COVID-19 impact on ST-elevation myocardial infarction incidence rate in a Italian STEMI network: a U-shaped curve phenomenon

Background Public health emergencies such as the COVID-19 outbreak may impact on the incidence rate of ST-elevation myocardial infarction (STEMI) in severely affected areas. However, this phenomenon demands attention also in areas where media and patients were focused on the COVID-19 pandemic, but the healthcare system was not overwhelmed by the huge number of COVID-19 patients. Methods and results In this observational study, we compared the incidence rate of all consecutive STEMI patients admitted at the University Hospital of Trieste, Italy, during March and April 2020 with the same 2 months of the previous 5 years (2015-2019). Patient characteristics were compared between 2020 and 2019. The incidence rate of STEMI admission in March-April 2020 was lower than those in March-April 2015-2019, 36 vs. 56 cases per 100 000 inhabitants/year [relative risk (RR) 0.65, 95% confidence interval (95% CI) 0.42-0.96, P = 0.045]. Considering that the incidence rates were constant in the past years (P = 0.24), the turnaround in 2020 is most likely due to the COVID-19 outbreak. Interestingly, this reduction was a dynamic phenomenon with a U-shaped curve during the 2-month period. System-of-care times were similar between 2020 and 2019; however in 2020, patients presented more frequently signs of heart failure compared to 2019 (Killip class >= 2 in 68% vs. 29%, P = 0.003). Conclusion During the COVID-19 outbreak, we observed a marked reduction in the STEMI incidence rate. This U-shaped phenomenon demands attention because a potential cause for the decrease in STEMI incidence may include the avoidance of medical care. Public campaigns aiming to increase awareness of ischemic symptoms may be needed during community outbreak.