Abstract 717: Utility of Biochemical and Echocardiographic Measures of Subclinical Organ Damage in Risk Prediction for First Ischemic Stroke: The Strong Heart Study
Background: American Indians suffer disproportionately high rates of stroke, surpassing whites and even African Americans. Improved prediction could enhance prevention efforts in this population. Although Echo and biochemical markers of subclinical end-organ damage or inflammation have been linked to ischemic stroke, the extent to which such parameters collectively enhance risk prediction is not well defined.
Methods: We investigated the predictive value of biochemical and Echo measures, singly and jointly, for ischemic stroke in American Indians participating in the 2nd Strong Heart Study exam. Subjects with prior coronary disease, heart failure, A Fib, stroke or renal disease or with TTE-defined ejection fraction <50%, segmental abnormalities, or valvular disease, were excluded. Laboratory markers included CRP, fibrinogen, and urine albumin-creatinine ratio (UACR), while Echo parameters comprised left atrial (LA) anteroposterior dimension, left ventricular (LV) mass and mitral annular calcium (MAC).
Results: Among 2548 subjects (mean age 59, women 65%, HTN 42%, diabetes 46%) with mean f/u of 9.8 years, 126 events occurred. In analyses adjusted for clinical variables (age, sex, BMI, HTN, diabetes, smoking, cholesterol/HDL ratio, and serum Cr), fibrinogen, UACR, LA size, and MAC, but not CRP or LV hypertrophy, were each significantly associated with first ischemic stroke. When backward elimination was applied to identify predictive covariates, only UACR (HR 1.22, 95% CI 1.11–1.35) and LA enlargement (HR 1.77, 95% CI 1.15–2.72) were retained as significant predictors. Addition of these 2 measures individually to a clinical model did not improve discrimination, but their joint inclusion significantly enhanced performance (c-statistic 0.71 vs 0.68, 0.033).
Conclusions: In this cohort with high prevalences of HTN and diabetes, LA diameter and UACR were strong predictors of first ischemic stroke independent of associated clinical, Echo and inflammatory markers, and jointly improved predictive-model performance for this outcome. These findings highlight the complementary utility of measures of subclinical cardiac and renal damage to risk prediction, which could help guide primary prevention strategies in this vulnerable population.