Mean platelet volume is associated with infarct size and microvascular obstruction estimated by cardiac magnetic resonance in ST segment elevation myocardial infarction.

: Mean platelet volume (MPV) is an indicator of platelet activation. High MPV has been recently considered as an independent risk factor for poor outcomes after ST-segment elevation myocardial infarction (STEMI). We analyzed 128 patients diagnosed with first STEMI successfully reperfused during three consecutive years. MPV was measured on admission and a cardiac magnetic resonance (CMR) exam was performed within the first week in all patients. Myocardial necrosis size was estimated by the area of late gadolinium enhancement (LGE), identifying microvascular obstruction (MVO), if present. Clinical outcomes were recorded at 1 year follow-up. High MPV was defined as a value in the third tertile (≥9.5 fl), and a low MPV, as a value in the lower two. We found a slight but significant correlation between MPV and infarct size (r = 0.287, P = 0.008). Patients with high MPV had more extensive infarcted area (percentage of necrosis by LGE: 17.6 vs. 12.5%, P = 0.021) and more presence of MVO (patients with MVO pattern: 44.4 vs. 25.3%, P = 0.027). In a multivariable analysis, hazard ratio for major adverse cardiac events was 3.35 [95% confidence interval (CI) 1.1-9.9, P = 0.03] in patients with high MPV. High MPV in patients with first STEMI is associated with higher infarct size and more presence of MVO measured by CMR.