Hematocrit level as a marker of outcome in ST-segment elevation myocardial infarction

Anemia is a well-known predictor of a poor outcome in patients with ST-segment elevation myocardial infarction (STEMI). In contrast, data relating erythrocytosis to clinical outcomes in patients with STEMI are limited. Because erythrocytosis predisposes to a prothrombotic state, we hypothesized it would be associated with an increased risk of thrombotic complications in patients with STEMI undergoing primary percutaneous coronary intervention. We studied 1,042 consecutive patients with STEMI who underwent primary percutaneous coronary intervention and were a part of our primary percutaneous coronary intervention registry from 2001 to 2007. Patients with cardiogenic shock and late arrival were excluded. Patients were allocated into 3 groups according to their baseline hematocrit: anemia (<36% for women and <39% for men), normal, erythrocytosis (>46% for women and >47% for men). The clinical outcomes were assessed at 1, 6, and 12 months. The patients with anemia had the greatest clinical risk profile. Patients with erythrocytosis had a lower risk profile than the other 2 groups, except for greater rates of smoking. The mortality rates were greatest among the patients with anemia, followed by the patients with erythrocytosis, who in turn had greater short-term mortality than patients with normal hematocrit. Multivariate analysis, which included patients with erythrocytosis and those with normal hematocrit (excluding the patients with anemia), revealed that erythrocytosis was associated with an odds ratio of 4.3 (95% confidence interval 1.4 to 13, p = 0.01) for 1-month mortality. In conclusion, although not as strong a predictor of mortality as anemia, erythrocytosis might be associated with increased short-term mortality compared to a normal hematocrit. The measurement of hematocrit can be used as a useful prognostic marker in patients with STEMI.