Wang et al. BMC Cardiovasc Disord (2021) 21:404 https://doi.org/10.1186/s12872-021-02210-3 RESEARCH ARTICLE Open Access Association of thrombocytopenia and infection in patients with ST-elevation myocardial infarction undergoing percutaneous coronary intervention Litao Wang1,2†, Weijiang Su3†, Jinhua Xue4†, Xiao Gong5, Yining Dai1, Jiyan Chen1, Ling Xue1, Pengcheng He1,2,6, Yuanhui Liu1* and Ning Tan1,2,6* Abstract Background: The impact of thrombocytopenia on infection in patients with ST-elevation myocardial infarction (STEMI) remains poorly understood. Aims: To evaluate the association between thrombocytopenia and infection in patients with STEMI. Methods: Patients diagnosed with STEMI were identifed from January 2010 to June 2016. The primary endpoint was in-hospital infection, and major adverse clinical events (MACE) and all-cause death were considered as secondary endpoints. Results: A total of 1401 STEMI patients were enrolled and divided into two groups according to the presence (n 186) or absence (n 1215) of thrombocytopenia. The prevalence of in-hospital infection was signifcantly higher in =the thrombocytopenic= group (30.6% (57/186) vs. 16.2% (197/1215), p < 0.001). Prevalence of in-hospital MACE (30.1% (56/186) vs. 16.4% (199/1215), p < 0.001) and all-cause death (8.1% (15/186) vs. 3.8% (46/1215), p 0.008) revealed an increasing trend. Multivariate analysis indicated that thrombocytopenia was independently= associated with increased in-hospital infection (OR, 2.09; 95%CI 1.32–3.27; p 0.001) and MACE (1.92; 1.27–2.87; p 0.002), but not all-cause death (1.87; 0.88–3.78; p 0.091). After a median follow-up= of 2.85 years, thrombocytopenia= was not associated with all-cause death at multivariable= analysis (adjusted hazard ratio, 1.19; 95%CI 0.80–1.77; p 0.383). = Conclusions: Thrombocytopenia is signifcantly correlated with in-hospital infection and MACE, and might be used as a prognostic tool in patients with STEMI. Keywords: Thrombocytopenia, Infection, ST-elevation myocardial infarction, Percutaneous coronary intervention Background *Correspondence: [email protected]; [email protected] Infection is an uncommon (reported prevalence of 2.4%) †Litao Wang, Weijiang Su and Jinhua Xue have contributed equally to this but potentially devastating complication in patients with work 1 Department of Cardiology, Guangdong Cardiovascular Institute, ST-elevation myocardial infarction (STEMI). Infection Guangdong Provincial Key Laboratory of Coronary Heart Disease in these patients is usually associated with a signifcantly Prevention, Guangdong Provincial People’s Hospital, Guangdong increased risk of mortality and morbidity, prolongs hos- Academy of Medical Sciences, Guangzhou 510100, China 2 Guangdong Provincial People’s Hospital, School of Medicine, South pitalization, and increases healthcare costs [1–3]. Given China University of Technology, Guangzhou 510100, China most infections are considered preventable, there is Full list of author information is available at the end of the article an urgent need to identify STEMI patients at high risk © The Author(s) 2021. 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The Creative Commons Public Domain Dedication waiver (http:// creat iveco mmons. org/ publi cdoma in/ zero/1. 0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Wang et al. BMC Cardiovasc Disord (2021) 21:404 Page 2 of 8 of infection, and implement interventions to prevent [15]. Te exclusion criteria were as follows: (a) with infection. chronic infammatory disease; (b) with chronic renal fail- Trombocytopenia is a common laboratory abnor- ure necessitating hemodialysis upon hospital admission; mality in patients presenting with acute myocar- (c) undergoing cardiac surgery; (d) who died within 24 h dial infarction (AMI) and always defned as a platelet after hospital admission; (e) without performing PCI; (f) 9 count < 150 × ­10 /L [4]. Baseline thrombocytopenia without platelet count data and (g) receiving dual anti- showed strong predictive capacity for major adverse platelet therapy (DAPT) or other medications potentially clinical events (MACE), ischemic target lesion revascu- causing thrombocytopenia before admission. Te study larization and 1-year death among patients with acute protocol was approved by Ethics Committee of our hos- coronary syndrome (ACS) undergoing