The impact of the COVID-19 pandemic on hospitalizations for acute myocardial infarction: The experience of the clinical cardiology unit, university hospital of Cagliari

During the COVID-19 pandemic, hospitalization rates for acute myocardial infarction (AMI) decreased worldwide. The aim of this study is that of evaluating the impact of the COVID-19 pandemic on the admission rate for AMI to our University hospital and evaluating if whether changes in air pollution may have influenced hospitalization rates for AMI in Sardinia and Northern Italy. We compared the admission rate for AMI in our department and we analize the density of nitrogen dioxide in Sardinia and Northern Italy in different periods: during the national lockdown (March 9-May 3, 2020), in the 8 weeks before the lockdown, in the 8 weeks after the lockdown and during the corresponding time period in 2019. A marked decline in AMI admissions was observed during the lockdown period in comparison with the 8 weeks before the start of the lockdown (-47%,95% CI 37.5-56.7,p<0.0001) and the corresponding period in 2019 (-52.8%,95% CI 43-65,p<0.0001). There was a significant reduction in hospitalizations for NSTEMI during the lockdown period in comparison with the 8 weeks before the start of lockdown (-71.8%,CI 95% 62.3-79.6,p<0.0001) and the corresponding time period in 2019 (-70.5%,CI 95% 60.9-78.5,p<0.0001). During the lockdown period, the hospitalizations for STEMI fell by 31.5% (95% CI 23.2-41.4,p = 0.19) and 49% (95% CI 39.4-58.6, 47 vs 24 admissions,p=0.009) in comparison to the 8 weeks before the start of lockdown and the corresponding period in 2019, respectively. We observed a rise in AMI admissions during the 8 weeks after the lockdown (+47%, IC 95% 37.5-56.7, p<0.0001), for both NSTEMI (+71.2%,IC 95% 61.7- 79.1,p<0.0001) and STEMI (+33.4%, IC 95% 24.9-43.1,p=0.15). In Sardinia the relative change in nitrogen dioxide density during the time of lockdown was negligible with little or no impact on the environment (-19%, IC 95% 12.5-27.7,p=0,65), if we consider it occurred within a range of very low values of nitrogen dioxide (11.5±3 e 14.1±5 μmol/m2). In contrast, in Northern Italy during the lockdown there was a marked decrease in NO2 concentration in comparison with the 8 weeks before the start of lockdown (-53%,IC 95% 43-62.4, 25.1 ±16.2 e 54.2±43.5 μmol/ m2,p<0,0001). Since air pollution did not change substantially in our region, the environment factor cannot explain the decline in the number of admissions for AMI we recorded during the lockdown. Fear of contagion is the most plausible reason for the drop of hospitalizations for AMI during the lockdown period.