title: Platelet count predicts cardiovascular mortality in very elderly patients with myocardial infarction.
abstract: BACKGROUND
  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).
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors: Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria.
authors: Georg
authors: G
authors: Goliasch
authors: Stefan
authors: S
authors: Forster
authors: Feras
authors: F
authors: El-Hamid
authors: Patrick
authors: P
authors: Sulzgruber
authors: Nicolai
authors: N
authors: Meyer
authors: Peter
authors: P
authors: Siostrzonek
authors: Gerald
authors: G
authors: Maurer
authors: Alexander
authors: A
authors: Niessner
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001792:Blood Platelets / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000097:blood / Q000401:mortality; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000401:mortality*; D010976:Platelet Count; D011237:Predictive Value of Tests; D011379:Prognosis