Out-of-hospital cardiac arrest incidence in the different phases of COVID-19 outbreakTo the editor, Last February, Europe was affected by the first wave of the COVID-19 pandemic. Now a second outbreak has begun. Albeit a close relationship between the pandemic trend and the incidence of out-ofhospital cardiac arrest (OHCA) has been documented during the first surge in different countries such as Italy 1,2 the United States 3,4 and France, 5 some elements still remain unclarified.Our aims were (1) to confirm the correlation between the incidence of OHCA and COVID-19 across a longer time period including the downward phase of the pandemic; (2) to compare the incidence of OHCA in the post-and pre-pandemic peak and (3) to verify whether the incidence OHCA correlated more closely with daily COVID-19 diagnoses or with the rate of ICU admissions. We considered all events of OHCA enrolled in the out-of-hospital cardiac arrest register of the Lombardy region (Lombardia CARe; ClinicalTrials.gov Identifier: NCT03197142) from January 1st, 2020 to October 9th, 2020 that have occurred in the provinces of Pavia, Lodi, Cremona, Mantua and Varese (total area 9061 km 2 ; total population of 2,435,939 inhabitants). The daily new cases of COVID-19 in the entire Lombardy region, as well as the daily count of COVID patients admitted in the intensive care units (ICU), were collected from National Department of Civil Protection (http://www.protezionecivile.gov.it/). During the study period, 2488 OHCAs occurred and resuscitation was attempted in 1629 of them (65.5%). The median age was 78 years (IQR 66À86 years); the event occurred at home in 1392 (85.5%); a medical aetiology was found in 1519 (93%); the event was witnessed in 756 (46.4%); the rhythm was non-shockable in 1393 (85.5%) and bystander CPR occurred in 519 (32%). As shown in Fig. 1, the trend of OHCA has followed the trend of the pandemic during both the ascending and the descending phase. A statistically significant correlation was found across the 283 days of observation, reinforcing the deep relationship between the pandemic and OHCA incidence. The