Return towards normality in admissions for myocardial infarction after the lockdown removal for COVID-19 outbreak in Italy.

Background: Investigations demonstrated a decrease of admissions for myocardial infarction (MI) during the CoronaVirus Disease-19 (COVID-19) outbreak. No study has evaluated the time required to reverse this downward curve of MI admissions.
Methods: This is a retrospective analysis on patients (N = 2415) admitted to the Emergency Departments for acute MI in nine Italian centers. Primary endpoint was the incidence rates (IRs) of MI admissions in the post-lockdown COVID-19 period (case-period: from May 4 to July 12, 2020) vs. the following control periods: January 1-February 19, 2020 (pre-lockdown period); February 20-May 3, 2020 (intra-lockdown period); May 4-July 12, 2019 (inter-year non-COVID-19 period).
Results: IR of admissions for MI in the post-lockdown period was higher than the intra-lockdown period (IR ratio, IRR: 1.60, 95% CI 1.42-1.81; p = 0.0001), was lower than the pre-lockdown period (IRR: 0.86, 0.77-0.96; p = 0.009) and similar to the inter-year non-COVID-19 period (IRR: 0.96, 0.87-1.07; p = 0.47). Within the case period, the increase in MI admissions was more pronounced in earlier vs later weeks (IRR 1.19, 95% CI 1.02-1.38, p = 0.024) and, compared to the inter-year control period, was significant for non ST-segment elevation MI (IRR: 1.25, 95% CI 1.08-1.46, p = 0.004), but was not observed for ST-segment elevation MI (STEMI), where hospitalizations were reduced (IRR 0.76, 95% CI 0.65-0.88, p = 0.0001).
Conclusions: Our study first indicates an increase in the number of admissions for MI after the removal of the national lockdown for COVID-19 in Italy. This increase was prevalent in the first weeks following the lockdown removal, but was under-represented in STEMI patients.
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