NEW ORLEANS — A depressed relative lymphocyte count was associated with an increased risk of death in patients with hypertrophic cardiomyopathy in a study with 962 patients.
The relative lymphocyte count (RLC) is an inexpensive, universally available test “that may be helpful in identifying patients with hypertrophic cardiomyopathy who have a worse prognosis,” Steve R. Ommen, M.D., said while presenting a poster at the annual scientific sessions of the American Heart Association.
“The relative lymphocyte count is part of the standard complete blood count, and involves no incremental cost,” added Dr. Ommen, a cardiologist at the Mayo Clinic in Rochester, Minn. A depressed RLC is a marker of systemic stress, and the results from prior studies have linked the marker to adverse outcomes in patients with other cardiovascular disease states.
Dr. Ommen and his associates reviewed case records for patients with hypertrophic cardiomyopathy who were seen at Mayo during 1994-2003. Patients were selected who had received a complete blood count within 1 week of their clinical evaluation.
RLC is the fraction of all leukocytes that are lymphocytes, expressed as a percent. The normal range is 20%-47%.
Among the 962 patients with hypertrophic cardiomyopathy, 258 (27%) had an RLC that was below normal. The mean RLC in this group was 14%.
During follow-up, which ranged from 1 month to 9.6 years (mean 1.8 years), the average mortality during the first year of follow-up was 3% in patients with a normal RLC, compared with 12% in those with a depressed RLC. During the first 5 years of follow-up, the average death rate was 15% in the group with a normal RLC at baseline, compared with 40% in those with a low RLC.
In a multivariate analysis that controlled for possible confounding clinical and demographic factors, three parameters were associated with a statistically significant increase in risk of death: increased age; atrial fibrillation, which boosted the risk of death 3.3-fold; and a depressed RLC, which raised the relative risk of death 2.1-fold, Dr. Ommen said.