Risk for Heart Attack Higher in Rheumatoid Arthritis Patients

Recent studies have shown that the risk of myocardial infarction (MI) or heart attack is higher in patients with rheumatoid arthritis (RA), as is the rate of heart failure. In fact, heart failure is a major cause of death in RA patients. One new study examined the symptoms and risk of dying from heart failure in RA patients, while another investigated heart attack risk and risk factors in these patients. The studies were published in the September issue of Arthritis & Rheumatism (http://www3.interscience.wiley.com/journal/76509746/home).

Little is known about how and why heart failure occurs or its clinical presentation in patients with RA. In order to shed light on these questions, researchers led by John M. Davis, III of the Mayo Clinic in Rochester, MN, conducted a study involving 103 patients with RA and 852 patients who did not have the disease, all of whom experienced heart failure for the first time between 1979 and 2000. Their analysis included information on the clinical presentation, the use of heart failure medications and echocardiogram results. They found that RA patients were less likely than those without the disease to have typical symptoms and signs of heart failure. They also showed that patients with RA had a higher frequency of preserved ejection fraction, a measurement of the efficiency with which blood is pumped out of the heart. This suggests that diastolic dysfunction, an abnormality in the way the heart fills when not contracting, may play an important role in heart failure in RA patients.

More importantly, the study also found that patients with RA were much more likely to die following the onset of heart failure than those without the disease, even though they had lower rates of high blood pressure, ischemic heart disease (reduced blood flow to the heart) and obesity. This is particularly noteworthy because preserved ejection fraction is thought to be associated with lower death rates in heart failure patients.

The authors note that evidence from other studies suggests that chronic immune activation and inflammatory mechanisms may play a role in heart failure. "It may be anticipated that patients with chronic systemic inflammatory diseases such as RA, who have markedly elevated levels of inflammation mediators such as cytokines and C-reactive protein, would therefore be at particularly high risk of heart failure progression and, consequently, of higher mortality," they state.

"It is conceivable that the subtle presentation of heart failure among patients with RA leads to difficulty in diagnosis and influences management," the authors conclude, adding that their study "points to the need or increased vigilance for the signs and symptoms of heart failure in patients with RA."

In another study published in the same issue, Frederick Wolfe of the National Data Bank for Rheumatic Diseases and Kaleb Michaud of the University of Nebraska Medical Center assessed heart attack risk and risk factors in RA patients. The study involved more than 17, 500 patients with RA and about 3,000 patients with noninflammatory rheumatic disorders who had a heart attack between 1999 and 2006. It examined a series of risk factors (some of which had not been studied previously), including high blood pressure, preexisting cardiovascular disease, diabetes, smoking, exercise, obesity and the number of other health conditions.

The study confirmed the results of previous studies showing that RA patients are at substantially greater risk of having a heart attack than those with noninflammatory rheumatic disorders. It also showed that apart from obesity, the risk factors in RA patients are not any more predictive of heart attack than in patients who do not have RA. There was a link between heart attacks and steroid use, which is not entirely unexpected, since steroids may increase cardiovascular risk by increasing the likelihood of high blood pressure, diabetes and high cholesterol. In fact, the study showed that steroid use is associated with the development of diabetes and high blood pressure in patients with RA.

As to why RA patients have a higher risk of heart attacks, the reasons remain unclear. The authors suggest that either RA produces cumulative damage that can't be detected by this type of study or that the study did not take into account disease severity as measured by joint assessment and lab tests, although previous studies that included these factors showed they had minimal predictive value.