Data whether the COVID-19 outbreak impacts the acute coronary syndromes (ACS) admissions and the time required to reverse the downward curve are scarce. We included all consecutive patients referred for an ACS who underwent PCI from February 17, 2020 to April 26, 2020 in a high-volume PCI coronary care unit. We compared the number of ACS patients in 2020 to the same period in 2018 and 2019. Predictors of adverse outcome in ST-elevation myocardial infarction (STEMI) patients were recorded: symptom-onset-to-first medical contact (FMC), and FMC-to-sheath insertion times. During the studied period (calendar weeks 8-17, 2018-2020), 144 ACS patients were included. In 2020, we observed two distinct phases in the ACS admissions: a first significant fall, with a relative reduction of 73%, from the week of lockdown (week 12) to 3 weeks later and then an increase of ACS. Median symptom-onset-to-FMC time was significantly higher in 2020 than in the two previous years (600 min [298-632] versus 121 min [55-291], p < 0.001). Median FMC-to-sheath insertion did not differ significantly (93 min [81-131] in 2020 versus 90 min [67-137] in 2018-2019, p = 0.57). The main findings are (1) a pattern of a U-curve in ACS admissions, with a first decrease in ACS admissions and a return to "normality" 4 weeks after; (2) a significant increase in the total ischemic time exclusively due to an increase in the symptom-onset-to-first-medical-contact time.