Clinical importance of thrombocytopenia in patients with acute coronary syndromes: a systematic review and meta-analysis

Low platelet count at admission has an adverse impact on outcome in patients with acute coronary syndromes: from the START Antiplatelet registry

Some previous observations suggest that a low platelet count is associated with an increased risk of adverse outcomes in patients with acute coronary syndromes (ACS). However, most of the data come from post-hoc analyses of randomized controlled trials and from studies including thrombocytopenia developed during hospital stay. Our aim was to assess the impact of low platelet count at admission on cardiovascular outcomes and treatment approach in patients hospitalized for ACS in a current real-life setting in Italy. Patients admitted to Italian coronary care units for ACS were enrolled in the START-ANTIPLATELET registry. Baseline clinical characteristics and treatment at discharge were recorded. Patients were followed-up at 6 months, 1 year and yearly thereafter. Low platelet count was defined as a count at admission < 150 > 100 k/µl or < 100 k/µL. Among 1894 enrolled patients, 157 (8.3%) had a platelet count < 150 > 100 k/µl and 30 (1.6%) < 100 k/µl. The median follow-up was 12.3 months (0.4-50.1). patients with low platelets were older (72 ± 10.4 vs 66 ± 12.4 years, p = 0.006), more frequently males (82.9 vs 72.1%, p = 0.001), hypertensive (90.0% vs 70.4%, p = 0.03), with non-valvular atrial fibrillation (NVAF) (17.1 vs 8.6%, p = 0.02), and peripheral arterial disease (11.5 vs 6.2% p = 0.01) and/or had a previous myocardial infarction (40 vs 18.7%, p = 0.008) and/or a PCI (14.6 vs 7.8%, p = 0.001) than patients with normal platelets. A slightly, but significantly, lower percentage of thrombocytopenic patients were treated with primary PCI (78.1 vs 84.4%, p = 0.04) and they were more frequently discharged on aspirin plus clopidogrel rather than aspirin plus newer P2Y12 antagonists (51.9 vs 65.4%, p = 0.01). MACE-free survival was significantly shorter in thrombocytopenic patients compared to patients with normal platelets (< 150 > 100 k/µl: 37.6 vs 41.8 months, p = 0.002; HR = 2.7, 95% CIs 1.4-5.2; < 100 k/µl: 31.7 vs 41.8 months, p = 0.01; HR = 6.5, 95% CIs 1.5-29.1). At multivariate analysis, low platelet count, age at enrollment, low glomerular filtration rate, low ejection fraction, a previous ischemic stroke and NVAF were independent predictors of MACE. A low platelet count at admission identifies a subgroup of ACS patients with a significantly increased risk of MACE and these patients should be managed with special care to prevent excess adverse outcomes.

Use of PRECISE-DAPT Score and Admission Platelet Count to Predict Mortality Risk in Patients With Acute Coronary Syndrome

The PREdicting bleeding Complications In patients undergoing Stent implantation and subsEquent Dual Antiplatelet Therapy (PRECISE-DAPT) score has been validated to predict bleeding complications in patients undergoing stent implantation and dual antiplatelet therapy. This score does not include the platelet count (PC), which has been shown to be an independent marker of mortality in patients with acute coronary syndrome (ACS). We assessed the role of the PRECISE-DAPT score calculated on admission for mortality risk prediction and evaluated whether the predictive accuracy of this score improved by adding the PC. In a retrospective cohort study of 1000 patients with ACS, after adjustment for relevant covariates, a PRECISE-DAPT score ≥25 was independently associated with mortality (hazard ratio [HR]: 7.91; 95% confidence interval [CI]: 4.37-14.30). When this score was combined with PC, compared to patients with PRECISE-DAPT <25 and PC ≥150 × 10⁹/L, the adjusted HR was 7.2 (95% CI 2.4-21.6) for those with PRECISE-DAPT <25 and PC <150 × 10⁹/L; 10.7 (95% CI: 5.2-21.9) for those with PRECISE-DAPT ≥25 and PC ≥150 × 10⁹/L; and 17.9 (95% CI 7.0-45.4) for those with PRECISE-DAPT ≥25 and PC <150 × 10⁹/L. Selecting thresholds for high-risk designation, the PRECISE-DAPT score integrated with PC had a higher prediction value, compared to the PRECISE-DAPT and Global Registry of Acute Coronary Events scores.