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Economic globalisation is causing the incidence and prevalence of heart failure to increase at an alarming rate around the world
The heart is arguably the organ that suffers most obviously from increasing economic globalisation. Although mortality from coronary artery and cerebrovascular diseases has been declining in western Europe and North America since the mid to late 1970s, this is not the case elsewhere in the world.1 Increasing industrialisation and urbanisation, while raising living standards and increasing lifespan for many, is also accompanied by a change of diet (increased calories, fat and salt), cigarette smoking, lack of exercise, and obesity.2 Diabetes, hypertension, and coronary artery disease are the initial consequences and heart failure follows, which is the end product of myocardial damage caused by these disease processes alone or more usually in combination.
In nearly all regions of the world heart failure is both common and on the rise.3,4 In Hong Kong, based on admissions to a teaching hospital serving a large community, the incidence rate is 3–3.8/1000/year rising to 20/1000/year in women over the age of 85 years.5 This is comparable to rates in western countries that range from 1 to 5 cases/1000/year.3 And in Hong Kong there has been a 10% annual increase in hospital admissions over the past five years (unpublished data). In Africa, at least 3–7% of all hospital admissions are caused by heart failure.6 In South America cardiovascular disease is now the leading cause of death, and the prevalence rate of heart failure is about 4% in those older than 65 years.4 Similar prevalence rates were found in an Arab population.7
AETIOLOGY
The cause of heart failure varies somewhat around the world. In China and Hong Kong hypertension is the most common cause, particularly in women, although coronary artery disease with diabetes is almost as common in men.5 In sub-Saharan Africa rheumatic heart disease is still common, especially in the young, but hypertension is the major cause in the large cities.8 In certain areas of Africa dilated cardiomyopathy, endomyocardial fibrosis, and peripartum heart failure (related to local heating customs in northern Nigeria9) are relatively common causes of hospital admission for heart failure.8,10 Interestingly hypertensive heart failure was the most common cause of sudden unexpected death in Nigeria, unlike in the west where coronary artery disease predominates.11 Chaga’s disease is still an important and understated cause of heart failure in South America, but coronary artery disease is increasingly the cause in the majority of cases.4 The high prevalence of hypertension in Asia probably accounts for the high frequency (about 50%) of heart failure with a relatively normal left ventricular ejection fraction, labelled as “diastolic heart failure”.12 However, the rise of coronary artery disease means it is likely to become the major cause in South Asia and China in the near future. In these two continents in which over half the world’s population live it is estimated that death from coronary heart disease will rise by 115–127% for Indian and 81–110% for Chinese women and men, respectively, from the level in 1990 to 2020.13 These estimates are based on demographic changes alone and do not take into account major increases in risk factors which are likely on present trends.
TREATMENT
Fortunately, for a previously dismal disease the treatment of heart failure has improved notably over the past 20 years. The most effective drug treatments (diuretics, angiotensin converting enzyme (ACE) inhibitors, β blockers, and spironolactone) are relatively cheap and could be available to the majority in most areas of the world. The more expensive options such as surgery, transplantation, left ventricular assist devices, and biventricular pacing are clearly only going to be available for a minority even in the richest economies. The evidence that different ethnic groups have the same mortality benefit from these standard medications is slim, as few large scale trials have included regions outside Europe and the USA, although smaller clinical trials have confirmed the effectiveness of ACE inhibitors and β blockers in Africa and Asia.14,15 It is likely, given the fundamental nature of the derangements in heart failure, that blockade of neurohormonal activation will be equally effective universally although dosages may differ slightly.
As always the concluding plea is the same; the answer is better prevention, particularly in developing or newly industrialised countries where an epidemic of cardiovascular diseases and diabetes is now unfolding. Treatment of heart failure is still expensive and not entirely successful, and the impairment of quality of life for many elderly by heart failure symptoms is substantial. But there is ground for some optimism. A large body of studies now implicates a few well known risk factors as the major determinants of both coronary artery disease and hypertension in the majority of individuals, and these are mainly caused by the changes in lifestyle and diet that accompany economic growth and industrialisation.2 Although newer risk factors and genetic polymorphisms may generate some academic interest we know enough already to be able to prevent the majority of cardiovascular diseases. Neither coronary artery disease nor hypertension need to exist and their elimination would also remove the two most debilitating vascular diseases, namely heart failure and stroke. Perhaps our targets should now be not only the tobacco trade but also the fast food industry, both of which are making great inroads in many developing countries.