Italy has been one of the first countries dealing with the spread of COVID-19 pandemic with more 80 than 200.000 positive cases and about 27.000 deaths at the end of April [1] . 81
According to the rapid surge in the number of cases, the Italian government imposed from March 82 9 th to May 4 th specific mobility restrictions (lockdown). 83
At the same time, the progressively increasing number of patients with pneumonia who needed ICU 84 treatment led to a reorganization of the entire health care system with a significant reduction of 85 cardiac surgery and research activities [2] . In the epicenter of the Italian epidemic, 16 of the 20 86 cardiac surgery units have completely discontinued their activities, and only the remaining 4 centers 87 have been considered as 'the hub' hospitals where emergent and urgent operations have been 88 performed [3] . However, Italy is a long peninsula and it was not uniformly affected by the 89 pandemic. Bologna, located in Emilia Romagna (the third region of Italy for number of infections) 90 was one of the main regional Hub centers attending the COVID-19 network. 91
The aim of this brief report is to investigate the impact of the COVID-19 during the peak pandemic 92 on the incidence and manifestation of acute type A aortic dissection (type A-AAD). 93
According to the study design and the exceptional status, Bologna University's Institutional Review 94 Board (IRB), advised this study is exempt from IRB submission although all the patient (and/or 95 relatives) gave us consent to use personal information. It was also conducted in accordance with the 96 ethical principles established in the Declaration of Helsinki. dissection was observed ( Figure 1 ). During the peak of pandemic in March we had a severe 106 reduction in the diagnosis of type A-AAD (only 2 patients were treated). On the contrary, in April 107 we faced a progressive increase of type A-AAD (n=10) with a peak of incidence at the end of 108
National lock-down (Central picture). Clinical and radiological signs of organ malperfusion were 109 frequently observed (6/10). Moreover, we detected an increase in the time between the onset of 110 symptoms and the hospital admission (mean 10.3 hours). Three patients died before arriving in the 111 operating room. A fourth patient died 2 days after the implantation of an uncovered stent-graft in 112 the abdominal aorta, prior to surgical repair, due to severe mesenteric malperfusion and extremely 113
poor clinical conditions. 114
The unusual high incidence of complicated type A-AAD was probably related to a treatment delay 115 and to the consequent progression of the aortic disease. To understand this phenomenon all survived 116 patients, relatives and medical personnel involved during this period were interviewed (table 1) . 117
According to the clinical records and interviews these are the final considerations: In conclusion, the outbreak of COVID-19 continues to constitute a public health emergency of 144 international concern influencing the time to diagnosis and causing a delay in the treatment of 145 cardiac diseases. Many countries are now facing the peak pandemic while others are aware of a new 146 diffusion of the infection in the next months; therefore, it is essential to promote medical care 147 assistance for all elective and acute pathologies in this evolving scenario. 148 