Method
This study was approved by the Medical Research Council (34858-3/2019/EKU). The Hungarian Myocardial Infarction Registry (HUMIR) is a prospective and comprehensive disease registry for patients with AMI. Since 1 January 2010, this online registry has collected personal and clinical data on consecutive patients treated for AMI events in Hungary, a Central European country with 9.8 million residents and a centralised healthcare system. The registry was operated on a voluntary basis between 2010 and 2013; however, by law, registration of all patients with myocardial infarction in the HUMIR has been mandatory for all healthcare providers since 1 January 2014 (statute CCXLVI/2013 of Hungary). Data capture covered 178 structured categories, including prehospital data, medical history, hospital treatment and coronary interventions. The data were recorded in the online database by healthcare professionals and administrators based on hospital documentation, and the information was continuously monitored and validated online. Outcome data—including vital status and repeated hospitalisation—were regularly received from the electronic database of the Hungarian Health Care Insurance Fund and National Central Statistical Office.
The aim of the registry is two-fold: to provide quality assurance for patient care and to build a database for research. All hospitals offering acute care participate in the programme, registering approximately 15,000 AMI cases annually; in 2021, the database contained 122,774 patients and 134,986 events. The National Health Insurance Fund is responsible for the financing of healthcare services, whereas acute inpatient care is funded by implementing a system similar to the American Diagnosis Related Groups (16). The diagnosis and treatment protocol for AMI are in line with the current European guidelines (17); thus, the treatment of myocardial infarction with ST-elevation (STEMI) cases is performed at centres prepared for invasive interventions. In Hungary, the capital has six invasive centres and the remaining regions of the country have 14. The operating principles of the centres in the capital and country differ to a certain extent; the six centres in the capital treat patients from the CR between 8 a.m. and 6 p.m. based on a regional principle. Between 6 p.m. and 8 a.m., these centres care for all patients in the region, whereas there is 24/7 care available in all countryside centres. According to the professional protocol for infarction care, the patient has to be transferred directly to a care centre providing cardiac catheterisation in the case of STEMI; if this is not possible, pharmacological anti-thrombotic therapy has to be introduced. In daily clinical practice, pharmacological revascularisation (thrombolysis) is rarely performed (0.1-0.3% of all cases).
In the case of myocardial infarction without ST-elevation (NSTEMI), the decision concerning the necessity of invasive treatment is based on the patient’s prognosis (e.g., GRACE score). Between 1 January 2016, and 31 December 2018, a total of 42,793 AMI cases were registered in the HUMIR database, with 18,435 being STEMI cases. During the 2-year interval (between 1 January 2017 and 31 December 2018), the emergency care data of 6,878 patients treated for myocardial infarction were also available; thus, in this patient cohort, it was possible to examine the time interval between the onset of symptoms and the reopening of the culprit vessel (total ischaemic time, TIT). The time interval between the onset of symptoms and the calling of emergency services was examined, along with the different time intervals of the emergency care process: arrival to location (T1), treatment on-site (T2) and time interval between transferring the patient from the original location to the hospital (T3). Time values were indicated by median time and quartiles, and we analysed the all-cause mortality of all cases observed until 30 November 2019. The R statistical programme package (version 3.6.3; https://www.r-project.org/about.html) was used for data processing; in the descriptive statistical analysis, we represented the distribution of category variables by frequency (and proportion value) and continuous variables by mean value (distribution) and median treatment time (quartiles). For the comparative analysis of the examined groups, we applied the Wilcoxon test for continuous variables in two-sample cases and the Kruskal–Wallis test in multiple-sample cases; for categorical variables, the Chi-squared test was used (WHO No. 95). For categorical variables, regional differences were evaluated using the Chi-squared and accompanying post-hoc test. The calculations of age-standardised rates in the particular regions were calculated by applying the direct method based on the official WHO guidelines. For the standard age group distribution, we applied the European age standard. When analysing fatalities, we used the stratified Cox-PH regression model (18). Because one of the major conditions of the applicability of the Cox regression model was not met (with the help of the Schoenfeld test, we determined that the risk ratios of the examined factors were not time-independent), the time variable was divided into three parts based on 30 and 365 days. Thus, this study aimed to determine the risk ratios of individual factors.