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.