percutaneous pital. Te study was carried out according to the Prin- coronary intervention (PCI) [5]. Additionally, throm- ciples of the Declaration of Helsinki 1975 and its later bocytopenia has been previously considered as a risk amendments. Written informed consents were obtained factor for worse outcomes and has been reported to be from patients or their relatives. independently associated with in-hospital mortality in ACS patients [6]. However, few studies have explored Study endpoints and follow‑up the prognostic value of thrombocytopenia for infection Trombocytopenia was defned as a platelet count 9 in patients with STEMI. In terms of etiological factors, < 150 × ­10 /L [4]. Te primary endpoint was the devel- in addition to congenital thrombocytopenia and pseu- opment of infection during hospitalization, which was dothrombocytopenia, diferent acquired causes can be defned as infection requiring antibiotics (refecting the included. Of which, infectious agents play a crucial role clinical infuence of infection compatible with the neces- for their contribution to a reduction in the platelet count sity for additional treatment) [16], and was determined in by suppressing the bone marrow directly or increasing medical records in accordance with ICD-10-CM codes, peripheral consumption of platelets [7–9]. including pneumonia (J18.9), pyelonephritis (N10), ure- Recent studies have reported that patients with corona- teritis (N28.86), urethritis (N34.1), cystitis (N30.90), virus disease 2019 (COVID-19) exhibited severe throm- and other infections (such as sepsis, A41.9; bactere- bocytopenia [10], and Helicobacter pylori (H. pylori) mia, R78.81 or unspecifed infectious disease, B99.9). infection was on the rise as a cause of immune throm- Additionally, the types of infections included pulmo- bocytopenia (ITP) [11], while another research dem- nary, urinary, or other (including abdominal sepsis, pri- onstrated that low platelet count was independently mary bacteremia, and unidentifed primary infection correlated with an increased risk of infection in patients site) infections. Te secondary endpoint was in-hospital with ITP [12], which indicated that infections were MACE, including all-cause death, stroke, and any bleed- closely associated with thrombocytopenia. Furthermore, ing during hospitalization. Other endpoints were also thrombocytopenia has been shown to be a poor prognos- documented, including all-cause death during hospitali- tic risk factor for systemic infections among patients from zation and follow-up. Patients were followed up through medical, surgical, mixed, or trauma ICUs [13], and mod- telephone-tracking methods or outpatient clinic inter- 9 erate thrombocytopenia (platelet count < 100 × ­10 /L) views for ≥ 1 year by trained nurses. was a potential risk stratifcation tool for severe Clostrid- ium difcile infection (CDI) [14]. Statistical analyses Given the potential value of thrombocytopenia in the Continuous variables with a normal distribution were prediction of infection, and in order to improve risk presented as mean ± SD, and compared using two-sam- stratifcation for these patients, we sought to investigate ple t-tests. Continuous variables with a non-normal dis- the association between thrombocytopenia and infection tribution were expressed as median and interquartile in patients with STEMI. ranges, and analyzed using Wilcoxon rank sum tests. Categorical variables (which are presented as percent- Methods ages) were compared using the chi-squared test or Fish- Study population er’s exact test (as appropriate). In-hospital outcomes Patients diagnosed with STEMI were enrolled from Janu- and follow-up outcomes were calculated using a logistic ary 2010 to June 2016 in Guangdong Provincial People’s regression model or Cox regression model in multivaria- Hospital. STEMI was diagnosed if patients presented ble analysis. As for sample size consideration, we applied within 12 h from the onset of symptoms including typi- a rule of thumb, namely, that the number of events per cal chest pain lasting for ≥ 30 min, not responsive to variable should be 10 or greater. We expected about no nitrates, with ST-segment elevation of ≥ 0.2 mV in at more than 11 factors in the development model; thus, least two contiguous leads, or left bundle-branch block at least 110 infections were needed. According