Platelet count predicts cardiovascular mortality in very elderly patients with myocardial infarction
Version of Record online: 9 FEB 2013
© 2013 The Authors. European Journal of Clinical Investigation © 2013 Stichting European Society for Clinical Investigation Journal Foundation
European Journal of Clinical Investigation
Volume 43, Issue 4, pages 332–340, April 2013
How to Cite
Eur J Clin Invest 2013; 43 (4): 332–340
- Issue online: 18 MAR 2013
- Version of Record online: 9 FEB 2013
- Accepted manuscript online: 10 JAN 2013 05:05AM EST
- Manuscript Accepted: 26 DEC 2012
- Manuscript Received: 9 OCT 2012
- Acute myocardial infarction;
- cardiovascular mortality;
- platelet count
The prognosis of elderly patients with acute myocardial infarction (AMI) is poor, and information on specific risk factors remains scarce. The aim of our study was to assess the influence of platelet count on cardiovascular mortality in very elderly patients with acute myocardial infarction (≥ 85 years of age).
We identified 208 elderly AMI patients and compared the platelet count with 208 matched young AMI patients (≤ 65 years) and 208 matched intermediate age AMI patients (66–84 years) who derived from the same cohort.
During a median follow-up of 4·7 years, 25% of patients (n = 156) died of cardiovascular causes (97 very elderly, 46 intermediate age and 13 young age patients). We detected a mean platelet count of 227G/l (SD ± 83) in very elderly AMI patients, of 236G/l (SD ± 78) in the intermediate AMI group and of 254G/l (SD ± 79) in 208 young AMI patients (anova P = 0·002). We revealed a significant interaction between age and platelet count with regard to cardiovascular mortality (p for interaction = 0·014). Platelet count displayed a significant risk transformation from an independent risk factor for cardiovascular mortality in very elderly AMI patients (adj. hazard ratio (HR) per 1-SD increase 1·25;95%CI 1·02–1·54;P = 0·028), via displaying no association with mortality in the intermediate age group (P = 0·10), to a strong inverse association in young patients (adj. HR 0·36;95%CI 0·18–0·68;P = 0·002).
Our study demonstrates an independent association between elevated platelet count and long-term cardiovascular mortality in the growing and vulnerable group of very elderly AMI patients. Nevertheless, the pathophysiologic mechanisms underlying this age-dependent effect have to be further clarified.