Anemia and atrial fibrillation

ST. LOUIS, MISSOURI. Anemia involves a lack of red blood cells (erythrocytes), or may be associated with a hemoglobin deficiency. A patient is classified as anemic if their hematocrit (packed red blood cell) level is below the normal range of 38-50% of total blood volume. In the USA it is estimated that 12% of people between the ages of 75 and 84 years, and 25% of people over the age of 85 years are anemic. Anemia is associated with increased mortality among patients with heart failure, chronic angina, and cancer. Researchers at the St. Louis School of Medicine now report that anemia also increases mortality and hospitalizations among elderly patients with atrial fibrillation (AF).

Their study involved 13,067 Medicare beneficiaries hospitalized with AF. Average age of the patients was 80 years and 58% were women. The group probably contained very few lone afibbers and no attempt was made to see if the conclusions of the study applied to them. More than half (57%) of the patients had heart failure, 37% had suffered a prior heart attack, 29% had a history of stroke or transient ischemic attacks (TIAs) while 25% had diabetes.

During a 12-month period, 3665 (28%) of the patients died. After adjusting for all likely confounders the researchers observed that male afibbers with a hematocrit level of 45-49.9% had the lowest mortality and that men with a hematocrit level of less than 25% had twice the risk of dying than did men at the optimum level. The optimum hematocrit level for women was 40-44.9% and the risk of dying increased by 41% for a hematocrit level of less than 25%.

Also during the 12-month observation period 8364 study participants were re-admitted to hospital. After adjusting for likely confounding variables the researchers found that those with a hematocrit level in the 25-29.9% range had a 28% increased risk of re-hospitalization when compared to those in the 40-44.9% range.

They conclude that anemia is an independent predictor of all-cause mortality and re-hospitalization among elderly patients hospitalized with atrial fibrillation and suggest that clinical trials are needed to determine if correcting anemia (iron supplementation?) is effective and safe in patients with AF.

Sharma, S, et al. Anemia: an independent predictor of death and hospitalizations among elderly patients with atrial fibrillation. American Heart Journal, Vol. 157, June 2009, pp. 1057-63

Editor’s comment: Although the findings of this study are unlikely to apply to the average lone afibber, it nevertheless points out the importance of maintaining an adequate hematocrit level, especially as one ages. Although Geritol (an iron tonic) used to be very popular among older people years ago, it has fallen out of favor based on medical advice that older people should avoid iron supplements. Will this advice ultimately turn out to be as “ill-advised” as the advice to avoid sun exposure? NOTE: People who suffer from hemochromatosis (iron overload) should not supplement with iron or vitamin C unless specifically advised to do so by their physician.

I do have one major problem with this study that links low hematocrit levels in afibbers to increased mortality. How did the researchers account for the effect of warfarin and aspirin usage (over 80% of all study participants were on one of these two drugs)? While aspirin and warfarin would likely have been beneficial for those with prior heart attack and stroke, both cause significant micro-bleeding which would certainly be a highly plausible cause for the high prevalence of anemia observed in the study.