Women with chest pain who have low hemoglobin levels are more likely to die or suffer a heart attack, heart failure, stroke or other cardiovascular event than women with normal hemoglobin levels, according to a new study in the June 2, 2004 issue of the Journal of the American College of Cardiology.
“There were several surprises from the study. First, women with low hemoglobin levels had a higher rate of death and cardiovascular events over a relatively intermediate length of follow up, averaging just over three years. In addition, the hemoglobin levels where these adverse events occurred are by standard definitions only mildly to moderately low. And a low hemoglobin level was a better predictor of adverse cardiovascular events than most traditional cardiovascular risk factors such as smoking, hypertension, age, or family history of heart disease,” said Christopher B. Arant, MD, from the University of Florida College of Medicine in Gainesville.
Previous studies have linked anemia (low hemoglobin) to poorer outcomes among heart attack and heart failure patients, but this study is the first to demonstrate a similar link for women who reported chest pain. Few of the study participants (less than 3 percent) had congestive heart failure and only 39 percent had a coronary artery blockage that would be considered severe.
This study involved 864 women who were part of the Women’s Ischemia Syndrome Evaluation (WISE) study, which is sponsored by the National Heart, Lung, and Blood Institute. About one woman in five (184) was anemic, with hemoglobin levels below 12 grams per deciliter of blood.
During an average follow-up period of slightly more than three years, 10.3 percent of the anemic women in the study died compared to 5.4 percent of the women with normal hemoglobin levels. When death and adverse cardiovascular events, including heart attack, stroke, and heart failure, were combined, 26 percent of the anemic women suffered a poor outcome compared to 16 percent of the women with normal hemoglobin levels. For every 1g/dl decrease in hemoglobin level, the cardiovascular event rate increased by 20 percent.
While Dr. Arant suggested checking hemoglobin levels in women with chest pain, he cautioned that many questions remain about what to do when low levels are found.
“Based on the results of this study, we feel that women presenting with chest pain do need hemoglobin levels checked. In addition, if a woman has a low hemoglobin level, the clinician should look for a cause. However, the level of hemoglobin which should be treated is not clear. Future studies should be done to determine if treating low hemoglobin in women with chest pain improves their outcomes. In addition, the optimal target of hemoglobin should also be determined in subsequent studies,” Dr. Arant said.
Since hemoglobin carries oxygen to the body’s organs, reduced oxygen delivery has been suspected as a possible cause of the observed links between anemia and cardiovascular events, but the researchers said this study suggests other possible factors.
“In this study, we showed that women with low hemoglobin levels have more inflammation as determined by blood markers. Inflammation is integrally involved in the atherosclerotic process. In addition, inflammation can cause low hemoglobin,” Dr. Arant said. “It is possible that inflammation is contributing to both the anemia and adverse events. However, some recent studies have shown that hemoglobin may be directly involved in vascular abnormalities that could potentially lead to adverse cardiovascular events. More research on this is clearly needed.”
The researchers collected only baseline measurements of hemoglobin. The data did not include the cause of anemia, whether it was treated, or whether hemoglobin levels in these women changed during the follow-up period.
Diana B. Petitti, MD, MPH, with the Southern California Kaiser Permanente Medical Group in Pasadena, Calif., noted that the best strategy for reducing morbidity and mortality is to identify and manage risk factors for cardiovascular disease.
“These data suggest that low hemoglobin is a risk factor for cardiovascular disease. The next step would be to determine whether screening for low hemoglobin and interventions to raise hemoglobin would alter the likelihood of developing disease. The disappointing findings about the effect of hormone replacement as a strategy for preventing cardiovascular disease in women makes identification of other ways to prevent cardiovascular disease in women a high priority,” Dr. Petitti said.
The American College of Cardiology, a 29,000-member nonprofit professional medical society and teaching institution, is dedicated to fostering optimal cardiovascular care and disease prevention through professional education, promotion of research, leadership in the development of standards and guidelines, and the formulation of health care policy.