Background: Heart failure is the leading cause of mortality in older people with bipolar disorder (BD). Studies examining cardiac structure and function in middle-aged patients with BD by using echocardiography and cardiac strain imaging are scant. Methods: We recruited 48 patients with bipolar I disorder (BD-I) older than 45 years to undergo conventional and tissue speckle tracking echocardiography. Data of 31 mentally healthy adults older than 45 years were randomly retrieved from the echocardiographic dataset and compared with the data of BD patients. Results: Patients with BD-I had significantly higher mean values of interventricular septal thickness (Cohen's d = 0.83, p = 0.001) and left ventricular internal diameter (Cohen's d = 0.90, p = 0.001) at end-diastole relative to controls. Additionally, BD-I patients exhibited significantly lower mean values of mitral valve E/A ratio (Cohen's d = 0.67, p = 0.007) and a more reduced global longitudinal strain (Cohen's d = 0.72, p = 0.029) than controls. Multiple linear regression revealed that body mass index was negatively correlated with the mitral valve E/A ratio (adjustment R2 = 0.363, p = 0.043) in patients with BD-I. Limitations: A relatively small sample size may limit generalization. Conclusions: After midlife, BD patients exhibit cardiac diastolic (low mitral valve E/A ratio) and systolic (reduced global longitudinal strain) dysfunction. High body mass index may play a role in the unfavorable cardiac function in aging patients with BD.
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