Association Between High‐Sensitivity Cardiac Troponin I and Cardiac Events in Elderly Women

Background Elderly women are at high risk of coronary heart disease ( CHD ) and heart failure. High‐sensitivity assays allow detection of cardiac troponin I (hsTnI) well below diagnostic cutoffs for acute coronary syndrome. We investigated the association between these levels with future cardiac events in community‐based ambulant white women aged over 70 years initially recruited for a 5‐year randomized, controlled trial of calcium supplements. Methods and Results This was a prospective study of 1081 elderly women without clinical CHD at baseline (1998) or hsTnI above the diagnostic cutoffs for acute coronary syndrome with 14.5‐year follow‐up hospitalization and mortality (events). Two hundred forty‐three (22%) women had CHD events, 163 (15%) myocardial infarction or CHD death (hard CHD ), and 109 (10%) heart failure. In 99.6% of available serum samples, hsTnI was above the level of detection (median, 4.5 ng/L; interquartile range, 3.6–5.8). After adjusting for Framingham risk factors, each SD natural log‐transformed hsTnI increase was associated with an increased hazard for CHD (hazard ratio, 1.34; 95% CI , 1.18–1.53; P <0.001) hard CHD (hazard ratio, 1.51; 95% CI , 1.29–1.76; P <0.001), and heart failure (hazard ratio, 1.65; 95% CI , 1.36–1.99; P <0.001). Step‐wise increases in relative hazards were observed with increasing quartiles of hsTnI ( P for trend, <0.001), whereas the addition of hsTnI to conventional risk factors modestly improved discrimination indices: Harrell's c‐statistic, net reclassification, and integrated discrimination ( P <0.05). Conclusions Cardiac troponin I is independently associated with future cardiac events in elderly women without apparent clinical manifestations. The addition of cardiac troponin I to conventional risk factors may modestly improve risk prediction in this setting.