Malaria, HIV/AIDS, and tuberculosis usually top the list of the world’s leading killers. But congestive heart failure is what worries Dr. Joao Lima. Anywhere there’s "progress," he says, there’s also more and more people suffering from this progressive, debilitating disease which has no cure.
"The rise of heart failure around the world is occurring in developing countries, such as India, large parts of Latin America, metropolitan China and in large cities anywhere in the world", says Lima, who is a MESA researcher based at Johns Hopkins University, Department of Cardiology.
The culprit? The so-called "good life." "The number of things we associate with modern living are also associated with cardiovascular disease, so heart failure threatens to become a huge health-care problem," Lima says.
PREVENTING A FAILING PUMP
How to best prevent heart failure before irreversible damage occurs is the core of Lima’s research. Congestive heart failure, known as CHF, occurs when the heart can’t pump enough blood to the body’s other organs. Causes include coronary artery disease, high blood pressure and diabetes. While progress has been made in reducing overall heart disease mortality in the United States, congestive heart failure is becoming such a common condition it’s been called a "new epidemic". About 5.8 million people in the United States have heart failure, resulting in more than 300,000 deaths each year.
THE BEGINNING OF THE END
"Heart failure is becoming increasingly a subject for medical research," Lima explains. "It costs a tremendous amount of the health care budget to treat patients in heart failure, because they are hospitalized and re-hospitalized and consume an enormous amount of dollars. And with heart failure, the quality of life plummets."
CHF was the most common diagnosis of hospitalizations in a 1994 study. It’s responsible for more hospitalizations than all cancers combined. And the problem is only expected to get worse as boomers age and people live longer with heart disease. Preventing congestive heart failure altogether is its best antidote.
MESA’s Heart Failure Findings
None of the 6,814 MESA participants had heart disease before the study began; 79 developed congestive heart failure within four years of the study. Those who suffered first-time heart failure were more likely to be older, male, obese, current smokers and have high-blood pressure and diabetes. Lima and others tracked MESA participants over four years to see if they could find markers – or physical changes within the body — as an indication of impending heart failure. They looked at these markers below, which had not previously been studied as indicators of future heart failure:
Metabolic syndrome: Cluster of conditions, such as increased blood pressure, elevated insulin levels, excess body fat around the waist or abnormal cholesterol levels, that occurring together, increase the risk of heart disease, stroke and diabetes.
Inflammatory markers: Certain proteins are released in the bloodstream that indicate an inflammatory process in the body – whether from an infection, atherosclerosis, or some other condition. These markers are higher in people with heart failure.
Insulin resistance: A condition where the body can no longer properly use insulin. It leads to excess glucose in the bloodstream and increased risk for diabetes and heart disease.
Albuminuria: Having too much of the protein, albumin, in the urine can be a sign of kidney disease.
MESA researchers also sought to understand how obesity factors into an increased risk for heart failure. They found that being obese is not a good predictor of congestive heart failure, but also that being a healthy weight does not necessarily lower one’s risk.
MESA researchers also looked at how the known risk factors for heart failure – high blood pressure, smoking, diabetes -- affected different ethnic groups. One important question MESA hoped to unravel is why African-Americans are 1.5 times more likely to develop heart failure.
"We looked at whether these risk factors tend to cluster in different ethnic groups leading to first-time heart failure," Lima explains. MESA found that African-Americans’ significantly higher rates of hypertension and diabetes appear to be the reason for their higher heart failure rate.
"The differences between ethnicities disappear if these two factors are taken out," Lima said.
Click to view an animation of heart failure (video from AHA’s Cardiovascular Media Library).
PREVENTING HEART FAILURE
MESA researchers hope the studies on heart failure are the first step in preventative care. Keeping blood pressure in a normal range, avoiding obesity, and prevention of coronary artery disease are likely preventive measures. If other specific risk factors can be established, doctors might then prescribe lifestyle changes and medication. Better drugs to improve the heart’s pumping ability and to open clogged arteries are also in the research pipeline.
"The dream in the future is to have a calculator for predicting heart failure," Lima says. "We would have a series of criteria and a doctor seeing a patient would put in some characteristics of the patient and the risk of heart failure would be calculated."
Sources
Heart Failure Fact Sheet; Centers for Disease Control and Prevention
http://www.cdc.gov/DHDSP/data_statistics/fact_sheets/fs_heart_failure.htm
Emory Healthcare Heart Failure Statistics
http://www.emoryhealthcare.org/heart-failure/learn-about-heart-failure/statistics.html
Heart Failure Society of America "What You Should Know About Heart Failure"
http://www.hfsa.org/hfsa-wp/wp/patient/questions-about-heart-failure/
American Heart Association "High Blood Pressure and African-Americans"
High-Blood-Pressure-and-African-Americans_UCM_301832_Article.jsp
MEDICAL JOURNAL ARTICLES PUBLISHED BY MESA RESEARCHERS:
Bahrami H, Kronmal R, Bluemke DA, Olson J, Shea S, Liu K, Burke GL, Lima JA. Differences in The Incidence of Congestive Heart Failure by Ethnicity: The Multi-Ethnic Study of Atherosclerosis. Arch Intern Med. 2008;168(19):2138-2145.
Bahrami H, Bluemke DA, Kronmal R, Bertoni AG, Lloyd-Jones DM, Shahar E, Szklo M, Lima JA. Novel Metabolic Risk Factors for Incident Heart Failure and Their Relationship with Obesity: The MESA (Multi-Ethnic Study of Atherosclerosis) Study. J Am Coll Cardiol. 2008;51(18):1775-1783.