Environmental Cardiology: Getting to the Heart of the Matter

Bob Weinhold

Environ Health Perspect. 2004;112(15) 

In This Article

A Heavy Burden for Hearts Worldwide

The most basic facts about CVD haven't been available for very long. The early decades of the 1900s, when physicians were just beginning to form groups to address heart diseases, were a time of "almost unbelievable ignorance" about these conditions, according to the AHA website.

That has changed, spurred in large part by the huge impact CVD has on people. Heart conditions such as heart attack and congestive heart failure are the leading killer in the United States, and stroke is third, according to the CDC's Deaths: Preliminary Data for 2002, released in February 2004. Combined, these two categories of CVD alone account for about 35% of all U.S. deaths, compared to 23% for cancers. Other serious health problems that fall into the CVD classification include aortic aneurysms, high blood pressure, and congenital cardiovascular defects.

CVD deaths had been declining sharply in the United States over the past few decades, but that curve has flattened out in recent years. Death rates for heart diseases (responsible for nearly 696,000 U.S. deaths in 2002) declined about 3% from 2001 to 2002, as did death rates for stroke (responsible for about 163,000 U.S. deaths in 2002). But death rates attributed to high blood pressure (responsible for about 20,000 U.S. deaths in 2002) rose about 3%, continuing a steady rise over the prior 20 years.

Other industrialized nations have seen similar patterns. The WHO says that CVD accounts for about one-third of global deaths, killing about 16.7 million people each year. Patterns in developing countries are quickly emulating those in developed countries, thanks to the imported western lifestyle and reductions in infectious disease deaths and other acute causes of death. The WHO estimates that CVD will be the leading killer in developing countries by 2010.

But there are huge variations from country to country. In 36 countries tracked by the AHA, CVD death rates differ dramatically, with rates in some of the most-affected countries, such as the Russian Federation, Bulgaria, and Romania, more than five times higher than in some of the least-affected countries, such as France, Japan, and Australia. Variations in factors such as diet, exercise, smoking, health care quality and availability, and pollution likely play a role in these differences.

Within a country, there also can be huge variations. In the United States, the CVD rate in the least-affected state, Minnesota, is less than 60% the rate in the most-affected state, Mississippi, according to the AHA's Heart Disease and Stroke Statistics--2004 Update. And the gap has been widening. Minnesota had a 27% decline from 1990 to 2000, while Mississippi saw a 12% decline.

Race and ethnicity are significant risk determinants. Black women in the United States are 2.5 times as likely as Asian and Pacific Islander women to die of diseases of the heart, and a similar ratio of 2.25 to 1 holds for black men, according to CDC statistics published in Women and Heart Disease and Men and Heart Disease. Death rates for American Indian, Alaska Native, Hispanic, and white men and women fall in between these two extremes.

Similar disparities exist for stroke, with the death rate for black men and women more than twice that of the least-affected groups--Hispanics, American Indians, and Alaska Natives--according to the CDC's 2003 publication Atlas of Stroke Mortality: Racial, Ethnic, and Geographic Disparities in the United States.

The elderly tend to be most vulnerable to CVD, and the problem is expected to worsen in many countries as populations age. But sudden cardiac-related deaths have increased dramatically among people under age 35, according to the CDC's 2003 report A Public Health Action Plan to Prevent Heart Disease and Stroke. And CVD is the third-leading cause of death for children under 15, according to the AHA.

Deaths aren't the only consideration. Chronic diseases, which the CDC says affect more than 90 million people in the United States alone, are often due to CVD. Diseases of the heart, high blood pressure, and stroke underlie about one of every five U.S. chronic disease cases.

CVD also includes cardiac birth defects. Among structural birth defects, cardiovascular malformations are the most common among live births, affecting 1 baby in 125, according to the March of Dimes. They are also the leading cause of birth defect-related infant deaths.

There is also growing evidence that prenatal exposures to some environmental pollutants, such as solvents, pesticides, and dioxins, may result in subtle functional abnormalities that show up as disease in adulthood. In the area of CVD, this hypothesis--although important--is only just beginning to receive much attention.

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