High serum sodium level in affective episode associated with coronary heart disease in old adults with bipolar disorder

Abstract

Objective Coronary heart disease (CHD) remains the principal cause of excessive natural deaths in bipolar patients; however, electrocardiogram analyses and clinical features predicting CHDs in elderly bipolar patients remain limited. We sought to examine the relationship between CHDs, as determined by electrocardiogram, and clinical characteristics. Methods We recruited bipolar I outpatients Diagnostic Statistical Manual of Mental Health (DSM-IV) who were more than 60 years old and had at least one psychiatric admission. Subjects were divided into two groups based on the presence or absence of CHD diagnosed by electrocardiogram analysis at entry of study. Clinical data were obtained by a combination of interviewing patients and family members and retrospectively reviewing medical records of the most recent acute psychiatric hospitalization. Results Eighty patients with bipolar disorder were enrolled. A total of 20 (25%) in the study had CHDs. The mean age at the time of entry into study was 67.6 ± 5.5 years old in group with CHD and 66.8 ± 6.8 years old in that without CHD. Among the clinical characteristics examined, higher mean levels of serum sodium and thyroxine during the acute affective phase as well as more first-degree family history with bipolar disorder were related to having CHD, particularly the serum sodium level. Conclusions About one fourth of old bipolar patients have CHDs in both Asian and Western populations. Aging patients with bipolar disorder may have unique clinical factors (e.g., hypernatremia or elevated thyroxine) related CHDs that could warrant special attention in their psychiatric and medical care to minimize cardiovascular disease and mortality.