Prehospital ECG in patients with acute myocardial infarction during the covid-19 pandemic

Introduction. Primary percutaneous coronary intervention (PCI) represents the preferred revascularization strategy among patients with acute ST-segment elevation myocardial infarction (STEMI). A decline in the rates of primary PCI has been observed globally during the outbreak of coronavirus disease-19 (COVID-19). Fear of exposure to in-hospital infection has been hypothesized as the main mechanism of this phenomenon, also contributing to a delayed presentation of patients with STEMI. However, a formal assessment of initial electrocardiograms (ECGs) among STEMI patients during the COVID-19 pandemic is still lacking. We therefore compared pre-hospital ECGs of STEMI patients hospitalized in Italy after the first reported case of COVID-19 on February 21. 2020 with data from the same period in 2019 to identifying potential changes between the two periods. Methods. Prehospital ECGs were obtained from the STEMI care network in the Campania region covering an area of about 5 8 million residents. STEMI patients were identified in the field through the emergency medical sen/ice (EMS) using a 12-lead ECG equipment available in the ambulance systems. A wireless transmission of prehospital ECGs for physician interpretation was performed by the EMS at the scene. Deidentified ECGs were analyzed by two expert reviewers who were blinded to date of recording. Pathological Q-waves were defined as a Q-wave with a duration £40 ms and/or depth £25% of the R-wave in the same lead or the presence of a Q-wave equivalent. These criteria have been shown to be associated with final infarct size at cardiac magnetic resonance. For all conventional STEMI, the timing of STEMI onset was estimated with the Anderson-Wilkins (AW) acuteness score, ranging from 1 (least acute) to 4 (most acute). Continuous data are reported as mean ± standard deviation and compared using Student's t-test. Categorical data are reported as frequencies and percentages and compared using the chi-square test or Fisher exact test as appropriate. Statistical analysis was performed with Stata 14.2 (StataCorp, College Station, Texas). Results. From February 21, 2020, to April 16, 2020, a total of 3,239 prehospital ECGs were recorded by the emergency medical system and 167 (5.15%) were classified as STEMI. During the same period in 2019, 3,505 pre-hospital ECGs were recorded and 196 (5.59%) were classified as STEMI. There was no difference between the two study periods in terms of age, gender, type (conventional vs. non-conventional) and location of STEMI. Pathological Q-waves were present in 54.5% of ECGs recorded during the COVID-19 period compared with 22.1% of ECGs recorded in the same period in 2019 (risk difference 32.3, 95% confidence intervals [CI], 21.2 to 43.5 percentage points). There was also an increase in the mean number of Q-waves during the COVID-19 compared with the control period (1.4 vs. 0.9;p<0.001). These findings remained similar when QS-A nd qR complexes were analyzed separately. Consistently, the AW score was significantly lower during the COVID-19 period (2.4 vs. 2.8;p<0.001). Conclusions. Our data indicate that prehospital ECGs of STEMI patients during the COVID-19 pandemic presented more frequently with signs of late ischemia compared with the equivalent period in 2019. Approximately, 1 out of 2 patients had already pathological Q-waves in the initial ECG. The AW acuteness score is superior to patient history (historical timing) in predicting myocardial salvage and mortality after reperfusion in STEMI patients, thus explaining the higher mortality rate and the increased risk of infarct-related complications observed during the COVID-19 pandemic. Our findings support the hypothesis that COVID-19 outbreak was associated with a deferral of first medical contact among STEMI patients, prompting the continuous need for public campaigns to increase awareness of ischemic symptoms and confidence in the hospitals organization to preserve their safety.