardial infarction among
Asians. An analysis from the INTERHEART study. J Am Coll Cardiol
2009; 53: 244-253.
Sasayama S. Heart disease in Asia. Circulation 2008; 118: 2669-2671.
Abstract
Das SK and Banerjee TK. Stroke. Indian scenario. Circulation 2008;
118: 2719-2724. Abstract
Kubo M, Hata J, Doi Y, et al. Secular trends in the incidence of and
risk factors for ischemic stroke and its subtypes in Japanese
population. Circulation 2008; 118: 2672-2678. Abstract
Wu Y, Huxley R, Li L, et al. Prevalence, awareness, treatment and
control of hypertension in China. Data from the China National
Nutrition and Health Survey 2002. Circulation 2008; 118: 2679-2686.
Abstract