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

Abstract

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.

Keywords: COVID-19; Hospitalizations; Myocardial infarction; Viral pandemic.

Fig. 1

IRRs of hospitalizations for MI in the case period vs control periods in the overall population and according to MI subtypes. CI = Confidence interval; IRR = Incidence rate ratio; MI = Myocardial infarction; NSTEMI = Non ST-segment elevation myocardial infarction; STEMI = ST-segment elevation myocardial infarction.

Fig. 2

Panel A. Weekly number of admissions for MI in 2020 and 2019. At a Negative Binomial (NB) model, ratio of means and 95% CI for the period May 4–July 12, 2020 were 0.81, 0.50–1.36 (p = 0.402), for the period February 20–May 3, 2020 were 0.68, 0.55–0.83 (p < 0.001). Panel B. Analysis within the case period: IRR of admissions for MI in the earlier time-frame (May 4–June 3, 2020) vs the later time-frame (June 4–July 12, 2020). CI = Confidence interval; IRR = Incidence rate ratio; MI = Myocardial infarction.